Geum japonicum Thunb. var. chinense (G. japonicum) is a cultivated medicinal plant and used as folk medicine, among which tannins are the main active ingredients. In this work, L-proline-lactic acid (Pro:La) as natural deep eutectic solvents (NADESs) was tailored for the total tannins extraction from G. japonicum with the optimal conditions as follows: water content of 29 %, solid-liquid ratio of 27:1 (mg/mL), extraction time of 48 min, and extraction temperature of 48°C. In high fat diet-induced obese mice, the total tannin extract of G. japonicum can significantly reduce the body weight and serum lipid levels, improve glucose tolerance impairment and insulin resistance, reduce islet hypertrophy and protect the liver. Targeted fractionation of the total tannin extract of G. japonicum led to the isolation of sixteen tannins. Notably, the isolated tannins, except for ellagic acid and 3,3′-di-O-methylellagic acid, possessed strong α-glucosidase inhibitory activities (IC₅₀: 1.401–4.801 μg/mL) and dose-dependently inhibited glucose consumption of Caco-2 model system in vitro. These results indicate that the NADES (Pro:La) can effectively extract total tannins from G. japonicum and provide a reference for further applications in medicine and healthcare products.

Geum japonicum Thunb。变种中华药材（ G. japonicum ）是一种栽培药用植物，用作民间药物，其中单宁是主要活性成分。本工作采用L-脯氨酸-乳酸（Pro:La）作为天然低共熔溶剂（NADES），用于提取日本刺参中的总单宁，最佳条件为：含水量29%，固-液比例为 27:1 (mg/mL)，提取时间为 48 分钟，提取温度为 48°C。在高脂饮食诱导的肥胖小鼠中，刺参总单宁提取物可显着降低体重和血脂水平，改善糖耐量损伤和胰岛素抵抗，减轻胰岛肥大，保护肝脏。对日本刺参总单宁提取物进行定向分馏，分离出 16 种单宁。值得注意的是，除了鞣花酸和3,3′-二-O-甲基鞣花酸外，分离的单宁具有很强的α-葡萄糖苷酶抑制活性（IC ₅₀ ：1.401–4.801 μg/mL），并且剂量依赖性地抑制Caco的葡萄糖消耗-2体外模型系统。这些结果表明NADES（Pro:La）可以有效地从刺参中提取总单宁，为进一步在医药保健品中的应用提供参考。