Antibacterial activity in the accessory nidamental gland extracts of the Indian squid, <i style="">Loligo duvauceli</i> Orbigny

Abstract

Antibacterial activity of accessory nidamental gland-butanol extracts from the Indian squid <i style="">Loligo duvauceli</i> in different stages of maturity was studied. The activity was evaluated by disc-diffusion method using five strains of bacteria. The extracts from ripe stage ANG showed antibacterial activity against gram negative bacterial strains, <i style="">Escherichia coli</i> and <i style="">Pseudomonas aeruginosa</i>, and gram positive bacteria, <i style="">Staphylococcus aureus.</i> Immature and spent gland extracts did not show any antibacterial activity. Spectrophotometric analysis of the ripe gland extract showed the maximum absorbance at 498.5 nm. This infers the presence of carotenoid pigments which impart the orange red colour to the ripe glands. Thin layer chromatography of the ANG-butanol extract revealed the presence of lipid components such as phospholipids, cholesterol, free fatty acids, triglycerides, fatty acid esters, and cholesteryl esters.<b style=""> </b>The total free fatty acid content was significantly higher in the ripe ANG (16.0 ± 0.143 mg oleic acid/g tissue), in comparison to the immature ANG (10.3 ± 0.114 mg oleic acid/g tissue). Gas chromatographic studies of immature and ripe stages revealed the presence of a mixture of fatty acids. The major unsaturated fatty acids content in the ripe stage was 1.973 mg/gm tissue, whereas in immature stage it was only 0.251 mg/g tissue. Significantly higher levels of unsaturated fatty acids in the ripe stage could be the factor responsible for the antibacterial activity of the ANG-butanol extract.