Phytochemical investigation of the stem bark of millettia oblata ssp. Teitensis for antiplasmodial andlarvicidal principles

Abstract

The genus Millettia is rich in flavonoids and isoflavonoids. In the search for compounds with antiplasmodial and larvicidal activities from medicinal plants, the stem barks of Millettia oblata ssp. teitensis were analysed. The dried and ground stem barks were extracted with the CH2ClziMeOH (1: 1) by cold percolation for 24 hours at room temperature. The crude extracts showed significant antiplasmodial activities with ICso values of 10.0±2.3 and 12.0±1.2 ug/rnl against chloroquine-resistant (W2) and chloroquine-sensitive (D6) strains of Plasmodium falciparum, respectively. Chromatographic separation of the extract led to the isolation of eight compounds. These were identified as durmillone (1), 4' -prenyloxyderrone (2), maximaisoflavone H (3), 8O-methylretusin (4), maximaisoflavone J (5), maximaisoflavone B (6), tephrosin (7) and lupeol (8). 4'-Prenyloxyderrone (2) is a novel compound. The remaining compounds are reported here for the first time from Millettia oblata ssp. teitensis. The identification of these compounds was based on spectroscopic techniques eH NMR, l3C NMR, HMBC, HMQC, COSY, DEPT, UV and MS). The novel compound, 4' -prenyloxyderrone (2) showed antiplasmodial activity with ICso of 6.0±O.9 and 5.4±1.0 ug/ml against (W2) and (D6), respectively. Durmillone (1) showed activity against (W2) and (D6) strains of Plasmodium falciparum with ICsovalue of 9.8±0.1 and 6.0±1.2 ug/ml, respectively. Lupeol (8) showed antiplasmodial activity with ICso value of 13.9±O.9 ug/ml against (D6). Tephrosin (7) showed antiplasmodial activity with ICso value of 11.5±O.3 and 12.7±O.9 ug/ml against (W2) and (D6) respectively. A mixture of Maximaisoflavone J (5) and Maximaisoflavone B (6) showed activity against (W2) and (D6) strains of Plasmodium falciparum with ICso value of 16.5±3.5 and 4.6±O.5 ug/rnl, respectively.