The antioxidant and antiproliferative activities of methanolic extracts from Njavara rice bran

Abstract

BackgroundFree radical-induced oxidative stress is the root cause for many human diseases. Naturally occurring antioxidant supplements from plants are vital to counter the oxidative damage in cells. The main objective of the present study was to characterize the antioxidant and antiproliferative potential of rice bran extracted from an important Indian rice variety, Njavara and to compare the same with two commercially available basmati rice varieties: Vasumathi, Yamini and a non medicinal variety, Jyothi.MethodsMethanolic extracts of rice bran from four varieties; Vasumathi, Yamini, Jyothi and Njavara were used to study their total phenolic and flavonoid contents, in vitro antioxidant activities including total antioxidant activity, scavenging of nitric oxide and 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical, reducing power and cytotoxic activity in C6 glioma cells. Correlation coefficient and regression analysis were done by using Sigmastat version 3.1 and Stata statistical package respectively.ResultsRice bran methanolic extract from Njavara showed the highest antioxidant and cell cytotoxic properties compared to the other three rice varieties. IC50 values for scavenging DPPH and nitric oxide were in the range of 30.85-87.72 μg/ml and 52.25-107.18 μg/ml respectively. Total antioxidant activity and reducing power were increased with increasing amounts of the extract. Total phenolic and flavonoid contents were in the range of 3.2-12.4 mg gallic acid-equivalent (GAE)/g bran and 1.68-8.5 mg quercetin-equivalent (QEE)/g bran respectively. IC50 values of cytotoxic assay (MTT assay) were 17.53-57.78 μg/ml. Correlation coefficient and regression analysis of phenolic content with DPPH and NO scavenging, MTT (-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay, total antioxidant assay and reducing power showed a highly significant correlation coefficient values (96-99%) and regression values (91-98%).ConclusionThe results of the present study show that the crude methanolic extract from Njavara rice bran contains significantly high polyphenolic compounds with superior antioxidant activity as evidenced by scavenging of free radicals including DPPH and NO. Njavara extracts also showed highest reducing power activity, anti-proliferative property in C6 glioma cells. In conclusion, it is conceivable that the Njavara rice variety could be exploited as one of the potential sources for plant - based pharmaceutical products.

Study of chemical composition and volatile compounds along with in-vitro assay of antioxidant activity of two medicinal rice varieties: Karungkuravai and Mappilai samba

“…The correlation coefficients (R) and coefficient of regression (R 2 ) were calculated for both rice varieties and are listed in Table 4. In general, the phenolic content had a strong positive correlation with both the antioxidant assay which is in accordance with previous studies (Yafang et al 2011;Rattanachitthawat et al 2010;Rao et al 2010). In both rice varieties, the correlation coefficient and regression coefficient were seen to be higher between TPC and FRAP when compared to TPC and DPPH.…”

“…It has been established through studies that many rice varieties have differences in their physiochemical composition (Storck et al 2005). Limited works have been done on measuring the bioactivity of some of the medicinal rice varieties used in the Indian system of medicine (Rao et al 2010;Deepa et al 2008). …”

Phytochemical screening, antioxidants and antimicrobial potential of Lantana camara in different solvents

“…With regards to reducing power, higher reducing activities can be attributed to higher amounts of polyphenolics and the reducing capacity of a compound may reflect its antioxidant potential [30] . It has been reported that the reducing properties are generally associated with the presence of reductones, which have been shown to exert antioxidant action by breaking the free radical chain by donating a hydrogen atom [31] .…”

Total Phenolic Contents and Free Radical Scavenging Activity of Different Parts of Jatropha Species

“…This significant correlation suggests that 75 and 80 % of the DPPH scavenging capacity of Jatropha species outcomes were due to the involvement of phenolic compounds. The remaining percentage may also come from others antioxidant compounds such as volatile oils, amino acids, vitamins and others, which are not limited to phenolics [36]. Moreover, a significant correlation between antioxidant activity and total phenolic contents proved that phenolic compounds may also contribute to the antioxidant activity of different parts of Jatropha species.…”