The original call for papers read like a catalogue of the field’s hottest frontiers: targeted protein degradation, molecular glues, covalent inhibitors, antibody-drug conjugates, macrocycles, nucleoside therapeutics, immuno-oncology agents, natural-product discovery, multicomponent reactions, advanced imaging and screening technologies, and artificial intelligence. That breadth is significant in itself. A decade ago, many of these approaches were considered speculative or confined to a handful of specialist laboratories. Today they constitute a mainstream toolkit, and the 58 accepted articles show researchers across medicinal chemistry, chemical biology, and pharmacology routinely combining them rather than working in silos. The result, according to the editorial framing the collection, is a discovery enterprise that is faster, more efficient, and increasingly sophisticated in how it approaches molecular design.

A central theme running through the issue is the development of efficient and diversity-oriented synthetic strategies for bioactive molecules. The published articles describe asymmetric and visible-light-promoted reactions, multicomponent and one-pot syntheses, iron-catalyzed functionalization, nanocatalytic and sonochemical methods, skeletal editing, total synthesis, and optimized synthetic routes. Each of these techniques addresses a persistent bottleneck in drug discovery: the speed and reliability with which chemists can actually make the molecules that computational and biological studies suggest might work. Visible-light photocatalysis, for example, allows bond formations under mild conditions that were previously difficult or impossible, while skeletal editing permits late-stage modifications of molecular frameworks that would once have required rebuilding a candidate from scratch. Multicomponent reactions compress multi-step sequences into single operations, dramatically shortening the path from idea to testable compound.

Crucially, the synthetic advances described in the collection are not presented as ends in themselves. The resulting compounds, which include diverse indoles, indolizines, heterocycles, molecular hybrids, peptides, and natural-product analogues with enhanced structural and stereochemical complexity, were investigated as anticancer, antimicrobial, antitubercular, antiviral, anti-inflammatory, antidiabetic, antiseizure, and neuroprotective agents. This direct linkage between methodology and biological application is what distinguishes the current wave of synthetic innovation from earlier eras in which method development and drug hunting often proceeded on separate tracks. When a new catalytic reaction can be evaluated within weeks against disease-relevant cell models, the feedback loop between chemistry and pharmacology tightens, and the odds that an interesting molecule becomes a therapeutic candidate improve accordingly.

Another striking pattern in the collection is the continuing shift beyond the traditional one drug-one target paradigm that dominated pharmaceutical research for much of the past half-century. Among the highlighted examples are dual inhibitors targeting BTK/FLT3, COX-2/5-LOX, and FAAH/sEH, enzyme pairs relevant to cancer and inflammation, alongside multifunctional agents designed for Alzheimer’s disease and reviews of xanthone hybrids and pyrazolopyrimidine-based dual inhibitors. Multi-target design acknowledges that complex diseases rarely hinge on a single protein, and that modulating several nodes of a pathological network simultaneously can be more effective than maximal blockade of one. The approach demands a different kind of medicinal chemistry, one in which selectivity is engineered across multiple binding sites rather than maximized against a single target, and the articles in the issue show that scaffold design and mechanistic understanding are being integrated to meet exactly that challenge.

The issue also surveys work on established and emerging molecular targets, including FAK, HDAC, ERα, PI3Kδ, p38 MAPK, EZH2, DprE1, histamine H1 and H2 receptors, SFRP1, PDE4B, and nitric oxide synthase. This list spans kinases, epigenetic enzymes, nuclear receptors, phosphodiesterases, and bacterial cell-wall biosynthesis machinery, reflecting the wide biological terrain on which modern medicinal chemistry now operates. A dedicated review on PROTAC technology underscores the prominence of targeted protein degradation, one of the most promising new therapeutic modalities of the past decade. Rather than inhibiting a protein’s activity, degraders recruit cellular disposal machinery to eliminate the disease-causing protein altogether, an approach that can succeed against targets long considered undruggable by conventional small molecules. Its inclusion alongside classical target families illustrates how new modalities are being folded into, rather than replacing, the existing discovery apparatus.

