Comparative study on the phytometabolites, total alkaloid and β-hematin inhibitory potential of stem bark methanol extracts of Annickia affinis and Annickia chlorantha

Abstract

For decades, Annickia chlorantha and Annickia affinis have been jointly referred to as Enantia chlorantha in literature.
Both plant species are commonly used for managing malaria and are difficult to tell apart. Their antimalarial activity
is attributed to protoberberine alkaloids. In the current study, we compared their phytometabolites, total alkaloid
content and β-hematin inhibitory potential. Both plant species were seen to possess the major phytochemicals assessed although in varied amounts, with A. affinis having more of phenolics, flavonoids, terpenoids, saponins, steroids, tannins and cardiac glycosides than A. chlorantha. Both plant species had comparable alkaloidal content. Using GC-MS, we observed that berberine; a classical protoberberine alkaloid is present in A. affinis and not A. chlorantha. Interestingly, both plant species had comparable β-hematin inhibitory potential despite A. affinis having an ~3-fold higher ability to inhibit malaria parasite growth than A. chlorantha. Inhibition of β-hematin formation in vitro is often used to screen for plant extracts with capacity to inhibit hemozoin polymerization within cultured malaria parasites. Our results thus suggest that inhibition of hemozoin polymerization may contribute to the antiplasmodial activity of both plant species and that berberine can serve as a useful biomarker for differentiating A. affinis from A. chlorantha.