UPLC-Q-TOF-MS法分析枇杷叶的倍半萜苷类化合物

Analysis of sesquiterpene glycosides from loquat leaves by UPLC-Q-TOF-MS

目的采用超高效液相-四级杆-飞行时间串联质谱(UPLC-Q-TOF-MS)技术对分离得到的枇杷叶总倍半萜苷类成分进行定性分析,并对其裂解途径进行研究总结。方法枇杷叶乙醇提取物经大孔树脂、聚酰胺柱色谱和RP-18柱色谱处理后,得到的枇杷叶总倍半萜苷采用Agilent ZORBAX SB-C18色谱柱(4.6 mm×100 mm,1.8μm),甲醇-0.1%甲酸水溶液为流动相进行梯度洗脱,ESI源负离子模式下采集质谱数据。结果从总倍半萜苷中得到5个倍半萜苷类化合物,其二级质谱裂解规律均相同,表现为逐个脱去寡糖链上的糖基,产生特征碎片离子m/z 675、529、383,最后生成m/z 205的特征苷元碎片。结论其中2个倍半萜苷类成分可能是仅在苷元C-6和C-7位上构型有差异的loquatifolin A和6,7-cis-nerolidol-3-O-α-L-rhamnopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→6)]-β-D-glucopyranoside。

AIM To analyze chemical constituents and fragmentation pathways of sesquiterpene glycosides isolated from loquat（ Eriobotrya japonica） leaves by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry（ UPLC-Q-TOF-MS）. METHODS Alcohol extract of loquat leaf was subjected to a variety of column chromatographies,then UPLC was performed on Agilent ZORBAX SB-C18 column with methyl alcohol-0. 1% formic acid in water as mobile phase in a gradient elution mode. The mass spectrometer equipped with electrospray ionization source was used as a detector under the negative ion mode. RESULTS 5 sesquiterpene glycosides had similar fragmentation pathways. The cleavage was presented in consecutive lose in monosaccharide residue of oligosaccharide chain to give specific product ions at m / z 675,529,383,finally yielding a signature aglycone ion at m / z 205. CONCLUSION These characteristic fragmentations may be loquatifolin A and 6,7-cis-nerolidol-3-O-α-L-rhamnopyranosyl-（ 1 →4）-α-L-rhamnopyranosyl-（ 1 →2）-[α-L-rhamnopyranosyl-（ 1 →6） ]-β-D-glucopyranoside,which exist the difference only at 6,7-C configuration.