SCREENING OF BIOLOGICAL ACTIVITIES FROM NOSTOC SPP. (CYANOPHYTA)

Abstract

Screening of antioxidant activity (AA), total polysaccharide content (TPC) and angiotensin I-converting enzyme (ACE) inhibitor from Nostoc spp., maintained at TISTR Algal Culture Collection (TISTR-ACC) was conducted. The AA was tested by free radical scavenging of lipid phase (antioxidant capacity of lipid-soluble compounds-ACL) against superoxide anion (O2) using photochemiluminescence (PCL) assay. From seventy-one samples of crude extracts, N. punctiforme TISTR 8167 showed the best AA of 481.55 µmol (Trolox equivalent)/g (crude extract), followed by N. parmelioides TISTR 8174, Nostoc sp. TISTR 9102, N. paludosum TISTR 9004, Nostoc sp. TISTR 9073 and N. commune TISTR 8870, the activities of which were in the range of 348-390 µmol (Trolox equivalents)/g (crude extract). The total polysaccharide content (TPC) was determined by phenol-sulfuric acid assay. From fifty-two samples, the high TPC at ≥120 mg g-1 (dry cell weight), were found in three strains. The highest TPC at 130 mg g-1 was obtained from N. commune TISTR 8299. Angiotensin I-converting enzyme inhibitory activity (ACE-IA) and soluble protein content (SPC) of Nostoc strains were determined from 70 to 58 samples, respectively. The ACE-IA was tested by the detection of hippuric acid (HA) content from the reaction between hippuryl-histidyl-leucine (HHL) and ACE in the presence or absence of ACE inhibitor through simulated digestion of the samples. The results revealed that the high activities in the range 78-86% were obtained from N. commune TISTR 8160, N. muscorum TISTR 8164, N. paludosum TISTR 8890, N. entophylum TISTR 8161 and N. punctiforme TISTR 8167, by which N. commune TISTR 8160 expressed the highest inhibitory activity at 86%. The results of SPC quantified by Bradford assay were in the range 0.03-1.41 mg ml-1, N. micro-scopicum TISTR 9078, exhibited the highest SPC among the tested samples. However, these results show no relationship between ACE-IA and SPC.