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Description
Seaweeds are one of the important living resources of the marine environment. The marine red seaweed Kappaphycus alvarezii is primarily grown in Sri Lanka and has given valuable bioactive compounds; however, its biochemical importance remains unknown. The bioactive properties, including antioxidant, antidiabetic, antibacterial, and anti-inflammatory activities of 70% methanolic extract of K. alvarezii were investigated using an in vitro method. The extract yield of seaweed K. alvarezii was 22.16 ± 0.49 %. Total phenolic and flavonoid contents were 0.99 ± 0.03 mg GAE/g extract and 0.40 ± 0.06 mg RE/g extract, respectively. Methanolic extract of K. alvarezii showed antioxidant activities, including DPPH scavenging (IC50: 10.48 ± 0.22 mg/ mL), total antioxidant (3.16 ±0.06 mg AAE/g extract), reducing ability (1.67 ± 0.02 mg AAE /g extract), and H2O2 scavenging activity (IC50: 2.06 ±0.07 mg /mL). Antidiabetic potential of K. alvarezii was measured in terms of inhibition of alpha-amylase activity with an IC50 value of 16.40 ± 0.72 mg /mL. Antioxidant and antidiabetic activities increased significantly with increasing concentration, indicating a dose-dependent response. Methanolic extract showed anti-inflammatory activities, including inhibition against bovine serum albumin denaturation (50.00 ± 3.72%), trypsin inhibitory activity (24.33 ± 0.84%), heat-induced haemolysis (22.62 ± 1.09 %), and hyposaline-induced Haemolysis (5.87 ± 0.36%) at 1mg/mL. Methanolic extract showed inhibition zones at 250 mg/mL and 500 mg/mL concentration against Staphylococcus aureus (8.50 ± 0.71mm and 10.50 ± 0.71mm), Bacillus subtilis (10.50±0.71 mm and 13.50 ± 0.71mm), and Escherichia coli (8.50±0.35 mm and 11.25 ± 0.35 mm), respectively. However, no activity against Salmonella enterica was observed. Results demonstrated that methanolic K. alvarezii extract could be a potential source of antioxidant, antidiabetic, anti-inflammatory, and antibacterial activities, and it may have great importance as a therapeutic agent in the food and pharmaceutical industries.
Keywords: Antioxidant, Antidiabetic, K. alvarezii, Phenolics, Seaweed
