Practiced as folk medicine since ancient times, bilimbi (Averrhoa bilimbi) is commonly
consumed and widely cultivated in Malaysia. In search for naturally occurring anticancer
agents, a potential fruit extract was found to exert anticancer properties in vitro without any
cytotoxic effect on normal cells. This study investigated the anti-proliferative effect and
underlying cell death pathway induced by bilimbi ethanolic extract on human non-hormonedependent
breast cancer cell line, MDA-MB-231. Anticancer potential of bilimbi extract was
conducted by investigating the in vitro growth inhibitory effect, DNA fragmentation, cell cycle
progression and anti-proliferation assay. Release of caspases, cytochrome c and apoptotic
proteins were demonstrated to determine the mechanism of cell death pathway. Findings
revealed that bilimbi inhibited growth of MDA-MB-231 cells through the induction of
apoptosis mediated by cell cycle arrest at G0/G1 checkpoint. Released of cytochrome c coupled
with up-regulation of caspase-3/7, caspase-9 and Bax pro-apoptotic proteins in addition to
down-regulation of dysfunctional p53 and Bcl-2 anti-apoptotic proteins implied that bilimbi
induced a p53-independent mitochondrial apoptosis pathway in MDA-MB-231. These results
suggest that bilimbi could induce tumor cell anti-proliferation through apoptosis. As a natural
product, bilimbi could be a promising anticancer agent and an inexpensive approach to cancer
chemoprevention strategy.