Abstract:
Garlic has long been known for its wide array of therapeutic effects, including hypolipidemic, antihypertensive,
antimicrobial, and possibly anticancer effects; conversely, some adverse effects of garlic, such as acute pain and
neurogenic inflammation, have also been reported. However, information detailing the toxicological significance of garlic is
scarce. In this study, the cytotoxicities of fresh garlic extract (FGE) and boiled garlic extract (BGE) and their underlying toxic
mechanisms were investigated using INT-407 intestinal epithelial cells. A brief exposure (20 minutes) to FGE induced a
concentration-dependent increase in cell death (37 2% at 300 mg=mL), but no cytotoxic effects were induced after exposure
to BGE. For FGE, only the high-molecular-mass (>10-kDa) proteins were associated with cytotoxic effects. FGE-treated cells
showed morphological changes such as increased cell rounding and fragmentation, suggesting programmed cell death (apoptosis).
Apoptosis of FGE-treated cells was evaluated by observing the fragmented multinuclei stained with Hoechst 33342.
From the cell cycle analysis, the increase in hypodiploidic cells and in the G2=M phase cell population suggested not only
apoptosis but also cell cycle arrest of FGE-treated cells. Pretreatment with N-acetyl-l-cysteine almost completely prevented
FGE-induced cell death, suggesting that reactive oxygen species (ROS) may play a key role in FGE-associated cytotoxicity.
Consumption of fresh garlic may be linked to potential cytotoxicity of intestinal cells when ROS scavengers are not present.