COLEUS (PLECTRANTHUS BARBATUS) – A MULTIPURPOSE MEDICINAL HERB

Abstract

Plectranthus barbatus Andr. (Syn. Coleus forskohlii Briq.) is a perennial herb, belonging to the family Lamiaceae. Its tuberous roots are found to be a rich source of forskohlin (coleonol) used as a potential drug for hypertension, congestive heart failure, eczema, colic, respiratory disorders, painful urination, insomnia, and convulsions. Clinical studies of the plant further support these traditional uses, indicating therapeutic benefit in asthma, angina, psoriasis and prevention of cancer metastases. Forskolin directly activates almost all hormone sensitive adenylate cyclases in intact cells, tissues and even solubilised preparation of adenylate cyclase. Stimulation of adenylate cyclase is thought to be the mechanism by which forskolin relaxes a variety of smooth muscles. Forskolin, by increasing cAMP level in turn, inhibits basophil and mast cell degranulation and histamine release, lowers blood pressure and intraocular pressure and it inhibits platelet aggregation, promotes vasodilation, bronchodilation, and thyroid hormone secretion. Coleus acts as a natural source of drug for many major diseases implying that there is a great demand for production and processing of the crop. The paper deals with botany, medicinal uses, phytochemistry, mechanism of action and case studies on coleus.