Fitoterapia 75 (2004) 355–359 0367-326X/04/$ - see front matter  2004 Elsevier B.V. All rights reserved. doi:10.1016/j.fitote.2003.12.024 Short report Cytotoxicity and antibacterial activity of extractives from Wedelia calendulacea A.K.M. Mottakin , R. Chowdhury , M.S. Haider , a b a K.M. Rahman , C.M. Hasan , M.A. Rashid * b b b, Department of Applied Chemistry and Chemical Technology, University of Dhaka, Dhaka 1000, a Bangladesh Phytochemical Research Laboratory, Faculty of Pharmacy, University of Dhaka, Dhaka 1000, b Bangladesh Received 22 January 2003; accepted 11 December 2003 Abstract The cytotoxicity and antibacterial activity of petroleum ether, chloroform and methanol extracts of Wedelia calendulacea were assayed by brine shrimp lethality bioassay and standardized disk diffusion method against 19 bacterial strains. Three diterpenes isolated from the plant were also evaluated for in vitro antibacterial activities. The LC for the crude 50 extracts against the brine shrimp nauplii were found to be 4.59 mgyml, 7.99 mgyml and 14.88 mgyml, respectively, whereas the positive control, vincristine sulfate showed an LC 50 of 0.58 mgyml. Among the crude extracts and pure compounds tested, (y)-kaur-16-en-19- oic acid isolated from the chloroform extract showed the highest inhibitory activity against most of the bacterial strains with mean zone of inhibition of 10–21 mm at 200 mgydisc.  2004 Elsevier B.V. All rights reserved. Keywords: Wedelia calendulacea; Compositae; Diterpenes; Cytotoxicity; Antibacterial activity Plant. W. calendulacea Less., collected from Dhaka in June 1999 and identified by Professor M. Salar Khan, Ex-Research Consultant, Bangladesh National Herbarium where a voucher specimen is maintained under the accession number, DACB-23274. *Corresponding author. Tel.: q880-2-9661900-20x6062; fax: q880-2-8615583. E-mail address: rashidma@aitlbd.net (M.A. Rashid).