Natural products of plant origin as anticancer agents.

Natural products have been used as effective remedies for the treatment of various ailments. Numerous plant products in the form of decoction, tincture, tablets and capsules have been clinically used for the treatment of different kinds of cancer. This review covers some of the important plants with clinically proven anticancer activity, including Catharanthus roseus, Podophyllum peltatum, Taxus brevifolia, Camptothecin acuminata, Cephalotaxus harringtonia, Viscum album, Onchrosia elliptica, Annona bullata, Asmina triloba and Rhizoma zedoariae. Synthetic analogues in some cases have also been prepared to improve the efficacy and decrease the side effects of parent compounds. The modes of action of clinically used drugs are also delineated.