水蒸汽蒸馏条件下鱼腥草中癸酰乙醛的高效提取及质谱定性

根据质谱学规律,剖析了在电子轰击下中药材鱼腥草中最关键的抗菌成分鱼腥草素(癸酰乙醛)的离子形成机理:癸酰乙醛的分子中存在两个-C=O,处于端位上的-C=O活性远大于-CH3,易失去H2O(M+18)、CO(M+ 28)等基团,产生较强的m/z180、170等离子碎片,此外,还易失去H2O+H2O(M+ -36)、H2O+CO(M+-46)、CO+CO(M+-56)等基团,产生m/z162、152、142等离子碎片,这同实验中得到的癸酰乙醛质谱图完全吻合,纠正了文献中对癸酰乙醛的错误定性.在此基础上采用常规、Ar气保护和减压三种水蒸汽蒸馏方式提取鱼腥草挥发油,发现在惰性气氛或较低温度下有利于癸酰乙醛的提取,与常规水蒸汽蒸馏条件相比,Ar气保护下癸酰乙醛的含量从0.03％提高至0.53％,而减压条件下癸酰乙醛的溶出效率进一步提高至3.37％.研究表明常规水蒸汽蒸馏条件下癸酰乙醛易氧化分解是得到较少癸酰乙醛的根本原因.

Highly Efficient Extraction of Decanoyl Acetaldehyde in Houttuynia cordata thunb Under Steam Distillation and Its Mass Spectrometric Analysis

Regarded as the antibiotic of traditional Chinese medicine,houttuynia cordata thunb(HCT) has been widely employed for clinic therapy.In this paper,one of the key effective components of HCT,houttuynium(decanoyl acetaldehyde) was studied in detail.At first,according to the law of mass spectrometry,the formation mechanism of decanoyl acetaldehyde ions was analyzed under electronic bombarding:there are two-C=O and the tip one is more active than-CH3 in decanoyl acetaldehyde molecular,so it is easy to lose H2O(M+-18),CO(M+-28) groups,resulting in a strong abundance of m/z180,170 ions.Furthermore,ions of m/z162,152,142 are produced when H2O+H2O(M+-36),H2O+CO(M+-46),CO+CO(M+-56) are lost easily.The results were consistent completely with the mass spectrum obtained by our experiment,contrasting with the mass spectrum definition of decanoyl acetaldehyde in the literature.Secondly,the essential oil from HCT was extracted by three steam distillation methods of normal,argon gas protection and decompression,respectively.The extraction efficiency of decanoyl acetaldehyde in the order of:normal < argon gas protection < decompression.Compared with the normal steam distillation,decanoyl acetaldehyde content in essential oil was increased remarkably from 0.03% to 0.53% under argon gas protection,and it further went to 3.37% under decompression.The results showed that oxidation and decomposition of decanoyl acetaldehyde led to lower content under the normal steam distillation.The study provides available data for further developing and utilizing of HCT and amending the existing quality control standards of HCT injection.