From rural practice to scientific evidence: synergistic antiplasmodial and antioxidant properties of combined Ageratum conyzoides and Bidens pilosa extracts

Abstract

Aim: This study evaluates the in vitro and in vivo antiplasmodial, hemolytic, and antioxidant activities of a combined extract of Ageratum conyzoides (A. conyzoides) and Bidens pilosa (B. pilosa), a traditionally used but scientifically unvalidated combination. Methods: Plant leaves were extracted via aqueous decoction and cold maceration, combining equal parts to mimic traditional preparation. In vitro antiplasmodial activity against the chloroquine-sensitive Plasmodium falciparum 3D7 (Pf3D7) strain was assessed using the SYBR Green I assay. Cytotoxicity was evaluated via hemolysis test, and antioxidant potential using DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)], and FRAP (ferric ion reducing antioxidant potential) assays. The most potent combination was tested for acute toxicity and curative antimalarial activity in a rodent model. Results: Extract yields ranged from 6.6% (cold maceration extract of B. pilosa) to 29.2% [aqueous decoction extract of combination (Cd)]. Extracts showed moderate to mild in vitro antiplasmodial activity [IC50 (median inhibitory concentration): 24.8–96.6 µg/mL], with the aqueous Cd showing potential synergism [CI (combination index) < 1]. No significant cytotoxicity was observed (< 10% hemolysis). Moderate to good antioxidant activity was found in DPPH [SC50 (median scavenging concentration): 134.65–307.55 µg/mL] and ABTS assays (SC50: 92.23–183.45 µg/mL), with Cd showing the highest activity. FRAP values were low. The Cd extract demonstrated no significant acute toxicity up to 5,000 mg/kg and significant in vivo antimalarial activity, achieving 65% parasite inhibition at 200 mg/kg/day. It also prolonged survival time, with a maximum survival of 28 days at 200 mg/kg/day. Conclusions: This preliminary investigation suggests that combined extracts of A. conyzoides and B. pilosa exhibit noteworthy in vitro and in vivo antiplasmodial activity against the tested strains. Further studies are warranted to validate these findings and develop optimized formulations as potential antimalarials.