New triterpenoid saponins with cytotoxic and anti-inflammatory properties from Weigela stelzneri.

Saponins are bioactive compounds occurring in many plant species having a wide range of biological activities such as immunoadjuvant, cytotoxic, analgesic, antimicrobial and anti-inflammatory activities, just to mention a few. The aim of our researches concerns the isolation, structural elucidation and biological investigation of saponins from various plant species [1]. In this context, the study of the roots and leaves of Weigela stelzneri (Caprifoliaceae) led to isolation of four new and two known oleanane-type saponins mainly by medium pressure- and vacuum-liquid chromatography on silica gel (normal and reversed-phase RP-18) [1]. The new compounds were elucidated by a combination of spectroscopic techniques including 1D-, 2D-NMR, and mass spectrometry as glycosides of oleanolic acid, three of them being monodesmosides at C-3 with a branched oligosaccharidic chain made of six sugar units, whereas the known ones were hederagenin derivatives. The six compounds were evaluated for their cytotoxicity against a human cancer cell line (colorectal SW480) and a mouse cancer cell line (mammary EMT6), and for their anti-inflammatory activity. The results show that two new compounds differing only by the first sugar unit of the hexasaccharidic chain at C-3 (arabinopyranosyl instead of xylopyranosyl) exhibited the strongest cytotoxicity on both cell lines (IC₅₀ 5.41 µM and 1.54 µM, respectively), which was better than those of the positive controls etoposide and methotrexate. Furthermore, they revealed a significant modulatory effect of the IL-1β production on human lymphocytes stimulated with endotoxins, showing therefore a strong anti-inflammatory potential.

References:

[1] Manase MJ, Mitaine-Offer AC, Miyamoto T, Tanaka C, Delemasure S, Dutartre P, Lacaille-Dubois MA. Triterpenoid saponins from Polycarpaea corymbosa Lamk. var. eriantha Hochst. Phytochemistry, 2014; 100: 150 – 155.