Bound phenolics extracts of jujube peel relieve cadmium‐induced toxicity by reducing lipid accumulation of <i>Caenorhabditis elegans</i>

To investigate the effect of bound phenolics extracts (BPEs) of jujube peel on relieving cadmium (Cd)-induced toxicity and its mechanism, the behavioral deficits, lipid accumulation, and fatty acid synthesis-related gene expression in Caenorhabditis elegans in Cd exposure group and BPEs improvement groups were determined and compared. The results showed that BPEs significantly improved Cd-induced behavioral deficits in C. elegans, and no significant differences could be found in low-dose (12.5 µg/mL) and high-dose (100 µg/mL) BPEs improvement groups. The treatment of BPEs effectively improved intestinal injury and lipofuscin and lipid accumulation. Especially, oil red O staining intensity in C. elegans treated with BPEs at 50 µg/mL was reduced by 12.60%. BPEs significantly controlled the increase in content of C16:0, C16:1, C18:0, C18:1, and C18:2 induced by Cd by regulating the lipid accumulation in Escherichia coli OP50. Cd exposure induced lipid accumulation in C. elegans by upregulating oleic acid synthesis-related gene expression in E. coli OP50. Furthermore, BPEs treatment significantly downregulated the fatty acid synthesis-related gene expression in C. elegans and E. coli OP50. This research could reveal the mechanism of BPEs of jujube peel in relieving Cd-induced toxicity and provide a theoretical basis for the development of functional foods rich in polyphenols. PRACTICAL APPLICATION: Jujube peel, a by-product of jujube processing, is usually discarded due to its coarse texture. However, jujube peel has been proven to possess abundant polyphenols, polysaccharides, and cyclic adenosine phosphate. In addition, in our previous research, bound phenolics extracts (BPEs) of jujube peel were found to perform better in lowering lipid accumulation than that of free phenolics extracts. This study further investigate the effect of BPEs of jujube peel on relieving Cd-induced toxicity and its mechanism on the base of our previous research. It could realize the comprehensive utilization of by-products of jujube processing.