Coleus forskohlii (POIR.) BRIQ.

Family : Lamiaceae

Synonym(s) : Coleus barbatus (Andr.) Benth., Coleus vettiveroides Jacob, Plectranthus comosus Sims, Plectranthus forskohlii auct., Plectranthus forskohlii Willd.

English Name : Coleus

Description

An aromatic perennial, with tuber-like roots and an erect stem reaching 60 cm. The roots are thick, tuberous, fasiculated, upto 20 cm long and 0.5-2.5 cm thick; conical, fusiform, straight and strongly aromatic. Leaves Usually pubescent, narrowed into petioles. Flowers very showy bluish to pale lavender coloured . Racemes are perfect; the calyx is fine toothed and deflexed in the front. Ovary four parted.

Habitat

Hilly arid areas of Gujarat temperate Himalayas and parts of Bihar.

Parts Used : Leaf and root

Herb Effects

Stimulates the central nervous system and adenyl cyclase activity, hypothermic, alleviates spasms and dilates bronchial tubes (root).

Active Ingredients

Forskolin, cleosol, barbatusin, coleol, coleonone, coleforsine and crocetindialdehyde (diterpenoids of root; forskolin is major one).

Medicinal Use

Stomach problems (leaf) and as a tonic (root); treat dyspepsia, indigestion, dysentery, vomiting, thirst fever, dermatitis, psoriasis, ulcer bleeding diseases, obesity, asthma and pediatric disorders like diarrhoea, thirst, vomiting and fever (plant).

Clinical Indications

Intracellular cAMP levels are decreased in numerous diseases, including asthma, cardiovascular disease, eczema, psoriasis, hypertension, angina, and obesity; forskolin's ability to elevate cAMP has been shown to be of benefit in these circumstances.

Cardiovascular Disease

Both animal and clinical studies demonstrate forskolin significantly lowers blood pressure via relaxation of vascular smooth muscle. (7,9,11,13) In a small study of seven patients with dilated cardiomyopathy, intravenous forskolin administered at 3 [micro]g/kg/minute significantly reduced diastolic blood pressure (17%) without increasing myocardial oxygen consumption; left ventricular function also improved. (9) In a similar study (patient sample size not available), 4 [micro]g/kg/ minute of intravenous forskolin given to dilated cardiomyopathy patients resulted in decreased vascular resistance and a 19-percent improvement in left ventricle contractility. Heart rate increased an average of 16 percent in study patients. Subjects also exhibited a 20-percent reduction in arterial pressure accompanied by symptomatic flush. (13) Forskolin's ability to inhibit platelet aggregation is of additional benefit in cardiovascular disease. (2,14)

Asthma and Allergies

Asthma and other allergic conditions are characterized by decreased cAMP levels in bronchial smooth muscle, as well as high levels of PAE In response to allergenic stimuli, mast cells degranulate, histamine is released, and bronchial smooth muscle contracts. Forskolin's activation of cAMP inhibits human basophil and mast cell degranulation, (12) resulting in subsequent bronchodilation. (10) Research has demonstrated aerosolized dry forskolin powder results in significant relaxation of bronchial muscles and relief of asthma symptoms. In one randomized, double-blind, placebo-controlled trial, 16 asthma patients were given a single inhaled (aerosolized) 10-mg dose of dry forskolin powder, an asthma medication (0.4 mg fenoterol), or placebo. Both fenoterol and forskolin administration resulted in significant, equivalent bronchodilation, but patients taking fenoterol experienced marked finger tremor response and a decrease in plasma potassium levels. These side effects were not observed in patients receiving forskolin. (5)

Psoriasis

Like asthma, psoriasis is characterized by decreased levels of cAMP in the skin in relation to another regulating substance, cyclic guanosine monophosphate (cGMP). This imbalance results in a much higher rate of cell division--1,000 times greater than normal, resulting in psoriatic outbreaks. Although study details are not available, Ammon et al reported an improvement in symptoms of psoriasis in four patients supplemented with forskolin. The ability of forskolin to regulate cAMP levels in skin cells has been shown to have therapeutic benefit for sufferers of psoriasis. (3)

Glaucoma

While there are no clinically proven alternative therapies for glaucoma, there are several treatments that may be beneficial and coleus is one of them. Clinical studies have shown that topical application of one percent forskolin eye drops resulted in significant decreases in intraocular pressure for up to five hours. Limited clinical experience suggests that oral forskolin appears to offer significant potential for sufferers of glaucoma. An Indian pharmaceutical company is currently engaged in clinical trials of a forskolin eye drop product.

