The study, published in PLOS Biology, began with a forward genetic screen, a classical technique in which researchers randomly mutate organisms and then hunt for mutants with altered traits. Rather than looking for worms that were sickened by CADs, the team searched for animals in which the worms’ response to these drugs had been switched on or off. That approach, combined with systematic mining of previously published gene expression datasets, revealed a striking pattern: exposure to cationic amphiphilic drugs reliably induces a small set of genes in C. elegans, most prominently the CYP-35B family of cytochrome P450 enzymes and a p-glycoprotein pump called PGP-13. Cytochrome P450s are the workhorses of drug metabolism across the animal kingdom, and p-glycoproteins are membrane transporters that expel foreign chemicals from cells. The discovery that both arms of this classic detoxification machinery are coordinated by CAD exposure suggested the worm was not merely reacting to damage but actively defending itself.

At the heart of this regulatory circuit sit two nuclear receptors, NHR-70 and NHR-107. Nuclear receptors are ligand-activated transcription factors, proteins that bind small molecules directly and, in response, switch specific genes on or off. The researchers showed that in mutants lacking functional NHR-70 or NHR-107, the induction of CYP-35B enzymes and PGP-13 in response to CADs collapses, placing these receptors upstream of the entire defense program. This architecture mirrors xenobiotic response pathways in mammals, where receptors such as PXR and CAR sense foreign chemicals and induce detoxification genes. The finding implies that the capacity to sense and respond to cationic amphiphilic compounds is an ancient feature of animal biology, one that predates the synthetic chemistry of the modern pharmaceutical industry by hundreds of millions of years.

To explore how broadly this response can be triggered, the team engineered a fluorescent reporter strain in which the pgp-13 promoter drives the production of a visible signal. When a worm encounters a compound that activates the defense system, the animal literally glows. Screening this reporter against a large panel of compounds, the researchers identified hundreds of human drugs that up-regulate the CAD defense system in living animals. The list was heavily enriched for molecules with the telltale cationic amphiphilic chemistry, confirming that the reporter responds specifically to this drug class rather than to chemical stress in general. In effect, the worm had become a living biosensor for one of the most troublesome categories of pharmaceutical side effects.

That sensing capability has immediate practical value. Phospholipidosis is notoriously difficult to predict during drug development because it often emerges only after prolonged exposure, and animal models in rodents are expensive and slow. Chemoinformatic analyses performed by the team, which use computational descriptors of molecular structure to correlate chemical features with biological activity, indicated that the pgp-13 reporter could serve as a rapid and inexpensive screen for identifying CADs with pathogenic potential in humans. A compound that lights up the worm’s defense system at low concentrations would be flagged for closer scrutiny before it ever reaches a clinical trial. Because the reporter operates in a whole living organism, it captures absorption, distribution and metabolism effects that cell-based assays frequently miss.

The researchers did not stop at detection; they dissected the biochemistry of the defense itself. Through mutant analyses coupled to metabolomics, the comprehensive measurement of small molecules in the animals, and structural modeling of the enzymes involved, they demonstrated that the CYP-35B cytochrome P450s are both necessary and sufficient for the metabolism of CADs. In other words, removing these enzymes leaves the worms unable to chemically modify the drugs, while their presence alone accounts for the observed metabolic transformations. Structural modeling pinpointed a single amino acid, aspartate 311 in the enzyme CYP-35B2, as the key player. This negatively charged residue sits in the enzyme’s active site and forms electrostatic interactions with the positively charged nitrogen of CADs, anchoring the drug in the correct orientation for oxidation. Mutating this residue disrupts the interaction, illustrating with atomic precision how the worm’s chemistry is tailored to this class of molecules.

Metabolism alone, however, is only half of the defense. Once the CYP-35B enzymes have chemically modified a CAD, the resulting metabolites must be removed from the body. The team showed that this export job falls to PGP-13, the p-glycoprotein pump whose expression is induced alongside the enzymes, and that PGP-14, a related transporter, acts partially redundantly with it. Worms lacking both pumps accumulate CAD metabolites and become markedly more vulnerable to drug-induced pathology. Conversely, animals with an intact defense system, functional receptors, active enzymes and working pumps, resist the lysosomal damage that these drugs would otherwise inflict. The full pathway, from sensing to metabolism to excretion, operates as a coherent physiological unit, and breaking any link in the chain compromises the whole system.

Perhaps the most intriguing question raised by the study is evolutionary: why would a microscopic nematode living in soil possess a defense system tailored to synthetic drugs invented in the twentieth century? The answer, the researchers propose, lies in the worm’s natural ecology. C. elegans feeds on bacteria, and many bacterial species produce small molecules with cationic amphiphilic properties as metabolic weapons or signaling compounds. When the team exposed worms to bacteria that likely cohabitate with C. elegans in nature, the CAD defense system was triggered, providing a plausible explanation for the pathway’s existence. The worm’s pharmaceutical defense, in this view, is not a response to human medicine at all but an ancient adaptation to the chemical warfare of its microbial environment. Modern CADs are, in a sense, accidental mimics of natural products the worm has been battling for millennia.

The implications extend well beyond nematode biology. For toxicologists, the study offers a mechanistically grounded model of phospholipidosis that can be manipulated genetically, something impossible in human tissue. For drug developers, the fluorescent reporter strain provides a cheap, high-throughput early warning system that could be deployed during lead optimization, long before costly animal studies. And for evolutionary biologists, the work adds a vivid example of how the chemical ecology of natural environments shapes the genetic toolkit that organisms later use to cope with anthropogenic chemicals. The same nuclear receptor logic that protects a soil worm from bacterial metabolites may underlie how human livers respond to the drugs in our medicine cabinets.

Future work will likely focus on identifying the natural bacterial molecules that activate NHR-70 and NHR-107, determining whether related receptor-driven CAD defenses exist in other animals, and validating the pgp-13 reporter against pharmaceutical libraries as a predictive toxicology platform. What is already clear is that C. elegans, long a favorite of developmental biologists, has now earned a place in pharmacology as well. A transparent worm with a glowing defense system may prove to be one of the most practical tools yet for keeping dangerous drugs out of the clinic, all thanks to an evolutionary arms race playing out quietly in the soil beneath our feet.

