Ancient Hindu Ayurvedic texts described the use of extracts from COLEUS species. An isolated diterpene from COLEUS FORSKOHLII, called forskolin, was demonstrated to be a hypotensive agent with spasmolytic, cardiotonic and platelet aggregation inhibitory activity. It has been shown to be a powerful activator of the enzyme adenylate cyclase in various tissues. Forskolin is thought to act on the catalytic subunit and also on the coupling mechanism of guanine regulatory sites (Ns and Ni) with the catalytic subunit. It is now clear that forskolin elicits physiological responses which have been shown to be cAMP-dependent.