Optimization of Deep Eutectic Solvent Extraction Process and Study on the Anti-Alcoholic Fatty Liver Disease Activity and Mechanism of Flavonoids From Lophatherum gracile Brongn.

Deep eutectic solvents (DESs) are a novel type of green extraction medium characterized by strong designability, biodegradability, and high extraction efficiency, making them highly promising for the separation of bioactive components from natural products. Lophatherum gracile Brongn. (L. gracile) is rich in various bioactive components, including flavonoids and polysaccharides. This study established a DES-based extraction system for flavonoids of L. gracile, optimized the process using response surface methodology, and evaluated the antioxidant activity, and hepatoprotective effects of the extracts against alcoholic liver disease (ALD) with focus on gut microbiota modulation. A choline chloride-malic acid DES was identified as the optimal extractant. Under the optimized conditions (extraction time of 60 min, water content of 32%, liquid-to-solid ratio of 61:1 mL/g, molar ratio of 1:1, ultrasonic power of 480 W, and temperature of 60°C), the extraction yield of L. gracile flavonoids reached 16.62 ± 0.27 mg/g. Compared to traditional ethanol extracts, the DES-extracted L. gracile flavonoids exhibited significantly stronger DPPH radical scavenging activity. Moreover, they demonstrated enhanced hepatoprotective effects in an ALD mouse model by ameliorating dyslipidemia, alleviating liver injury, and improving hepatic histopathology. Notably, the DES extracts more effectively reshaped the alcohol-disrupted gut microbiota by increasing beneficial bacteria (e.g., Akkermansia and Lactobacillus) while suppressing pathogenic genera (e.g., Escherichia-Shigella and Bacteroides). These findings provide an efficient and environmentally friendly extraction strategy for L. gracile flavonoids and offer experimental evidence for their potential application in alcoholic liver disease prevention and treatment through gut microbiota modulation.