Ayurvedic phytochemicals offer a multi-target route against antimicrobial resistance

A 2026 review argues that the most credible contribution of Ayurvedic plants to the antimicrobial-resistance crisis may not be as replacements for antibiotics, but as multi-target adjuncts capable of disrupting bacterial cell walls, damaging membranes, inhibiting essential enzymes and interfering with resistance machinery. The analysis synthesizes previously published evidence on plants including Calotropis procera, neem (Azadirachta indica), holy basil (Ocimum sanctum), several Acacia species and Asparagus racemosus. It is a literature review rather than a new experimental or clinical study, and its central proposal remains preclinical: chemically diverse plant mixtures may pressure several essential bacterial systems at once, making resistance less likely to evolve than under a single-target drug and potentially restoring the activity of antibiotics that bacteria have learned to withstand.

The rationale begins with the design of modern antibiotics. Most act on one principal molecular target, whether cell-wall synthesis, protein synthesis, nucleic-acid synthesis, folate metabolism or membrane function. That specificity creates a corresponding escape route: bacteria can alter the target, increase drug efflux, enzymatically inactivate the compound or protect the target with dedicated proteins. A single mutation or acquired resistance mechanism may therefore be enough to blunt the drug. By contrast, the review notes, bacterial resistance can also spread through mobile genetic elements, allowing resistant genes to move between related and unrelated species. A strategy aimed at several conserved targets would not make resistance impossible, but it would require bacteria to overcome several pressures simultaneously rather than relying on one successful adaptation.

Ayurvedic antibacterial preparations are presented in this context as naturally occurring polypharmacological mixtures. Their activity is attributed not to one plant-specific constituent but to recurring classes of secondary metabolites, including flavonoids, tannins, saponins, phenolic acids and terpenoids. These compounds converge on features shared by many bacteria, including the cell envelope and enzymes needed for replication and metabolism. The review cites serial-passage evidence in which Staphylococcus aureus, Acinetobacter baumannii and Pseudomonas aeruginosa evolved resistance less readily against a historical multi-component antimicrobial than against single-target controls. This observation supports the general logic of multi-target pressure, although it does not establish that any particular Ayurvedic preparation will behave similarly in patients.

The review focused on peer-reviewed studies retrieved from Google Scholar, PubMed and Scopus, using terms that included “antimicrobial resistance,” “Ayurveda,” “polypharmacology,” “antibiotic adjuvants,” “phytochemicals” and “multi-target mechanism.” Calotropis procera, Azadirachta indica, Ocimum sanctum, the Acacia genus and Asparagus racemosus were selected for detailed treatment because they were frequently cited in the surveyed literature and had comparatively well-characterized mechanisms; this was a qualitative judgment rather than a numerical threshold. Studies reporting stand-alone antibacterial effects without mechanistic detail, non-peer-reviewed work and studies of non-human pathogens were excluded. The authors generated no new experimental, in vitro, in silico or clinical data, so their synthesis maps reported mechanisms and identifies translational gaps rather than testing therapeutic benefit.

Evidence summarized across the cell envelope shows several routes of antibacterial action. Quercetin, a flavonoid found in A. indica, has been reported to interact with the peptidoglycan layer, increase permeability and damage the wall in laboratory studies. Tannins can form complexes with cell-wall proteins and interfere with adhesins, enzymes and envelope transport systems. Neem constituents including azadirachtin, salannin, meliantriol, mahmoodin and nimbin have also been reported to interfere with cell-wall or membrane synthesis in vitro. In Calotropis procera, flavonoids appear to bind wall and membrane components, while eugenol from O. sanctum alters membrane permeability, allows intracellular material to leak and inhibits membrane ATPase. Saponins can insert into lipid bilayers and disorder membrane lipids, and phenolic acids may interact with both the polar surface and the hydrophobic interior of the membrane.

Other constituents target enzymes required for bacterial survival and replication. In vitro findings summarized in the review indicate that azadirachtin and quercetin inhibit DNA gyrase and its ATPase activity. Docking studies attribute the activity of luteolin from Bacopa monnieri to high affinity for a gyrase-binding site, while phenolic compounds are reported to interfere with dihydrofolate reductase, gyrase B and topoisomerase IV. A compound identified in A. indica as O-geranyl β-D-mannofuranoside was reported in combined in silico and laboratory work to bind penicillin-binding proteins PBP2X and PBP4, as well as tyrosyl-tRNA synthetase and DNA gyrase. Such results indicate multiple possible points of action, but molecular docking and in vitro exposure do not demonstrate that a compound will reach an infection site at an effective concentration in a person.

Perhaps the most relevant mechanism for an adjuvant role is direct interference with bacterial resistance systems. Rutin, a flavonoid associated with C. procera, has been reported in computational and in vitro studies to inhibit beta-lactamases and efflux pumps while reducing biofilm formation. In Klebsiella pneumoniae, it reportedly downregulated about 15 genes associated with biofilm formation. Rutin hydrate had minimum inhibitory concentrations of 128–1,024 micrograms per millilitre across tested strains and produced a fractional inhibitory concentration index below 0.5 when combined with amikacin against four strains, a result classified as synergy. Separately, quercetin inhibited beta-lactamase in amoxicillin-resistant Staphylococcus epidermidis and restored susceptibility, with a fractional inhibitory concentration index of 0.5. These are laboratory interaction results, not evidence that either phytochemical is ready for clinical use.

