基于电子眼技术和化学指纹图谱的陈皮与蒸陈皮质量差异分析

Quality Difference Analysis of Raw and Steamed Products of Citri Reticulatae Pericarpium Based on Electronic Eye Technique and Chemical Fingerprint

目的:探究蒸陈皮与陈皮2种饮片间的质量差异。方法:基于15批陈皮及15批蒸陈皮的自身对照样本,利用电子眼技术从外观角度测定陈皮和蒸陈皮的颜色,通过明度值(L^(*))、黄蓝值(b^(*))、红绿值(a^(*))和总色值(E_(ab)^(*))客观表征陈皮及蒸陈皮的质量差异;在此基础上,采用超高效液相色谱法(UPLC)建立指纹图谱评价方法,流动相乙腈(A)-0.1%甲酸水溶液(B)梯度洗脱(0~5 min,5%A;5~30 min,5%~20%A;30~60 min,20%~52%A),检测波长270 nm,流速0.3 m L·min^(-1),柱温30℃,从化学成分角度比较陈皮及蒸陈皮间的质量差异,并利用相关性分析揭示外观颜色差异与内在化学成分差异之间的相关性。结果:陈皮蒸制后整体颜色加深,其中L^(*)、b^(*)和E_(ab)^(*)整体呈下降趋势,说明陈皮蒸制后颜色变暗加深且由黄向蓝转变但仍偏向黄色,a^(*)整体呈上升趋势,说明陈皮蒸制后颜色更偏向红色。在陈皮和蒸陈皮的指纹图谱中共确定了24个色谱峰,并对其中13个主要色谱峰进行了鉴定。精密度、稳定性、重复性考察显示,与参照峰(峰14,橙皮苷)比较,其余色谱峰相对峰面积及相对保留时间的相对标准偏差(RSD)均<3.0%。指纹图谱化学计量学统计分析结果表明,陈皮与蒸陈皮之间存在一定差异,并确定了7个主要差异性成分,其中5-羟基麦芽酚和5-羟甲基糠醛为蒸陈皮特征成分;相关性分析结果表明,除以上2种特征成分外,峰4、峰10(维采宁-2)、峰23(桔皮素)和峰24(5-去甲基川陈皮素)4个成分与样品颜色变化(E_(ab)^(*))亦存在明显相关性(P<0.05,P<0.01)。结论:陈皮蒸制前后不仅化学成分发生了变化,颜色也发生了改变。将陈皮蒸制前后的化学成分差异特征峰与颜色差异特征峰比较后发现,5-羟基麦芽酚、5-羟甲基糠醛和峰4为共有的特征差异成分,可为建立蒸陈皮特征性质量控制方法、快速评价陈皮和蒸陈皮饮片质量差异提供参考。

Objective:To explore the quality differences between steamed products and raw products of Citri Reticulatae Pericarpium(CRP).Method:The color of steamed products and raw products of CRP was determined from the perspective of appearance by electronic eye technique,and the quality differences between them was objectively characterized by the luminous value(L^(*)),yellow-blue value(b^(*)),red-green value(a^(*))and total chromatic value(E^(*)ab).Based on this,ultra-high performance liquid chromatography(UPLC)was used to establish a fingerprint evaluation method with the mobile phase of acetonitrile(A)-0.1%formic acid aqueous solution(B)for gradient elution(0-5 min,5%A;5-30 min,5%-20%A;30-60 min,20%-52%A),detection wavelength at 270 nm,flow rate of 0.3 mL·min-1 and column temperature of 30℃.The quality differences between steamed products and raw products of CRP were compared from the perspective of chemical composition,and correlation analysis was used to reveal the correlation between the difference in appearance color and the difference in internal chemical composition.Result:After being steamed,L^(*),b^(*)and E^(*)ab of CRP showed an overall decreasing trend,indicating that the color of the steamed products darkened and deepened from yellow to blue but still tended to be yellow,while a^(*)showed an overall increasing trend,indicating that the color of the steamed products tended to red.A total of 24 peaks were identified in the fingerprint profiles of raw products and steamed products of CRP,and 13 of the main peaks were identified.The precision,stability and repeatability studies showed that compared with the reference peak(peak 14,hesperidin),the relative standard deviations(RSDs)of the relative peak area and relative retention time of the remaining peaks were<3.0%.The results of chemometric statistical analysis showed that there were some differences between raw products and steamed products of CRP,and 7 main differential components were identified,among which 5-hydroxymaltol(peak 1)and 5-hydroxymethylfurfural(peak 2)were the characteristic components of steamed products.The correlation analysis results showed that,in addition to the above two characteristic components,four components of peak 4,peak 10(vicenin-2),peak 23(tangeretin)and peak 24(5-demethylnobiletin)also correlated significantly with the color change(E^(*)ab)of the samples(P<0.05,P<0.01).Conclusion:Before and after steaming,not only the chemical composition changes,but also the color.Comparing the characteristic peaks of chemical composition difference and color difference before and after steaming of CRP,it is found that 5-hydroxymaltol,5-hydroxymethylfurfural and peak 4 are common characteristic difference components,which can provide a reference for establishing the characteristic quality control method of steamed products,and quickly evaluating the quality difference between raw products and steamed products of CRP.