Journal of Medicinal Plants Research Vol. 7(12), pp. 706-712, 25 March, 2013 Available online at http://www.academicjournals.org/JMPR DOI: 10.5897/JMPR11.446 ISSN 1996-0875 ©2013 Academic Journals Full Length Research Paper Antioxidant potential and secondary metabolites in Ocimum sanctum L. at various habitats Kandasamy Selvam 1 *, Rathika Rajinikanth 1 , Muthusamy Govarthanan 1, 2 *, Agastian Paul 3 , Thangasamy Selvankumar 1 and Arumugam Sengottaiyan 1 1 Department of Biotechnology, Mahendra Arts and Science College, Kalippatti, Namakkal (Dt), Tamilnadu- 637501, India. 2 Division of Biotechnology, Advanced Institute of Environment and Bioscience, College of Environmental and Bioresource Sciences, Chonbuk National University, Iksan 570 752, South Korea 3 Department of Plant Biology and Biotechnology, Loyola College, Chennai - 600 034. Accepted 3 May, 2011 In this study, the secondary metabolites and antioxidant property of holy basil (Ocimum sanctum Linn.) Plant at various habitats was compared with those of respective callus cultures induced from each explants in in-vitro. The callus cultures were successfully initiated on Murashige and Skoog (MS) medium supplemented with 2,4-dichlorophenoxy acetic acid (2,4-D) (1 mg/L) combined with different concentrations (0.1 to 1.0 mg/L) of kinetin as plant growth regulators. The distribution of flavonoids and phenolic compounds in the plant extracts were analyzed by using Aluminium (III) chloride colorimetric assay with standards. Flavonoids were found in all callus extracts in comparison with wild plant parts at various habitats. In this study, the antioxidant activity of the extracts was evaluated in vitro antioxidant-testing systems. The secondary metabolites of flavonoid and phenolic acid contents of the O. sanctum were studied in different habitats and in-vitro callus culture extract. Among these studies hills and wet land habit plants showed maximum secondary metabolites than the other habitats. The antioxidant potential was studied by dot blot assay. Among these results, we concluded that, the environmental stress factors such as dryness, temperature, salt and soil pH is an essential factor for release of secondary metabolites antioxidant potent of O. sanctum L. Key words: Ocimum sanctum, callus culture, secondary metabolites, antioxidant activity. INTRODUCTION Natural products are important sources for biologically active drugs. There has been an increasing interest in the study of medicinal plants as natural products in different parts of the world (Gazzaneo et al., 2005). Medicinal plants containing active chemical constituents with high antioxidant property play an important role in the prevention of various degenerative diseases (Lukmanul et al., 2008) and have potential benefits to the society. *Corresponding author. E-mail: ksk.selvam@gmail.com. The medicinal value of these plants depends on bioactive phytochemical constituents that produce definite physiological action in the human body. Some of the most important bioactive phytochemical constituents include alkaloids, flavonoids, phenolics, essential oils, tannins and saponins (Krishnaiah et al., 2009). Phenolics are commonly found in medicinal plants and have been reported to have multiple biological effects, including antioxidant activity. Potential sources of antioxidants have been found in leaves, oilseeds, barks and roots (Marija et al., 1999). Natural antioxidants from plant sources are potent and safe due to their harmless nature,