Wang G S
Institute of Pharmacy, Beijing Fourth Pharmaceutical Works, China.
J Ethnopharmacol. 1989 Sep;26(2):147-62. doi: 10.1016/0378-8741(89)90062-7.
Mylabris is the dried body of the Chinese blister beetle. The species used in medicine are Mylabris phalerata and M. cichorii. The use of mylabris as a traditional medicine in China can be traced back more than 2000 years, and it is still used as a folk medicine today. In recent studies, it has been found that mylabris possesses antitumor properties, increases the number of leucocytes, and has irritant effects on the urinary organs. The active constituent of mylabris is cantharidin. The synthesis of cantharidin is rather difficult. In order to find a less toxic analogue of cantharidin, its hydrolytic compound, disodium cantharidate, and its demethylated form, norcantharidin, were prepared. By biochemical and biological methods, it was found that these compounds may affect cancer cells in several ways. In clinical studies, antihepatoma effectiveness sequentially increased from cantharidin to disodium cantharidate to norcantharidin. Disodium cantharidate showed less urinary irritation than cantharidin while norcantharidin showed little to no such irritation. It appears that the two methyl groups of cantharidin are not the main functional groups for antitumor activity and for the stimulation of bone marrow but are associated with urinary irritation. Hydrocantharidimide, methylcantharidimide and dehydronorcantharidin have also been studied. All these compounds, except the last one, have been produced as antitumor agents in China. Since demethylated cantharidin may be prepared by total synthesis, it may be more suitable for medical investigation than cantharidin itself.
斑蝥是中国芫菁科昆虫的干燥体。入药的品种为南方大斑蝥和黄黑小斑蝥。斑蝥在中国作为传统药物使用可追溯到2000多年前，如今仍作为民间药物使用。最近的研究发现，斑蝥具有抗肿瘤特性，能增加白细胞数量，对泌尿器官有刺激作用。斑蝥的活性成分是斑蝥素。斑蝥素的合成相当困难。为了找到一种毒性较小的斑蝥素类似物，制备了其水解化合物斑蝥酸钠和去甲基化形式去甲斑蝥素。通过生化和生物学方法发现，这些化合物可能以多种方式影响癌细胞。在临床研究中，抗肝癌效果从斑蝥素到斑蝥酸钠再到去甲斑蝥素依次增强。斑蝥酸钠的尿路刺激性比斑蝥素小，而去甲斑蝥素几乎没有这种刺激。看来斑蝥素的两个甲基不是抗肿瘤活性和刺激骨髓的主要官能团，而是与尿路刺激有关。羟基斑蝥胺、甲基斑蝥胺和脱氢去甲斑蝥素也已被研究。除最后一种外，所有这些化合物在中国都已作为抗肿瘤药物生产。由于去甲基化斑蝥素可通过全合成制备，它可能比斑蝥素本身更适合医学研究。