Cancer Metastases

Many metastasizing tumor cell lines induce platelet aggregation both in vitro and in vivo. Upon aggregation, platelets release substances that promote tumor growth. (8) Researchers have demonstrated forskolin's ability to block platelet aggregation via its stimulation of platelet adenylate cyclase and increase of intracellular cAME (14) Agarwal and Parks gave 82 [micro]g forskolin to mice 30-60 minutes prior to injection with a highly metastatic melanoma cell line (B16 F10). Forskolin reduced tumor colonization in the lungs by 70 percent. (1)

Obesity and Weight Loss

In a recent study, six overweight women took 25 mg of coleus (250 mg capsules of 10% standardized forskolin extract) twice daily for eight weeks. At the end of the eight-week trial, the participants lost a mean of ten pounds, and reduced their percentage of body fat by nearly 8%. Blood pressure levels also trended lower during the trial. (4)


Dosage

Extract: 50-100 mg of standardized coleus extract two to three times per day/15% forskolin.

Contraindication

Caution should be taken when combining this herb with blood-pressure medications and "blood thinners."

Reference

1. Agarwal KC, Parks RE Jr. Forskolin: a potential antimetastatic agent. Int J Cancer 1983;32:801-804

2. Agarwal KC, Parks RE Jr. Synergistic inhibition of platelet aggregation by forskolin plus PGE1 or 2-fluoroadenosine: effects of 2',5'-dideoxyadenosine and 5'-methylthioadenosine. Biochem Pharmacol 1982;31:3713-3716.

3. Ammon HP, Muller AB. Forskolin: from an Ayurvedic remedy to a modern agent. Planta Med 1985;6:473-477

4. Badmaev V, Majeed M, Conte A, Parker JE. Diterpene forskolin: a possible new compound for reduction of body weight by increasing lean body mass. Townsend Lett 2001;June: 115.

5. Bauer K, Dietersdorfer F, Sertl K, et al. Pharmacodynamic effects of inhaled dry powder formulations of fenoterol and colforsin in asthma. Clin Pharmacol Ther 1993;53:76-83.

6. Chandel et al., Biodiversity in Medicinal and Aromatic Plants in India.

7. Dubey MP, Srimal RC, Nityanand S, Dhawan BN. Pharmacological studies on coleonol, a hypotensive diterpene from Coleus forskohlii. J Ethnopharmacol 1981;3:1-13.

8. Kim HK, Song KS, Chung JH, et al. Platelet microparticles induce angiogenesis in vitro. Br J Haematol 2004;124:376-384.

9. Kramer W, Thormann J, Kindler M, Schlepper M. Effects of forskolin on left ventricular function in dilated cardiomyopathy. Arzneimittelforschung 1987;37:364-367.

10. Lichey I, Friedrich T, Priesnitz M, et al. Effect of forskolin on methacholine-induced bronchoconstriction in extrinsic asthmatics. Lancet 1984:2:167.

11. Lindner E, Dohadwalla AN, Bhattacharya BK. Positive inotropic and blood pressure lowering activity of a diterpene derivative isolated from Coleus forskohlii: forskolin. Arzneimittelforschung 1978;28:284-289.

12. Marone G, Columbo M, Triggiani M, et al. Forskolin inhibits the release of histamine from human basophils and mast cells. Agents Actions 1986;18:96-99.

13. Schlepper M, Thormann J, Mitrovic V. Cardiovascular effects of forskolin and phosphodiesterase-III inhibitors. Basic Res Cardiol 1989;84:S197-S212.

14. Siegl AM, Daly JW, Smith JB. Inhibition of aggregation and stimulation of cyclic AMP generation in intact human platelets by the diterpene forskolin. Mol Pharmacol 1982;21:680-687.