Subject of Research: A cationic amphiphilic drug defense system in Caenorhabditis elegans

Article Title: The nematode Caenorhabditis elegans has a cationic amphiphilic drug (CAD) defense system

Article References: Tokmakjian, L., Han, D., Sihuta, K., Aggarwal, A., Pirhadi, S., Wang, Y., Burns, A. R., Cooke, B., Ren, S., Gavrielatos, M., Liu, J., Krause, H. M., Cummins, C. L., Nodwell, J., Koes, D. R., & Roy, P. J. (2026). The nematode Caenorhabditis elegans has a cationic amphiphilic drug (CAD) defense system. PLOS Biology, 24(9), e3004006. https://doi.org/10.1371/journal.pbio.3004006

Image Credits: AI Generated

DOI: 10.1371/journal.pbio.3004006

Keywords: Caenorhabditis elegans, cationic amphiphilic drugs, phospholipidosis, cytochrome P450, p-glycoprotein, nuclear receptors, lysosome, drug metabolism, chemoinformatics, toxicology, genetic screen, microbiome

The new platform, described in Advanced Science, addresses a long-standing gap in preclinical cancer research. The standard approach of growing tumors under the skin of mice fails to reproduce the brain’s unique extracellular matrix, immune environment, and drug delivery constraints, because the blood–brain barrier simply is not present in a subcutaneous model. Orthotopic models, in which tumor cells are surgically implanted into the brain, offer better predictive value but demand advanced surgical skill, specialized imaging such as MRI or CT to track tumor growth, and raise significant ethical concerns. In vitro models have improved considerably in recent years, particularly as regulatory agencies have begun approving animal-free alternatives for preclinical testing, but most existing blood–brain barrier models either separate their cellular compartments behind scaffolds or lack tumor cells entirely.

The team used an extrusion-based 3D bioprinter to fabricate polylactic acid microwell chambers coated with agarose, into which they printed mixtures of human cerebral microvascular endothelial cells, human brain vascular pericytes, and U-87 MG glioblastoma cells at a one-to-one-to-one ratio. Within twenty-four hours, the cells spontaneously assembled into compact spheroids roughly 300 micrometers in diameter. Confocal microscopy of spheroids labeled with distinct fluorescent cell trackers revealed a striking self-organized architecture: endothelial cells formed the outermost layer, pericytes occupied an intermediate position, and glioblastoma cells comprised the core. Critically, a substantial fraction of pericytes migrated into the tumor core, and follow-up co-culture experiments demonstrated cytoplasmic mixing between pericytes and tumor cells, a phenomenon documented in real glioblastoma tumors in which cancer cells exploit pericyte interactions to drive progression. Because earlier scaffold-based models physically separated their compartments, they could not reproduce this direct cellular intimacy.

Functionally, the spheroids behaved like the barrier they were meant to mimic. Immunofluorescence imaging showed robust expression of the tight junction proteins ZO-1, occludin, and claudin-5, along with the efflux transporter P-glycoprotein, with more than ninety percent of outer-layer endothelial cells expressing all four proteins. When the researchers applied a 40-kilodalton fluorescent dextran tracer, the blood–brain–tumor barrier spheroids proved less permeable than bare tumor spheroids but slightly more permeable than tumor-free blood–brain barrier spheroids assembled with astrocytes in place of tumor cells. That intermediate, leaky phenotype is precisely what clinicians observe in glioblastoma patients, where tumor-induced vascular changes compromise barrier integrity without eliminating it.

With the model validated, the researchers turned to their candidate drug: a ruthenium(II) polypyridyl complex with a molecular weight of 871.9 grams per mole. Unlike most chemotherapy agents, which target DNA directly, ruthenium compounds kill cancer cells by generating reactive oxygen species such as singlet oxygen and hydroxyl radicals. Cancer cells already operate at elevated oxidative stress levels due to their rapid metabolism and survive only by leaning heavily on antioxidant systems like glutathione. An additional burst of ROS tips that balance into catastrophe, damaging DNA, proteins, and lipids until the cell dies. Confocal imaging showed the ruthenium compound accumulating in mitochondria and the endoplasmic reticulum of U-87 MG cells, and dose-dependent ROS generation was confirmed with a fluorescent probe. The compound triggered mitochondrial permeability transition, disrupted calcium homeostasis, and reduced U-87 MG viability by half at a concentration of 22.3 micromolar.

The most intriguing finding concerned how the compound interacts with the barrier itself. Treatment with the ruthenium complex increased expression of alpha-smooth muscle actin and F-actin in pericytes, promoting contractile changes that loosen barrier structure. It also elevated secretion of matrix metalloproteinase-9, an enzyme that degrades extracellular matrix and erodes tight junctions, and endothelin-1, a vasoconstrictor associated with increased barrier permeability. Tight junction protein levels in endothelial cells dropped significantly at 20 micromolar. When cells were pretreated with the antioxidant N-acetylcysteine, these effects were largely abolished, with the scavenger suppressing 69 to 77 percent of the drug-induced increases in MMP-9 and endothelin-1 and restoring tight junction protein expression nearly to baseline. In other words, the compound appears to open its own path through the barrier via the very reactive oxygen species it generates, facilitating paracellular transport in addition to partial passive diffusion across endothelial cells.

Permeability experiments confirmed this dual mechanism. While the dextran tracer showed roughly 3.5-fold higher fluorescence in tumor-only spheroids than in blood–brain barrier spheroids, the ruthenium compound distributed nearly equally across all three spheroid types, with ratios hovering near 1.0. Transwell assays using endothelial monolayers further showed that the compound is only a partial P-glycoprotein substrate, with an efflux ratio of 1.7-fold upon inhibition, far lower than the 4.4-fold ratio observed for osimertinib, an approved cancer drug that proved unsuitable for brain delivery due to both strong efflux and a narrow therapeutic window. Temozolomide, the current standard of care for glioblastoma, showed no P-glycoprotein involvement at all, crossing exclusively by passive diffusion.

