Total phenolic content, antioxidant and cytotoxic activities of citrus hystrix leaf extracts

Abstract

Citrus hystrix (C.hystrix) locally known as Limau purut is a culinary flavouring that is common in Malaysia and South East Asian cuisine as well as in herbal preparations. The aim of this study is to evaluate the antiproliferative, antioxidant and total phenolic content of ethanolic and aqueous extract of C.hystrix leaves. Qualitative phytochemical screening was also conducted to detect the presence of phytochemical compounds. The cytotoxic effect of the extracts on colon cancer cells (HT29) were determined by MTT assay. For the antioxidant activity, 2, 2, diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay was used. Total phenolic content (TPC) was evaluated by using Folin-Ciocalteu method. Qualitative phytochemical screening was carried using standard procedures. The ethanolic extract of C.hystrix exhibited higher percentage yield of 22.05 % compared to 19.22 % of aqueous during the solvent extraction method. The cytotoxic activity of the extracts showed IC50 values of 0.25 and 3.25 mg/ mL for ethanolic and aqueous extract respectively indicating stronger cytotoxic effects on HT29 cells in ethanolic extract. The TPC was also higher in ethanolic extract compared to aqueous which was 0.12 and 0.104 mg of GA/ g of extract respectively. For the antioxidant activity, both the ethanolic and aqueous extract showed IC50 values of > 8 mg/mL in comparison of 0.03 mg/mL of the standard ascorbic acid, indicating low antioxidant activity. Both the ethanolic and aqueous extract of C.hystrix exhibited a weak, negative correlation between TPC and percentage inhibition of DPPH with R2 value of 0.2278 and 0.434 respectively. The phytochemical screening of the extracts reveals the presence of several phytochemical compounds namely alkaloid, saponin, flavonoid and fixed oil and fats with maximum presence of phytochemicals in ethanolic compared to aqueous extract of C.hystrix. Relatively, the present result shows that the ethanolic extract of C.hystrix, which exhibited higher percentage yield, antiproliferative activity, TPC content and maximum presence of phytochemicals can be used as a potential source of anticancer agent but not a good source of natural antioxidants.