Biochemical Systematics and Ecology 32 (2004) 665–674 www.elsevier.com/locate/biochemsyseco Chemical analysis and biological activities of the essential oil of Teucrium leucocladum Boiss. (Lamiaceae) Assem M. El-Shazly a, , Karam T. Hussein b a Faculty of Pharmacy, Department of Pharmacognosy, Zagazig University, Zagazig, Egypt b Faculty of Science, Department of Zoology, Zagazig University, Zagazig, Egypt Received 17 August 2003; accepted 20 December 2003 Abstract The chemical composition of the water-distilled essential oil and n-hexane–ether extract of Teucrium leucocladum Boiss. were determined by GLC and GLC–MS. Altogether 72 com- pounds were identified. The sesquiterpene alcohols, patchouli alcohol (31.24% and 29.66%) and a-cadinol (9.29% and 21.54%) were the main components in the oil and the extract, respectively. a-Cadinol was isolated and characterized using MS, 1 H- and 13 C-NMR spectral analyses. Furthermore, the oil and the extract were tested for their bacterostatic and anti- fungal activities; they showed broad and potent activity against Pseudomonas aeruginosa, Bacillus subtilis and Candida albicans. A marked larvicidal activity of the essential oil, n- hexane–ether extract and crude ethanolic extract was also observed against Culex pipiens, Musca domestica and Ceratitis capitata larvae. # 2004 Published by Elsevier Ltd. Keywords: Teucrium leucocladum; Lamiaceae; Essential oil; n-Hexane–ether extract; Patchouli alcohol; a-Cadinol; Larvicidal; Antimicrobial 1. Introduction The cosmopolitan genus Teucrium (Lamiaceae) comprises approximately 100 species, which occur in the Mediterranean region (Boulos, 2002). Many Teucrium species are known for their medicinal utilisation and exhibit interesting biological  Corresponding author. Fax: +20-55-2303266. E-mail address: assemels2002@yahoo.co.uk (A.M. El-Shazly). 0305-1978/$ - see front matter # 2004 Published by Elsevier Ltd. doi:10.1016/j.bse.2003.12.009