The head-to-head comparison inside the bioprinted spheroids delivered the study’s most striking result. Using a fluorescent cell death probe that itself penetrates the barrier, the researchers quantified tumor cell killing at single-cell resolution within intact spheroids. Paclitaxel and cisplatin, both established chemotherapies, produced negligible cell death, consistent with their inability to cross the blood–brain–tumor barrier. Temozolomide and the ruthenium compound both induced significant tumor cell death, but after normalizing for dose and potency, the ruthenium compound achieved a relative permeability of 14.2 compared with 10.6 for temozolomide, despite being administered at a concentration slightly below its own IC50. Flow cytometry cross-validated these imaging results, showing roughly 21.7 percent tumor cell death for the ruthenium compound versus 19.9 percent for temozolomide, while controls and the two non-penetrant drugs remained near baseline.

The platform also proved adaptable beyond a single laboratory cell line. When the researchers rebuilt the spheroids using two patient-derived glioblastoma cell lines, SNU-4210 and SNU-5026, the same layered architecture emerged, and the ruthenium compound again outperformed temozolomide, generating roughly 2.1 to 2.3 times higher cell death signal across the tumor core. This patient-derived validation matters because glioblastoma is notoriously heterogeneous, and models that only work with established cell lines often fail to predict clinical responses.

The authors are careful to note the caveats. The model measures relative rather than absolute permeability, the 48-hour exposure window may not suit every compound, and barrier opening driven by ROS-mediated tight junction damage is mechanistically distinct from favorable intrinsic penetration, raising questions about the balance between drug delivery and neurovascular safety that will require in vivo evaluation. MMP-9 and endothelin-1 are also pleiotropic mediators involved in tumor invasion and treatment resistance, not simple barrier biomarkers. Even so, the study delivers two significant contributions at once: a bioprinted, scaffold-free model that captures the cellular crosstalk of the tumor-barrier interface, and the first ruthenium-based ROS-generating agent evaluated within such a system, one that killed glioblastoma cells more efficiently per dose than the standard-of-care drug while tolerating concentrations that left endothelial cells unharmed. For a disease where nearly every drug candidate dies at the barrier, both advances deserve close attention.

Subject of Research: A 3D bioprinted blood–brain–tumor barrier spheroid model for evaluating ROS-generating ruthenium anticancer compounds against glioblastoma

Article Title: 3D Bioprinted Blood–Brain–Tumor Barrier Spheroid‐Based In Situ Evaluation of Anticancer Compounds Against Glioblastoma: ROS‐Producing Ruthenium as a Potential Therapeutic Candidate

Article References: Lee, H., Jeon, C. H., Kim, D., Lee, M., Kwon, M., & Song, J. M. (2026). 3D Bioprinted Blood–Brain–Tumor Barrier Spheroid‐Based In Situ Evaluation of Anticancer Compounds Against Glioblastoma: ROS‐Producing Ruthenium as a Potential Therapeutic Candidate. Advanced Science, Article e78150. https://doi.org/10.1002/advs.78150

Image Credits: AI Generated

DOI: 10.1002/advs.78150

Keywords: glioblastoma, blood-brain barrier, 3D bioprinting, spheroid model, ruthenium compound, reactive oxygen species, blood-brain-tumor barrier, temozolomide, P-glycoprotein, tight junctions, pericytes, drug permeability

The central insight behind the work is that resistance to doxorubicin is not a single mechanism but a coordinated defense. P-glycoprotein, an ATP-dependent efflux transporter embedded in the membranes of many cancer cells, actively pumps the drug back out, keeping intracellular concentrations below lethal thresholds. Meanwhile, CD44, a cell surface glycoprotein implicated in adhesion, invasion, metastasis and the survival of cancer stem cells, helps maintain a reservoir of therapy-refractory cells that can seed recurrence after treatment ends. Reserpine was selected as a chemosensitizer because it can potentially silence both pathways simultaneously. Before any formulation work began, the team used AutoDock Vina molecular docking to test this hypothesis computationally, comparing reserpine against verapamil, a clinically established P-glycoprotein inhibitor used as a reference ligand.

The docking results were striking. Reserpine bound P-glycoprotein with a predicted affinity of −9.07 kcal/mol, substantially stronger than verapamil’s −7.10 kcal/mol, forming hydrogen bonds with residues including Lys287, Lys822 and Arg785 while its aromatic rings and methoxy groups anchored the molecule through hydrophobic and pi-stacking contacts with Phe766, Val831 and Ala288, among others. Against CD44, reserpine scored −7.46 kcal/mol versus verapamil’s −6.34 kcal/mol, stabilized by hydrogen bonds to Asn100, Ser95 and Ser109 and hydrophobic interactions with Ala99, Tyr79 and Ile96. These in silico findings, the authors note, provide the first mechanism-based computational evidence that reserpine can simultaneously target P-gp mediated drug efflux and CD44-mediated tumor stemness, positioning it as a rational partner for doxorubicin rather than merely an additive.

With the biological rationale established, the formulation challenge was to build a carrier that would keep the drug pair confined to the tumor. The team turned to poloxamers, triblock copolymers of poly(ethylene oxide) and poly(propylene oxide) that are FDA-accepted, biocompatible and famous for a reversible sol-gel transition near body temperature. Using a cold method, the researchers dissolved poloxamer 407 and poloxamer 188 in chilled phosphate buffer, allowed full hydration over 24 hours at 4 °C, and then loaded doxorubicin into one portion of the polymer solution while reserpine, aided by a small amount of Tween 80, was sequestered into the hydrophobic cores of poloxamer micelles in the other. The two streams were combined at a 5:1 doxorubicin-to-reserpine weight ratio, yielding a final concentration of 2 mg/mL doxorubicin and 0.4 mg/mL reserpine in a clear, homogeneous sol.

