In Vitro Antioxidant and Antiproliferative Activities of Novel Orange Peel Extract and It’s Fractions on Leukemia HL-60 Cells

In the present work, novel orange peel was extracted with 100%EtOH (ethanol) and fractionated into fourfractions namely F1, F2, F3, F4 which were eluted from paper chromatographs using 100%EtOH, 80%EtOH,50%EtOH and pure water respectively. The crude extract and its four fractions were evaluated for theirtotal polyphenol content (TPC), total flavonoid content (TFC) and radical scavenging activity using DPPH(1,1-diphenyl-2-picrylhydrazyl) assay. Their cytotoxic activity using WST assay and DNA damage by agarosegel electrophoresis were also evaluated in a human leukemia HL-60 cell line. The findings revealed that F4 hadthe highest TPC followed by crude extract, F2, F3 and F1. However, the crude extract had the highest TFCfollowed by F4, F3, F2, and F1. Depending on the values of EC50 and trolox equivalent antioxidant capacity,F4 possessed the strongest antioxidant activity while F1 and F2 displayed weak antioxidant activity. Further,incubation HL-60 cells with extract/fractions for 24h caused an inhibition of cell viability in a concentrationdependentmanner. F3 and F4 exhibited a high antiproliferative activity with a narrow range of IC50 values(45.9 - 48.9μg/ml). Crude extract exhibited the weakest antiproliferative activity with an IC50 value of 314.89μg/ml. Analysis of DNA fragmentation displayed DNA degradation in the form of a smear-type pattern uponagarose gel after incubation of HL-60 cells with F3 and F4 for 6 h. Overall, F3 and F4 appear to be good sourcesof phytochemicals with antioxidant and potential anticancer activities.