Leishmanicidal and Antimicrobial Activities of 4-Quinolone Alkaloids from Stems of the Medicinal Plant Waltheria indica (Malvaceae) and Their Chemotaxonomic Significance

A chemical investigation of the stem of Waltheria indica (Malvaceae) yielded twelve 4-quinolone alkaloids, which were primarily waltheriones. These were waltherione A (1), waltherione B (2), waltherione C (3), waltherione G (4), waltherione H (5), waltherione J (6), waltherione L (7), waltherione P (8), chamaedrone (9), 8-deoxy-antidesmone (10), antidesmone (11), and the previously unreported alkaloid N-methoxy-waltherione A (12). These alkaloids belong to an unusual class of 4-quinolones and therefore, have chemosystematic significance for distinguishing the Waltheria and Melochia genera from the rest of the Malvaceae family. The ability of the alkaloid isolates to reverse the phenotypic expression of fluconazole-resistance was tested by using a mutant strain of Saccharomyces cerevisiae that expressed a Candida albicans transporter. Of the isolates tested, waltherione G afforded a positive result. Leishmanicidal activity and bactericidal tests were also performed using the isolated alkaloids, which showed promising results.

本研究对锦葵科（Malvaceae）蛇婆子（Waltheria indica）的茎部开展化学成分研究，共分离得到12种4-喹诺酮类生物碱（4-quinolone alkaloids），其中主要成分为沃尔塔酮类（waltheriones）。具体包括沃尔塔酮A(1)、沃尔塔酮B(2)、沃尔塔酮C(3)、沃尔塔酮G(4)、沃尔塔酮H(5)、沃尔塔酮J(6)、沃尔塔酮L(7)、沃尔塔酮P(8)、查马酮(9)、8-脱氧安替斯莫宁(10)、安替斯莫宁(11)，以及此前尚未见报道的生物碱N-甲氧基沃尔塔酮A(12)。此类生物碱隶属于罕见的4-喹诺酮类化合物家族，因此具备区分蛇婆子属（Waltheria）、马松子属（Melochia）与锦葵科其余类群的化学分类学价值。本研究采用表达白色念珠菌（Candida albicans）转运蛋白的酿酒酵母（Saccharomyces cerevisiae）突变菌株，测试了分离所得生物碱逆转氟康唑耐药表型的能力。在受试化合物中，沃尔塔酮G呈现阳性结果。此外，本研究还针对分离得到的生物碱开展了利什曼原虫杀伤活性与杀菌活性测试，结果均表现出良好的应用前景。