Biofilms offer a second reason for exploring these compounds as adjuncts. These multicellular aggregates are enclosed in a self-produced extracellular matrix that limits drug penetration, supports horizontal gene transfer and can shelter metabolically dormant persister cells. Biofilms also favor quorum-sensing communication, specialized efflux and the exchange of resistance genes among neighboring bacteria. Several plant constituents act on those processes. Catechin from A. indica was reported to degrade the extracellular polymeric substances that bind a biofilm together and to reduce quorum sensing by 94.56% plus or minus 2.56% in Porphyromonas gingivalis through reduced LuxS activity. Quercetin reduced S. epidermidis biofilm formation at concentrations of 125–1,000 micrograms per millilitre by lowering intercellular-adhesion gene expression and polysaccharide-intercellular-adhesin production. Other evidence reviewed indicates that tannins can inactivate adhesins, while tannin-rich plant fractions inhibit quorum sensing in P. aeruginosa.

The proposed translational strategy is to combine a standardized multi-component plant extract with an existing antibiotic rather than asking the plant material to cure a resistant infection alone. In principle, matrix degradation may improve antibiotic access; inhibition of beta-lactamase may protect a vulnerable antibiotic; and efflux inhibition may increase the intracellular concentration of a drug. Demonstrating that a combination is genuinely synergistic, however, requires more than observing a larger effect than either ingredient produces alone. The review recommends standardized mathematical benchmarks such as Loewe additivity and fractional inhibitory concentration calculations. In the latter method, an index of 1 represents additivity, a value below 1 indicates synergy and a value above 1 indicates antagonism. Time-kill and other common assays can misclassify interactions, so the choice and interpretation of tests are central to the credibility of future results.

Translation is constrained by reproducibility, safety, pharmacokinetics and regulation. Plant composition can vary with season, harvest time and geography, making potency difficult to standardize; analytical methods such as HPLC-ESI-MS/MS can characterize preparations but are slow and costly. Contamination is another documented problem: some commercial preparations have been reported to contain lead, mercury or arsenic at 100–10,000 times recommended limits, while some traditionally processed metal-containing formulations have been associated with elevated human exposure. Herbal medicines are not inherently safe, either, because of adulteration, misidentification, intrinsic plant toxicity, overdose or interactions with conventional drugs. Polyphenols can interfere with iron uptake, digestive enzymes and cytochrome P450 enzymes, which may alter the metabolism of co-administered medicines.

The concentrations that look effective in laboratory assays also raise a major delivery problem. Rutin hydrate at 128–1,024 micrograms per millilitre and quercetin at 125–1,000 micrograms per millilitre reflect direct exposure of cultured bacteria, not concentrations demonstrated in human plasma or infected tissue. Many phytochemicals are poorly soluble, enzymatically degraded, rapidly metabolized or unable to cross biological barriers, including the gastrointestinal tract, endothelial linings and blood-brain barrier. Liposomes, solid lipid nanoparticles and nanostructured lipid carriers are being investigated as ways to improve stability, absorption, dispersion and targeted delivery, but the review reports no new demonstration of clinical performance for these systems. Regulation presents an additional mismatch because most approval frameworks are designed around a single defined active ingredient, while a botanical extract may contain many constituents whose relative concentrations vary with source and processing.

Clinical evidence remains limited. The review notes that most studies supporting the multi-target mechanisms are in vitro, in silico or otherwise preclinical, and that relatively few herbal products have progressed through controlled human trials. Pelargonium sidoides is cited as an established example with clinical evidence for respiratory illnesses, but it does not establish the clinical efficacy of the antimicrobial adjuvants discussed here. The review itself contributes no new experiments, human data or direct test of a phytochemical–antibiotic combination. Its most supportable conclusion is therefore a research proposition: standardized Ayurvedic-derived mixtures merit formal evaluation as antibiotic adjuncts and anti-biofilm agents, with defined compositions, rigorous interaction testing, safety assessment, pharmacokinetic measurement and appropriately designed clinical trials. Until those steps are completed, the evidence supports biological plausibility and a clear testing strategy, not readiness to treat resistant infections with herbal products or to replace existing antibiotics.

Subject of Research: Preclinical review of Ayurvedic phytochemicals as multi-target antibiotic adjuncts against antimicrobial resistance

Article Title: Rethinking Ayurvedic antibacterials: a mechanistic case for multi-target phytochemicals as adjuvants against antimicrobial resistance

Article References: Narayanan KN, H., & Panchapakesan, S. S. S. (2026). Rethinking Ayurvedic antibacterials: a mechanistic case for multi-target phytochemicals as adjuvants against antimicrobial resistance. Frontiers in Pharmacology, 17, Article 1946531. https://doi.org/10.3389/fphar.2026.1946531

Image Credits: AI Generated

DOI: 10.3389/fphar.2026.1946531

Keywords: antimicrobial resistance, Ayurvedic medicine, phytochemicals, antibiotic adjuvants, biofilms, polypharmacology, beta-lactamase, efflux pumps, quorum sensing, drug development, Rethinking, Ayurvedic