Abstract

Phenolic compounds have been extracted from red algae (Eucheuma cottonii) and brown algae (Sargassum sp.) and the antioxidant activity assay using DPPH method has been done. The extractions were carried out on dried and fresh samples by digestion method using ethanol: water (50:50) as solvents and followed by liquid-liquid extraction using hexane and ethyl acetate as solvents. The extraction results were qualitatively analyzed using Folin-ciocalteu and TLC methods, while quantitative analysis was performed by determination of total polyphenol levels and antioxidant activity using UV-Vis spectrophotometer. Identification with Folinciocalteu reagent showed the presence of polyphenol compounds in the ethanol fraction and ethyl acetate fraction. The TLC results showed a spot with a relatively equal Rf value between ethyl acetate fraction and gallic acid standard in both samples. The highest polyphenol content was obtained from the ethyl acetate fraction of fresh samples, 0.59% for red algae and 0.34% for brown algae while the ethanol fraction of dried samples had the lowest polyphenol content of 0.08% for red algae and 0.01% for brown algae. In the antioxidant activity assay, the best results were obtained from the ethanol fraction of dried red algae sample with IC50 value of 52,36 ppm (strong antioxidant activity) and the ethyl acetate fraction of fresh brown algae sample with IC50 value of 7095 ppm. The lowest antioxidant activity were observed on the ethyl acetate fraction of dried red algae sample with IC50 value of 400,867 (very weak antioxidant activity) and the ethanol fraction of dried brown algae sample with IC50 value of 1918 ppm.