Exosome-like nanoparticles, often abbreviated ELNs, are tiny membrane-bound vesicles that plants package and release into their extracellular space. Roughly analogous to the exosomes that animal cells use to shuttle proteins, lipids, and genetic material between cells, these plant-derived vesicles have attracted intense interest over the past decade as potential natural drug delivery platforms. Unlike synthetic nanoparticles, they are biocompatible by construction, stable across a range of conditions, and come preloaded with bioactive molecules that the plant itself has synthesized. Previous work has shown that ELNs from ginger, grapefruit, lemon, ginseng, and other edible and medicinal species can modulate inflammation in animal cells, influence the gut microbiome, and even deliver regulatory RNAs across the species barrier. The new study extends this growing catalog to a plant whose medicinal pedigree stretches back generations but whose nanoscale secrets had not previously been cataloged in detail.

The researchers began by isolating the nanoparticles from Paederia foetida tissue and characterizing their physical properties with two complementary techniques. Nanoparticle tracking analysis, which infers particle size and concentration from the Brownian motion of individual vesicles under laser illumination, revealed a population of vesicles ranging from 25 to 200 nanometers in diameter, with the bulk of the distribution centered around 90 nanometers. Transmission electron microscopy then confirmed that these particles possess the characteristic cup-shaped or spherical vesicular morphology expected of membrane-enclosed nanoparticles. That size range is significant from a drug delivery standpoint: particles below roughly 200 nanometers can penetrate biological barriers, accumulate in inflamed tissue through enhanced permeability effects, and are readily taken up by immune cells, all properties that make them attractive candidates for pharmaceutical development.

Having established that the vesicles exist and fall within a therapeutically interesting size window, the team turned to their chemical contents. Using high performance liquid chromatography, they identified five terpenoids packaged within the Paederia foetida-derived nanoparticles: geniposidic acid, andrographolide, asiatic acid, scandoside, and loganin. Each of these compounds has an established anti-inflammatory resume in the pharmacological literature. Geniposidic acid has been shown to alleviate osteoarthritis progression by inhibiting inflammation and chondrocyte ferroptosis. Andrographolide suppresses inflammatory responses in macrophages and in murine models of acute colitis through activation of AMPK signaling. Asiatic acid exhibits anti-inflammatory and antioxidant activities in models of fulminant hepatic failure. Scandoside exerts its effects by suppressing both NF-κB and MAPK signaling in macrophages, while loganin attenuates cartilage inflammation by modulating the TLR4/MyD88/NF-κB axis. Finding all five co-packaged inside a single population of natural nanoparticles suggests that the vesicle membrane may serve as a delivery vehicle that concentrates these compounds and protects them on their journey to target tissues.

The terpenoids, however, were only half of the story. The researchers also performed microRNA sequencing on the isolated nanoparticles, generating a profile of the small regulatory RNAs that the plant packages into its vesicles. The results were striking: a total of 1,170 distinct microRNAs were detected in the Paederia foetida nanoparticles. MicroRNAs are short, roughly 21 to 24 nucleotide RNA molecules that regulate gene expression by binding to complementary sequences in messenger RNAs and triggering their degradation or blocking their translation. When the team ranked the vesicle microRNAs by abundance, the top 50 most plentiful species all belonged to the MIR159 family, a conserved plant microRNA family best known for its roles in plant development and pollen formation.

The prominence of MIR159 is particularly intriguing because of a body of evidence suggesting that plant microRNAs can act across kingdom boundaries. In a landmark 2016 study, researchers reported that miR159 from plants could inhibit the growth of breast cancer cells in mammals by targeting transcripts in the tumor cells. Other work has demonstrated that plants export small RNAs in extracellular vesicles to silence virulence genes in fungal pathogens, and that plant-derived exosomal microRNAs can shape the composition of the gut microbiota in animals that consume them. Cotton plants have been shown to export microRNAs that inhibit fungal virulence genes, and citrus-derived miR169 has been computationally proposed as a candidate antiviral agent against SARS-CoV-2. The enrichment of MIR159 in Paederia foetida vesicles places this plant squarely within the emerging conversation about edible and medicinal plants as sources of cross-kingdom gene regulators.

