基于热分析及抗干旱胁迫的地黄干燥特性研究

Drying Characteristics of Rehmannia glutinosa Root Based on Thermal Analysis and Resistance to Drought Stress

目的:探讨鲜地黄干燥过程中化学成分的动态变及抗干旱胁迫作用对化学成分的影响。方法:采用热分析技术,对比模拟空气(N_2∶O_2=4∶1)、氩气(Ar)两种不同气氛,及从室温升至200℃、程序升温两种不同升温方式对鲜地黄干燥过程的影响。HPLC以Hypersil GOLD aQ C_(18)(250 mm×4.6 mm)为色谱柱,以乙腈∶0.1%磷酸溶液为流动相对4种环烯醚萜类成分及毛蕊花糖苷进行含量测定。指纹图谱的建立以乙腈(A)-0.1%磷酸溶液(B)为流动相进行梯度洗脱(0~12 min,5%~10%A;12~40 min,10%~15%A;40~70 min,15%~25%A;70~85 min,25%~28%A),分析各样品色谱图的差异性。结果:鲜地黄于惰性气氛(Ar)下,热失重及热失重速率均大于模拟空气气氛下的相应数值。在地黄的整个阴干过程中,4种环烯醚萜类成分及毛蕊花糖苷含量均呈现出0~27 d内升高、30~33 d后降低的变化趋势。随干燥程度的增加,各阴干品(S_1~S_(11))与市售生地黄(SS)HPLC指纹图谱相似度增大;就不同阴干程度的鲜地黄相对相似度而言,在阴干至18 d内,相对相似度持续减小。结论:干燥气氛及升温速率对鲜地黄的干燥过程有较大的影响。在地黄阴干过程中,抗干旱胁迫作用对相关药效成分的含量存在影响,这种影响以阴干15 d后表现较为突出。

Objective： To explore the dynamic variables of chemical constituents in the process of drying fresh rehmannia root and the effect of drought stress resistance on the chemical constituents.Methods： Thermal analysis was used to compare the effect of two atmospheres,i.e.,simulated air VS argon（Ar）,and of two heating modes,i.e.,heating from room temperature to 200 ℃ VS programmed heating,on the process of drying rehmannia root.HPLC,with Hypersil GOLD aQ C（18）（250 mm × 4.6 mm） as the chromatographic column and acetonitrile： 0.1% phosphoric acid solution（B） as the mobile phase,was used to determine the content of four iridoids and verbascoside.A fingerprint spectrum was established by gradient elution using acetonitrile（A）-0.1% phosphoric acid solution as the mobile phase（0 - 12 min,5% - 10% A; 12 - 40 min,10% - 15% A; 40 - 70 min,15% - 25% A; 70 - 85 min,25% - 28% A）,to analyze the differences between the chromatograms corresponding to various samples.Results： Fresh rehmannia root exhibited greater thermal weight loss and thermal weight loss rate in inert atmosphere（Ar） than in simulated air atmosphere.Throughout the drying of rehmannia root in the shade,the content of all four iridoids and verbascoside increased during day 0 - 27 and decreased during day 30 -33.The similarity between the fingerprint spectra of the drying products（S1-S（11）） and that of the dried rehamnnia root commercially available increased as the drying process proceeded; the relative similarities between the fingerprint spectra of differently dried products decreased continuously from day 18 of the drying process.Conclusion： The atmosphere for the drying and heating rate has a significant effect on the drying process of fresh rehmannia root.In the drying process of rehmannia root in the shade,the resistance to the drought stress has an effect on the content of the corresponding medicinal components which becomes more obvious after 15 d of drying.