In vitro and In vivo antimalarial activities of Avicennia africana P. Beauv. (Avicenniaceae) ethanolic leaf extract

Background

The emergence of widespread drug-resistant strains of the malaria parasites militates against strives for more potent antimalarial drugs.

Aim

The present study evaluated the antimalarial activity of A. africana ethanolic crude extract in vitro and in vivo against Plasmodium berghei -infected mice in anticipation of acquiring scientific evidence for it used by mangrove dwellers to treat malaria in Ghana.

Methodology

The pulverized dried leaves were extracted with 70% ethanol (v/v) and screened for phytochemicals using standard protocols. The in vitro antimalarial activity was investigated against chloroquine-sensitive Plasmodium falciparum (Pf3D7 clones), MRA-102, Lot:70032033, via SYBR® Green I fluorescent assay method using positive control Artesunate (50–1.56 × 10⁻³ μg/mL). In the in vivo studies, doses (200–1500 mg/kg) of AAE were used in the 4-day suppressive and curative tests, using P. berghei-infected mice. Artemether/lumefantrine (1.14 mg/kg) and normal saline were used as positive and negative control respectively.

Results

The phytochemical analysis revealed the presence of alkaloids, saponins, flavonoids, glycosides, tannins, terpenoids and phytosterols. The extract showed an IC₅₀ of 49.30 ± 4.40 μg/mL in vitro and demonstrated complete parasite clearance at dose 1500 mg/kg in vivo with a suppressive activity of 100% (p < 0.0001) in the 4-day suppressive test. The extract demonstrated high curative activity (p < 0.0001) at 1500 mg/kg with 100% parasite inhibition and the oral LD₅₀ > 5000 mg/kg in mice.

Conclusion

The results demonstrated that A. africana crude extract has antimalarial activity both in vitro and in vivo supporting the traditional use of the plant to treat malaria.