To probe what these 1,170 microRNAs might actually be doing, the researchers deployed a battery of bioinformatic tools, including the target prediction programs psRobot and miRanda, followed by Gene Ontology and KEGG pathway enrichment analyses. On the plant side of the ledger, the predicted targets were enriched in pathways governing phytohormone signal transduction, MAPK signaling cascades, and terpenoid biosynthesis, suggesting that the vesicle cargo plays roles in the plant’s own stress responses and metabolic regulation. But the more provocative findings emerged when the team ran the same predictions against the human genome. The microRNAs were predicted to target genes involved in adipocytokine signaling, infection-related immunity, and cancer-associated pathways. Among the key predicted human targets were NFKB1, the gene encoding a subunit of the central inflammatory transcription factor NF-κB, and MAP2K6, a kinase in the p38 MAPK cascade that participates in inflammation and apoptosis signaling.

Those two targets deserve particular attention. NF-κB sits at the hub of the mammalian inflammatory response, controlling the expression of cytokines, chemokines, and survival factors, and its dysregulation is implicated in virtually every chronic inflammatory disease as well as many cancers. MAP2K6, meanwhile, relays stress signals into the cell interior and influences decisions about cell death and inflammatory activation. If plant microRNAs delivered by these nanoparticles can meaningfully dampen the activity of such genes in animal tissues, the therapeutic implications would be considerable, ranging from treatment of inflammatory bowel disease to adjunctive cancer therapy. The authors of the new study are careful to frame these findings as predictions, since computational target prediction is a screening step rather than proof of functional regulation, but the convergence between the predicted targets and the known anti-inflammatory chemistry of the packaged terpenoids paints a coherent picture of a vesicle system oriented toward inflammation control.

The work also fits into a broader translational push surrounding plant-derived nanovesicles. Recent reviews have cataloged their potential as green delivery platforms, functional food ingredients, and therapeutic agents for conditions ranging from colitis to cardiovascular disease, and studies of yam-derived nanoparticles have reported protective effects against acute liver injury. Medicinal plants are of special interest because their vesicles combine a drug delivery function with intrinsic pharmacological activity, a dual-action profile that synthetic carriers struggle to replicate. Paederia foetida itself has a documented phytochemical and pharmacological profile, and earlier work by the same lead author compared the terpenoid content and anti-inflammatory effects of related Rubiaceae species on macrophage cells, providing a foundation for the present nanoscale analysis.

Considerable hurdles remain before any of this reaches the clinic. The cross-kingdom activity of dietary plant microRNAs in mammals remains an actively debated question, with questions of bioavailability, dose, and stability in the digestive tract still being worked out. Functional validation of the predicted targets, uptake studies in animal models, and safety and standardization work all lie ahead. Nevertheless, the study provides a detailed molecular inventory of a previously unexplored medicinal plant’s nanoparticle cargo, and it demonstrates a workflow, from physical characterization through chromatography and small RNA sequencing to cross-species bioinformatics, that can be applied to the vast pharmacopoeia of traditional medicines still awaiting nanoscale scrutiny. For a plant long valued in folk medicine for cooling inflammation, the discovery that its tiniest emissaries carry both anti-inflammatory chemistry and microRNAs aimed at inflammatory genes offers a satisfying, if preliminary, molecular vindication of traditional practice.

Subject of Research: Isolation and molecular characterization of exosome-like nanoparticles from the medicinal plant Paederia foetida

Article Title: Isolation and characterization of exosome-like nanoparticles from Paederia foetida (Rubiaceae) and analysis of their miRNA and terpenoid composition

Article References: Peng, Y., Demidchik, V., Medvedev, S., & Smolikova, G. (2026). Isolation and characterization of exosome-like nanoparticles from Paederia foetida (Rubiaceae) and analysis of their miRNA and terpenoid composition. Plant Biosystems, 160(5), Article 280. https://doi.org/10.1007/s44473-026-00271-w