Three candidate formulations were screened, and the winner, designated F2, contained 22% poloxamer 407 and 15% poloxamer 188. Its physicochemical profile read like a checklist for intratumoral injection: a pH of 5.5 to 6.1 compatible with the acidic tumor microenvironment, low viscosity of 380 to 460 centipoise at refrigeration temperature for easy handling, higher but still injectable viscosity of 1320 to 1580 centipoise at 25 °C, syringeability times of 4 to 7 seconds through an 18-gauge needle, and a rapid sol-gel transition between 38.5 and 41.2 °C with gelation times of just 37 to 42 seconds. Gel strength, measured by a modified falling-weight test, ranged from 47 to 56 seconds, sufficient to maintain structural integrity at the injection site. Drug content was high at 94 to 96 percent, and entrapment efficiency peaked at 91.6 percent for F2, confirming that both drugs were retained efficiently within the matrix.

Spectroscopic and thermal analyses then probed what had happened to the drugs inside the gel. Fourier transform infrared spectroscopy preserved all characteristic peaks of doxorubicin, reserpine and both poloxamers in the finished formulation, with only minor shifts, indicating physical encapsulation without chemical interaction. Differential scanning calorimetry told a more dramatic story: the sharp melting endotherms of crystalline doxorubicin at 180.4 °C and crystalline reserpine at 274.5 °C vanished or were greatly reduced in the loaded gel, leaving only a broad poloxamer transition near 54.7 °C. X-ray diffraction corroborated this, showing that the distinctive sharp peaks of both drugs disappeared entirely upon loading, replaced by the broad halos of the semicrystalline polymers. Together, these data demonstrate that both drugs exist in an amorphous, molecularly dispersed state within the gel matrix, a form that generally favors improved solubility and release behavior.

Microscopy and light scattering filled in the nanoscale picture. Dynamic light scattering measured a mean hydrodynamic particle diameter of 90.22 nanometers with a polydispersity index of 0.492, placing the carriers firmly in the size range associated with good tumor tissue penetration. A zeta potential of −32.6 millivolts indicated strong electrostatic repulsion between particles, enough to prevent aggregation during storage. Scanning electron micrographs at 370-fold and 600-fold magnification revealed an irregular, porous, interconnected network of cavities and channels, exactly the architecture expected to admit water, swell gradually and release drug by diffusion through hydrated pathways rather than in a sudden burst. Three-month stability studies at both 4 to 8 °C and 25 °C with 65 percent relative humidity confirmed the formulation remained clear and homogeneous, with only slight viscosity drift and no loss of entrapment efficiency.

Release behavior proved to be the system’s most elegant feature. In dialysis experiments run at 38 °C, the gel released only 36 percent of its doxorubicin and 28 percent of its reserpine over 24 hours at physiological pH 7.4, but at pH 5.5, mimicking the acidic tumor microenvironment, release jumped to 96 percent for doxorubicin and 82 percent for reserpine. Because poloxamers lack intrinsic pH-responsive groups, the authors attribute this selectivity to temperature-driven micellization and polymer relaxation combined with pH-dependent changes in drug ionization and solubility. Kinetic modeling showed the Korsmeyer-Peppas equation fit best, with R² values of 0.91 to 0.96 and release exponents of 0.65 to 0.70, consistent with non-Fickian anomalous transport governed by both diffusion and polymer relaxation. The biological payoff came in MTT assays against MCF-7 breast cancer cells: the dual-drug gel achieved an IC₅₀ of 21.8 µg/mL, roughly half that of free doxorubicin at 42.6 µg/mL and a quarter that of free reserpine at 84.3 µg/mL, while the blank gel left more than 90 percent of cells viable, confirming carrier biocompatibility.

Safety data from an acute toxicity study in Swiss albino mice rounded out the picture. Animals receiving intratumoral injections of either the doxorubicin gel or the dual-drug gel at a 5:1 ratio survived the full 14-day observation period with normal behavior, feeding and weight gain. Hematology showed no significant changes in hemoglobin, red blood cell or white blood cell counts, biochemistry revealed normal AST, ALT, urea and creatinine levels, and histopathological examination of the breast, heart, liver, spleen and kidney found no necrosis, inflammation or degenerative changes in any treatment group. The authors are candid about the study’s limits: cytotoxicity was demonstrated only in MCF-7 cells, not in triple-negative models such as MDA-MB-231, and no reserpine-only gel group was included in the animal work, so the independent contribution of the chemosensitizer remains to be defined. Future studies, they write, will address triple-negative cell lines, orthotopic tumor models, and detailed pharmacokinetic and biodistribution profiling. Still, the convergence of computational docking, nanoscale characterization, tumor-selective release and clean safety data makes a compelling case that an old alkaloid and a smart gel, injected straight into the tumor, could give one of oncology’s workhorse drugs a second act against its own resistance mechanisms.

Subject of Research: A thermoresponsive in situ poloxamer gel co-delivering doxorubicin and reserpine to overcome multidrug resistance in breast cancer

Article Title: A novel in situ gel system for potentiating doxorubicin efficacy through reserpine co-therapy

Article References: Fiaz, H., Hameed, H., Al-Hussain, S. A., Irfan, A., Shabbir, M., & Zaki, M. E. A. (2026). A novel in situ gel system for potentiating doxorubicin efficacy through reserpine co-therapy. Journal of Saudi Chemical Society, 30(2), Article 24. https://doi.org/10.1007/s44442-026-00071-z

Image Credits: AI Generated

DOI: 10.1007/s44442-026-00071-z

Keywords: breast cancer, doxorubicin, reserpine, in situ gel, P-glycoprotein, CD44, multidrug resistance, poloxamer, drug delivery, molecular docking, thermoresponsive hydrogel, chemosensitizer

The team, led by Yimei Zheng, Boyu Chen and colleagues at Guangdong Ocean University, built a self-microemulsifying drug delivery system, or SME, around luteolin. These systems are concentrated mixtures of oil, surfactant and co-surfactant that remain as clear liquids in a capsule but spontaneously bloom into nanoscale droplets, typically 20 to 100 nanometers across, the moment they meet gastrointestinal fluid. The sudden explosion of surface area dissolves lipophilic molecules that would otherwise sit undissolved in the gut lumen, protects them from oxidation and pH swings, and presents them to the intestinal epithelium in a form cells readily accept. What distinguishes this formulation from most previous nanocarriers is the deliberate choice of emulsifier: D-α-tocopheryl polyethylene glycol 1000 succinate, better known as TPGS, a Food and Drug Administration-approved amphiphilic polymer that happens to be a potent inhibitor of P-glycoprotein itself.

