- Plant kingdom has been a time-tested source of drugs, considering the fact that plant-derived natural products represent a large proportion of drugs in clinical use. Despite this, it is a fact that about 85% of the existing 250,000–500,000 species of higher plants have not been so far surveyed for biological activity.
- Despite spectacular advances in extraction technology, separation science, analytical instrumentation not much is known about the SM composition of most of the world’s higher plants. 5–15% of plants that have been surveyed so far have been screened mostly for a single type of biological activity. Hence, plant SMs being genus or even species specific, a huge resource of undiscovered and potentially useful drugs are yet to receive scientific attention. For example, more than half of the plants in the tropics that contain most of the world’s plant species have never been phytochemically studied. It is estimated that the chemistry of 99% of the plant species comprising the vast flora of the Brazilian rainforest remains unknown.
- This limited scientific study on higher plants is especially a serious concern considering the current rate of extinction and decimation of tropical floras and ecosystems.
- One of the first drug plants to be rendered extinct in the ancient world was Silphium (Ferula sp.), a birth-control agent highly valued by ancient Romans. Its employment as a contraceptive was so widespread that this difficult-to-cultivate plant no longer existed in the Mediterranean area or anywhere else, after 3rd century AD.
- Many unrecorded valuable medicinal plants like ‘soma’ mentioned by legendary Ayurvedic physicians such as Charaka have been unavailable ever since prehistoric times, so much so they are considered mythical plants.
- Climate change, increasing population making demands on land and resources, as well as commercial exploitation of the environment all play a part in this and result in loss of habitats.
- Today tropical rainforests are under threat of such habitat destruction. Several species endemic to biodiversity ‘hotspot’ areas—said to represent 44% of all vascular plant species and 35% of all vertebrate species in about 1.4% of the earth’s surface—are threatened with extinction due to massive habitat loss.
- Some 400 medicinal plants including Taxus sp.ecie, Hoodia sp.ecie (e.g. Hoodia gordonii used as appetite suppressant in Namibia), many magnolia species (ancient genus under Magnoliaceae), crocus species (source of valuable saffron) have been identified as being at risk of extinction from over collection and deforestation as per a 2008 report from the Botanic Gardens Conservation International—a consortium representing botanic gardens across 120 countries.
- Global boom in exploiting plant resources for newer drugs has brought up several issues related to farming practices. For example, ginseng is being field farmed to produce enough ginseng to meet rising demand. Unlike wild-growth ginseng, field-raised ginseng is susceptible to fungus, making fungicide contamination of the drug a problem to be dealt with. Sandalwood, echinacea, black cohosh, which are to be collected from root/wood growth often in excess of 50 years, are now being collected from younger trees. It is not known if the same medicinal effect will be ensured in these.
- Not much time is left before the disappearing flora could be adequately catalogued and studied. We are losing out on the significant opportunity of surveying our plant resources for therapeutically useful compounds. The imminent extinction or increasing rarity of species is thus a loss of potential new drugs in the coming years.
- Another disturbing fallout of biodiversity erosion is the irretrievable loss of basic affordable or valuable medicines of local inhabitants and ethnic groups of these biodiversity regions.
- While disappearance of the world’s biodiversity and habitats is a serious issue being realized world over, not much attention is being paid to the imminent loss of local traditional medical knowledge which may not last long.
- Apart from disturbance of ecosystems due to overexploitation and climate change, breakdown of traditional living patterns, urbanization and westernization of societies is leading to irretrievable loss of ethnomedical knowledge systems.
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