Antioxidant properties of phlorotannins from brown seaweed Cystoseira trinodis (Forsskål) C. Agardh

The antioxidant potential of the crude extract and different fractions of Cystoseira trinodis collected from Mandapam coast was determined using total antioxidant capacity and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity. The dichloromethane (DCM) fraction isolated from crude methanolic extract by different solvent extractions exhibited prominent antioxidant activity. The DCM fraction was further fractionated with column chromatography to yield 45 fractions. All the column-purified fractions were subjected to thin-layer chromatography, leading to the production of 7 fractions. The antioxidant activities of crude methanolic extract and subfractions were evaluated. The F5 fraction exhibited higher total phenol content and antioxidant properties. Thin-layer chromatography and UV spectral analysis revealed that all subfractions contained phenolic compounds especially phlorotannins. To the best of our knowledge, the present study is the first report on the isolation and purification of phlorotannins from the brown seaweed C. trinodis from India. Further phytochemical research is needed to identify the active principles responsible for the antioxidant activity. The results can be extrapolated to clinical studies.