Comparative Study on Antioxidant Activities, Total Phenolic Compound and Pigment Contents of Tropical Spirulina platensis, Gracilaria arcuata and Ulva lactuca Extracted in Different Solvents Polarity

Abstract

These study aimed to determine antioxidant activity, total phenolic compound and pigment content of tropical S. platensis, G. arcuata and U. lactuca. S. platensis was extracted with aquadest (SPA), while G. arcuata and U. lactuca were extracted with n-hexane (GAH and ULH), ethyl-acetate (GAE and ULE) and methanol (GAM and ULM). The IC50 value was used to calculate the ability of extract to inhibit free radicals using DPPH (515 nm). The TPC was determined using Folin-Ciocalteu (725 nm). Phycocyanin (620 nm), phycoerythrin (652 nm), allophycocyanin (562 nm), carotenoid (470 nm) and chlorophyll (645 nm and 662 nm) were measured based on color intensity. The results indicated that SPA was able to inhibit free radicals (46.12±2.03%), contains TPC (26.64±0.16 mg/GAE samples) and dominated by phycocyanin pigments (0.301±0.09 mg/g). G. arcuata extracted with ethyl-acetate (GAE) showed the best value with IC50 136.267±0.28 ppm, TPC 303.507±1.155 mg/GAE samples, carotenoid 0.528 ±0.009 μmol/g and chlorophyll a 2.845 ±0.069 mg/g. The U. lactuca extracted with ethyl-acetate also showed the best value with IC50 462.560±2.44 ppm, TPC 210.129±1.387 mg/GAE samples, carotenoid 0.442 ±0.046 μmol/g and chlorophyll a 9.216 ±0.103 mg/g. This results conlcuded that macroalgae extracted with ethyl acetate had better activity which categorized as moderate antioxidant.