Horse Chestnut Saponins–Escins, Isoescins, Transescins, and Desacylescins

Abstract

Escins constitute an abundant family of saponins (saponosides) and are the most active components in Aesculum hippocastanum (horse chestnut—HC) seeds. They are of great pharmaceutical interest as a short-term treatment for venous insufficiency. Numerous escin congeners (slightly different compositions), as well as numerous regio-and stereo-isomers, are extractable from HC seeds, making quality control trials mandatory, especially since the structure–activity relationship (SAR) of the escin molecules remains poorly described. In the present study, mass spectrometry, microwave activation, and hemolytic activity assays were used to characterize escin extracts (including a complete quantitative description of the escin congeners and isomers), modify the natural saponins (hydrolysis and transesterification) and measure their cytotoxicity (natural vs. modified escins). The aglycone ester groups characterizing the escin isomers were targeted. A complete quantitative analysis, isomer per isomer, of the weight content in the saponin extracts as well as in the seed dry powder is reported for the first time. An impressive 13% in weight of escins in the dry seeds was measured, confirming that the HC escins must be absolutely considered for high-added value applications, provided that their SAR is established. One of the objectives of this study was to contribute to this development by demonstrating that the aglycone ester functions are mandatory for the toxicity of the escin derivative, and that the cytotoxicity also depends on the relative position of the ester functions on the aglycone.

Phenolic-Based Discrimination between Non-Symptomatic and Symptomatic Leaves of Aesculus hippocastanum Infested by Cameraria ohridella and Erysiphe flexuosa

“…Such results have proved that leaf phytochemistry is the best way to evaluate and predict plant health status before some changes are visible to the human eye. Furthermore, other groups of metabolites should also be analyzed in plant response to unfavorable conditions, such as saponins with their cytotoxic activity [ 5 ].…”

“…Cultivated as an ornamental tree, it is often found in European cities, towns, parks, and woodlands [ 2 ] and is known as a medicinal, pharmaceutical, and cosmetic species [ 3 ]. This plant synthesizes metabolites representing different groups, e.g., secondary metabolites such as phenolic compounds, flavonoids, tannins, saponins, and coumarins [ 4 , 5 , 6 , 7 , 8 , 9 ] ( Table 1 ). Overall, the highest concentration of chemicals is detected in its seeds, but they are also contained in the fruit, bark, leaves, buds, and embryonic callus tissue [ 6 ].…”