African Journal of Pharmacy and Pharmacology Vol. 6(25), pp. 1854-1859, 8 July, 2012 Available online at http://www.academicjournals.org/AJPP DOI: 10.5897/AJPP12.277 ISSN 1996-0816 ©2012 Academic Journals Full Length Research Paper Bioactivity potential of extracts from ascidian Lissoclinum fragile N. Sri Kumaran 1 , S. Bragadeeswaran 1 *, T. Balasubramanian 1 and V.K Meenakshi 2 1 Centre of Advanced Study in Marine Biology, Faculty of Marine Science, Annamalai University, Parangipettai - 608 502, India. 2 A. P. C. Mahalakshmi College for Women, Tuticorin - 628 016, Tamil Nadu, India. Accepted 4 June, 2012 Ascidians are marine biofouling animals with a proven ability to synthesis bioactive substances. This study investigated the bioactive potential of ascidian Lissoclinum fragile, found in the coastal waters of Tuticorin Southeast coast of India. Freshly collected ascidian soaked in methanol for five days and filtered through filter paper. The solvent was concentrated by rotary evaporator which reduced the pressure to give a dark brown gummy mass. The collected gummy mass was separately extracted successively with acetone, n-butanol, chloroform, ethyl acetate and dichloromethane. These extracts were used for antimicrobial, heamolytic and cytotoxic assays. In antibacterial assay bacterial pathogen, S. typhi exhibit high zone of inhibition (14.1 ± 0.01 mm) against dichloromethane extract. In antifungal assay, fungal pathogen Penicillium species showed high zone of inhibition (12.3 ± 0.07 mm) against n- butanol extract. In haemolytic assay, n-butanol extract showed high heamolytic activity in chicken erythrocytes (64 HU), goat erythrocytes (16 HU) and cow erythrocytes (16 HU). In cytotoxic activity, n- butanol extract exhibited high LC 50 value (97 μg/ml) against brine shrimps. These results indicate that the ascidian L. fragile has remarkable antimicrobial, haemolytic, and cytotoxic activities. Key words: Ascidian, Lissoclinum fragile, haemolytic and cytotoxic activities, antimicrobial. INTRODUCTION The biodiversity of the marine environment constitute a practically unlimited resource of active substances for the development of natural bioactive products. Of the natural products isolated from marine organisms, less than 1% have been examined for pharmacological activities (Fusetani, 2002). Biological activities that have been frequently observed in marine invertebrate crude extracts include antibiosis against human microbial pathogens, marine microorganisms, and cytotoxicity (Mayer et al., 2007). Many marine invertebrate secondary metabolites have presented both antibiotic and cytotoxic activities as a result of increased research into these bioassays for new drugs (Newman et al., 2003). A large proportion of natural compounds that have been extracted from marine *Corresponding author. E-mail: drpragathi@gmail.com. Tel: +91 4144 243223/269 or +91 9894823364. invertebrates, especially sponges, ascidians, bryozoans, of biologically active compounds, especially amino acid derived nitrogenous secondary metabolites (Rinehart, 2000) and antimicrobial, antiviral, and anti-inflammatory compounds (Davidson, 1993). Although, research on bioactive compounds from ascidians was recently initiated, the first marine natural product entering human clinical trials, Didemnin B, is an ascidian metabolite. Several ascidian compounds in anticancer preclinical or clinical trials include the tetrahydroisoquinolone alkaloid, ‘Ecteinascidin 743’ from Ecteinascidia turbinata; cyclic depsipeptides, ‘Dehydrodidemnin B’ and ‘Didemnin B’ from Trididemnum solidum; cyclic peptide, ‘Vitilevuamide’ from Didemnin cuculiferum; and ‘Diazonamide’, from Diazona angulata (Jain et al., 2008). Potential ascidians need to be explored for pharmaceutical use, and a broad based screening of ascidians for bioactive compounds is necessary. This study evaluates the biological properties from the biofouling ascidian Lissoclinum fragile, collected