Comparison of Phytochemicals and Antioxidant Activity of the Polysaccharide and de-polysaccharide Methanol Extracts of Brown Seaweed Chnoospora minima

Abstract

Chnoospora minima is a brown alga enriched with unique bioactive compounds which are ideal candidates for pharmaceutical, cosmeceutical and nutraceutical industries. During this study, C. minima was extracted using 80% methanol and de-polysaccharide crude methanol extract was obtained by ethanol precipitation followed by separation of the polysaccharide portion. The crude methanol extract of C. minima and its fractions were subjected to analyse phytochemicals and antioxidant activities. For the assessment of radical scavenging activity, DPPH, FRAP, ABTS+, and ORAC assays were conducted. Ethyl acetate fractions of both polysaccharide (IC50:0.67 ± 0.01 mg/mL) and depolysaccharide (IC50:0.59 ± 0.015 mg/mL) crude methanol extracts exhibited DPPH radical scavenging activity in terms of antioxidant activity. Similarly, the highest level of ORAC, FRAP, and ABTS+ activity was observed in the ethyl acetate fractions of de-polysaccharide (ORAC:19.73 ± 5.31 mg TE/g; FRAP: 20.34 ± 1.72 mg TE/g; ABTS+: 0.06 ± 0001 IC50(mg/ml)) and polysaccharide crude methanol extracts (ORAC:16.22 ± 4.31 mg TE/g; FRAP: 19.23 ± 1.98 mg TE/g; ABTS+:0.08 ± 0.002 IC50(mg/ml)). High TPC was observed in the depolysaccharide crude methanol extract (298.07 ± 0.003 mg GAE/g) and aqueous fraction (141.2 ± 0.002 mg GAE/g) of the polysaccharide crude methanol extract. Highest TFC was observed in both aqueous fractions of depolysaccharide (594.23 ± 0.001 mg QE/g) and polysaccharide (113.46 ± 0.001 mg QE/g) crude methanol extracts. Chloroform fractions exhibited the highest TAC for polysaccharide (2.20 ± 0.45 mg PE/g), and depolysaccharide (2.79 ± 0.31 mg PE/g) samples. Therefore, the depolysaccharide C. minima sample exhibited high level of antioxidant activity along with a high content of phytochemicals which can further be utilized to determine bioactivities that lead to future drug development.