Journal of Planar Chromatography 29 (2016) 3 347 Summary Plant metabolite varies with season and geographic conditions. The present study is aimed at the identifcation of the potential chemo- types of Coleus forskohlii, available in the natural habitat of Nil- giri hills and adjoining area, in order to provide a basic lead for the industry concerning commercial exploitability, including the location-specifc commercial cultivation of the plant. The efect of intra-specifc variability in the forskolin content among the popu- lations was estimated using high-performance thin-layer chroma- tography (HPTLC)‒densitometric method. The roots of fourteen naturally occurring populations from the entire hill range were collected, covering the wide topography from foot hills up to the highest peak. The method developed for the quantifcation of for- skolin was validated and found to be linear, specifc, and accurate with precision and accuracy. The limit of detection (LOD) and lim- it of quantifcation (LOQ) were 1.04 and 3.16 ng spot −1 . Precision studies (both inter-day and intra-day) were within the standard limit of relative standard deviation (RSD) (%) less than 3%. The quantifcation of forskolin within the population revealed that it varied from 0.0046 ± 0.0005 (NBC-36) to 1.156 ± 0.003% (NBC- 46). The analysis of variance (ANOVA) suggested that there are signifcant di ferences in forskolin content among the populations. A positive correlation (Karl Pearson) was found between the alti- tude and the forskolin content. The cluster analysis of the popula- tion on forskolin content suspected the presence of two chemotypes. The study suggests the presence of chemotaxonomic variation among the populations which can be due to the change in phyto- geographical factors. P.K. Shukla, A. Misra, M. Kumar, A.K.S. Rawat, and S. Srivastava, Pharmacog- nosy and Ethnopharmacology Division, CSIR ‒ National Botanical Research Institute, Lucknow (U.P.) 226 001, India; S. Rajan, Survey of Medicinal Plants and Collection Unit, Emerald, Nilgiri 643 209, India; and P.K. Agarwal, NASF, ICAR, KAB-II, New Delhi 110 011, India. E-mail: sharad_ks2003@yahoo.com 1 Introduction Coleus forskohlii (Wild.) Briq. (Family: Lamiaceae), com- monly known as “Patharchur”, grows wild in the arid and semi-arid regions of India, Nepal, and Thailand. The roots have been used in various Ayurvedic medicines and cosmetic products and have huge industrial potential. Ethnobotanical studies suggest its usage as a condiment for heart ailments and stomach cramps [1, 2]. It has also been reported for anti-an- aphylactic [3], amoebicidal [4], antiplatelet [5], gastroprotec- tive [6], and antioxidant activities [7]. In the Indian traditional systems of medicine, the roots are recorded in a broad range of ailments, viz., as an anthelmintic agent, furthermore in the management of skin infections and eruptions, in veterinary practice, etc. [8–10]. Forskolin, a labdane diterpenoid, is the active secondary metab- olite of this species. Recent research has shown that forskolin has positive efects against a wide range of conditions such as asthma, glaucoma, hypertension, hair loss, cancer, and obesity [11, 12]. Commercially, a synthetic derivative of forskolin has been approved for cardiac surgeries, heart complications, and vasospasm in mammalian cerebral [13, 14]. A patented appli- cation suggests forskolin in potentiating of lean body mass and management of mood disorders and also as a skin-conditioning agent to support localized fat loss on topical application [15]. It is a unique phytochemical that serves as an adenylate cyclase activator and leads to an increase in the cAMP load in the mam- malian body [16]. The study on the chemical diversity in C. forskohlii has been extensively forwarded, and at present, 68 diferent diterpenoids had been identifed, categorized into abi- etanes and labdanes types with specifc distribution in diferent plant tissues [17, 18]. Recently, it has been reported that for - skolin is accumulated in a specifc type of root cells which are present in the cork area, suggesting its localized biosynthetic pathway [19]. The biosynthesis of the secondary metabolites in plants is not only controlled genetically but it is also strongly afected by diferent biotic and abiotic stresses [20]. These stress conditions afect the production of secondary metabolites and other active ingredients which are usually responsible for their medicinal Intra-Specifc Chemotypic Variability of Forskolin Content in Coleus forskohlii (Wild.) Briq. Growing in Nilgiri Hills of India Pushpendra Kumar Shukla, Ankita Misra, Manish Kumar, Soundararajan Rajan, Pawan Kumar Agrawal, Ajay Kumar Singh Rawat, and Sharad Srivastava* Key Words: Coleus forskohlii Chemotype Forskolin High-performance thin-layer chromatography Phytogeographic variation Journal of Planar Chromatography 29 (2016) 5, 347–355 DOI: 10.1556/1006.2016.29.5.4 0933-4173/$ 20.00 © Akadémiai Kiadó, Budapest