The volatile oil of Mentha haplocalyx is widely used in medicine, food, and cosmetics. However, a large amount of its residue after steam extraction of volatile oil is abandoned, resulting in a waste of resources. The method of aqueous two-phase flotation coupled with preparative high-performance liquid chromatography was established for the separation and purification of nonvolatile active compounds from Mentha haplocalyx for the first time. The parameters of the two-phase aqueous flotation were optimized. Under the optimal conditions including flotation solvent PEG 1000 aqueous solution (1:1, w/w), pH 5, (NH₄)₂SO₄ concentration of 350 g/L in aqueous phase, N₂ flow rate of 20 mL/min, and flotation time of 20 min, the flotation efficiency of linarin, hesperidin, and didymin was 82.24, 76.38, and 89.33%, respectively. The linarin and hesperidin with the high purities of 95.8 and 97.2%, respectively, were obtained by using preparative high performance liquid chromatography. The neuroprotective effect of linarin against H₂O₂-induced oxidative stress in rat hippocampal neurons was investigated. The experimental result indicated that linarin could alleviate H₂O₂-induced oxidative stress. The work indicated that the combination of aqueous two-phase flotation and preparative high performance liquid chromatography is a feasible and practical method for the purification of nonvolatile active substances from Mentha haplocalyx, which would provide a reference process for the comprehensive utilization of M. haplocalyx. Especially, linarin might be used as a good source of natural neuroprotectants.

中文翻译：

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水相两相浮选结合制备型高效液相色谱法纯化薄荷中的亚麻苦苷和橙皮苷，并评价亚麻苦苷的神经保护作用

Mentha haplocalyx的挥发油广泛用于医药、食品和化妆品。但其挥发油蒸汽提取后的残留物大量废弃，造成资源浪费。首次建立了水相两相浮选结合制备型高效液相色谱法分离纯化薄荷中非挥发性活性化合物的方法。优化了两相水浮选的参数。在浮选溶剂PEG 1000水溶液(1:1, w/w)、pH 5、(NH ₄ ) ₂ SO ₄水相浓度350 g/L、N _{2 等最佳条件下}流速为20 mL/min，浮选时间为20 min时，亚麻苦苷、橙皮苷和双帝明的浮选效率分别为82.24、76.38和89.33%。采用制备型高效液相色谱法分别得到纯度分别为95.8%和97.2%的亚麻苷和橙皮苷。研究了亚麻油苷对 H ₂ O ₂诱导的大鼠海马神经元氧化应激的神经保护作用。实验结果表明，linarin可以减轻H ₂ O ₂-诱导的氧化应激。的工作表明，双水相浮选和制备高效液相色谱法的组合对于非易失性活性物质从纯化可行和实用的方法薄荷haplocalyx，这将对于综合利用提供参考进程M. haplocalyx。特别是，linarin 可用作天然神经保护剂的良好来源。