Evaluation of the antioxidant and cytotoxic activities of crude extracts from marine Chlorella sp.

The potential usage of Chlorella as an emerging source of novel and safe pharmacologically important compounds sparked scientists’ interest currently due to its numerous bioactive properties, like anticancer, antioxidant, anti-inflammatory, and anti-microbial. Bioactivities from freshwater Chlorella have been studied previously. However, those isolated from marine water have been poorly investigated. Therefore, this study was undertaken to explore the antioxidant activity and cytotoxicity of the marine Chlorella sp. extracts isolated from the Malaysian coastal area. The result showed that methanolic extract was found the most efficient one among seven solvents of different polarities, resulting in the highest extraction yield (41%), TPC (13.32 ± 0.93 mg GAE/g extract), and TFC (40.35 ± 1.26 mg QE/g extract). In terms of antioxidant activity, methanol extract showed the highest radical scavenging activity that was revealed through DPPH (44.98 ± 2.06 mg TAEC/g extract) and ABTS (33.15 ± 1.50 mg TAEC/g extract) assays. This crude methanolic extract also reduced the viability of (32.07 ± 4.54%) human breast cancer, MCF-7 cells at 100 μg/ml after 48 h of incubation. GC/MS analysis of methanolic extract disclosed the abundance of diterpene and fatty acid esters as the most prevailing metabolites, which are reported to have antioxidant and anticancer properties. This study advocates that marine Chlorella sp. has a promising antioxidant and cytotoxic activity, which could be used as pharmaceuticals and nutraceuticals.