Abstract

Background: Ocimum gratissimum has folklorically been ascribed to possess several medicinal activities, including antimalarial.

O bjective: This research explored the antimalarial activity in its essential oil and the anti-anaemic effect of Hibiscus sabdariffa (Hs) in combination.

Methods: Ocimum gratissimum essential oil (OGE) was extracted through hydro distillation and analyzed using GC/MS. Hs extract was obtained using cold maceration. Pre-formulation studies tested their antimalarial and anti-anemic activities using different concentrations of the essential oil and the Hs extract. Nanoemulsions containing OGE and Hs extract were formulated and characterized using scanning electron microscopy (SEM), particle size, and polydispersity index (PDI). Post-formulation anti-anaemic and antimalarial evaluations were conducted.

Results: The pre-formulation animal studies showed that the group administered 10 ml/kg of 20% oil had the highest reduction in parasitaemia. Also, 230 mg of Hs gave the highest anti-anaemic activity. SEM imaging showed homogenous dispersion of the emulsions. Particle sizes and PDI (size, PDI) were (56.17nm, 0.478), and (44.40 nm, 0.461) for the 10% and 20% nanoemulsions, respectively. The post-formulation suppressive animal studies gave a maximum parasitemia reduction of 88.1, and 100%, respectively, for the treatment groups administered 4ml/kg of 20% nanoemulsion and Artemether-Lumefantrine (AL) 2.3/13.7mg/kg respectively; and a percentage reduction in parasitemia (curative test), of 74.66 and 99.69% respectively. Hematocrit values and body weight were increased in the groups treated with the emulsion.

Conclusion: Emulsions containing O. gratissimum essential oil and H. sabdariffa extract showed effectiveness in reducing parasitaemia and reversing anaemia in a dose-dependent manner.

Keywords: Ocimum gratissimum, Hibiscus sabdariffa, malaria, parasitaemia, essential oil, anaemia.