Departamento de Química e Bioquímica/Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Edifício C8, Campo Grande, 1749 016 Lisboa, Portugal.
Rapid Commun Mass Spectrom. 2010 Dec 15;24(23):3432-40. doi: 10.1002/rcm.4791.
Five isoflavones, daidzein, genistein, formononetin, prunetin and biochanin A, known for their biological properties, are investigated by electrospray ionization mass spectrometry in the positive ion mode. The most probable protonation sites are determined taking into account semi-empirical calculations using the PM6 Hamiltonian. Fragmentation mechanisms are proposed based on accurate mass measurements, MS(3) experiments and supported by the semi-empirical calculations. Some of the fragmentation pathways were found to be dependent on the substitution pattern of the B-ring and the ions afforded by these fragmentations can be considered as diagnostic. It was possible to distinguish between prunetin and biochanin A, two isobaric isoflavone aglycones included in this study. Furthermore, a comparison of the fragmentation patterns of genistein and biochanin A, two isoflavones, with those of their flavone counterparts, apigenin and acacetin, enabled us to identify some key ions mainly due to structural features, allowing distinction to be made between these two classes of compounds.
五种异黄酮，大豆苷元、染料木黄酮、芒柄花素、樱黄素和大豆苷 A，因其生物特性而被研究，采用电喷雾电离质谱在正离子模式下进行检测。考虑到使用 PM6 哈密顿量的半经验计算，确定了最可能的质子化位点。基于精确质量测量、MS(3)实验和半经验计算提出了碎裂机制。一些碎裂途径被发现取决于 B 环的取代模式，并且由这些碎裂产生的离子可以被认为是具有诊断价值的。可以区分樱黄素和大豆苷 A，这两种异黄酮苷元是本研究中包含的两个等质量异黄酮。此外，对染料木黄酮和大豆苷 A 这两种异黄酮与它们的黄酮类似物，芹菜素和木犀草素的碎裂模式进行比较，使我们能够识别出一些主要由于结构特征而产生的关键离子，从而可以区分这两类化合物。
