In vitro antiplasmodial activity of marine sponge Stylissa carteri associated bacteria against Plasmodium falciparum

ObjectiveTo identify the possible antiplasmodial drugs from bacteria associated with marine sponge Stylissa carteri (S. carteri).MethodsThe 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 μ g/mL) from isolated bacterial strains were screened for antiplasmodial activity against Plasmodium falciparum (P. falciparum) and potential extracts were also screened for biochemical constituents.ResultsTwelve samples of S. carteri were collected and subjected for enumeration and isolation of associated bacteria. The count of bacterial strains were maximum in November 2007 (34 × 104 CFU/g) and the average count was maximum during the monsoon season (203 × 103 CFU/g). Thirty two morphologically different bacterial strains were isolated from S. carteri and the ethyl acetate bacterial extracts were screened for antiplasmodial activity against P. falciparum. The antiplasmodial activity of a strain THB17 (IC50 20.56 μ g/mL) extract is highly comparable with the positive control chloroquine (IC50 19.59 μ g/mL) and 13 bacterial extracts which showed IC50 value of more than 100 μ 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 strains 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 strains.ConclusionsThe ethyl acetate extract of THB17 possesses lead compounds for the development of antiplasmodial drugs.