Formulation development began with pseudo-ternary phase diagrams, a classical pharmaceutical tool for mapping where oil, surfactant and water coexist as a stable microemulsion. The researchers combined TPGS as surfactant, polyethylene glycol 400 as co-surfactant and isopropyl myristate as the oil phase, titrating water into 25 different compositions and watching for turbidity and phase separation. The sweet spot emerged at a TPGS-to-PEG 400 mass ratio of 2:1, which produced the largest microemulsion region. Below that ratio, insufficient TPGS left interfacial tension too high; above it, the relative shortage of PEG 400 compromised co-solubilization. Oil content mattered just as much: higher proportions of isopropyl myristate destabilized the system by diluting the emulsifiers, echoing earlier reports that oil fractions above roughly 40 percent tend to yield unstable emulsions.

Three candidate formulations, designated TP12-I2, TP11-I2 and TP21-I3, were loaded with luteolin at 50 milligrams per gram of carrier and put through a demanding characterization gauntlet. Dynamic light scattering showed narrow, monomodal size distributions with mean droplet diameters below 50 nanometers. The formulations survived alternating 4 and 45 degree Celsius cycles, freeze-thaw swings between minus 20 and 25 degrees, and centrifugal stress in a LUMiSizer analyzer without significant changes in droplet size or visible phase separation. Transmission electron microscopy confirmed uniform, spherical particles with no aggregation. Fourier-transform infrared spectroscopy revealed subtle shifts in luteolin’s phenolic C–O stretch at 1265 wavenumbers and its carbonyl band moving from 1656 to 1653 wavenumbers, fingerprints of hydrogen bonding between the drug and its carrier, while ultraviolet-visible spectra retained luteolin’s characteristic 255 and 350 nanometer peaks, proving the molecule emerged chemically intact.

Release and antioxidant performance both improved markedly. In dialysis experiments, free luteolin plateaued after about 12 hours with only 9.23 percent cumulative release, whereas the encapsulated drug kept diffusing past the 24-hour mark, reaching 39.43 percent, a 4.3-fold enhancement driven by the enormous oil-water interfacial area of the nanodroplets. In DPPH and ABTS radical-scavenging assays, the SME formulations outperformed free luteolin at equivalent concentrations, an effect the authors attribute partly to improved solubility and partly to TPGS itself, which contributed measurable radical-scavenging activity of its own. Dye dispersion and conductivity experiments traced how the formulation behaves in the gut: below 40 percent water it forms water-in-oil structures, transitions through a bicontinuous phase between 40 and 70 percent, and completes inversion to a gut-friendly oil-in-water microemulsion above 70 percent hydration.

The cellular story is where the design philosophy pays off. Using Caco-2 monolayers, the gold-standard model of the intestinal barrier, the team showed that luteolin-SME accumulated inside cells at significantly higher levels than free luteolin within 15 minutes, with uptake rising linearly for an hour before slowing. Cooling cells to 4 degrees Celsius slashed uptake, proving the process is energy-dependent, and a panel of endocytosis inhibitors pinpointed the routes: chlorpromazine and nystatin, which block clathrin-mediated and caveolae-mediated pathways respectively, both suppressed uptake, while amiloride, a macropinocytosis blocker, had no significant effect. The nanodroplets, in short, enter intestinal cells through the same receptor-driven machinery cells use to internalize nutrients.

The P-glycoprotein evidence is the study’s most layered contribution. Verapamil and cyclosporine A, two canonical efflux inhibitors, each boosted luteolin uptake, confirming the flavonoid is a genuine P-gp substrate. TPGS alone also increased intracellular luteolin, and a rhodamine 123 assay showed that luteolin-SME reduced P-gp efflux activity in a concentration-dependent manner. Western blotting then revealed something subtler: the formulation downregulated total P-gp protein expression, with the effect scaling with TPGS content, suggesting both immediate functional blockade and a longer-term suppression of the pump itself. Molecular docking simulations tied the mechanism together at the atomic level, showing TPGS and luteolin bind the same substrate pocket of P-gp with binding energies of minus 8.0 and minus 7.2 kilocalories per mole, both hydrogen-bonding to the GLN-191 and THR-195 residues. TPGS, in other words, acts as a competitive antagonist that physically occupies the pump’s recognition site.

Permeability and pharmacokinetics translated the cellular mechanisms into whole-body numbers. Across validated Caco-2 monolayers with transepithelial electrical resistance near 900 ohms per square centimeter, the apparent permeability coefficients of the SME formulations ran 2.8 to 3.5 times higher than free luteolin, aided by a transient, fully reversible 25 to 35 percent loosening of tight junctions that recovered within 24 hours. In mice given 200 milligrams per kilogram orally, the area under the plasma concentration-time curve soared from 8.628 to 247.729 milligrams per liter times hours, a 29-fold increase, while peak plasma concentration jumped 16-fold from 1.705 to 27.546 milligrams per liter. Mean residence time lengthened from 3.889 to 6.57 hours, the half-life extended, and clearance dropped dramatically. Fluorescent biodistribution imaging with the dye DiR showed the formulation lingering in the intestine at 10 hours, long after the free-probe signal had vanished, and concentrating more strongly in liver and kidney.

Therapeutically, the payoff appeared in inflammation models. In lipopolysaccharide-stimulated RAW264.7 macrophages, luteolin-SME cut nitric oxide, TNF-α and IL-6 by roughly 77, 49 and 48 percent relative to the inflamed group, restored catalase and superoxide dismutase activities, suppressed the lipid peroxidation marker MDA, and reduced reactive oxygen species far more effectively than free luteolin, while nudging macrophage morphology from a pro-inflammatory M1 state toward an anti-inflammatory M2-like phenotype and protecting mitochondrial membrane potential. In an LPS-induced sepsis model in mice, the formulation lowered serum TNF-α, IL-6 and IL-1β by about 37, 26 and 39 percent, reduced the liver enzymes ALT and AST by roughly 65 and 64 percent, and preserved near-normal hepatic architecture under the microscope. Biosafety testing showed no cytotoxicity across intestinal, liver and macrophage cell lines and hemolysis rates below 5 percent. The authors present the platform as a general solution for poorly soluble, efflux-limited natural products, a class that includes many of the flavonoids now being studied for chronic inflammatory disease, and the 29-fold bioavailability leap suggests the strategy deserves close attention from anyone trying to turn promising plant chemistry into medicine that actually reaches the bloodstream.

