Inhibition of Triacylglycerol Accumulation and Oxidized Hydroperoxides in Hepatocytes by Allium cepa (Bulb)

Recent studies have demonstrated that dietary plant extracts can inhibit the development of lipid droplets (LDs) and oxidized LDs (oxLDs) in hepatic cells. These findings suggest that such extracts may be beneficial in combating metabolic dysfunction-associated fatty liver disease (MAFLD) and its more advanced stage, metabolic dysfunction-associated steatohepatitis (MASH). We examined nine <i>Allium</i> extracts (ALs: AL1-9) to assess their capacity to decrease lipid droplet accumulation (LDA) and oxidative stress by suppressing lipid formation and oxidation in liver cells. Among the <i>Allium</i> extracts tested, AL6 exhibited significant inhibitory effects against LDA. Furthermore, we employed our lipidomic method to assess the accumulation and suppression of intracellular triacylglycerol (TAG) and oxidized TAG hydroperoxide [TG (OOH) n = 3] by AL6 in liver cells under oleic acid (OA) and linoleic acid (LA) loading conditions. These findings indicate that foods derived from <i>Allium</i> species prevent the formation of lipid droplets by decreasing intracellular lipids and lipid hydroperoxides in the hepatocytes. Analysis of the metabolome of bioactive lipid droplet accumulation inhibition (LDAI) AL6 using LC-MS/MS and 1D-NMR [¹H, ¹³C, DEPT 90, and 135] techniques revealed that AL6 is primarily composed of carbohydrates, glucosidic metabolites, and organosulfur compounds, with small amounts of polyols, fatty acyls, small peptides, and amino acids. This implies that AL6 could be a valuable resource for developing functional foods and drug discovery targeting metabolic dysfunction-associated fatty liver disease (MAFLD)/metabolic dysfunction-associated steatohepatitis (MASH) and related disorders.