LAUSR

Abstract Natural sources have always been the primary sources of bioactive principles. Cyanobacteria with its wide spectrum of metabolites represents a favourable source of compounds having medicinal properties like antioxidant, anti-proliferative etc. In this study we tested different organic extracts [Diethyl ether (DE), Dichloromethane (DM), Ethyl acetate (EA) and Heptane (HE) extracts] of cyanobacterium Nostoc muscorum NCCU-442 for the same. Antioxidant activity was evaluated through DPPH and FRAP assay. Phenolic content was estimated using FCR reagent as phenolic compounds are the well-established antioxidants. MTT assay was used to estimate anti-proliferative activity against cervical cancer cell line, SiHa. DE extract was found to have the highest Phenolic content, i.e. 96.71 ± 2.41 mgGAE/g as well as most antioxidant effect in DPPH assay (IC50 =118 ± 0.34 µg/ml) and FRAP assay (EC1 =380.7 ± 2.43 µg/ml). The order of phenolic content of different extracts is: DE > EA> DM > HE. The order of antioxidant potential was same as the phenolic content. HE extract had the least antioxidant effect in the two assays (IC50 =686 ± 3.3 µg/ml and EC1 >10 mg/ml for DPPH and FRAP respectively). All the extracts showed anti-proliferative activity against the cancer cell line in the order: DE (IC50 = 70 ± 0.22 µg/ml) > HE (116.5 ± 0.53 µg/ml) > EA (205 ± 0.77 µg/ml) > DM (190 ± 0.45 µg/ml). During Gas Chromatography-Mass Spectrometry (GC-MS), bioactives like Benzofuranone derivatives, Myristoleic acid, Resorcinol, Citronellyl butyrates, hydroquinone, hexadecanoic acid, farnesol were identified in the organic extracts. Thus, our study indicated that Nostoc muscorum NCCU-442 has an inherent capacity as a potential source of therapeutic compounds.