Brown seaweed has the potential as a natural antioxidant, one of the types of brown seaweed is Sargassum plagyophyllum. This study was aimed to determine the proximate composition, identification of phytochemical components, and antioxidant activity of S. plagyophyllum extract. S. plagyophyllum was extracted by multilevel maceration method using organic solvents based on its polarity consists o…