Seaweed or sea macroalgae are rich in potential compounds which can be used for the treatment of disease. Padina australis is one important brown classes (Phaeophyes). One bioactive P. a phenolic compound and its derivatives (flavonoid). In this research, was collected from Bayah Beach, Banten, Indonesia. For extraction flavonoids australis, ultrasound-assisted (UAE) employed. study, three-leve...