Forskolin (7 beta-acetoxy-8, 13-epoxy-1 alpha,6 beta,9 alpha-trihydroxy-labd-14-ene-11-one) is the main active ingredient in the Ayurvedic herb Coleus forskohlii. Coleus is a member of the mint family and grows in subtropical areas in India, Burma, and Thialand. Forskolin has been extensively researched in the medical field for use in the treatment of allergies, respiratory problems, cardiovascular diseases, glaucoma, and many other conditions. It has also recently gained popularity as a fat loss agent.

Forskolin is an extract of an Ayurvedic herb that resensitizes cell receptors by activating the enzyme adenylcyclase and increasing the levels of cyclic AMP in cells. Cyclic AMP is an important signal carrier that is necessary for the proper biological response of cells to hormones. It is required for cell communication in the hypothalamus/pituitary gland axis and for the feedback control of hormones, including thyroid, HGH, Cortisol, DHEA, Testosterone, and Melatonin.

Forskolin appears to bypass this need for direct hormonal activation of adenylate cyclase via transmembrane activation. As a result of this activation of adenylate cyclase intracellular cAMP levels rise. The physiological and biochemical effects of a raised intracellular cAMP level include: inhibition of platelet activation and degranulation; inhibition of mast cell degranulation and histamine release; increased force of contraction of heart muscle; relaxation of the arteries and other smooth muscles; increased insulin secretion; increased thyroid function; and increased lipolysis (fat destruction). Recent studies have found forskolin to possess additional mechanisms of action independent of its ability to directly stimulate adenylate cyclase and cAMP dependent physiological responses. Specifically forskolin has been shown to inhibit a number of membrane transport proteins and channel proteins through a mechanism that does not involve the production of cAMP. The result is again a transmembrane signaling that results in activation of other cellular enzymes.

Forskolin causes the arteries to relax. Because this can lower blood pressure, forskolin should not be used in tandem with blood pressure-lowering medications. Forskolin relaxes the bronchial muscles and may dangerously increase the potency or action of certain asthma drugs, including albuterol, theophylline, and beclomethasone. The basic mechanism of action of forskolin is the activation of an enzyme, adenylate cyclase, which increases cyclic adenosine monophosphate (cAMP) in cells. Cyclic AMP is perhaps the most important cell-regulating compound. Once formed it activates many other enzymes involved in diverse cellular functions. Under normal situations cAMP is formed when a stimulatory hormone (e.g., epinephrine) binds to a receptor site on the cell membrane and stimulates the activation of adenylate cyclase. This enzyme is incorporated into all cellular membranes and only the specificity of the receptor determines which hormone will activate it in a particular cell. Forskolin appears to bypass this need for direct hormonal activation of adenylate cyclase via transmembrane activation. As a result of this activation of adenylate cyclase intracellular cAMP levels rise. The physiological and biochemical effects of a raised intracellular cAMP level include: inhibition of platelet activation and degranulation; inhibition of mast cell degranulation and histamine release; increased force of contraction of heart muscle; relaxation of the arteries and other smooth muscles; increased insulin secretion; increased thyroid function; and increased lipolysis. Recent studies have found forskolin to possess additional mechanisms of action independent of its ability to directly stimulate adenylate cyclase and cAMP dependent physiological responses. Specifically forskolin has been shown to inhibit a number of membrane transport proteins and channel proteins through a mechanism that does not involve the production of cAMP. The result is again a transmembrane signaling that results in activation of other cellular enzymes. Research is underway in the attempt to determine the exact receptors to which the forskolin is binding. Another action of forskolin is on antagonizing the action of platelet-activating factor (PAF) by interfering with PAF binding to receptor sites. PAF plays a central role in many inflammatory and allergic processes including neutrophil activation, increasing vascular permeability, smooth muscles contraction including bronchoconstriction, and reduction in coronary blood flow.