Antioxidant and antiproliferative activities of Azanza garckeana and Portulaca oleracea on HeLa cells

Abstract

Mortality and incidence rates of cervical cancer are on the rise in sub-Saharan Africa, particularly in Botswana. Current cervical cancer management strategies such as chemotherapy and radiation are not fully effective as they bring about major side effects and issues such as drug resistance. Indigenous plants of Botswana have been used in ethnomedicine to treat conditions related to cancer. Two known indigenous plants; Azanza garckeana and Portulaca oleracea have been found to contain phytochemicals which contribute to their antioxidant and anticancer properties. The aim of this study was to evaluate the antioxidant and anti-proliferation potential of extracts derived from Portulaca oleracea and Azanza garckeana. The study started with the derivation of extracts from the leaves, stems and roots of these two plants using six different solvents; methanol, ethanol, chloroform, distilled water, hexane and isopropanol in order of their polarity. Phytochemical screening of the extracts was then done to determine different secondary metabolites present. Total phenolic and flavonoid content of the different extracts was determined followed by the determination of the antioxidant activity of the extracts. GC-MS analysis was then conducted to detect different bioactive compounds present in the extracts. Anti-proliferation activity was determined by the cell viability assay; MTT to determine the IC50 values of the different extracts. It was found out that methanol effectively extracted antioxidant compounds. P. oleracea stem and leaf methanolic extract had high total phenolic and flavonoid content of 16.25 ± 0.48 TE mg/100 g, 16.39 ± 0.51 TE mg/100 g, 45.81 ± 1.02 QE mg/100 g and 41.70 ± 3.69 QE mg/100 g respectively whereas A. garckeana leaf methanolic had high total phenolic and flavonoid content of 14.00 ± 1.00 TE mg/100 g and 52.03 ± 2.44 QE mg/100 g respectively. xii | P a g e It was also found out that chloroform extracts had good antioxidant activity as the P. oleracea stem chloroform extracts gave a high antioxidant compounds concentration of 687.50 ± 0.88 TE Mmol/g and radical scavenging activity of 97.83 % ± 1.59 due to the presence of antioxidant compounds in the extracts. Methanolic and ethanolic extracts displayed anti-proliferative activity towards HeLa cells used in study and the extracts affected cell viability in a dose dependent fashion. A. garckeana leaf ethanolic extracts reduced cell viability by 92.00 % at 400 µg/ml extract concentration, P. oleracea leaf methanolic extracts reduced cell viability by 89.00 % at 400 µg/ml extract concentration, A. garckeana leaf methanolic extracts reduced cell viability by 91.00 % and P. oleracea stem methanolic extracts reduced cell viability by 69.00 % at 400 µg/ml extract concentration. The IC50 values of the extracts which measured the cytotoxicity degree of the extracts were found to be 329.31 µg/mL ± 54.69, 176.44 µg/mL ± 25.49 µg/mL, 190.47 µg/mL ± 46.10, 242.09 µg/mL ± 23.60, 22.78 µg/mL ± 10.37 for P. oleracea leaf methanolic extract, A. garckeana leaf methanolic extract, A. garckeana leaves ethanolic extract, P. oleracea stem methanolic extract and cisplatin (anti cancer drug) respectively. The anti-proliferative and antioxidant activity of the extracts of P. oleracea and A. garckeana was speculated to be due to the presence of antioxidant and anticancer compounds in the extract such as; 10-acetoxy-1,4a-dimethyl-9-oxo-1,2,3,4,4a,9-hexahydrophenanthrene-1-carboxylic acid, methyl ester ,octasiloxane,1,1,3,3,5,5,7,7,9,9,11,11,13,13,15,15-hexadecamethyl-, methoxy-2-[(3-methoxyphenyl)methylene]-,(E), cholestan-26-oic 3(2H)-benzofuranone, acid, 6- 3,7,12-trihydroxy-, (3α,5β,7α,12α)-, 3-O-Methyl-D-glucose, cyclononasiloxane and octadecamethyl.