Natural products and biomolecule-inspired scaffolds remain a major focus of the collection, and the evidence assembled suggests that nature is far from exhausted as a source of molecular diversity. Studies on phorbazole D, menominin A, polyprenylated acylphloroglucinols, oleanolic and alepterolic acids, Eucommiae folium, µ-conotoxins, honey-bee antimicrobial peptides, and marine cyclopeptides demonstrate the remarkable chemical inventiveness of the natural world, from terrestrial plants to venomous cone snails and social insects. What has changed is the technology brought to bear on these molecules. Total synthesis, analogue generation, chemical ligation, mass spectrometry, network pharmacology, and cell-based screening are overcoming longstanding challenges in natural-product discovery and optimization, problems of supply, structural complexity, and limited optimization potential that historically kept many natural products out of the clinic despite compelling biological activity.

The synergy between computation and experimentation emerges as perhaps the defining feature of the modern discovery pipeline. Molecular docking, molecular dynamics simulations, pharmacophore modeling, network pharmacology, and integrated in silico-in vitro workflows now support compound prioritization and mechanistic studies across the collection. These are not decorative additions; they determine which of millions of conceivable molecules get synthesized and tested, effectively allocating scarce laboratory resources. AI-assisted analysis, label-free cell-based screening, high-resolution LC-Orbitrap mass spectrometry, and zebrafish disease models further illustrate advances in compound characterization, phenotypic screening, and translational validation. Phenotypic screening in whole organisms such as zebrafish is particularly notable, because it allows compounds to be evaluated for efficacy and toxicity in a living system before the costly transition to mammalian models, catching failures earlier and more cheaply than traditional pipelines allow.

The collective message of the 58 articles is that new technologies in drug discovery are not defined by any single platform or methodology, but by the integration of innovative chemistry, emerging therapeutic modalities, computational prediction, advanced screening technologies, and rigorous biological validation. This multidisciplinary convergence is expanding druggable chemical space, the universe of molecules that can realistically be made, characterized, and developed into medicines, while accelerating therapeutic discovery and enabling increasingly sophisticated approaches to drug design. For decades, the pharmaceutical industry has grappled with declining productivity per research dollar, and collections like this one suggest a credible path forward: rather than betting on any single breakthrough, the field is stacking multiple incremental advantages in synthesis, target biology, computation, and screening into compounding gains across the entire pipeline.

In closing the special issue, Shi thanks the authors, reviewers, and the editorial team of Molecular Diversity, and expresses the hope that the collection will stimulate new collaborations, inspire continued technological innovation, and contribute to making drug discovery faster, more efficient, and more successful while preserving the molecular and mechanistic diversity that underpins transformative medicines. That emphasis on diversity is more than rhetorical. History shows that transformative drugs often emerge from unexpected chemical territory, and the deliberate cultivation of varied scaffolds, modalities, and screening strategies is the best insurance against the field narrowing prematurely around fashionable targets. If the technologies surveyed here continue to mature and interconnect, the coming decade of drug discovery may look markedly different from the last, with molecules designed, synthesized, and validated at a pace and precision that earlier generations of researchers could scarcely have imagined.

Subject of Research: Emerging technologies and multidisciplinary approaches in drug discovery

Article Title: New technologies in drug discovery

Article References: Shi, T. (2026). New technologies in drug discovery. Molecular Diversity. https://doi.org/10.1007/s11030-026-11711-2

Image Credits: AI Generated

DOI: 10.1007/s11030-026-11711-2

Keywords: drug discovery, medicinal chemistry, targeted protein degradation, PROTAC, molecular glues, natural products, artificial intelligence, multicomponent reactions, phenotypic screening, dual inhibitors, chemical biology, Molecular Diversity

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