Abstract
The study area, Southwest coast of India (Kollam coast) was recognized as an exclusive habitat for diverse seaweeds. Brown algae constitute one of the abundant seaweed biodiversity in the Kollam coast. In the present study, the brown alga, Lobophora variegata was extracted in methanol and the crude extract was evaluated on different hierarchical organisms including pathogenic bacteria, mosquito pupae, nematodes and plant seeds. The algal extract invariably displayed toxicity in all organisms tested. The magnitude of toxicity against organisms was in the order of bacterial pathogens > mosquito pupae > nematodes > plant seeds. The crude extract was fractionated using different solvent systems and the phyco-constituents of the algal fraction were investigated by Gas Chromatography analysis. The present findings revealed that the column purified fraction of L. variegata extract contains fatty acids which may elicit the activity on test organisms.