决明子提取物潜在风险因子分析

本文主要综述了决明子的功效及近些年服用决明子后的不良反应,并对决明子的主要成分及含量进行分析,筛查出其中的潜在风险因子,主要有蒽醌类物质,植物甾醇及其氧化物和生物碱等。重点对这些潜在风险因子进行分析,包括它们的性质、结构和安全性分析。大黄素等蒽醌类物质具有平面刚性结构,能显著抑制L-02细胞的活性;植物甾醇与胆固醇的结构类似,易被氧化而产生与胆甾醇氧化物(COPs)类似危害的植物甾醇氧化物(POPs),谷甾醇氧化物能显著抑制HepG2的细胞活性;腺嘌呤对大鼠口服也具有明显的急性毒性。最后对决明子提取物的毒理性研究进行展望,指出应建立体外毒理学评价模型、剂量-反应模型和结构-毒性模型,形成基础毒理数据库,构建保健食品安全性评价预警体系,提出安全限值建议。     

Selective synthesis of oleyl alcohol via catalytic and non-catalytic liquid-phase methyl oleate reduction

The upgrading of oleyl alcohol synthesis via methyl oleate reduction using NaBH₄ without H₂ supply was investigated. It was possible to synthesize selectively oleyl alcohol with high yields. Non-catalytic and catalytic experiments were developed trying to improve the low final oleyl alcohol yield previously obtained. The effect of reaction temperature, methyl oleate/NaBH₄ molar ratio and properties of different catalysts on final oleyl alcohol yield were analyzed. Thus, alumina-supported metal (M) catalysts (M = Fe, Ce, Mo) were synthesized by incipient wetness impregnation. The M/Al₂O₃ catalysts were characterized in their chemical, textural, structural and acid–base properties using ICP, N₂ physisorption, XRD and temperature-programmed desorption (TPD) of NH₃ and CO₂. During non-catalytic methyl oleate reduction, final methyl oleate conversion and oleyl alcohol yield of 94% were obtained using a methyl oleate/NaBH₄ molar ratio of 0.11 at 333 K. Catalytic activity of M/Al₂O₃ solids increases as acid site number and ionic potential of M cations increase. In addition, the reaction mechanism for fatty acid methyl ester reduction was investigated from a theoretical approach using Density Functional Theory method at B3LYP/6-31++G(d,p) computational level. Results obtained during theoretical calculations confirmed that the formation of reducing alcoxyborohydride species is energetically favored and allowed to understand the events at microscopic level involved in the reaction mechanism.