Subject of Research: A TPGS-functionalized self-microemulsifying drug delivery system that enhances the oral bioavailability and anti-inflammatory efficacy of the flavonoid luteolin by inhibiting P-glycoprotein efflux.

Article Title: Boosting luteolin bioavailability via P-glycoprotein efflux inhibition: a self-microemulsifying drug delivery systems

Article References: Zheng, Y., Chen, B., Huang, X., Ai, C., Teng, H., & Chen, L. (2026). Boosting luteolin bioavailability via P-glycoprotein efflux inhibition: a self-microemulsifying drug delivery systems. Journal of Advanced Research, 88, 1095-1117. https://doi.org/10.1016/j.jare.2026.01.030

Image Credits: AI Generated

DOI: 10.1016/j.jare.2026.01.030

Keywords: luteolin, self-microemulsifying drug delivery system, TPGS, P-glycoprotein, oral bioavailability, flavonoids, Caco-2 cells, pharmacokinetics, anti-inflammatory, antioxidant, nanocarriers, sepsis

The central obstacle the researchers set out to overcome is a vicious cycle linking low oxygen to drug resistance. Solid tumors, especially aggressive ones like triple-negative breast cancer, are chronically starved of oxygen because their hastily built blood vessels are irregular and dysfunctional. Oxygen can only diffuse about 100 to 200 micrometers from a functioning vessel, leaving tumor cores severely hypoxic. In this oxygen-poor environment, a transcription factor called hypoxia-inducible factor-1 alpha, or HIF-1α, becomes stabilized and switches on genes for ATP-binding cassette transporters—most notably P-glycoprotein, the efflux pump encoded by ABCB1. P-glycoprotein literally pumps chemotherapeutics like paclitaxel back out of the cell, rendering them useless. Blood transfusions and hyperbaric oxygen therapy can ease systemic hypoxia, but neither reliably relieves hypoxia inside the tumor itself.

Previous attempts to solve this problem have used hemoglobin-based oxygen carriers, since hemoglobin is the body’s natural oxygen transporter and can also catalyze the generation of reactive oxygen species. But free hemoglobin degrades rapidly, is dose-dependently toxic, and provokes systemic inflammation. Liposome-encapsulated hemoglobin improves stability, yet conventional formulations lack spatial precision, often pooling in the liver and spleen. The new study, led by Xunyi You and colleagues with senior author Ye Cao, took a different route: rather than relying on passive accumulation, the team attached their drug-loaded liposomes loosely to the surfaces of intact red blood cells—a strategy known as RBC hitchhiking.

The concept is elegantly physical. The liposomes bind to red blood cells through weak, reversible interactions such as van der Waals forces and electrostatic attraction, without being internalized. When the cell-liposome complexes are injected intravenously, they travel through the bloodstream until they squeeze through narrow capillaries. The shear forces in these tight passages mechanically scrape the nanoparticles off the red cell surfaces and transfer them to the capillary endothelium, dramatically increasing accumulation in the first capillary-rich organ downstream of the injection site. For drugs injected into a tail vein, that organ is the lung—precisely where triple-negative breast cancer metastasizes. The team’s earlier work had already shown that combining liposomes with RBC hitchhiking extends blood half-life and boosts pulmonary accumulation.

Building on that foundation, the researchers formulated liposomes from the phospholipid DPPC, the pH-sensitive lipid DOPE, and cholesterol, encapsulating both paclitaxel and purified hemoglobin in a single nanoparticle. The resulting LEHP particles measured between 100 and 200 nanometers in diameter with a polydispersity index below 0.2, indicating a highly uniform population, and transmission electron microscopy confirmed smooth, spherical structures. Paclitaxel encapsulation efficiency was 83.32 percent for hemoglobin-free liposomes and 58.27 percent for the hemoglobin-loaded version, the reduction likely reflecting the protein occupying space in the aqueous core. Critically, the hemoglobin inside LEHP showed a P50 of about 10.20 mmHg—substantially lower than the roughly 26.5 mmHg of normal adult hemoglobin—meaning a left-shifted oxygen dissociation curve and enhanced oxygen loading in the pulmonary circulation, with favorable release under the low-oxygen conditions of the tumor.

The hitchhiking step itself proved remarkably gentle on the carrier cells. After optimizing the ratio of liposomes to red blood cells, confocal microscopy showed liposomes uniformly coating the erythrocyte membranes while preserving their native biconcave disc shape. The engineered cells maintained their CD47 expression—the “don’t eat me” signal that prevents clearance by the immune system—showed no significant increase in phosphatidylserine exposure, retained normal osmotic fragility profiles, and kept their deformability index unchanged, preserving the mechanical flexibility needed to squeeze through splenic sinuses and lung capillaries.

Inside tumor cells, the payload executes a coordinated attack on two fronts. First, delivered hemoglobin alleviates hypoxia, which destabilizes HIF-1α and removes the transcriptional activation of ABCB1, sharply downregulating P-glycoprotein and restoring the cell’s vulnerability to paclitaxel. Second, the iron released from hemoglobin fuels the Fenton reaction, converting hydrogen peroxide into highly reactive hydroxyl radicals. The team documented the three hallmarks of ferroptosis—an iron-dependent form of cell death driven by lipid peroxidation: elevated labile ferrous iron, surging lipid peroxides, and a collapse of mitochondrial membrane potential. Molecular analysis showed LEHP suppressing the antioxidant guardian GPX4 and its regulator Nrf2 along with the cystine transporter SLC7A11, while upregulating the transferrin receptor, driving NCOA4-mediated ferritinophagy to liberate stored iron, and boosting ACSL4 to supply polyunsaturated fatty acid substrates for membrane oxidation. When cells were pretreated with ferrostatin-1, a specific ferroptosis inhibitor, LEHP-induced cell death was profoundly reversed—confirming ferroptosis as the dominant killing mechanism, with a minor complementary contribution from apoptosis at high drug concentrations.

