Keawpradub N, Kirby G C, Steele J C, Houghton P J
Department of Pharmacy, King's College London, U.K.
Planta Med. 1999 Dec;65(8):690-4. doi: 10.1055/s-1999-14043.
Methanol extracts prepared from various parts of Alstonia scholaris, A. macrophylla and A. glaucescens, collected from Thailand, have been assessed for antiplasmodial activity against multidrug-resistant K1 strain of Plasmodium falciparum cultured in human erythrocytes. Pronounced antiplasmodial activity was exhibited by methanol extract of the root bark of A. macrophylla with an IC50 value of 5.7 micrograms/ml. Thirteen indole alkaloids were isolated from the active extract. These alkaloids and a semisynthetic bisindole O-acetylmacralstonine were subsequently tested against the K1 strain of P. falciparum. Pronounced antiplasmodial activity was observed mainly among the bisindole alkaloids, particularly villalstonine and macrocarpamine with IC50 values of 0.27 and 0.36 microM, respectively. The potent alkaloids were further tested against T9-96, the chloroquine-sensitive strain of P. falciparum. It has been found that the active alkaloids, in contrast to chloroquine, have significantly higher affinity to the K1 strain than to the T9-96 strain.
从泰国采集的鸡骨常山、大叶鸡骨常山和灰叶鸡骨常山不同部位制备的甲醇提取物，已针对在人红细胞中培养的多药耐药恶性疟原虫K1株进行了抗疟活性评估。大叶鸡骨常山根皮的甲醇提取物表现出显著的抗疟活性，IC50值为5.7微克/毫升。从活性提取物中分离出13种吲哚生物碱。随后对这些生物碱和一种半合成双吲哚O - 乙酰基鸡骨常山碱针对恶性疟原虫K1株进行了测试。主要在双吲哚生物碱中观察到显著的抗疟活性，特别是鸡骨常山裂碱和大果鸡骨常山胺，IC50值分别为0.27和0.36微摩尔。将强效生物碱进一步针对氯喹敏感的恶性疟原虫T9 - 96株进行测试。已发现，与氯喹相比，活性生物碱对K1株的亲和力显著高于对T9 - 96株的亲和力。
