The scale of the problem is enormous. According to the review, roots account for roughly 30 percent of the raw material consumed by the global medicinal and aromatic plant industry, and bark for about 13 percent. Harvesting these tissues almost always means uprooting or felling the entire plant. For slow-growing perennials used in Ayurveda, Siddha, Unani and Traditional Chinese Medicine, that is a death sentence repeated thousands of times a year. Excessive or careless bark removal disrupts water and nutrient transport so severely that trees often die, and illegal trade compounds the pressure on wild populations, eroding both species richness and genetic diversity.

The authors are careful to stress that substitution cannot be assumed from traditional reputation alone. The biosynthesis, transport and storage of secondary metabolites are typically organ-specific and dependent on tissue development, so the profile of a root or a piece of bark may differ dramatically from that of a leaf. Concentrations also shift with plant age, growth stage, season, genotype and environment. Their proposed standard is therefore rigorous: a candidate substitute must be validated by systematic comparative profiling of marker compounds using techniques such as high-performance thin-layer chromatography (HPTLC), high-performance liquid chromatography (HPLC) or liquid chromatography–tandem mass spectrometry (LC–MS/MS), supported by quantitative assays of total phenolics, flavonoids and other chemical classes.

The first case study is Myrica esculenta, the Himalayan bayberry known locally as kaphal, whose stem bark is used across Uttarakhand and neighboring regions for headaches, asthma, chronic coughs, wounds and toothaches. Comparative analysis found that stem bark does contain far more total phenolics—276.78 milligrams of gallic acid equivalents per gram of dry weight versus 31.24 for small branches—and more flavonoids, 121.68 versus 12.94 milligrams of quercetin equivalents per gram. Yet qualitative HPTLC profiling revealed congruent bands in both tissues, indicating that the same classes of secondary metabolites, including gallic acid, catechin, proanthocyanidins, myricanol and myricanone, are present in small branches. That chemical overlap, the authors note, matches what traditional healers already do when they substitute branches for bark, and it underpins the species’ antioxidant, anti-inflammatory and antimicrobial activities documented in fruit, leaf and bark extracts.

Pelargonium sidoides, the African geranium of South Africa and Lesotho, offers perhaps the most striking quantitative case. Its roots are the source of a widely used remedy for respiratory infections, and its coumarins and phenolic acids have been studied for antibacterial, immunomodulatory and even HIV-1 entry-inhibiting effects. When researchers compared wild and acclimatized plants using UPLC-MS/MS, the aerial parts outperformed the underground organs for all three marker phenolic acids. Wild aerial tissues contained 231.08 micrograms of gallic acid per gram of dry weight against 72.7 in underground parts, and protocatechuic acid was roughly 70-fold higher in wild aerial tissue than underground. Salicylic acid followed the same pattern. The authors conclude that these data directly support replacing root harvests with aerial harvests, a shift that would leave the perennial geophyte intact in the soil.

Warburgia salutaris, the endangered pepper-bark tree of southern and eastern Africa, shows that substitution can even improve yields. Its drimane-type sesquiterpenoids, warburganal and polygodial, are the compounds behind its reputation as one of Africa’s most valuable natural antimicrobials, used against coughs, malaria-like fevers, wounds and stomach ailments. Quantitative measurements found leaves yielding 0.05 percent polygodial and 0.06 percent warburganal, matching or exceeding bark yields of 0.03 and 0.06 percent, while a Venda genotype produced 0.04 and 0.09 percent respectively. Because leaves are harvested non-destructively and present a simpler extraction matrix than bark, the review describes leaf substitution as both conservation-friendly and commercially practical for this threatened Canellaceae species, whose extracts have also shown activity against Mycobacterium tuberculosis and, in the case of iso-mukaadial acetate, potent antimalarial effects with an in vitro IC50 of 0.44 micrograms per milliliter against Plasmodium falciparum.

The remaining two examples come from Asia. Litsea chinensis, a genus member used in Indian and Chinese traditional medicine for diarrhea, diabetes, inflammation and colds, showed a trade-off: heartwood carried more flavonoids, 100.32 versus 41.74 micrograms of quercetin equivalents per gram, but small branches carried more total phenolics, 64.13 versus 58.32 micrograms of gallic acid equivalents per gram. HPTLC profiles of hexane, ethyl acetate and ethanolic extracts revealed many shared bands between heartwood and branches, supporting branch substitution for a tree whose heartwood harvest is inherently lethal. Aegle marmelos, the bael tree sacred in India for five millennia, produced an even cleaner result: stem extracts contained 59.89 percent more total phenolics than root extracts, 21.64 percent more flavonoids, 13.58 percent more tannins, and nearly identical alkaloid levels, with thin-layer and high-performance liquid chromatography confirming umbelliferone and scopoletin in both organs. The authors conclude that bael stems are a viable stand-in for roots.

What makes the review more than a chemistry exercise is its policy framing. The authors align plant-part substitution with India’s Biological Diversity Act, the Convention on Biological Diversity, the Nagoya Protocol, WHO-IUCN-WWF conservation policy and United Nations Sustainable Development Goals 3, 13 and 15, which cover health, climate action and life on land. India’s National Medicinal Plants Board and the Central Council for Research in Ayurvedic Sciences, under the Ministry of AYUSH, already promote the scientific validation of substitutes for threatened, high-demand species, and the review itself was supported by a National Medicinal Plants Board project. In effect, substitution offers regulators a lever that cultivation programs alone cannot: it reduces demand pressure at the source while ex situ propagation and controlled-environment agriculture scale up supply.

The authors are candid about the gaps. Quantitative equivalence varies among species and even among genotypes, as the Pelargonium and Warburgia data show, and pharmacological equivalence—proof that a leaf extract performs like a bark extract in the body—still requires rigorous in vivo and in vitro pharmacodynamic and toxicological studies across broader disease models. Their future agenda calls for embedding substitution guidelines in national and international biodiversity and pharmaceutical regulations, training traditional healers, cultivators and industry stakeholders in standardized harvesting and quality control, extending the approach to additional high-value taxa and ecosystems with ecological mapping and community-based monitoring, and partnering with pharmaceutical and nutraceutical manufacturers to translate validated substitutions into scalable products. If those steps follow, the humble leaf—regrown every season while the tree stands—may become the pharmaceutical industry’s most sustainable raw material, and the difference between a medicinal forest that survives and one that is dug up, strip by strip, for medicine.

Subject of Research: Plant part substitution based on phytochemical equivalence as a conservation strategy for overharvested medicinal plants

Article Title: Plant part substitution as a sustainable conservation strategy for some medicinal plants based on phytochemical equivalence

Article References: Muley, M., Dondulkar, A., Ghagare, A., Meshram, S., Prasad, S., & Itankar, P. (2026). Plant part substitution as a sustainable conservation strategy for some medicinal plants based on phytochemical equivalence. Discover Plants, 3(1), Article 407. https://doi.org/10.1007/s44372-026-00875-8

Image Credits: AI Generated

DOI: 10.1007/s44372-026-00875-8

Keywords: medicinal plants, plant part substitution, phytochemical equivalence, conservation, HPTLC, HPLC, LC-MS/MS, bark harvesting, sustainable harvesting, Nagoya Protocol, ethnopharmacology, biodiversity