On occasion, a natural product lead compound may help elucidate a new mechanism of interaction with a biological target for a disease state under investigation. Natural products may serve to provide molecular inspiration in certain therapeutic areas for which there are only a limited number of synthetic lead compounds.

Thus natural product research can make substantial contributions to drug innovation by presenting us with novel mechanism of action, such as stabilization of cellular microtubules by paclitaxel or the topoisomerase-I inhibiting activity of camptothecin. Similarly yohimbine derived from yohimbe bark and structurally related to reserpine, unlike classic α-antagonists like phentolamine and phenoxybenzamine, is much more active at presynaptic α₂-adrenoreceptors than at post synaptic vascular α₁-adrenoreceptors. This selectivity makes it a useful pharmacological probe for studying adrenergic innervation.

Remarkably even crude herbal preparations can find a useful niche as pharmacological research tools. While the therapeutic role of ipecacuanha as an emetic in drug poisonings has declined, emesis induced by this herb still has a niche as a useful model for testing the therapeutic activity of new anti-emetic drugs.

Ginseng is an herb, the pharmacological activity of whose extracts and constituents has given a new perspective to drug-activity correlation. The spectrum of activities associated with this herb and its constituents are quite inconsistent with the unidimensional activity patterns so far attributed to drugs. An ancient and time-honoured drug in Chinese medicine, the roots of Panax quinquefolius or ginseng is one of the major botanical drugs of US foreign trade. Containing a complex mixture of steroidal and pentacyclic triterpenoid saponins, the drug acts ‘favourably’ on metabolism, central nervous system (CNS) and endocrine secretions. Thoroughly studied by modern methods of analysis, it is also constituted of groups of high molecular weight polysaccharides and acetylenic compounds and D group vitamins in addition to the major saponins. A baffling array of activities ranging from hypoglycaemic, anti-ulcer, immunomodulatory, anti-tumour to hypotensive effects are reported for its constituents. Employed in Asia for the treatment of anaemia, diabetes, gastritis, sexual impotence, insomnia, neurasthenia, etc., arising from old age, it is also an extremely popular remedy in the recent years in the west for improvement of stamina, concentration, resistance to stress and to disease. The drug is described as an ‘adaptogenic’ since it helps the body adapt to stress in general. The refreshingly new activity profile of this drug has given new research impetus to drugs like ashwagandha used for similar indications in Indian traditional medicine.

As modern science begins to appreciate the complexities of living systems, it is rediscovering principles that may be consistent with oriental insights. For example the medicinal properties of water, its ability to rid the body of disease-permeating factors through a unique residual memory effect has been extensively explained in the verses of Atharvana Veda. These references have been discounted as an extrapolation of the solvent properties of water. However today the concept of water memory proposed by Jacques Benveniste, a French immunologist, though not consistent with currently accepted scientific laws, is published in Nature. This work has gained support from a section of the scientific community open to paranormal claims. With further experimentation it is possible that this claim may be proven right thereby scientifically validating the references in Atharvana Veda.