Phytochemical and Bioactive Analysis of Extracted Brown Macroalgae (Dictyota implexa) Collected in Vietnam

Brown algae are considered a marine algae resource for human health. This study investigated ethanol extract's chemical composition and biological activity from brown algae Dictyota implexa. The extract from D. implexa was examined for total contents of quercetin, tannic acid, phenolic, flavonoid, polysaccharides, agar, and fucoidan, and the antioxidant, anti-inflammatory, antibacterial, cytotoxic, and α-amylase inhibitory activities of the crude extract were determined. Results revealed the presence of a source of phenolic (85.95 ± 1.21 mg GAE/g of the sample), flavonoid (245.6 ± 2.83 mg QE/g of the sample), and tannin (172.179 mg/g DW) compounds in the extract. Evaluating antioxidant activity proved the ethanol extract of D. implexa possessed the highest activity on two testing methods of DPPH scavenging capacity and reducing power. Besides, the anti-inflammatory activity was potent in the extract with an IC₅₀ value of 9.95 ± 1.51 μg/mL. Concerning antimicrobial activities, the ethanol extract of D. implexa (70 mg/mL) showed potential inhibitory ability against E. coli and B. cereus. Moreover, the algal extract displayed cytotoxic activity against HeLa cells and inhibited α-amylase activity with an IC₅₀ value of 276.82 μg/mL. The current findings demonstrated that exploring novel natural resources offers a promising avenue for advancements in human health and economic well-being.