Anti-Cancer Potential of Ethanolic and Water Leaves Extracts of Annona Muricata (Graviola)

Abstract

Cancer is a major cause of mortality and morbidity globally and overall survival rate is still low despite advances in surgery, radiotherapy and chemotherapy. Plants have played a significant role in the treatment of cancer and infectious diseases for a very long time. Annona muricata has been widely used in the treatment of cancer and diseases in many countries. However, there had been no documented scientific study to validate the medicinal importance of Annona muricata, despite its wide usage in Uganda. The objective of this study was to determine the phytochemical composition, anti-oxidant and cytotoxic properties of ethanolic and water leaves extracts of Annona muricata. Phytochemical analysis was conducted using standard qualitative methods and a Chi- Square Goodness of fit test was used to assign the relative abundance of the different phytochemicals. Gas Chromatography Mass Spectroscopy Analysis was also conducted. The antioxidant activity was determined using the DPPH and reducing power methods whereas the in vitro cytotoxic activity was determined using three different cell lines. Phytochemical screening of the extracts showed them to be rich in secondary class metabolite compounds of alkaloids, saponins, terpenoids, flavonoids, coumarins and lactones, anthraquinones, tannins, Cardiac glycosides, phenols and phytosterols. Total phenolic compounds in the water extract were 683.69±0.09 μg/ml Gallic Acid Equivalent while it was 372.92±0.15 μg/ml Gallic Acid Equivalent in the ethanolic extract. Using Gas Chromatography Mass Spectroscopy Analysis, the ethanolic leaves extract of Annona muricata showed 25 constituents of which 12 of the compounds were identified. The major constituents were two unidentified compounds with percentage peak areas of 23.51% and 16.8%. Of the identified compounds, the outstanding in composition were 7-Tetradecenal, (Z) (peak area 9.39%), n-Hexadecanoic acid (peak area 7.12%), Oleryl Alcohol (peak area 6.15%), Phytol (peak area 5.61%), cic, cis, cic-7,10,13-Hexadecatrienal (peak area 4.26%), 2-Pentadecanol (peak area 3.93%), 9,12-Octadecadienoic acid, ethyl ester (peak area 3.21%), 1,2-Benzenedicarboxylic acid, butyl octyl ester (peak area 2.67%), and 1,E-11,Z-13-Octadecatriene (peak area 2.15%), while the rest had less than 2% composition by peak area. The reducing power was 216.41μg/ml in the ethanolic extract and 470.51μg/ml Gallic Acid Equivalent in the water extract. In vitro antioxidant activity IC50 was 2.0456mg/ml and 0.9077mg/ml for ethanolic and water leaves extracts of Annona muricata respectively. The ethanolic leaves extract was found to be selectively cytotoxic in vitro to cancer cell lines (EACC, MDA and SKBR3) with IC50 Values of 335.85μg/ml, 248.77μg/ml, 202.33μg/ml respectively, while it had no cytotoxic effect on normal spleen cells. The data also showed that water leaves extract of Annona muricata had no cytotoxic effect at all tested concentrations. TLC fractionation of the ethanolic leaves extracts revealed 11 fractions and tested for the different activities, of which 4 fractions had the best cytotoxic activity. The results showed that Annona muricata possesses antioxidant and cytotoxic activities that need to be studied further so as to establish the suitable uses of this plant in cancer therapy.