Biochemical and Antioxidant Properties of Seagrasses from Tanjung Adang Laut Shoal, Johor, Malaysia

by: Lau Sheng Hann Emmclan, Muta Harah Zakaria, Fatin Mohd Ikhsan Natrah, Japar Sidik Bujang and K. Hayashizaki


The search for marine phytochemicals as an alternative antioxidant source has gained considerable attention in the past few decades. This study attempts to determine the biochemical composition and antioxidant activity of five seagrass species, i.e., Enhalus acoroides, Halophila spinulosa, Cymodocea serrulata, Halodule uninervis and Syringodium isoetifolium based on their leaf and rhizome. The seagrass methanolic extracts were used to determine the total phenolic content (TPC), total flavonoid content (TFC), ferric reducing antioxidant power activity (FRAP), 2,2-diphenyl-1-picrylhydrazyl activity (DPPH) and 2,2’-azino-bis (3-ethylbenzothiazoline- 6-sulphonic acid activity (ABTS). Significantly higher (p<0.05) TFC was obtained in seagrass leaves compared to rhizomes for all species, with H. spinulosa getting the highest record of 68.37 ± 2.92 mg QE/g. A very strong correlation was observed between rhizome’s TPC and FRAP (r=0.99, p<0.05), and DPPH (r=0.97, p<0.05) and ABTS (r=0.99, p<0.05) activities, indicating the antioxidant activities are attributable to phenolic compounds from seagrass extracts. Total phenolic content was highest in E. acoroides rhizomes (76.19 ± 3.37 mg GAE/g) and the rhizome of this species possessed significantly higher (p<0.05) antioxidant activity in terms of FRAP (10.56 ± 0.74 x 10-4 mg Fe2+/g), DPPH (114.99 ± 2.17 μM TE/g) and ABTS (144.34 ± 10.67 μM TE/g) compared to similar parts of other seagrass species. These values were also significantly higher (p<0.05) than synthetic antioxidant butylated hydroxytoluene (FRAP activity 3.70 ± 0.12 x 10-4 mg Fe2+/g and DPPH activity 45.80 ± 0.83 μM TE/g) and commercial ascorbic acid (DPPH activity 94.33 ± 0.42 μM TE/g), suggesting their potentials as alternative natural antioxidant sources. Further studies are required to isolate and identify these compounds that are responsible for the antioxidant activity.

Keywords: seagrass, biochemical, antioxidant activity