Identification of possible antimalarial constituent(s) from the leaves of Ochna kibbiensis: A phytochemical, in vivo and in silico approaches

Abstract

Background

Malaria is a major public health problem especially in developing countries such as Nigeria and its treatment is being compromised by resistance of the parasite to most of the available drugs, including the current gold-standard artemisinins. Ochna kibbiensis Hutch. & Dalziel, a synonym of Ochna staudtii Gilg has been employed in ethnomedicine for the treatment of malaria, dysentery, among others.

Purpose of the study

This study was aimed at identifying possible antimalarial constituents from O. kibbiensis leaves using phytochemical and in silico approach.

Methods

The antimalarial effect of the methanol leaf extract and its fractions (hexane, dichloromethane, ethylacetate, and butanol) was investigated according to the methods described by Ryley and Peters suppressive, and curative test using Chloroquine-sensitive Plasmodium berghei (NK65). In silico studies was conducted using on Schrödinger Suite 2021–2 utilizing the Glide-Ligand Docking panel of Maestro 12.8, SwissADME and ProTox-II online serves.

Results

The extract and fractions exhibited significant (p < 0.05) suppression of parasitaemia at 500, 250 and 125 mg/kg, respectively; butanol fraction was the most active with 94.0, 98.0 and 84.0 % chemo-suppression while the methanol extract was the least active with 32.5, 40.0 and 62.0 % chemo-suppression and the standard drug, chloroquine (CQ, 5 mg/kg) had 94.0 %. Also, the butanol fraction showed significant (p < 0.05) and dose-dependent effect in the curative test with 58.14, 74.40 and 94.20 % cure and CQ had 69.80 % at the tested doses while n-hexane fraction was the least active with 41.9, 14.0 and 2.3 % cure. Encouraged by these results, the butanol fraction was subjected to purification using chromatographic techniques which afforded 4′-O-(2E-decenyl) rutin or 4′-O-(2E-decenyl) quercetin-3-rutinoside as the major bioactive constituent. The identity of the compound was determined on the basis of chemical tests, and NMR analysis. The compound exhibited good binding affinity (-6.822 kcal/mol) and stability against pfLDH with appropriate and acceptable drug-like abilities and safety profile.

Conclusion

In conclusion, the leaf of O. kibbiensis have demonstrated significant antimalarial effect with a flavonol diglycoside as the major bioactive compound. To the best of our knowledge, this compound is isolated for the first time from the plant.