A natural source of saponin: Comprehensive study on interfacial properties of Chubak (Acanthophyllum Glandulosum) root extract and related saponins

Chubak (Acanthophyllum Caryophyllaceae) is a shrubby plant with saponin-rich roots. This feature makes this plant to a new source of natural surfactant. This article presents some basic information about the surface activity of Chubak root extract (CRE) and the corresponding purified saponin. The Calendasaponin B and Calendasaponin D were characterized in the purified saponin using Liquid Chromatography-Mass Spectrometry as the two main saponins. The dynamic surface tension and dilational surface visco-elasticity of CRE and the purified saponin were studied using a profile analysis tensiometer. The equilibrium surface tensions of CRE and the purified saponin in the concentration range up to the CMC show that the used purification method is not efficient to separate the complete saponin content of CRE. The surface activity of CRE started at 0.005 g/l, while the minimum saponin concentration for a first visible surface tension decrease was 0.0012 g/l. The uniform trend in surface dilational elasticity and viscosity of CRE and the purified saponin is the evidence for the similarity of dominant surface-active compounds in both samples. Comparing the short time surface tension of oscillating and steady drops showed the impact of adsorption layer oscillations on the surface tension variations.