Evaluating the Antiplasmodial Activity of Picrasma javanica Stem Bark Extract and Its Synergy With Artesunate in Rodent Malaria Models.

Malaria remains a global health challenge, exacerbated by the emergence of drug-resistant Plasmodium strains. This study evaluates the antimalarial activity of Picrasma javanica stem bark extract and its combination with artesunate (ART) in Plasmodium berghei-infected mice. The extraction yield using hexane at a 1:5 (w/v) ratio was 7.8% w/w. Acute toxicity assessment indicated no mortality or adverse effects at doses up to 2000 mg/kg. In suppressive activity tests, P. javanica stem bark extract exhibited dose-dependent efficacy, achieving 13.3%, 36.4%, and 52.5% parasitemia inhibition at doses of 100, 200, and 400 mg/kg, respectively, with significant inhibition at higher doses (p < 0.05 and p < 0.01). ART showed 90.7% suppression (p < 0.001). In curative tests, the extract at 400 mg/kg reduced parasitemia by 31.0% (p < 0.05), while ART achieved 75.3% suppression (p < 0.001). The effective dose (ED(50)) values were 404.9 mg/kg for P. javanica stem bark extract and 2.03 mg/kg for ART. Combination treatments at ED(50) ratios of 40/60 and 20/80 (extract/ART) resulted in 65.9% (p < 0.01) and 81.7% (p < 0.001) inhibition, respectively, with the 20/80 ratio showing a significant synergistic interaction (CI = 0.44121). The mean survival time (MST) for the untreated group was 12.2 ± 1.9 days. P. javanica stem bark extract and ART alone extended MST to 21.4 ± 2.4 and 21.8 ± 2.4 days, respectively (p < 0.05), while the 20/80 combination achieved the longest MST of 28.6 ± 1.7 days (p < 0.01; p < 0.05 vs. monotherapies). These findings highlight the potential of P. javanica stem bark extract as a complementary antimalarial agent when used with ART, offering a promising approach for combating drug-resistant malaria.