Image Credits: AI Generated

DOI: 10.1007/s44473-026-00271-w

Keywords: exosome-like nanoparticles, Paederia foetida, microRNA, terpenoids, anti-inflammatory, cross-kingdom regulation, MIR159, NF-κB, drug delivery, medicinal plants, nanoparticle tracking analysis, Plant Biosystems

The protein at the center of the new work is the retinoic acid receptor alpha, or RARα, which is highly active in colorectal tumors and drives both proliferation and metastatic invasion. Traditional RARα modulators, built on retinoic acid scaffolds, suffer from chemical instability, excessive lipophilicity, and poor oral bioavailability, and they can provoke toxicity in the liver, skin, and bones. To escape these limitations, the researchers turned to proteolysis-targeting chimera, or PROTAC, technology. PROTACs are bifunctional molecules that simultaneously grip a target protein and an E3 ubiquitin ligase, forming a ternary complex that tags the target for destruction by the cell’s own ubiquitin–proteasome system. Because each PROTAC molecule dissociates after every degradation event and can engage targets repeatedly, this catalytic mechanism holds the promise of overcoming the drug resistance that plagues conventional inhibitors.

The team began with AR7, an atypical RARα antagonist, and selected its optimized derivative CA77.1 as the target-binding ligand. Molecular docking against the RARα structure (PDB:5K13) revealed that CA77.1 binds with a calculated energy of −7.379 kcal/mol, anchored by a key hydrogen bond to Arg276 and an extensive hydrophobic network. Crucially, a terminal methyl group on CA77.1 protrudes into the solvent-exposed region outside the ligand-binding pocket, providing an ideal attachment point for a linker without disturbing the core binding interactions. By covalently joining CA77.1 to thalidomide, a ligand for the E3 ubiquitin ligase CRBN, the researchers created a degrader that remains active in both oxygen-rich and hypoxic tumor regions, overcoming the hypoxia-dependent activation that limited the parent compounds.

Through systematic synthesis of six candidate molecules with varying carbon-chain and piperazine linkers, the team identified Z1 as the standout. Z1 degraded RARα with a DC50 of 6.02 ± 1.05 μM and a maximum degradation of 85.4 percent, an activity roughly 43.6 times greater than that of CA77.1 itself. Western blotting confirmed that Z1 left the related receptors RARβ and RARγ untouched, demonstrating high subtype selectivity. Mechanistic experiments sealed the case: cycloheximide chase assays showed accelerated decay of pre-existing RARα protein, while pre-treatment with the competitive ligand ATRA, the E1 enzyme inhibitor MLN4924, the proteasome inhibitor MG132, or excess thalidomide all blocked degradation, confirming the classical PROTAC pathway of direct binding and ubiquitin-proteasome-mediated clearance.

Molecular dynamics simulations running 100 nanoseconds provided atomistic support for the design. Z1 formed stable hydrogen bonds with both RARα and CRBN, with calculated binding free energies of −139.394 kJ/mol and −111.138 kJ/mol respectively, and per-residue energy decomposition pinpointed Pro407, Val395, and Ser225 as the thermodynamic core of RARα recognition. Functionally, Z1-induced degradation suppressed phosphorylation of AKT at Ser473 in a concentration-dependent manner while leaving total AKT unchanged, and it markedly reduced expression of MMP2, an enzyme that tumors use to invade surrounding tissue. This AKT–MMP2 axis, the authors note, had not been systematically characterized in earlier RARα degradation studies and offers a fresh mechanistic window into how acute protein elimination restrains cancer progression.

In vitro assays in HCT116 colorectal cancer cells painted a striking picture of Z1’s antitumor potency. Flow cytometry showed concentration-dependent arrest of cells at the G2/M phase, with the arrested population rising 3.7-fold at 100 μM. At 50 μM, Z1 completely abolished colony formation, whereas the same concentration of CA77.1 allowed more than 300 colonies to grow. Annexin V staining revealed that Z1 drove 34.6 to 55.2 percent of cells into late apoptosis, well above the 24.6 percent seen with CA77.1. Scratch assays demonstrated up to 90.4 percent inhibition of cell migration, and Transwell experiments showed that 50 μM Z1 cut the invasion rate to 10.8 percent, an 81.2 percent reduction relative to the parent compound.

