Vol. 7(25), pp. 1886-1893, 3 July, 2013 DOI: 10.5897/JMPR12.1323 ISSN 1996-0875 ©2013 Academic Journals http://www.academicjournals.org/JMPR Journal of Medicinal Plants Research Full Length Research Paper Antibacterial, antioxidant and phytochemical investigation of Thuja orientalis leaves Nakuleshwar Dut Jasuja 1 *, Suresh K. Sharma 2 , Richa Saxena 1 , Jyoti Choudhary 1 , Ramavtar Sharma 2 and Suresh C. Joshi 3 1 Department of Biotechnology and Allied Sciences, Jayoti Vidyapeeth Women’s Univer sity, Jharna, Jaipur -303007, Rajasthan, India. 2 Department of Botany, University of Rajasthan, Jaipur, Rajasthan, India. 3 Department of Zoology, University of Rajasthan, Jaipur, Rajasthan, India. Accepted 30 June, 2013 In the present study, leaves of Thuja orientalis were powdered and extracted by soxhlet extractor in two solvent systems that is, (E 1 ) ethyl acetate: chloroform: ethanol (40: 30: 30) and (E 2 ) methanol: distilled water (70:30). This study conferred the screening of phytochemical constituents, antioxidant activity and antibacterial activity of crude E 1 and E 2 extract and its fractions. Antioxidant activity was carried out by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The results indicate that E 2 extract (70% methanolic extract) had the highest antioxidant effect (85.25% inhibition) at 100 μg/ml concentration and the crude extracts (E 1 and E 2 extract) showed significant (P ≤ 0.05) inhibitory activity against both gram positive and gram negative organisms. It was active against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Agrobacterium tumefaiens. The minimum inhibitory concentrations (MICs) of E 1 extract ranged from 0.40 to 0.85 mg/ml and E 2 extract 0.55 to 1.15 mg/ml. The highest antibacterial potentiality was exhibited by E 2 extract. The fractions also exhibited antimicrobial activity against all the selected microorganisms. The study revealed that T. orientalis is a promising phytomedicine for antioxidant and antibacterial activity. Key words: Thuja orientalis, 2,2-diphenyl-1-picrylhydrazyl (DPPH), extracts, fractions, minimum inhibitory concentrations (MICs). INTRODUCTION Plant derived bioactive substances are good source of medicines that play a significant role for human health and also used against different types of microbial disease (Ateş et al., 2003; Şengül et al., 2005; Nair, 2005; Dülger et al., 2005; Kumar et al., 2006; Mathabe et al., 2006). Plants have great medicinal relevance; infections have increased to a great extent and resistant against anti- biotics become an ever increasing therapeutic problem (Venkatesan and Karrunakaran, 2010). Moreover, in recent years, plant extract and their phytochemicals are getting more importance as they have the great potential sources for microbial and viral inhibitors. A number of researchers have focused their interest to investigate phytochemical constituents of plant for human health (Jasuja et al., 2012a). The bioactive constituents of plants such as tannins, flavonoids (Mandalari et al., 2007), saponins (Avato et al., 2006), terpenoids (Funatogawa et al., 2004) and alkaloids (Navarro and Delgado, 1999) have great antimicrobial activity. Nowadays, research has gained a renewed focus to *Corresponding author. E-mail: nakuljasuja@gmail.com. Tel: +91-9414658277.