2009 Kyung Hee University Press 200 Oriental Pharmacy and Experimental Medicine 2009 9(2), 200-205 www.opem.org OPEM Secondary metabolites (Triterpenes) from Couroupita guianensis Rokeya Begum 1,† , Mohammad S Rahman 2 , A M Sarwaruddin Chowdhury 1 , Choudhury M Hasan 2 and Mohammad A Rashid 2,3, * 1 Department of Applied Chemistry and Chemical Technology, Faculty of Engineering and Technology, University of Dhaka, Dhaka-1000, Bangladesh; 2 Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Dhaka, Dhaka-1000, Bangladesh; 3 Centre for Biomedical Research, University of Dhaka, Dhaka-1000, Bangladesh Received for publication January 14, 2008; accepted January 07, 2009 SUMMARY The n-hexane and carbon tetrachloride soluble fractions of a methanolic extract of the stem bark of the Couroupita guianensis furnished three compounds, identified as β-amyrin (1), betulin-3β- caffeate (2) and lupeol-3β-caffeate (3). The structures of the isolated compounds were deduced by extensive spectroscopic analysis as well as by comparison with published values. Compounds 1-3 were subjected to antioxidant screening through free radical scavenging activity by DPPH (1,1- diphenyl-2-picrylhydrazyl), where compound 2 showed moderate antioxidant activity with IC value 108.0 µg/ml. Key words: Couroupita guianensis; Lecythidaceae; β-amyrin; Betulin-3β-caffeate; Lupeol-3β-caffeate INTRODUCTION The plant Couroupita guianensis (English name- Cannon ball tree, local names-Nagalingam, Shibalingam) belonging to the family of Lecythidaceae is an evergreen tree and it is planted in road sides of different districts of Bangladesh (Haque, 1986). The plant of this genus is used for treating skin diseases of livestock by the local Indian (Usher, 1984). Various parts of C. guianensis are known to exhibit antifungal activity (Khan et al., 2003). Previous chemical investigations of C. guianensis revealed the occurrences of 6,12-dihydro-6,12-dioxoindolo- [2,1-b]quinazoline (tryptanthrin), indigo, indirubin, isatin (Bergman et al., 1985), couropitone, β-amyrin, β-amyrone, β-amyrin acetate, stigmasterol, ergosta- 4,6,8(14),22-tetraen-3-one, β-sitosterol and its glycoside (Anjaneyulu, 1998; Dictionary of natural products, 2001). This paper details the isolation and structure elucidation of three triterpenoids β-amyrin (1), betulin-3β-caffeate (2) and lupeol-3β-caffeate (3). Although β-amyrin has been previously documented from C. guianensis, this is the first report of occurrence of betulin-3β-caffeate (2) and lupeol-3β- caffeate (3) from this plant. MATERIALS AND METHODS General experimental procedure NMR spectra were acquired by using Ultra Shield Bruker DPX 400 NMR instruments. The 1 H and 13 C *Correspondence: Mohammad A Rashid; Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Dhaka, Dhaka-1000, Bangladesh; Tel: +88028612069, 966190073, Fax: +88028612069; E-mail: rashidma@aitlbd.net, rashid_phdu @yahoo.com † On leave from Department of Agricultural Chemistry, Sher-e-Bangla Agricultural University, Dhaka-1207, Bangladesh. DOI 10.3742/OPEM.2009.9.2.200