The DOPE lipid added a self-amplifying delivery trick. In the acidic lysosome, DOPE destabilizes membranes and releases hemoglobin; the liberated ferrous iron then generates radicals that attack the polyunsaturated fatty acids concentrated in the lysosomal membrane itself. That peroxidation increases membrane permeability, accelerating the escape of both hemoglobin and paclitaxel into the cytosol—a ROS-dependent positive feedback loop that the team observed as early as two hours after treatment. The researchers describe the net effect as “re-oxygenation injury”: chronically hypoxic cells, adapted to survive without oxygen, are suddenly overwhelmed by an oxygen influx that their antioxidant defenses cannot absorb, triggering a catastrophic oxidative collapse.

In vivo, the advantages compounded. In mice bearing 4T1 breast cancer lung metastases, RBC-hitchhiked liposomes produced a 2.7-fold increase in pulmonary fluorescence intensity and a 4.6-fold improvement in the lung-to-liver ratio compared with liposomes alone, with lung signals persisting up to 48 hours. In the therapeutic experiment, paclitaxel monotherapy failed to arrest tumor progression, and each partial strategy—hemoglobin without hitchhiking, or hitchhiking without hemoglobin—fell short on its own. Only the fully integrated RBC-LEHP platform achieved sustained regression: at the day 13 endpoint, pulmonary bioluminescence in the RBC-LEHP group was (7.70 ± 2.86) × 10⁴, roughly three orders of magnitude below the LEP group’s (2.19 ± 0.37) × 10⁷. Histology showed intact bronchial architecture and no edema or fibrosis in treated lungs, with no systemic toxicity in the heart, liver, spleen, or kidneys, and reduced Ki67 proliferation, CD31-marked microvessel density, and MMP2 and MMP9 metastasis markers.

Perhaps most strikingly, the treatment remodeled the tumor immune microenvironment, markedly increasing infiltration of CD4-positive and CD8-positive T cells and shifting the lung tumors from an immunologically cold state toward an inflamed, hot one. High-throughput proteomics of lung tissue confirmed the mechanism at the systems level: NCOA4 upregulation and GPX4 downregulation enforcing ferroptotic commitment, HIF-1α and P-gp suppression restoring chemosensitivity, and suppression of the epigenetic driver EZH2 and the pro-survival factor CEBPB dismantling the tumor’s transcriptional survival programs. The authors caution that some hepatic accumulation was observed at 24 hours, though without histological signs of liver damage, and that systemic immune responses in peripheral lymphoid organs remain to be profiled. Still, the study establishes a compelling template—targeted delivery, hypoxia alleviation, ferroptosis plus chemotherapy, tumor suppression—that could extend beyond breast cancer to any malignancy whose resistance is rooted in the oxygen-starved depths of the tumor.

Subject of Research: A biomimetic erythrocyte-hitchhiking liposome system delivering hemoglobin and paclitaxel to overcome hypoxia-driven chemoresistance in triple-negative breast cancer lung metastasis via ferroptosis

Article Title: Oxygen-augmented erythrocyte-liposome hybrids to overcome paclitaxel resistance in triple-negative breast cancer metastasis via enhanced ferroptosis

Article References: You, X., Zhu, K., Li, W., Wang, H., Zhong, R., Li, S., Liu, J., Wong, Y. S., Venkatraman, S. S., & Cao, Y. (2026). Oxygen-augmented erythrocyte-liposome hybrids to overcome paclitaxel resistance in triple-negative breast cancer metastasis via enhanced ferroptosis. Materials Today Bio, 41, Article 103705. https://doi.org/10.1016/j.mtbio.2026.103705

Image Credits: AI Generated

DOI: 10.1016/j.mtbio.2026.103705

Keywords: triple-negative breast cancer, ferroptosis, red blood cell hitchhiking, liposomes, tumor hypoxia, HIF-1alpha, P-glycoprotein, paclitaxel, drug resistance, lung metastasis, hemoglobin, nanomedicine

The study, led by Ju Hee Kim and Jungbin Song with colleagues at CHA University, Kyung Hee University, and Korea University Guro Hospital, examined three herbal formulations: Bojungikgitang, Ijintang, and Cheongsanggyeontongtang. All three have long histories of symptomatic use in East Asian traditional medicine for cardiovascular and cerebrovascular conditions—precisely the patient populations most likely to be taking anticoagulants. The research team designed a fixed-sequence, two-period clinical trial in which healthy volunteers received a single 60-milligram dose of edoxaban alone, and then received the same dose after repeated dosing with one of the three herbal formulations. The design allowed each participant to serve in part as their own control, isolating the effect of the herbal co-administration from natural interindividual variability in drug handling.

Edoxaban is a direct factor Xa inhibitor, a member of the direct oral anticoagulant family that has largely displaced warfarin in many markets because it requires no routine monitoring and has fewer dietary interactions. Its disposition in the body, however, depends heavily on the efflux transporter P-glycoprotein and, to a lesser extent, on cytochrome P450 3A4 (CYP3A4) metabolism, which produces an active metabolite known as M4. This pharmacological profile makes edoxaban particularly vulnerable to interactions with drugs—and potentially herbal phytochemicals—that inhibit or induce P-glycoprotein or CYP3A4. Strong P-glycoprotein inhibitors such as quinidine and cyclosporine are already known to raise edoxaban levels, while inducers such as rifampin can slash them, and the edoxaban label reflects those established interactions.

