Toxicity Concerns of Medicinal Plants

Traditional medicinal systems rely heavily on plants and plant-derived products. Herbal remedies have generally been considered safe and complementary, and alternative medicine is becoming popular day by day. However, due to lack of adequate quality control and information, use of these products may sometimes lead to serious local and systemic toxicities. Various herbal drugs have been reported to produce dermatitis, cardiotoxicity, nephrotoxicity, hepatotoxicity, and nephrotoxicity. Besides, herbal medicines prepared from Ginkgo leaf, St. John's Wort and Asian Ginseng root are also known to interact with conventional drugs producing various adverse reactions such as bleeding disorders, phototoxicity, and mania.

The toxic effects of plants such as Parthenium hysterophorus, Datura stramonium, and Thevetia neriifolia upon accidental exposure and Argemone mexicana and Lathyrus sativus used as adulterants, are well documented. Calotropis procera, a wild-growing tropical plant has been used in some traditional medicinal systems for the treatment of various ailments, including ulcers, piles, and tumours. Experimentally, different parts of this plant have been shown to exhibit anti-inflammatory, anti-microbial, anti-malarial, anti-cancer, antipyretic and analgesic properties. The latex, although known for its medicinal properties, has been found to produce hepatotoxicity at higher doses. Accidental exposure to the latex has also been reported to produce inflammatory reactions such as dermatitis, keratitis, and toxic iridocyclitis. We have demonstrated that such an inflammatory response is mediated through both histamine contained in the latex, as well as by release of histamine from mast cells. In addition, synthesis and release of prostaglandins also contributes to this response. Further, antihistamines are more effective in attenuating the proinflammatory response elicited by the latex as compared to standard anti-inflammatory drugs.

Thus, it is important to study the toxic effects of plant-derived medicinal products, and to have guidelines for their use in therapeutics.