Qualitative and quantitative phytochemical analysis of brown seaweed Sargassum polycystum collected from Bangladesh with its antioxidant activity determination

Abstract

Seaweeds possess considerable potential for developing and enhancing pharmaceutical drugs because of their wide variety as abundant sources of numerous bioactive secondary metabolites, making them well-suited for developing and enhancing pharmaceutical drugs. This study evaluated the antioxidant, secondary metabolites, total phenolic content, and total flavonoid content of various crude extracts (methanol, ethanol) and their fractions (50 % and 70 %) of Sargassum polycystum. Fourier transform infrared (FT‐IR) analysis was also performed to identify the active chemical composition of the crude extracts. The results showed that various extracts contained varying concentrations of terpenoid, saponin, phlobatannin, cardiac glycosides, phenolic, and flavonoid. FT-IR analysis confirmed the presence of phenols, carboxylic acid, ketones, ethers, aromatics, amides, and sulfonates. 100 % methanolic extract contained the maximum concentrations of total phenols (80.13 mg of GAE/g) and total flavonoids (38.33 mg of quercetin/g). 100 % methanol extracts exhibited higher antioxidant activity in the DPPH assay (78.32 %, IC50 = 1.59 mg/ml) and ABTS assay (69.82 %, IC50 = 2.39 mg/ml). The bio-functional activity of crude extracts depended on their extract and concentration. The present study demonstrates that the macroalgae S. polycystum contains noteworthy secondary metabolites and natural antioxidants, indicating their potential utilization in various pharmacological and functional food applications.