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The underlying mechanisms of the anticancer activity of the ethanolic extract of mango peel (EEMP) and its constituents were investigated. EEMP induced death of human cervical carcinoma HeLa cells through apoptosis, as evidenced by the increased cell population in the sub-G1 phase and the appearance of fragmented nuclei. Treatment of the cells with EEMP also downregulated anti-apoptotic Bcl-2 expression, resulting in the proteolytic activation of caspase-3, 7, 8, and 9 and the degradation of poly (ADP-ribose) polymerase (PARP) protein. The major components of mango peel were identified by liquid chromatography-electrospray ionisation tandem mass spectrometry and gas chromatography-mass spectrometry. Our data suggest that EEMP is an excellent source of quercetin 3-O-galactoside, mangiferin gallate, isomangiferin gallate, quercetin-3-O-arabinopyranoside, and mangiferin along with unsaturated fatty acids oleic acid, linoleic acid, and ethyl linoleate, which may help to prevent cervical cancer and may be a useful agent for the treatment of some other malignancies.

The antiproliferative activities of the chloroform fraction (CF) of guava ( Psidium cattleianum Sabine) leaf extract were evaluated using several cancer cell lines. Maximum cytotoxicity was observed in SNU-16, a human gastric carcinoma cell line, at concentrations of 50–100 μg/ml. Flow cytometric analysis demonstrated that CF treatment resulted in a marked accumulation of SNU-16 cells in the sub-G1 phase at concentrations of 100–200 μg/ml. The induction of apoptosis in SNU-16 cells was confirmed by immunoblotting using antibodies against Bcl-2, Bax, poly (ADP-ribose) polymerase (PARP), caspase-8, and caspase-3. The major CF phytochemicals were identified as ferulic acid, genistein, 3′, 4′, 5′ trimethoxy flavone, phlorizin, and oleanolic acid by high performance liquid chromatography coupled with a photo diode array and electrospray ionisation mass spectrometry (HPLC–PDA-ESI-MS). The results suggest that phytochemicals in the CF of guava ( P. cattleianum ) leaf extract induce apoptosis in SNU-16 cells. These findings may lead to new strategies for treating human gastric cancer.

The antioxidant and antiproliferative properties of flesh and peel of mango (Mangifera indica L.) were investigated. The cytoprotective effect of mango flesh and peel extracts on oxidative damage induced by H2O2 in a human hepatoma cell line, HepG2, were determined, and the underlying mechanism was examined by a single-cell electrophoresis assay (comet assay). Treatment of HepG2 cell with mango peel extract prior to oxidative stress was found to inhibit DNA damage. The free radical scavenging activities of mango flesh and peel extracts were evaluated by electron spin resonance (ESR). The mango peel extract exhibited stronger free radical scavenging ability on 1,1-diphenyl-2-picrylhydrazyl (DPPH) and alkyl radicals than mango flesh extract, regardless of ripeness. Similarly, peel extract exhibited significant antiproliferative effect against all tested cancer cell lines, compared to that of flesh extract, in a dose-dependent manner. The result also showed that the antiproliferative activity of mango flesh and peel extracts correlated with their phenolic and flavonoid contents. Thus, mango peel, a major by-product obtained during the processing of mango product, exhibited good antioxidant activity and may serve as a potential source of phenolics with anticancer activity.