Antioxidant property of leaves and calluses extracts of in-vitro grown 5 different Ocimum species

Abstract

In this study, the antioxidant property of leaf and callus extracts of five selected in vitro grown Ocimum species (Ocimum sanctum, Ocimum kilimandscharicum, Ocimum gratissimum, Ocimum basilicum, and Ocimum americanum) and their respective callus extracts was investigated. The callus cultures were successfully initiated on Murashige and Skoog (MS) medium supplemented with 2,4-dichlorophenoxy acetic acid (2,4-D) (1mg L) combined with different concentrations (0.1-0.4 mg L) of kinetin as plant growth regulators. Total phenolic contents were estimated using the Folin-Ciocalteu reagent. 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power, <TEX>$F</TEX><TEX>e^{2+}$</TEX> chelating activity, and <TEX>${\beta}$</TEX>-carotenelinoleic acid bleaching assays were used to determine the biological effects of the extracts. Interestingly, all the callus extracts exhibited significant (p<0.05) increase in phenolic contents and antioxidant activity. Furthermore, a liner correlation was obtained between the total phenolic contents and free radical scavenging activity (<TEX>$R^2$</TEX> = 0.783). The extracts of leaves and calluses of Ocimum species exhibited activity in all the in vitro antioxidant assays, but its extent was less potent that the positive controls butylated hydroxyl anisole (BHA) and ascorbic acid. A higher accumulation of phenolics in the callus extracts suggests that isolation of high-concentration materials with antioxidant activivity is possible from in vitro callus cultures rather than field-grown plant organs. Furthermore, these extracts may be used as an effective preservative in the food industry.