EVALUATION OF ANTIOXIDANT ACTIVITIES OF ALGAE AND EFFECT OF SOLVENT EXTRACTION SYSTEM

The present communication is mainly focused to study   the antioxidant activities of the four different extracts (benzene, chloroform, acetone and methanol) of five algae including Aphanothece pallida, Anabena variabilis, Aphanothece saxicola, Lyngbya major, Nitella flagelliformis.  The total phenolic content varied from 2.99±0.23 to 25.38±0.22 mg/g, 4.20±0.135 to 14.10±0.13 mg/g, 3.07±0.22 to 27.03±0.11 mg/g and 2.34±0.03 to 4.87±0.14 mg/g dry material in the benzene, chloroform, acetone and methanol extracts of the algae respectively. The flavonoid content and flavonol content were found to be highest in the chloroform extract of Nitella flagelliformis and the  least amount of flavonoids present in the acetone extract  of Lyngbya major (4.88 ± 0.14 mg/g). The 1, 1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging effect of the extracts were determined spectrophotometrically. The highest radical scavenging was observed in the acetone extract of   Nitella flagelliformis with IC₅₀ = 0.15±0.01 mg dry material. The greater amount of phenolic compounds leads to more potent radical scavenging effect as shown by the acetone extract of Nitella flagelliformis.   The reducing power of the extracts of the plants were also evaluated as mg AAE (ascorbic acid equivalent)/g dry material. The chloroform extract of Nitella flagelliformis showed the highest reducing power 231.08±2.01 mg AAE/g dry material. The results indicate that these algae can be utilized as natural antioxidant in order to prevent free radical toxicity