Regulatory Effect and Mechanism of Oenothein B in Reducing Fat Accumulation in Caenorhabditis Elegans

Abstract Oenothein B (OEB) displays various biological activities, including immunomodulatory, antioxidant, and anticancer effects. However, the underlying mechanisms remain unclear. Therefore, in this study, the effect of OEB isolated from Eucalyptus leaves on fat deposition and its underlying mechanism are explored in Caenorhabditis elegans （C.elegans) . OEB shows remarkable antioxidative capacity by reducing reactive oxygen species (ROS) and enhancing the activities of antioxidant enzymes, including superoxide dismutase (SOD) and glutathione peroxidase (GSH‐Px). Oil Red O (ORO) and Nile Red staining show that OEB significantly inhibits fat accumulation. Furthermore, the size and number of lipid droplets in transgenic DHS‐3::GFP worms decrease, and the ratios of unsaturated fatty acids in worms are increased by OEB. Furthermore, quantitative reverse transcription‐polymerase chain reaction （qRT‐PCR） analysis shows that the expression of mdt‐15 , fat‐5 , fat‐7 , fasn‐1 , pod‐2 , vit‐2 , and tub‐1 is remarkably changed by OEB. Fat inhibition by OEB is abolished in the tested mutants. These results suggest that the mechanism underlying the inhibitory effects of OEB on fat deposition is dependent on dietary restriction as well as fatty acid synthesis, β ‐oxidation, and storage. This study provides new insights into the mechanisms underlying lipid metabolism regulation by OEB. Practical Applications : Obesity is a global health problem and a risk factor for cardiovascular disease, diabetes, and many forms of cancer. Evidence in the scientific literature shows that some polyphenols play an important role in inhibiting obesity. OEB has a surprisingly broad spectrum of biological activities, including immunomodulatory, antioxidant, and anticancer activities. In this study, the effect of OEB on fat metabolism and its related mechanisms in Caenorhabditis elegans are investigated. The findings outlined in the current study show that OEB is effective in reducing fat accumulation, enhancing the ratios of unsaturated fatty acids, and affecting fat metabolism pathways in C. elegans . This study will be helpful in elucidating the characteristics and underlying mechanisms of lipid metabolism by OEB.