Abstract

The aquaculture industry commonly makes use of microalgae as live feed. Chaetoceros sp., a diatom, and
Nannochloropsis sp., a unicellular green microalga, have both been reported to contain a substantial amount of
polyunsaturated fatty acids and carotenoids. Their potential as natural sources of antioxidants has gained recent
attention. This study focuses on determining the antioxidant properties of the different solvent extracts, namely
hexane, dichloromethane, chloroform and methanol, from both microalgae. The evaluation of antioxidant
capacities was done by Folin-ciocalteu, 1,1-diphenyl-2-picrylhydrazyl radical-scavenging, metal chelating,
nitro-blue tetrazolium reduction and ferric-reducing antioxidant power assay. Results showed that the non-polar
solvent extracts from the diatom were highest in antioxidant power, whereas both polar and non-polar solvent
extracts of green microalgae showed good antioxidant potential. In general, Chaetoceros sp. had higher
antioxidant capacities than Nannochloropsis sp. This study suggests that different solvent extracts contain
different potential antioxidant compounds able to scavenge different types of free radicals.

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