Promising antimicrobial activity of <i>Moringa oleifera</i> seed extract fractions

Abstract

Abstract This study investigated the antiplasmodial and antibacterial activities of fractionated extracts of Moringa oleifera seeds, focusing on the influence of solvent polarity on bioactivity. The results revealed a polarity-dependent distribution of activity. Polar aqueous extracts (crude and residual fractions) exhibited the most pronounced antiplasmodial effects against Plasmodium falciparum (3D7 strain), with IC₅₀ values of 107–135 µg/mL. Time-dependent analyses of the crude and residual fractions showed that parasitaemia declined steadily over time, and consequently, percentage inhibition increased with time, with both extracts reaching 70–80% inhibition by 48 hours at higher concentrations. In contrast, moderately polar organic fractions, notably ethyl acetate and dichloromethane, demonstrated strong antibacterial activity against both Gram-positive and Gram-negative clinical isolates, including resistant strains such as MRSA and ESBL-producing Escherichia coli. Minimum inhibitory concentrations (MICs) ranged from 6.3 to 25 mg/mL for the ethyl acetate fraction, and all active fractions exhibited bactericidal properties (MBC/MIC ≤ 4). Comparative analysis showed that while antiplasmodial activity was moderate relative to the standard drug (chloroquine), antibacterial activity was robust and clinically promising. Fractionation revealed that distinct phytochemical classes underlie the two activities: polar compounds appear responsible for antiplasmodial effects, whereas moderately polar compounds drive antibacterial potency. The moderate antiplasmodial activity is significant in the context of adjunctive therapy and resistance management, while the strong antibacterial activity is highly relevant to the global challenge of antimicrobial resistance. Together, the results position Moringa oleifera as a promising source of phytochemicals for integrated infectious disease management, particularly in regions where malaria and bacterial co-infections are prevalent.