Phytochemical investigation of zanthoxylum gilletii (rutaceae) for antiplasmodial biomolecules

Abstract

Currently, the problem of resistance posed by the malaria causing parasites to the available drugs, demands for collective scientific research to counter the recurrent problem. In addition to this, the malaria vector has also become resistant to the current pesticides of choice putting the lives of people especially those living in Saharan and sub-Saharan Africa highly at risk. In this study the stem bark of Zanthoxylum gilletii was air dried and pulverized into fine powder. The plant material was extracted using 50% methanol in dichloromethane and the extract subsequently subjected to column chromatography (CC) using silica gel as the stationary matrix and different solvents systems of varying polarities. The fractions obtained from the main column were purified by further CC using both silica gel and Sephadex LH 20 and crystallization yielding a total of six compounds including; three benzophenanthridine alkaloids; dihydrochelerythrine (64), 8acetonyldihydrochelerythrine (66), norchelerythrine (67), one terpenoid, lupeol (63), one lignin, seasamine (65) and an amide, fagaramide (68). The pure compounds obtained were characterized using spectroscopic techniques. The crude extract and the isolated compounds from this plant were evaluated for anti-plasmodial activities against three strains of Plasmodium falciparum namely; chloroquine-sensitive Sierra Leone (D6) and chloroquine-resistant Indochina (W2) and artemisinin resistant strain (3D7). The crude extract exhibited good anti-plasmodial activities with IC50 values of 2.52, 1.48 and 1.43 µg/ml against W2, D6 and 3D7, respectively. Three pure compounds tested which were isolated in sufficient yields also exhibited interesting activities against the three strains of Plasmodium falciparum. Seasamine (65) showed good activities with IC50 values of 1.92, 3.23 and 2.94 µg/ml while 8-acetonyldihydrochelerythrine (66) showed moderate activities with IC50 values of 4.02, 4.06 and 3.37 µg/ ml against the W2, D6 and 3D7 strains, respectively. Fagaramide (68) was inactive, exhibiting IC50 values of 15.15, 7.73 and 7.72 µg/ml against W2, D6 and 3D7, Plasmodium strains, respectively........................