Plectranthus L′ Herit., is a complex genus of the family Lamiaceae (Labiatae) that contains about 300 species distributed in tropical Africa, Asia and Australia [1]. Taxonomically the genera Coleus and Plectranthus are recombined by the Japanese authors to the genus Plectranthus [2]. One of the most important species of this genus is Plectranthus barbatus Andr., which is commonly referred to by a number of synonyms such as Plectranthus forskohlii Briq, Plectranthus forskalaei Willd., Plectranthus kilimandschari (Gürke) H. L. Maass., Plectranthus grandis (Cramer) R. H. Willemse, Coleus forskohlii Briq., Coleus kilimandschari Gürke ex Engl., Coleus coerulescens Gürke, Coleus comosus A. Rich., and Coleus barbatus (Andr.) Benth [1]. Plectranthus barbatus grows perennially over the tropical and subtropical regions of the Indian subcontinent and is cultivated commercially for its use in pickles. It is also distributed over parts of Pakistan, Sri Lanka, tropical East Africa, Asia (South of Arabian Peninsula, China) and Brazil [3-5]. P. barbatus is one of the most commonly used medicinal species of the genus Plectranthus. A diversity of traditional medicinal uses of P. barbatus in India (Hindu and Ayurvedic medicine), East and Central Africa, China, and Brazil have been reported. The majority of uses are for intestinal disturbance and liver fatigue, respiratory disorders, heart diseases and certain central nervous system disorders [1, 3, 4, 6, 7]. P. barbatus root extracts, such as the 50% ethanolic and methanolic extracts were therefore, in the middle of the 1970s, independently involved in screening programs for biological activities such as cardiovascular properties in the Central Drug Research Institute (CDRI), Lucknow, India, and by the group at Hoechst India Limited in Bombay, India. Reports from both research groups revealed the hypotensive and antispasmodic effects of the root extracts as well as the isolation of the major active principle which was named coleonol by CDRI [

Pharmacology ! Plectranthus barbatusStudies on several extracts with various polarities obtained from different parts of P. barbatus revealed a number of pharmacological properties that may justify most of the traditional uses of P. barbatus, for example, organic extracts were reported to possess anti-inflammatory, antimicrobial [1, 2], antioxidant [3], cytotoxic [4], hypotensive [5,6], spasmolytic [7], hepatoprotective [8] and antifeedant [9] activities as well as activity against Ehrlichʼs ascites tumor in mice [10]. An alcoholic extract of the P. barbatus roots was shown to exhibit marked inhibitory action against Escherichia coli toxin-induced secretory response in rabbits and guinea pig ileal loops [11]. It has been shown that a hydroalcoholic extract of P. barbatus (880 mg/kg/day) exerted a variety of toxic effects on the different periods of pregnancy in rats; for example, in the period before embryo implantation, it caused a delay in fetal development and anti-implantation and, after embryo implantation, a delay in the development associated with maternal toxicity [12]. The water extract of P. barbatus leaves was found to exert hypoglycemic, hypotensive and antispasmodic activities [13]. It has been demonstrated that the water extract (WE) of the stems and leaves, at a dose of 1 g/kg p. o., shortened the sleeping time induced by pentobarbital by 37 %, and at a dose of 2 g/kg p. o. enhanced the intestinal transit of charcoal by 30% in mice. The WE (2 g/kg/intraduodenal) also reduced the gastric secretions (3.9 ± 1.0 to 0.5 ± 0.2 mL/4 h), and total acid secretion (34.4 ± 11.0 to 2.7 ± 0.5 mEq/L) and raised gastric pH (2.2 ± 0.3 to 6.5 ± 0.8) in rats. The treatment with WE (2 g/ kg p. o.) was also found to protect against lesions induced by ethanol or cold-restraint stress, in pylorus-ligated rats [14]. Similar results were obtained by Schultz et al. [15] who reported that the WE of the leaves (0.5-0.1 g/kg) injected into the duodenal lumen decreased the volume (62 and 76 %) and total acidity (23 and 50%) of gastric Abstract ! Plectranthus barbatus Andr. is one of the most important species of the genus Plectranthus L′ Herit. (Lamiaceae), with a wide variety of traditional medicinal uses in Hindu and Ayurvedic traditional medicine as well as in the folk medicine of Brazil, tropical Africa and China. The plant has therefore been an attractive target for intensive chemical and pharmacological studies up to now. This review presents data about the phytochemistry, ethnobotanical uses and pharmacology of Plectranthus barbatus as well as the pharmacology of its constituents. In addition to essential oil, abietane diterpenoids and 8,13-epoxy-labd-14-en-11-one diterpenoids are the main constituents found in Plectranthus barbatus. The major ethnobotanical uses are for intestinal disturbance and liver fatigue, respiratory disorders, heart diseases and certain nervous system disorders. Forskolin as one of the major constituents with its unique adenylyl cyclase activation that underlies the wide range of pharmacologic...

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