Evaluation of bioactive chemical composition, phenolic, and antioxidant profiling of different crude extracts of Sargassum coriifolium and Hypnea pannosa seaweeds

Seaweed as a source of functionally bioactive components has been well recognized due to its beneficial effects for human health. However, beneficial health effects of seaweeds vary with the different aspects especially geographical location of the seaweed. In the present study, two seaweeds (Sargassum coriifolium, Hypnea pannosa) were collected from Bangladesh and crude extracts were prepared using methanol, ethanol and water as extraction solvent. Here, we determined preliminary phytochemical composition, total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity of crude extracts using different qualitative and quantitative in vitro assays. Overall, screening of phytochemicals revealed that both the seaweeds contain diverse type bioactive compounds including terpenoid, saponin, phlobatannin, cardiac glycosides, phenolic and flavonoid depending on the seaweed species and extraction solvents used. FT-IR spectroscopy also confirmed the presence of phenols, carboxylic acid, ketones, ethers, aromatics, amides and sulfonates at varying degree. Methanol extract of S. coriifolium and H. pannosa showed highest activity followed by ethanol and water extracts. Here, methanolic extract of S. coriifolium showed highest amount of TPC (128.56 mg of GA/g), TFC (58.29 mg of quercetin/g), DPPH (75.01%, IC₅₀ = 1.03 mg/ml), ABTS (72.24%, IC₅₀ = 1.55 mg/ml), hydrogen peroxide (71.64%, IC₅₀ = 1.98 mg/ml), phosphomolybdenum (28.08 mg of ASE/g) and reducing power assays (938.5208 mg of ASE/g). A positive correlation was found among TPC and different antioxidant assays. These results confirmed the presence of diverse type of chemical composition with its antioxidant activity which will be useful for pharmacological as well as in functional food application.