Abstract
Crude oil contamination poses significant environmental challenges, requiring eco-friendly
remediation strategies. This study comparatively evaluated the extraction, purification, and
functional performance of saponin-rich extracts from five tropical plants: Ziziphus mauritiana
(ZM), Balanites aegyptiaca (BA), Glycine max (GM), Erythrina senegalensis (ES), and Euphorbia
hirta (EH). Ultrasound-assisted extraction with 70% ethanol was employed, followed by
fermentation-based purification. Extracts were assessed for yield, total saponin content, purity,
surface tension, critical micelle concentration (CMC), droplet size distribution, and emulsion
stability. Results revealed substantial differences among species. BA showed the highest
extraction yield (99.38%), whereas ES and EH contained the greatest total saponin content
(653.95 and 525.80 mg/g, respectively). Purification efficiency was highest for ES (60.20%)
and ZM (56.30%). Surface activity analysis demonstrated that BA and ZM achieved the lowest
surface tension (30.53 and 31.31 mN/m) and CMC values (56.42 and 60.21 mg/L), indicating
strong micellization. Dynamic Light Scattering showed ZM produced the smallest droplets
(24.63 nm) and lowest PDI (0.208), yielding stable nanoemulsions with superior emulsification
stability (81.39%). Comparative ranking indicated ZM > GM > ES > BA > EH, with ZM and
GM emerging as the most promising biosurfactant sources. Overall, this work highlights the
potential of tropical plant-derived saponins, particularly from ZM and GM, as sustainable
alternatives to synthetic surfactants for crude oil dispersion and bioremediation.