An accurate, cost-effective and simple colorimetric method for the quantification of total triterpenoid and steroidal saponins from plant materials

Abstract

Saponins are heterosides widely distributed in the plant kingdom. Their properties are used in many industrial sectors, such as food, cosmetics, agriculture, and pharmaceuticals, and their use is increasing due to the market trend to use natural ingredients. Although many techniques exist to quantify saponins (e.g., gravimetric, foaming, spectrophotometric or chromatographic), none of these allow simultaneous accurate, rapid and inexpensive analysis of both triterpenoid and steroidal saponins. A new colorimetric method constituted of p-anisaldehyde and sulfuric acid was developed and avoids all of the above disadvantages. Parameters used in this method allow a similar molar absorptivity for steroidal and triterpenoid saponins with high specificity in complex matrices reducing the sample preparation step and allowing quantification of saponins blends.

Keywords: Chromogenic reaction; Plant extracts; Spectrophotometric quantification; Steroidal saponin; Total saponins; Triterpenoid saponin.