To measure what the herbal formulations did to edoxaban, the researchers quantified plasma concentrations of both the parent drug and its active M4 metabolite using liquid chromatography coupled with tandem mass spectrometry, a gold-standard bioanalytical technique aligned with international ICH M10 validation guidance. Pharmacokinetic parameters—the area under the concentration-time curve, peak concentrations, and clearance measures—were compared between treatment periods using linear mixed-effects models, a statistical framework well suited to repeated-measures crossover designs. In parallel, the team assessed pharmacodynamic effects using prothrombin time and activated partial thromboplastin time, the two coagulation assays most commonly used to gauge anticoagulant intensity at the bedside. Finally, in laboratory experiments, the formulations were tested for their capacity to inhibit CYP3A4 activity in vitro.

The pharmacokinetic results were striking in their divergence. Bojungikgitang approximately doubled systemic exposure to edoxaban, effectively reproducing the magnitude of interaction seen with known strong P-glycoprotein inhibitors. At the other extreme, Cheongsanggyeontongtang reduced edoxaban exposure by roughly 40 percent—a reduction in the range that regulators associate with inducers of the drug’s clearance pathways and one that could, in theory, erode the anticoagulant’s protective effect against stroke. Ijintang, by contrast, exerted only minimal effects on the drug’s pharmacokinetic profile. The active metabolite M4 followed the same directional pattern as the parent compound in each case, indicating that the herbal formulations were shifting edoxaban’s overall systemic disposition rather than selectively rerouting its metabolism.

Perhaps the most provocative—and most cautionary—finding came from the pharmacodynamic measurements. Despite the substantial pharmacokinetic shifts, the researchers detected no significant changes in prothrombin time or activated partial thromboplastin time in any of the herbal co-administration groups. In other words, a patient’s exposure to edoxaban could double, or fall by 40 percent, while the standard laboratory coagulation tests remained essentially silent. This dissociation matters because clinicians sometimes lean on coagulation assays when concerns arise about anticoagulant intensity, and the results suggest those assays are poor sentinels for herb-driven changes in edoxaban levels. The therapeutic window of a drug, not the laboratory value alone, ultimately determines whether exposure changes translate into bleeding or thrombotic risk.

The mechanistic work offered clues about how the divergent effects arise. In vitro testing showed negligible inhibition of CYP3A4 by Bojungikgitang and Ijintang and only weak inhibition by Cheongsanggyeontongtang, indicating that direct CYP3A4 blockade is unlikely to explain the doubling of edoxaban exposure seen with Bojungikgitang. The more plausible culprit is interference with P-glycoprotein, the efflux pump that governs edoxaban’s intestinal absorption and biliary excretion. Many phytochemicals common in traditional formulas—including compounds found in ginseng, licorice, and astragalus, herbs represented in some of these formulations—have been shown in laboratory studies to modulate P-glycoprotein and CYP enzymes. The precise constituent responsible for the Bojungikgitang effect, however, remains to be pinned down, and the authors’ data do not permit attribution to a single botanical ingredient.

The clinical context amplifies the significance of the findings. Surveys of Korean medical hospital practice have documented frequent combination therapy between herbal extracts and antiplatelet or anticoagulant drugs in ischemic stroke patients, and Korean medicine clinical practice guidelines for stroke, developed under the National Institute for Korean Medicine Development, formalize herbal care pathways for the same patients who often need anticoagulation. Case reports from around the world have described increased bleeding in patients combining oral anticoagulants with herbal products ranging from saffron to Salvia miltiorrhiza, and St John’s wort has been shown to lower rivaroxaban exposure in controlled human studies. Meanwhile, cohort data have suggested that some concurrent Chinese herbal medicine use may even be associated with fewer major bleeding events, underscoring that the herb-drug interaction landscape is neither uniformly dangerous nor uniformly benign—it is formulation-specific, and largely unmapped.

That is precisely the gap this trial helps to fill. By testing three named, commercially supplied formulations under controlled conditions in healthy volunteers, and by measuring both drug levels and clotting outcomes with validated methods, the Korean team has converted a vague anxiety—herbs might interact with blood thinners—into concrete, quantifiable risk statements: Bojungikgitang approximately doubles edoxaban exposure, Cheongsanggyeontongtang cuts it by about 40 percent, Ijintang is relatively benign, and conventional coagulation tests will not warn you about any of it. The authors conclude that clinical consideration is warranted when edoxaban is combined with Bojungikgitang or Cheongsanggyeontongtang, and the magnitude of the observed changes supports that caution, situating both interactions on par with labeled drug-drug interactions of edoxaban.

Important caveats temper the translation to patient care. The study enrolled healthy volunteers, not the older, multimorbid patients with atrial fibrillation or venous thromboembolism who actually take edoxaban, and it could not assess hard clinical endpoints such as bleeding or stroke. Fixed-sequence designs and modest sample sizes, typical of exploratory interaction studies, also limit generalizability, and the duration of herbal pre-dosing may not capture longer-term induction or adaptation effects. Even so, the work delivers a clear, actionable message for prescribers, pharmacists, and practitioners of traditional medicine alike: herbal formulations are not pharmacologically inert companions to modern anticoagulants. Until larger outcome studies are done, patients taking edoxaban who also use Bojungikgitang or Cheongsanggyeontongtang deserve explicit attention, honest conversations about herbal supplement use, and a healthy skepticism toward coagulation tests that may not reveal what the body is actually doing.

Subject of Research: Herb-drug interactions between traditional Korean herbal formulations and the anticoagulant edoxaban

Article Title: Effects of Bojungikgitang, Ijintang, and Cheongsanggyeontongtang on the pharmacokinetics and pharmacodynamics of edoxaban

Article References: Kim, J. H., Song, J., Kim, M., Kim, H., Cho, H.-Y., & Chung, H. (2026). Effects of Bojungikgitang, Ijintang, and Cheongsanggyeontongtang on the pharmacokinetics and pharmacodynamics of edoxaban. Journal of Pharmaceutical Investigation. https://doi.org/10.1007/s40005-026-00828-z

Image Credits: AI Generated

DOI: 10.1007/s40005-026-00828-z

Keywords: edoxaban, herb-drug interaction, Bojungikgitang, Ijintang, Cheongsanggyeontongtang, pharmacokinetics, pharmacodynamics, direct oral anticoagulants, P-glycoprotein, CYP3A4, traditional Korean medicine, clinical trial