Abstract:To achieve the high-value utilization of discarded branches and leaves of Buddleja officinalis， the in vitro antioxidant activity and in vivo hypolipidemic efficacy of its flavonoid extract were systematically investigated in this paper. The antioxidant activity of flavonoids from the branches and leaves of Buddleja officinalis was investigated by evaluating their scavenging rates against DPPH radicals， ABTS+ radicals， and O2- radicals. An ICR mouse model induced by a high-fat diet was established， and the mice were divided into a normal control group， a model control group， a positive control group， and low-， medium-， and high-dose extract groups， with continuous intervention for 10 weeks. In vitro experiments showed that the median inhibition concentration values of the purified extract for scavenging DPPH radicals， ABTS+ radicals， and superoxide anion radicals were 31.7， 18.4， and 106.6 μg/mL， respectively. Among them， the scavenging activity against ABTS+ radicals was superior to that of VC （15.3 μg/mL）， and the scavenging activity against DPPH radicals was superior to that of the crude extract （55.1 μg/mL） and VC （35.7 μg/mL）. In vivo lipid-lowering results showed that， the abnormal increase in body weight of mice was significantly inhibited by the high-dose group（P<0.05）， and its efficacy in controlling body weight and improving organ indices was comparable to that of the positive control group. Serum total cholesterol （TC）， triglyceride （TG）， low-density lipoprotein cholesterol （LDL-C）， and atherosclerosis index were dose-dependently reduced by the extract， and the abnormal elevation of high-density lipoprotein cholesterol was corrected. After 8 weeks of intervention， the blood lipid indices in the high-dose group basically returned to normal， and the down-regulation effect on LDL-C was superior to that of the positive control group. The total antioxidant capacity and superoxide dismutase activity in serum and liver tissues were enhanced； the malondialdehyde content was decreased， and the nitric oxide level was regulated by the extract， thereby protecting the body by maintaining oxidative homeostasis. Meanwhile，the deposition of TC and TG in liver tissues was reduced， and reversed the feedback inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase induced by a high-fat diet， restoring the enzyme activity to near-normal levels （P<0.05）， thereby indirectly regulating endogenous cholesterol synthesis.