Alpha-linolenic acid rich Allium porrum methanolic extract potentially inhibits HT-115 human colon cancer cells proliferation via mitochondria mediated apoptotic mechanism

Colon cancer is the third most devastating cancer type in morbidity and mortality associated with severe comorbidities in developing and developed countries. Dietary supplementation of alpha-linolenic acid has a beneficial effect on intestinal dysfunction. In the present study, we processed Allium porrum (Leek) for extraction and identified the bioactive metabolites with the potential of antiproliferative effect in HT-115 (human colon carcinoma) cells. We preliminarily analyzed the cytotoxic effects of methanol, chloroform, and hexane extracts of leek on HT-115 cells. In vitro cytotoxicity assay revealed that leek methanol extract (LME) significantly prohibited cell proliferation in a dose-as well as time-dependent manner, compared with hexane and chloroform extracts of leek. We found that LME at 0.4 and 0.2 μg/mL inhibited HT-115 cell proliferation by 50% at both 24 and 48 h. Cell morphological analysis and nuclear staining indicated that 22% of cells became apoptotic and ∼4% were necrotic after treatment with 0.4 μg/mL of LME. RT-PCR and western blot analysis showed that mRNA and protein expression levels of apoptotic markers such as p53, Bax, caspase-9, and caspase-3 were up-regulated, whereas Bcl-2 was down-regulated in cells exposed with 0.4 μg/mL LME, compared with the levels in untreated control cells. Lipid peroxidation marker (LPO) was significantly elevated in LME-treated cell lysates. The activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were significantly decreased in LME-treated cell lysates when compared with control HT-115 cells. In conclusion, the observed results demonstrate that LME significantly inhibits colon cancer cell growth via the mitochondria mediated caspase-dependent apoptosis mechanism.