Cytotoxicity, antitumor-promoting and antioxidant activities of Annona muricata in vitro

Annona muricata or soursop belongs to the family Annonaceae and is a plant enriched with annonaceous acetogenin. This plant had been traditionally used for the treatment of various infectious and inflammatory diseases. This study aimed to determine the cytotoxicity, antitumor-promoting and antioxidant activities of Annona muricata various extracts and its isolated acetogenin, annonacin in vitro. All samples were subjected to the inhibition of Epstein-Barr virus early antigen (EBV-EA) activation assay induced by the tumor promoter, 12-O-tetradecanoylphorbol 13-acetate (TPA) on Raji cells. Prior to EBV-EA assay, [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] (MTT) assay was performed to determine the samples' cytotoxicity against Raji cells. Antioxidant activity was performed via 2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), ferric reducing antioxidant potential (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. Annonacin exhibited remarkable cytotoxic activity with IC50 of 2.9 +/- 1.3 mu M. Inhibition against EBV-EA activation occurred in the following order: hexane leaf > annonacin > aqueous fruit > dichloromethane leaf > methanol leaf > aqueous leaf > ethanol leaf. Methanol leaf extract demonstrated the highest antioxidant activity in all assays and exhibited the most powerful free radical scavenger (87%). Annonacin consistently displayed the lowest antioxidant activity in all assays performed. The findings reported for the first time the antitumor-promoting effects of various extracts of Annona muricata and annonacin in vitro, thus validating their promising anticancer potential.