Bioactivity-guided fractionation of antimalarial active extract of Spondias mombin Linn stem bark

Abstract

Herbs have proven to be viable therapeutic alternatives for treatment of diseases like malaria. This study explores the phytochemical, nutritional, antioxidant and antimalarial potentials of Spondias mombin Linn. stem bark. Hexane, methanol, ethanol and aqueous extracts were separately obtained from dried pulverized stem bark, while the most active extracts were fractionated by column chromatography. Extracts/fractions were screened for phytochemical, nutritional and antioxidant properties using established protocols, while antimalarial activity was against Plasmodium berghei NK65 in mice using the chemo-suppressive, prophylactic, curative and mean survival time (MST) tests. Phenolics, flavonoids and tannins were detected in all the extracts. Percentage nutritional composition of the plant material showed it contained moisture (5.14 ± 0.01%), crude fibre (1.00 ± 0.01%), nitrogen free extract (66.18 ± 0.42%), crude protein (7.42 ± 0.10%), crude fat (18.24 ± 1.01%) and crude ash (2.03 ± 0.01%). The extracts scavenged ferrous and DPPH radicals with methanol extract having the highest antioxidant activity. Extracts reduced parasitaemia and prolonged MST relative to infected untreated group. Aqueous and ethanol extracts were the most active in the chemosuppressive (81.63%: MST 20.00 ± 2.21 days) and prophylactic (87.48%: MST 18.20 ± 2.48 days) tests respectively. The hydro-ethanol extract was partitioned into hexane, hexane:ethylacetate-HE, ethylacetate-EA, ethylacetate:methanol-EM and methanol residue-MR fractions. The fractions had varying antimalarial activity with some almost doubling MST relative to infected untreated group. The highest activity was in EA administered group with chemo-suppression 78.32%, MST: 17.80 ± 1.12 days; prophylaxis 66.51%, MST: 15.00 ± 0.31 days; curative 76.70%, MST: 16.80 ± 0.48 days. Therefore, Spondias mombin stem bark has rich phyto-nutritional constituents possibly linked to its antimalarial activity.