Composition analysis and preliminary structural characterization of the flavonoids from Lycium barbarum leaves

A flavonoids extract was obtained from Lycium barbarum leaves by ethanol refluxing method in high temperature，and its total flavonoids content was 347.00 mg/g detected by aluminum nitrate－sodium nitrite colorimetric method.The preliminary structural characterization of the flavonoids extract were determined by UV － visible spectroscopy (UV － Vis) and Fourier transform infrared spectroscopy (FT－IR) .The results showed that the flavonoids extract in Lycium barbarum leaves contained A－benzoyl ring and B－cinnamoyl ring structures in UV－Vis spectra，and had main characteristics of flavonoids functional groupsincluding C = C group，a hydroxyl group，a phenolic hydroxyl group，methoxy and methyl groups in FT－IR spectra，which indicated that the extract from Lycium barbarum leaves had the typical structure of flavonoids.The composition of flavonoids in the extract was analyzed by high performance liquid chromatography (HPLC) .The result showed that rutin，chlorogenic acid，quercetin，caffeic acid，p－coumaric acid and campherol existed in the flavonoids extract.The contents of them were 100.74，42.83，23.59，2.94，0.31 and 0.08 mg/g respectively，indicating that the extract was a kind of natural flavonoids substances rich in rutin，chlorogenic acid and quercetin，and had the value of development and utilization in natural food additives and functional food materials.