Herbal Remedies and Phytochemicals: Focus on Safety and Toxicological Evaluation

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The use of plants with medicinal properties evolved with man based on the fact that a sound health is essential for survival propelled by day-to-day activities. Man overtime identified useful plants and employed such in the treatment of diverse debilitating conditions. Such folkloric uses of plants were continuously passed from generations to generations orally and documentarily. This transfer of usage and knowledge of medicinal plants has ensured that the application of herbs in the prevention, cure and treatment of various diseases, and enhancement of mental well-being has remained with man. It is estimated that 70-80% of the world’s population depends on herbal remedies for primary health care owing to perceived inadequacy of orthodox medical practice(s) and medicines, and strong believe in the efficacy and safety of herbal remedies. Presently, there is an upsurge in the popularity and patronage of herbal medicines and products both in developing and developed countries. Over the years the list of botanicals with proven efficacy, including Ispaghula, Garlic, Ginseng, Ginger, Ginkgo, St. John’s wort, Saw palmetto etc, has grown and such is the believe of modern science in the traditional use(s) of plants that folkloric use is a strong criterion for the selection of plants for bioactivity-guided fractionation as a means of isolating, characterizing and identifying bioactive phytochemicals. This approach has yielded success with numerous examples of drugs employed in orthodox medicine, including aspirin, atropine, artemisinin, colchicine, digoxin, ephedrine, morphine, physostigmine, pilocarpine, quinine, quinidine, reserpine, taxol, tubocurarine etc, discovered with history of use in traditional medicine as a lead. A number of drugs with enhanced efficacy and safety have also been developed by structural modification of identified phytochemicals. A generally tenable reason for the increase in the patronage and use of botanicals worldwide, apart from assurance of efficacy, is perceived safety. In fact, herbal remedies are promoted to the general public as “natural and absolutely safe”. The reality on ground is that upsurge in patronage coupled with sustained and rigorous publicity as being “completely safe” has generated understandable concern on the safety of herbal remedies and derived phytochemicals. This is especially in view of the adverse effects associated with potentially toxic constituents of plants including aristolochic acids, pyrrolizidine alkaloids, benzophenanthrine alkaloids, lectins, viscotoxins, saponins, diterpenes, cyanogenetic glycosides and furonocoumarins. Pharmacological and toxicological evaluations of medicinal plants are essential for drug development but so much has been done in screening herbal medicines for efficacy based on traditional claims while less emphasis is placed on the issue of safety, as reports of efficacy far outnumber those of toxicity. There is therefore the need to step up the investigation of herbal remedies and phytochemicals for short and long-term toxicity manifestations and ensure the effectual open communication of such findings.

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