ANTIBACTERIAL ACTIVITIES AND BRINE SHRIMP LETHALITY BIOASSAY OF THE CHLOROFORM EXTRACT OF STEM BARK OF CRATAEVA NURVALA BUCH HAM

Antibacterial and cytotoxic activities of the chloroform extract of the stem bark of Crataeva nurvala (Bengali nameBorun; FamilyCapparidaceae) were studied. Antibacterial activity was determined against two Gram positive (Bacillus cereus, Bacillus megaterium,) and four Gram negative (Escherichia coli, Shigella dysenteriae, Shigella sonnei, Shigella boydii) human pathogenic bacteria by disc diffusion method. The range of zone of inhibition of the extract was 8.3 to 22.1 mm. The extract showed no activity against Bacillus megaterium. Brine shrimp lethality bioassay method was used to determine the toxicity of the plant extract and ampicillin trihydrate was used as positive control. The LC50 values of standard ampicillin trihydrate and extract were 11.48 μg/ml and 14.12 μg/ml respectively. In addition serial dilution technique was used to determine the minimum inhibitory concentration (MIC) of the plant extract. The MIC values were recorded 62.5 μg/ml against both Escherichia coli and Bacillus cereus. INTRODUCTION: The frequency of life threatening infections caused by pathogenic micro-organisms has increased worldwide and is becoming an important cause of morbidity and mortality in immunocompromised patients in developing countries . Although huge number of antimicrobial agents has been discovered, the pathogenic micro-organisms are developing resistance against these agents day by day. In third world countries irrational use of antimicrobial agents is the major cause of such resistance. In recent year, attempts have been made to investigate the indigenous drugs against infectious diseases . Research in the field of indigenous plants is a significant aspect of developing safer antimicrobial principles through isolation, characterization, identification and biological studies. The plant Crataeva nurvala belonging to the family Capparidaceae is a leafy small to medium sized soft wooded tree with fragrant white flowers and oblong to rounded hard fruits, grows on the banks of canals, rivers, lakes etc. It is an evergreen tree growing widely in all parts of Bangladesh, Pakistan, India, Philippine, South America, China, Africa etc . The bark of the tree is an important drug for problem affecting the kidneys and bladder. It is especially effective in the urinary complaints, kidney and bladder stones (inhibit the formation of stones), fever, vomiting and gastric irritation. It also acts as contraceptive and oxytocic; juice of the bark is given to women after childbirth. Barks are also laxative and lithontriptic. They increase appetite and billiary secretion .