An Investigation into the Efficacy of the Combined Methanol Extract of Zanthoxylum asiaticum and Delonix regia on Plasmodium berghei-Infected Mice and Its Effects on Blood Parameters

Abstract

Aims: This study assessed the effectiveness of single and fixed-ratio combinations of extracts from Zanthoxylum asiaticum and Delonix regia against Plasmodium berghei, as well as their effects on haematological parameters in mice. Methodology: Distilled water was used to clean the collected plant samples, which were then dried in the shade to achieve a constant weight. Plant parts were ground into a fine powder using an electric blender. Extraction was subsequently done using methanol. Tests for anti-plasmodial activity of individual and fixed-ratio combinations of plant extracts were conducted using Peters' four-day suppressive test and Rane's test protocol. Thin blood smears were stained with Giemsa stain and examined microscopically to determine the level of parasitaemia in mice following treatment with plant extracts. Data were analysed using Minitab 19 software and GraphPad Prism version 9. Differences with a p-value of less than 0.05 were regarded as statistically significant. Results: The extracts caused dose-dependent suppression of parasitaemia in infected mice. Zanthoxylum asiaticum exhibited the highest overall activity, with suppression most pronounced at 500 and 250 mg/kg body weight, while the 100 mg/kg dose led to moderate suppression. Delonix regia showed antiplasmodial activity but with lower potency compared to Z. asiaticum at equivalent doses. Notably, the fixed-ratio combination (250 mg/kg + 250 mg/kg; 1:1) resulted in a suppression rate comparable to the highest single extract dose and significantly decreased parasite loads relative to the negative control (p < 0.05). Haematological assessment indicated that most blood indices (Hb, leucocytes, platelets, MCV, MCH, MCHC, and haematocrit) were not significantly affected under the tested conditions, suggesting limited haematological toxicity; however, RBC counts showed a significant difference (at p < 0.05) between control and treated groups in the measured data. Conclusion: This study has demonstrated that these plant extracts are both safe and effective against Plasmodium berghei.