Secondary metabolites, antimicrobial, brine shrimp lethality & 4 th instar Culex quinquefasciatus mosquito larvicidal screening of organic & inorganic root extracts of Microcos paniculata.

The present investigation highlights the antimicrobial, toxic & larvicidal activities of the root extracts of Microcos paniculata using various organic & inorganic solvents (methanol, chloroform and water). Antimicrobial, toxicity & larvicidal outcomes were studied by means of agar disc diffusion, brine shrimp lethality bioassay (BSLB) & standard WHO protocol with slight modification. The susceptibility of the microorganisms to the plant extracts was compared with standard antibiotic ciprofloxacin. Root chloroform extract (RCE) revealed a broad spectrum of antimicrobial activity in contrast to other extracts, particularly significant against gram negative bacteria, Vibrio cholerae being the most (zone of inhibition 27 mm).Moreover, the RCE was found to be the most toxic to brine shrimp nauplii, with LC50 of 19.4 μg/ml, whereas anticancer drug vincristine sulphate (VS) proved LC50 value 1.7 μg/ml indicating that there is a possibility of finding potent toxic compounds in this plant have affinity relatively for non- polar solvents. 4 th instar Culex quinquefasciatus larval mortality was observed and recorded after 24 h exposure period. Both the root methanolic extract (RME) & RCE exhibited larvicidal effects with LC50 of 257.3 μg/ml & 267.6 μg/ml respectively. Taken together, these results suggest that the organic fractions, RME & RCE could be potential sources of natural antimicrobial, toxic & larvicidal agents.