Antihyperlipidemic effect of Vaccinium dunalianum buds based on biological activity screening and LC-MS

The buds of Vaccinium dunalianum Wight are used as folk medicine in the Yi settlement of the Yunnan Province, China. It has long been used as herbal tea in the local area owing to its effects of lowering blood lipids and body weight. However, there are only a few studies on its antihyperlipidemic effects, effective substances and mechanisms, especially its effectiveness in diet-induced hyperlipidemia.This study aimed to elucidate the therapeutic effects, pharmacodynamic material bases, and mechanisms of V. dunalianum buds on diet-induced hyperlipidemia.A high-fat diet-induced hyperlipidemic Sprague-Dawley (SD) rat model was established. Rats were gavaged with different doses of aqueous extract of V. dunalianum(VDW) for 8 weeks and their sera and organ samples were collected. The antihyperlipidemic effect of VDW on SD rats was evaluated based on the biochemical indices and histopathological outcomes. Liquid chromatography-mass spectrometry(LC-MS) was used to determine the main components in VDW, which were separated and purified using sequential chromatographic methods. Their chemical structures were determined using high-resolution electrospray ionization mass spectroscopy and nuclear magnetic resonance spectroscopy. 6'-O-caffeoyl-arbutin, as the principal component of VDW, was also evaluated for its antihyperlipidemic activity using an approach similar to that used for VDW. Lastly, the potential targets of VDW and 6'-O-caffeoyl-arbutin in lowering blood lipids were screened out using network pharmacology, and the selected targets were docked with arbutin derivatives. The expression of target proteins was determined using western blotting to illustrate the antihyperlipidemic mechanisms of VDW and 6'-O-caffeoyl-arbutin.VDW reduced triglyceride, total cholesterol, low-density lipoprotein, alanine transaminase, and aspartate transaminase levels in the serum of modeled rats, and increased high-density lipoprotein levels. There was an improvement in steatoses, and lipid droplet accumulation decreased in vivo after VDW intervention. LC-MS revealed that VDW mainly contained arbutin and chlorogenic acid derivatives. Sixteen compounds were isolated and identified. 6'-O-caffeoyl-arbutin was the main compound of VDW (>21.67%) that showed obvious antihyperlipidemic effect with low hepatic damage at different doses. PTGS2, ADH1C, and MAOB were screened out using network pharmacology and they showed strong correlations with arbutin derivative through molecular docking. Results from WB showed that VDW and 6'-O-caffeoyl-arbutin could reduce blood lipid levels by reducing the protein expression of PTGS2, ADH1C, and MAOB.6'-O-caffeoyl-arbutin was the main component of V. dunalianum buds. VDW and 6'-O-caffeoyl-arbutin could regulate blood lipid levels in the high-fat diet-induced rat model of hyperlipidemia without damaging their vital organs. Furthermore, they could regulate the expression of PTGS2, ADH1C, and MAOB proteins and play a role in lowering blood lipids. The findings of this study lay a foundation for the further development of V. dunalianum and 6'-O-caffeoyl-arbutin as health supplements or drugs for the management of hyperlipidemia.