Abstract

Objective: To identify the possible antiplasmodial drugs from bacteria associated with marine sponge Stylissa carteri (S. carteri). Methods: The S. carteri samples were collected from Thondi coast and subjected for enumeration and isolation of associated bacteria. Filter sterilized extracts (100, 50, 25, 12.5, 6.25 and 3.125 毺 g/mL) from isolated bacterial isolates were screened for antiplasmodial activity against Plasmodium falciparum (P. falciparum) and potential extracts were also screened for biochemical constituents. Results: Twelve samples of S. carteri were collected and subjected for enumeration and isolation of associated bacteria. The count of bacterial isolates were maximum in November 2007 (34暳 104 CFU/g) and the average count was maximum during the monsoon season (203暳 103 CFU/g). Thirty two morphologically different bacterial isolates were isolated from S. carteri and the ethyl acetate bacterial extracts were screened for antiplasmodial activity against P. falciparum. The antiplasmodial activity of a isolate THB17 (IC 50 20.56 毺 g/ mL) extract is highly comparable with the positive control chloroquine (IC50 19.59 毺 g/mL) and 13 bacterial extracts which showed IC 50 value of more than 100 毺 g/mL. Statistical analysis reveals that, significant in vitro antiplasmodial activity (P<0.05) was observed between the concentrations and time of exposure. The chemical injury to erythrocytes showed no morphological changes in erythrocytes by the ethyl acetate extract of bacterial isolates after 48 h of incubation. The in vitro antiplasmodial activity might be due to the presence of reducing sugars and alkaloids in the ethyl acetate extracts of bacterial isolates. Conclusions: The ethyl acetate extract of THB17 possesses lead compounds for the development of antiplasmodial drugs.

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