In vitro antiplasmodial activity of leaves and stem bark fractions of Spathodea campanulata P. Beauv (Bignogniaceae)

Malaria is a potentially fatal disease caused by Plasmodium parasites transmitted by infected Anopheles mosquitoes, and its management is increasingly hampered by growing drug resistance. This study aims to evaluate the antiplasmodial activity of different fractions obtained from the leaves and stem bark of Spathodea campanulata. Dried plant materials were extracted to produce dichloromethane, ethyl acetate, and hexane fractions. Phytochemical screening and absorption spectrophotometry were used to identify and quantify secondary metabolites. Antiplasmodial activity was assessed against Plasmodiun falciparum 3D7 and Dd2 strains, and IC₅₀ values were determined. Leaves showed high alkaloid levels, especially in the hexane, ethyl acetate, and dichloromethane fractions (1028.36 ± 21.36, 950.03 ± 25.44, and 641.8 ± 8.16 µg QiE/mg DM). In stem bark, alkaloids were also abundant in the hexane fraction (793.2 ± 25.32 µg QiE/mg DM). Polyphenols were most concentrated in the ethyl acetate fractions (209.64 ± 3.91 and 212.51 ± 1.29 µg GaE/mg DM for leaves and stem bark), and flavonoid levels were highest in the ethyl acetate and hexane fractions of both plant parts. Dichloromethane fractions of leaves and stem bark, as well as the ethyl acetate stem bark fraction, showed good activity against Pf 3D7 (IC₅₀: 16.69–19.84 µg/mL). The ethyl acetate fractions of leaves and hexane fractions of both plant parts demonstrated moderate activity (IC₅₀: 30.85–38.69 µg/mL). Against Pf Dd2, only the dichloromethane fractions and the stem bark ethyl acetate fraction showed moderate activity (IC₅₀: 25.91–39.17 µg/mL). These activities are likely linked to alkaloid, polyphenol, and flavonoid content. The most active fraction was the dichloromethane fraction of the stem bark, which was effective on both strains and may represent potential therapeutic alternatives.