Untargeted metabolomics of fermented onion (Allium cepa L) using UHPLC Q-TOF MS/MS reveals anti-obesity metabolites and in vivo efficacy in Caenorhabditis elegans

The bioconversion of onion extracts with P. acidilactici MNL5 enhances the metabolites and has a synergistic lipid-reduction impact that is beneficial for anti-obesity studies. The 48 h fermented onion extracts (FOE) demonstrated an enhanced inhibitory activity against pancreatic lipase (89.5 +/- 1.25 %) as compared to the raw onion extract (ROE) (33.4 +/- 0.86 %). The antioxidant properties of FOE significantly increased compared to the ROE inhibitory effect on DPPH (99.5 +/- 2.40 mg vitamin C equiv./mg, DW FOE), and ABTS (104.5 +/- 2.32 mg vitamin C equiv./mg, DW FOE). Based on FOE's higher antioxidant activity, UHPLC-Q-TOF-MS/MS demon-strated dramatic changes in the untargeted metabolite profile as compared to ROE. Moreover, C. elegans sup-plemented with FOE and quercetin exhibited an enhanced lifespan activity, lipid reduction, and decreased triglycerides. FOE can lower cholesterol and enhance quercetin to promote pancreatic lipase activity for syn-ergistic anti-obesity effects.