Activity Guided Isolation and Characterization of Antiplasmodial Agents of some Local medicinal Plants

Abstract

Combined Plant Mixture (CPM) in ratio of 1:1 (Vitex doniana, Diospyros mesipiliformis, Acacia polyacantha, Parinari macrophylla, Ficus sycomorus and Parkia biglobosa) was extracted with methanol and screened for antimalarial activity. The CPM Methanol extract residue was suspended in water and fractionated with Hexane (HX), Ethylacetate (EA) and n-Butanol (BUT). The Methanolic CPM extract has shows some antimalarial activity with Mean Survival Times (MST) of 10.16 to 12.16 days. All the mice in control group were found dead on 14^th day of study and one mice was still alive on 14^th day in both the groups with 15% and 30% parasitaemia against Plasmodium yoelli nigeriensis N₆₇ and Plasmodium berghei K₁₇₃ respectively. The EA fraction was the most active against P. yoelli nigeriensis N₆₇ having 2 mice surviving up to 14^th day with 5.5% parasitaemia and MST of 13.4 days. Fractions of water (WT), HX and BUT have 12.5, 25, and 100% (dead) parasitaemia with mean survival times of 12.6, 9.33 and 8.5 days against 100% (dead) parasitaemia and 8.20 days of MST when compared with control. HX fraction was the most active against P. berghei K₁₇₃ followed by BUT fraction with one mice surviving up to 14^th day without parasitaemia but with MST of 15.0 and 13.5 days respectively. EA and WT fractions have 22.66 and 100% (dead) parasitaemia with mean survival times of 11.80 and 10.80 days respectively. Chromatographic separation of EA fraction of the CPM extract resulted in the isolation of Gallic acid (Figure 2, Fractions 79-83), 3β-OH-α-amyrin (Figure 3, Fractions 45-46), 5,7,3’,4’,5’- pentahydroxy-3-O-glucophyranoside flavones (Figure 4, Fractions 128-157)-[myricetin 3-O-β-rhamnopyranoside], 5,7,3’,4’ tetrahydroxy-3-o-glucopyranoside flavones(Figure 5, Fractions 126-141)-[quercetin 3-O-β-rhamnopyranoside], and 3,5,7,3’,4’-Pentahydroxy flavones (Figure 6, Fractions 87-112)-[quercetine]. The compounds were characterized using ESI-MS, IR, ¹H ¹³C, HMBC/HSQC and COSY-NMR data. These findings suggest that the combined extracts possess antiplasmodial properties.

Keywords: Antimalarial, combined plant mixture, ¹H ¹³C NMR, activity guided fractionation