RP-HPLC法测定地黄饮子中马钱苷含量

采用高效液相色谱法（HPLC）,测定地黄饮子药材中的马钱苷,色谱柱为Kromasill C18柱（50 mm×4.6 mm,5μm）,流动相采用乙腈-水（15∶85）,流速0.8 mL/min,进样量20μL,检测波长240 nm,柱温室温。结果表明,马钱苷的保留时间约为7 min,进样量在0.079 2～1.98μg范围内,其峰面积与浓度呈良好的线性关系（r=0.999 7）。平均回收率为98.87%,RSD小于2%（n=6）,其他成分不干扰本实验。方法专属性强,准确可靠,可用于地黄饮子药材中马钱苷的含量测定。     

Loganic Acid Methyltransferase: Insights into the Specificity of Methylation on an Iridoid Glycoside

Loganin is an iridoid glycoside of interest as both an intermediate in the biosynthesis of indole alkaloids in plants and as a bioactive compound itself. Loganic acid methyltransferase catalyzes the methylation of a monoterpenoid glycoside precursor to produce loganin and demonstrates stereospecificity for the (6S,7R) substrate. We have biochemically characterized this biocatalyst and elucidated the basis for its strict substrate specificity. These studies could help facilitate the design of new classes of monoterpenoid indole alkaloids of pharmaceutical interest.     

马钱苷对胎牛血清诱导的L02细胞脂肪变性的抑制作用

为了探究马钱苷对细胞脂肪变性的抑制作用及相关机制,以50%胎牛血清诱导L02细胞建立脂肪变性模型,通过MTT法和油红O染色法测定了马钱苷对脂变细胞增殖的抑制情况,并采用相应试剂盒测定了实验细胞上清液中谷草转氨酶(aspartate aminotransferase,AST)、谷丙转氨酶(alanine aminotransferase,ALT)和乳酸脱氢酶(lactate dehydrogenase,LDH)酶活、总胆固醇(total cholesterol,TC)和甘油三酯(triglycerides,TG)水平以及细胞内TC、TG和硫代巴比妥酸反应物(thiobarbituric acid reactive substances,TBARS)水平。MTT结果显示,与模型组相比,马钱苷各浓度组可显著抑制脂变细胞增殖(p<0.05),抑制率为14.6%~26.91%;油红O观察发现,马钱苷处理能够剂量依赖性减少胞浆内脂滴累积;与模型组相比,马钱苷处理组细胞胞外AST、ALT和LDH酶活分别下降26.70%~52.58%、24.83%~61.23%和14.53%~28.83%,胞外TC和TG水平分别下降50.46%~68.76%和32.51%~53.37%,胞内TC和TG水平分别下降11.48%~32.79%和10.50%~18.30%,胞内TBARS水平下降40.33%~60.10%,呈现明显剂量-效应关系,且效果均强于自然恢复组。实验结果表明,马钱苷能够显著减少因脂质代谢紊乱和脂质过氧化引起的L02细胞损伤,抑制胎牛血清诱导的L02细胞脂肪变性。