ISSN 2278- 4136 ZDB-Number: 2668735-5 IC Journal No: 8192 Volume 1 Issue 3    Online Available at www.phytojournal.com     Journal of Pharmacognosy and Phytochemistry  Vol. 1 No. 3 2012                                                www.phytojournal.com                                                Page | 40   In vitro Membrane Stabilizing Activity, Total Phenolic Content, Cytotoxic, Thrombolytic and Antimicrobial Activities of Calliandra surinamensis (Wall.) Md. Al Amin Sikder 1 , Md. Shaikhul Millat 2 , Abida Sultana 2 , Mohammad A. Kaisar 1 , and Mohammad A. Rashid 1,* 1. Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Dhaka, Dhaka-1000, Bangladesh.  [E-mail: rashidma@univdhaka.edu]  2. Department of Pharmacy, State University of Bangladesh, Dhaka-1205, Bangladesh Different extractives of leaf of Calliandra surinamensis were evaluated for antimicrobial activity along with membrane stabilizing, thrombolytic and cytotoxic activities. The total phenolic content was also determined and expressed in gallic acid equivalent. The membrane stabilizing activity was assessed by heat and hypotonic solution induced method. In the present studies, the crude methanolic extract (ME) of leaf of C. surinamensis demonstrated strong membrane stabilizing activity, whereas its chloroform (CSF) and pet ether (PESF) soluble fractions revealed moderate membrane stabilizing properties. In brine shrimp bioassay, the aqueous (AQSF) soluble fractions revealed the highest lethality. In antimicrobial screening, the chloroform (CSF) and aqueous (AQSF) soluble fraction demonstrated strong antimicrobial activity against 13 pathogenic microorganisms. The chloroform (CSF) soluble fraction exhibited the highest inhibition against microbial growth having zone of inhibition ranged from 13.0±0.82 mm to 18.3±1.25 mm and maximum zone of inhibition was found 18.3±1.25 mm against Salmonella typhi. In thrombolytic study, the chloroform (CSF) soluble fraction demonstrated mild thrombolytic activity in human blood specimen. Keyword: Calliandra surinamensis, Membrane Stabilizing, Thrombolytic, Antimicrobial. 1. Introduction Botanical medicine or phytomedicine refers to the use of any plant’s seeds, berries, roots, leaves, bark, or flowers for medicinal purposes [1] . Even among prescription drugs, minimum 25% contain at least one compound derived from plants. The percentage might be higher if we include over-the-counter (OTC) drugs [2] . In developing countries, about 75% of the world populations rely on traditional medicine for their primary health care [3] . Worldwide, infectious disease is one of the main causes of death accounting for approximately one-half of all deaths in tropical countries. This is really alarming as it was once believed that we would eliminate infectious disease by the end of the millennium. This can be attributed to the increases in respiratory tract infections and HIV/AIDS. Other contributing factors are an increase in antibiotic resistance in nosocomial and community acquired infections [4] . The antimicrobial screening which is the first stage of antimicrobial drug research is performed to ascertain the susceptibility of various bacteria to