1,9-dideoxyforskolin from Coleus forskohlii (forskolin), a highly oxygenated labdane diterpenoid is an activator of adenylate cyclase. An extract of the plant Coleus forskohlii has been used for centuries in Ayurvedic medicine to treat various diseases such as hypothyroidism, heart disease, and respiratory disorders. Preliminary studies have shown that forskolin can increase fat metabolism thus reduce fat accumulation in both animals and humans. Coleus forskohlii extract and forskolin extract were investigated for treatment obesity and in preventing asthma attacks in patients with mild persistent or moderate persistent asthma. Extracted from the aerial parts of Coleus forskohlii forskolin was also found to be active against HIV(NL4-3). Forskolin can be synthesized in 12 steps (12% overall yield) from ptychantin A, which has been isolated from liverwort Ptychanthus striatus and is a widely used as a biochemical tool. It activates adenyl cyclase, thereby increasing intracellular concentration of cAMP and thus activating the protein kinase A (PKA) signal transduction pathway. PKA-dependent and -independent effects of forskolin on the expression of drug-metabolizing enzymes in liver suggested that herbal therapy with C. forskohlii extract should be approached cautiously due to the potential for herb-drug interactions in patients on combination therapy.