In vitro Antioxidant Activity and α- Amylase Inhibitory Activity of Methanolic Extract of Sri Lankan Marine Brown Algae Chnoospora minima (Hering 1841)

Abstract

Chnoospora minima (Herring) is a brown algae that belongs to Family Scytosiphonaceae. The current study investigated the total phenolic (TP), total flavonoid contents (TFC), antioxidants and anti-amylase activity of the methanolic extract of C. minima. The sample was extracted with 70% methanol and polysaccharides were separated. The resulting polyphenol portion was obtained for analysis. TP, TF contents were determined using standard methods. Antioxidant assays were conducted using ferric reducing antioxidant power (FRAP), ferrous iron chelating activity, DPPH and ABTS radical scavenging activity. Anti-diabetic potential was assessed using anti-amylase assay. TP and TF contents were 2950.72±87.09 (μg gallic acid equivalent/g of sample) and 39.36±7.81 (μg quercetin equivalents/g of sample) respectively. The free radical scavenging activity of the C. minima revealed that the reduction of DPPH occurred in a concentration-dependent manner with high reductions occurring at the highest concentrations. The DPPH and ABTS radical scavenging activity of C. minima was 959.45±13.91 and 5734.22±120.11 μg trolox equivalent for 1 g sample respectvely. The IC50 of ABTS and DPPH radical scavenging activity was 74.34±1.56 μg/ml and 452.42±6.51 μg/ml when compared to the standard trolox (IC50:8.68±0.06 μg/ml). The ferric reducing antioxidant power of C. minima was 293.32±59.66 μg Trolox per 1g of sample. The ferrous iron chelating activity of the methanolic extract of C. minima was 278.22±5.62 μg EDTA per 1 g of sample. The anti-amylase assay showed that, C. minima inhibited the activity of α-amylase with IC50 value of 17.93±0.19 μg/ml and the percentage inhibition varied from 89.58 to 3.69. According to the results, methanolic extract of C. minima possessed high antioxidant and α-amylase inhibition activity, thus increasing its potential therapeutic property.