Bioactive Extracts from Padina boryana Thivy from Phu Quoc Island, Vietnam: In vitro Antioxidant, Anticancer, Alpha-glucosidase inhibitory, Anti-inflammatory, Antimicrobial, and Hepatoprotective Activities

The brown alga Padina boryana Thivy has been studied for its bioactive properties. This study aimed to evaluate the antioxidant, anticancer, alpha-glucosidase inhibitory, anti-inflammatory, antimicrobial, and hepatoprotective activities of Padina boryana extracts. The antioxidant activity was investigated using DPPH and ABTS radical scavenging, and ferric reducing power assays. The anticancer activity was determined via cytotoxic activity on human lung carcinoma (A549) and human embryonic kidney (HEK 293) cancer cell lines. Alpha-glucosidase inhibitory activity was determined using standard method, anti-inflammatory activity was assessed via nitric oxide (NO) inhibition assay, antimicrobial activity was assessed using the broth microdilution assay, and the hepatoprotective activity was evaluated using CCl4-induced hepatotoxicity in HepG2 cells. Results showed that the algal extracts have low DPPH scavenging activity, but effective ABTS scavenging activity with EC50 value of 52.09 µg/mL for the ethyl acetate (EA) extract. The EA extract had the highest ferric-reducing power with EC50 of 61.7 µg/mL. The petroleum ether (PE) extract had the highest cytotoxic effect with EC50 values of 38.19 µg/mL and 33.28 µg/mL against A549, and HEK 293 cells, respectively. All extracts showed significant alpha-glucosidase inhibitory activity, with EA being the most potent (IC50 = 3.01 µg/mL). The PE extract showed notable NO inhibitory activity with IC50 of 50.91 µg/mL. No significant antimicrobial activity was observed except for EtOH and PE extracts, which inhibited Staphylococcus aureus and Bacillus subtilis. The extracts did not demonstrate significant hepatoprotective effect. These findings highlight the potential of Padina boryana as a valuable source of natural therapeutic agents.