Evaluation of antioxidant activities and total phenolic contents of different solvent extracts of selected marine diatoms

Abstract

Antioxidant properties and total phenolic content were evaluated in three different solvent extract of three selected marine diatoms, Chaetoceros curvisetus, Thalassiosira subtilis and Odontella aurita. Diatoms were extracted using methanol, acetone and hexane by a three-step sequential extraction procedure. Total phenol content, and the antioxidant properties such as total antioxidant activity, DPPH radical scavenging activity, nitric oxide radical scavenging activity, hydrogen peroxide radical scavenging activity and ferric reducing power of diatom extracts (methanol, acetone and hexane) were determined. Results showed that total phenolic content and antioxidant properties were higher in methanolic extract of O. aurita. Total phenol content (0.55 ± 0.031 mg/g gallic acid equivalent), total antioxidant activity (0.97 ± 0.044mg/g ascorbic acid equivalent), DPPH radical scavenging activity (15.25%), hydrogen peroxide radical scavenging activity (54.73%), Ferric reducing power assay (1.032 ± 0.031 mg/g ascorbic acid equivalent) and nitric oxide radical scavenging activity were maximum in C. curvisetus (32.37%). Thus, phenolic compounds were not the only major contributor to the antioxidant capacities of these marine diatoms. The microalgae could contain different antioxidant compound than the other plants.