Yet like all PROTACs, Z1 carries the field’s chronic handicaps: high molecular weight, poor water solubility, and weak membrane permeability. The team’s solution came from an unexpected source, the roots of Polygonatum sibiricum, a plant long valued in traditional medicine. Using a juicing, filtration, and ultracentrifugation workflow, the researchers isolated exosome-like nanoparticles, or PsELNs, that measure roughly 116 nanometers across, carry a mildly negative zeta potential of −5.8 mV, and display the characteristic disk-like morphology of plant vesicles. Their cargo of triglycerides forms a hydrophobic core that stabilizes hydrophobic drugs, while their natural tropism for colonic tissue and their ability to accumulate in tumors through the enhanced permeability and retention effect make them unusually well suited to colorectal cancer applications.

Encapsulation of Z1 within PsELNs achieved a drug-loading efficiency of 43.1 percent, exceeding values reported for goji berry and ginger vesicles, and the loaded particles grew only modestly to 143 nm while retaining an intact bilayer. Stability testing was impressive: at acidic pH 5.5 mimicking the tumor microenvironment, 77.38 percent of Z1 remained intact after 24 hours versus just 40.65 percent for the free drug, and the formulation resisted thermal stress at 44 °C, stayed stable in serum for 72 hours, and showed minimal leakage over 60 days of storage. Confocal microscopy and flow cytometry confirmed that Z1/PsELNs entered HCT116 cells far more efficiently than free Z1, and the encapsulated drug degraded RARα with a DC50 of 2.95 μM, a 2.2-fold improvement that translated into stronger apoptosis induction and greater cytotoxicity in vitro.

The decisive test came in living animals. Near-infrared imaging of tumor-bearing nude mice showed that DiR-labeled PsELNs accumulated in tumors at 2.13 times the level of the free dye, peaking at 24 hours after injection, while hemolysis rates below 5 percent confirmed blood compatibility. Over 16 days of tail-vein treatment, the Z1/PsELNs group showed significantly stronger tumor growth inhibition than mice receiving free Z1, with in vivo antitumor efficacy increasing 1.8-fold. Histopathology revealed extensive tumor cell damage, Ki67 staining showed the fewest proliferating cells, and both immunohistochemistry and Western blotting confirmed the lowest RARα levels in the nanoparticle-treated tumors, all without body-weight loss or organ damage. The authors propose that the intestinal stability and colon-targeting behavior of PsELNs could eventually support an oral PROTAC formulation, a goal that would address both gastrointestinal degradation and site-specific accumulation. By fusing event-driven protein degradation chemistry with a biocompatible, naturally derived delivery vehicle, the study charts a credible translational path for PROTAC therapeutics in colorectal cancer and illustrates how plant nanotechnology may help the next generation of degrader drugs reach their targets intact.

Subject of Research: A RARα-targeting PROTAC delivered by Polygonatum sibiricum exosome-like nanoparticles for colorectal cancer therapy

Article Title: Synthesis of RARα–PROTAC and its delivery via Polygonatum sibiricum exosome-like nanoparticles for the treatment of colorectal cancer

Article References: Zhu, G., Zhao, Y., Chen, M., Lu, S., Xu, L., Chen, G., Zeng, L., & Chen, J. (2026). Synthesis of RARα–PROTAC and its delivery via Polygonatum sibiricum exosome-like nanoparticles for the treatment of colorectal cancer. Materials Today Bio, 40, Article 103651. https://doi.org/10.1016/j.mtbio.2026.103651

Image Credits: AI Generated

DOI: 10.1016/j.mtbio.2026.103651

Keywords: colorectal cancer, PROTAC, RARα, protein degradation, Polygonatum sibiricum, exosome-like nanoparticles, drug delivery, nanomedicine, ubiquitin-proteasome system, AKT signaling, MMP2, targeted therapy