The MALDI-TOF Analysis of Aconitum Alkaloids in Proprietary Chinese Medicine and in the Concoction of Fuzi

Abstract

In theory, the kinds and relative amounts of aconitum alkaloids in proprietary Chinese medicines should be consistent with those in Fuzi. However, this feature has not been noted enough and no direct experimental evidence to prove it. In this work MALDI-TOF-MS was used to analysis 19 kinds of proprietary Chinese medicines, benzoylmesaconine and hypaconitine have been proved to be the predominant monoester and diester alkaloids respectively. In addition, the MALDI-TOF analysis of the concoction of seven kinds of Chinese medicine has confirmed that the acidity of concoction will improve the aconitines contents and the toxicity of concoction, but this rule was not suited for Lonicera nitida, Rhizoma Chuanxiong or Chaenomeles sinensis. The Aconitum plants are widely used in China as an analgesic, a cardiotonic, and an anti rheumatism treatment. Among all the species Aconitum, the lateral roots of Aconite (Aconitum Camicheali Debx, Fuzi), main roots of Aconite (Chuanwu) and roots of Aconitum kusnezoffii Reichb (Caowu) are the three kinds of plant medicines that are collected in Chinese Pharmacopoeia, and some of other Aconitum plants have been used as folk medicine. It is well known that diester diterpenoid aconitine (DDA) and its analogues isolated from Aconitum plants contribute to the bioactivity and the high toxicity for the heart and the central nervous system. Fortunately, aconitines are heat-unstable and will be conversed into less toxic monoester diterpenoid alkaloids (MDA) or lipo-alkaloids after processing [1], therefore, the amounts of highly toxic aconitine are lower than those of monoester diterpenoid alkaloids in processed aconite and proprietary Chinese medicines (PCMs). For monitoring the possible toxicity of Chinese medicines, high-performance liquid chromatography (HPLC) has been frequently used for quantification analysis of aconitines. Generally, only aconitine, mesaconitine and hypaconitine three standards could be purchased and most of research was limited in these 3 alkaloids [2]. Therefore, qualitative analysis is also essential for PCM besides quantitative analysis. In contrast to chromatographic methods, matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS) determines the molecular mass of alkaloids, which represents an inherent physical property and is feasible for high-throughput analysis of different samples containing aconitines.