Coleus

Botanical Description & Habitat

Coleus forskohlii, C. barbatus

Family
Labiatae

Common Names
Forskolin
Pashana beddhi plant

Habitat
Tropical and subtropical regions; India

Medicinal Parts
The plant, but mainly the root

Historical Properties & Uses

Coleus plants have been a part of Ayruvedic medicine for hundreds of years. Hindu physicians and lay people alike use it as a tonic and panacea: cardiotonic, respiratory stimulant, nervous system tonic, gastrointestinal tonic. Almost important in folk medicine is the urinary disinfectant, diuretic property.

Method of Action

The pharmacology of forskolin
In 1977, a series of diterpenes were isolated from the roots of c. forskohlii which had potent cardiovascular actions. The most potent of these was 7alpha-acetoxy-8, 13alpha-1, 6beta, 9alpha-trihydroxylabd-14-ene-11-one vii which fortunately was reduced the term forskolin.

Within a couple of years it was determined forskolin works by increasing intracellular cyclic AMP concentrations and augment cyclic AMP-dependent protein kinase activity, and this all occurs ultimately because forskolin activates adenylate cyclase.

In recent years, the active components of c. forskohlii, forskolin and celenol, have been intensely studied, with most of the attention going to forskolin. As a consequence of its action on adenylate cyclase, forskolin has been found to have positive inotropic, antihypertensive, and platelet aggregation inhibitory action. Most of the preliminary lab screening and pre-clinical work was concluded by about 1984, and serious clinical trials were set to get under way.

Forskolin activates adenylate cyclase
Most of pharmacology of forskolin can be reduce to one action: the activation of adenylate cyclase in cell membranes to produce cyclic AMP.

The cardiotonic properties mentioned in the preceding paragraph depend on this effect, as do the herb's effects on lipolysis and steroidogensis, on electrolyte secretion by the salivary glands and colon, on the herb's antispasmodic effects, even on its ability to activate post-traumatic nerve regeneration.

Clinical trials on the hypotensive action of forskolin are currently underway.

Forskolin reduces intra-ocular pressure
One of the most intriguing actions of forskolin is the ability to reduce intraocular pressure by reducing the build up of aqueous humor, and by increasing ciliary body flow.

This again depends upon the activation of adenylate cyclase. Clinical trials on the ability of forskolin to reduce the glaucoma are underway in Europe. The results are not yet in.

Colenol produces effects similar to those of forskolin: namely, lowering of blood pressure, positive inotropic effect in small doses, central nervous system depressant effect in large doses.

Drug Interactions & Precautions

Data is not presently available on this topic.

Safety Factors & Toxicity

The effects of forskolin and digitalis may additive. Do not use both together except under the direction of a physician. Some people may experience mild allergic reactions.

Preparation & Administration

Capsule
Use 1 - 4 300mg capsules per day

References

Bhat, et.al. Structures and stereochemistry of new labdane diterpenoids from coleus forskohlii Briq. Tetrahedron Letters, 19, 1669, 1977.

Daly, J. Forskolin, adenylate cyclase, and cell physiology.: An overview. Adv. Cyclic Nucleotide Protein Phosphorylation Res., 17, 81-89, 1984.

Hawthorn, M.H., Chess-Williams, R.C, Grassby, P.F. & Broadley, K.J. The use of forskolin to investigate the site of cardiac beta-adrenoreceptor supersensitivity. Journal of Autonomic Pharmacology, 5(3), 231, 1985.

Kilmer, S.L., R.C. Carlsen, Forskolin activation of adenylate cyclase in vivo stimulates nerve regeneration. Nature, 307, 455- 457, 1984

Metzger & Lidner. The positive inotropic acting forskolin, a potent adenylate cyclase activator. Arzneimittel Forschung, 31, 1248-1250, 1981.

Mowrey, Daniel B., Ph.D. Exper. Psych., Brigham Young University. Director of Nebo Institute of Herbal Sciences. Director of Behavior Change Agent Training Institute. Director of Research, Nova Corp.

Rodger, I.W. & M. Shahid. Forskolin, cyclic nucleotides and positive inotropism in isolated papillary muscles of the rabbit. British Journal of Pharmacy, 81, 151-159, 1984.

Seamon, K.B. & J.W. Daly. Activation of adenylate cyclase by the diterpene forskolin does not require the guanine nucleotide regulatory protein. Journal of Biol. Chem., 256, 9799-9801, 1981.

Seamon, K.B., W. Padgett & J.W. Daly. Forskolin; unique diterpene activator of adenylate cyclase in membranes and intact cells. Proc. Nat. Acad. Sci. USA, 78, 3363, 1981.

Seamon, K.B., Vaillancourt, R., et.al. Binding of <3H>- forskolin to rat brain membranes. Proc. Nat. Acad. Sci.USA, 81, 5081, 1984.