Comparison of Antioxidant Activity of Nigella sativa and Bunium bulbocastanum using Different Extraction Methods

Abstract

Nigella sativa and Bunium bulbocastanum are types of cumin seeds that have been used in traditional medicine in Sri Lanka. The aim of this study was to compare antioxidant properties of 85% ethanol and ethyl acetate extracts of N. sativa and B. bulbocastanum. Total phenolic content (TPC) and total flavonoid content (TFC) of the seeds were determined by using Folin-Ciocaltue method and Aluminium chloride method respectively. There was no significant difference between TPC levels of N. sativa ethanol extract compared to the ethyl acetate extract. However, TPC of ethyl acetate extract of N. sativa was significantly different when compared to B. bulbocastanum. Highest TPC was observed in B. bulbocastanum ethyl acetate extract 155.1 mg Gallic Acid Equivalent (GAE)/100 g while the lowest was observed in N. sativa ethanol extract 56.9 mg GAE/100 g. Results showed that there was no significant difference between the TFC of N. sativa and B. bulbocastanum extracts. Highest TFC was observed in N. sativa ethyl acetate extract 49.8 mg Rutin Equivalent (RE)/100 g while the lowest was observed in B. bulbocastanum ethanol extract 21.7 mg RE/100 g. Free radical scavenging activity of the seeds was analysed by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and results indicated that there was a significant difference between the extracts. Ferric Reducing Antioxidant Power (FRAP) values of N. sativa were not significantly different from FRAP values of B. bulbocastanum. Highest FRAP was observed in B. bulbocastanum ethanol extract 5.4 g Fe (II)/100 g. According to these results it is evident that there is a high antioxidant activity in ethyl acetate extract of both seeds.
Keywords: Total phenolics, Flavonoids, DPPH, FRAP