Natural product to modern discovery of their active ingredients and eventually to the development of new drugs. A large number of currently prescribed drugs have been either directly derived from or inspired by natural products. A few representative examples are listed below. Some of the oldest natural product based drugs are analgesics. The bark of the willow tree has been known from antiquity to have pain relieving properties. This is due to presence of the natural product salicin which in turn may be hydrolyzed into salicylic acid. A synthetic derivative acetylsalicylic acid better known as aspirin is a widely used pain reliever.
Moronic acid Moronic acid Moronic acid (3-oxoolean-18-en-28-oic acid) is a natural triterpene. Moronic acid can be extracted from "Rhus javanica", a sumac plant traditionally believed to hold medicinal applications. The molecule has also been extracted from Mistletoe ("Phoradendron reichenbachianum"). Bevirimat, a derivative of the related triterpenoid betulinic acid, is under development as an anti-HIV drug; however, moronic acid has shown better antiviral profiles "in vitro" than bevirimat. A particular moronic acid derivative showed potent anti-HIV activity with EC values of 0.0085 μM against NL4-3, 0.021 μM against PI-R (a multiple protease inhibitor resistant strain), and 0.13 μM against FHR-2 (an HIV strain