Antioxidant activity of different varieties of red seaweed, Kappaphycus alvarezii from Sabah

The objective of the present study was to determine the to determine the antioxidant activity of five varieties of Kappaphycus alvarezii grown in Semporna, Sabah using 1,1-diphenyl-2-picrylhydrazyl radical scavenging (DPPH) assay, ferricreducing antioxidant power (FRAP) assay and beta carotene bleaching (BCB) assay and also to evaluate the total phenolics, total flavonoid and total carotenoids content. Methanol extract was used for analysis. Antioxidant activity, total phenolic content, total flavonoid content and total carotenoids content was determined using UV VIS spectrophotometer. Among the five varieties, Brown variety was found to have the highest DPPH (3.80 ± 0.09 µg/ml), FRAP (251.73 ± 0.798 µM.ml�¹ dry extract), BCB (85.82 ± 0.04%) and total phenolics content (17.49 ± 0.04 µg PGE mg PGE g�¹ dry extract) value. Total phenolics contents was found to correlate strongly with and IC50 and FRAP. Green Flower variety showed the second best second best antioxidant activity overall. The third best variety is Green variety, followed by Giant variety and Crocodile variety is the weakest which showed the lowest antioxidant activity and total phenolic content. On the other hand, Green variety gives the highest flavonoid (34.29 ± 4.14 mg QE/g dry extract) content and total carotenoids (64.85 ± 0.63 mg/100g dry extract) content.