Optimization of Extraction Process by Response Surface Methodology of Total Flavonoids from Ziziphus Jujube Flesh and its Sedative-Hypnotic Effects

Background & aims This study optimizes the extraction process of total flavonoids from Ziziphus jujube flesh (TFZJF) by response surface methodology and investigating its sedative-hypnotic effects and mechanisms in a para-chlorophenylalanine (PCPA)-induced insomnia mouse model. It provides theoretical support for the further comprehensive utilization of Ziziphus jujube fruit and flesh. Methods Single-factor experiment and Box–Behnken response surface design were used to study the ethanol reflux extraction process of TFZJF, with flavonoid extraction rate as the indicator, to obtain the optimal extraction process of TFZJF. An insomnia model in mice was induced via an intraperitoneal injection of PCPA, and the effects of TFZJF on this model, along with its underlying mechanisms, were assessed using various approaches, including sodium pentobarbital-induced sleep potentiation, HE staining of tissue sections, ELISA, RT-PCR, WB, and serum metabolomics. Results The results showed that the optimized extraction conditions for TFZJF included a solid–liquid ratio (SLR) of 1:25 g·mL?1, ethanol concentration of 60%, and extraction time of 60 min, yielding an extraction efficiency of 1.98%. Data from the experimental groups indicated dose-dependent sleep improvement in the insomnia model, with the high-dose TFZJF (TFZJF-H) group exhibiting the most significant effect, followed by the medium-dose (TFZJF-M) and low-dose (TFZJF-L) groups. Metabolomic analysis revealed that TFZJF administration positively impacted the metabolic profile of PCPA-induced insomnia, particularly affecting pathways related to phenylalanine, tyrosine, cytochrome P450, and alanine metabolism on non-targeted metabolomics. Conclusions The extraction process is stable and reliable, which can be used for the extraction of TFZJF; meanwhile, TFZJF demonstrated significant sleep-enhancing effects in the PCPA-induced insomnia mouse model, supporting its potential for resource development and the utilization of non-medicinal parts of Ziziphus jujube.