Garlic peel extract as an antioxidant inhibits triple-negative breast tumor growth and angiogenesis by inhibiting cyclooxygenase-2 expression.

Garlic peels are frequently disposed of as agro-waste; their bioactivity and physiological activity for health benefits and disease protection are neglected. This study aims to examine the potential inhibitory effects of garlic peel extract as an antioxidant on 4 T1 triple-negative breast cancer (TNBC) tumors in mice. The bioactive constituents of garlic peel were identified through HPLC-MS/MS analysis, while the antioxidant properties of garlic peel extract were assessed using peroxyl radical scavenging capacity (PSC) and cellular antioxidant activity (CAA) assays. Subsequently, the inhibitory effects of garlic peel extract on 4T1 tumor growth were evaluated using a 4T1 model. The results showed that 433 polyphenol compounds were found in garlic peel extract; among them, flavonoids and phenolic acid are the primary polyphenols with natural antioxidant activity, and both high and low concentrations of the extract exhibited tumor-suppressive effects. Immunohistochemistry was employed to assess the expression levels of COX-2, CD31, VEGFA, MMP2, and MMP9 in tumor tissues in order to investigate the antioxidant properties of garlic peel extract, specifically its ability to suppress COX-2 expression. The findings of this study offer a foundation for the advancement of garlic peel-based functional products and contribute to the identification of potential anti-cancer agents and therapeutic targets.