Biochemical composition and antioxidant properties of some seaweeds from Red Sea coast, Egypt

The current study investigated the biochemical composition and antioxidant properties of four seaweeds: Laurencia sp. (Rhodophyta), Cystoseira myrica, Hydroclathrus clathratus and Padina pavonica (Ochrophyta). The highest amount of carbohydrates was (215.78 mg/g dry wt.) in Laurencia sp. and proteins content was maximum (50 mg/g dry wt.) in Laurencia sp. and Cystoseira myrica. The highest values of free amino acid content were recorded in the brown seaweed species Cystoseira myrica (4.01 mg/g dry wt.). The pressurized hot water extract of Cystoseira myrica has the highest total phenolic content (1.61 mg GAE/g dry wt.). Cystoseira myrica contained the highest amounts of flavonoids (3.35 mg/g dry wt.), ascorbic acid (9.07 mg/g dry wt.) and α-tocopherol (27.25±0.00 abs. at 520 nm/g dry wt.). Furthermore, the ethyl alcohol extract of Cystoseira myrica showed high antioxidant capacities (541.6 mg/g dry wt.) and achieved the most powerful reducing ability among all of the different extracts of algal species. Statistical evaluation by Spearman correlation between the TAC assay and the total phenolic contents was found to be significant, but the correlation was nonsignificant between FRAP assay and the total phenolic contents. The composition of elements of the studied seaweed species was also analyzed. The most significant macro-elements present in the studied seaweeds were K, Na and Ca, representing that the seaweeds are good sources of these elements. Since, these seaweeds are widespread in the Egyptian waters, their biochemical composition and antioxidant capacities made them promising candidates for industrial, nutritional and pharmaceutical applications. DOI: http://dx.doi.org/10.5281/zenodo.1478863