Chemosystematically valuable triterpenoid saponins from Glandularia x hybrida

Authors: MOHAMED, NESMA - Assuit University; MAKBOUL, MAKBOUL - Assuit University; FARAG, SALWA - Assuit University; WANG, YAN-HONG - University Of Mississippi; MOHAMED, SHAYMAA - Assuit University; ROSS, SAMIR - University Of Mississippi

Submitted to: Phytochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2020
Publication Date: 4/24/2020
Citation: Mohamed, N.M., Makboul, M.A., Farag, S.F., Wang, Y., Mohamed, S.M., Ross, S.A. 2020. Chemosystematicaly valuable triterpenoid saponins from Glandularia x hybrida. Phytochemistry. 175:112367. https://doi.org/10.1016/j.phytochem.2020.112367.
DOI: https://doi.org/10.1016/j.phytochem.2020.112367

Interpretive Summary: Phytochemical investigation of Glandularia x hybrida roots’ extract resulted in isolation and identification of five firstly reported saponins, along with eleven structurally diverse compounds including triterpenoidal aglycones, iridoids, and phenylpropanoids. Some of the obtained saponins evaluated for their anti-inflammatory activities using the carrageenan-induced paw edema protocol, in which two of them exhibited significant activities. Structural diversity of these isolated secondary metabolites supported the chemotaxonomic classification of the genus under investigation.

Technical Abstract: Phytochemical investigation of the ethanolic extract of Glandularia x hybrida roots resulted in the isolation and identification of five previously undescribed saponins, 3-O-jl-o-xylopyranosyl-hederagenin-28-O-j3-o-glucopyr­anosyl (1-+ 2)-O-j3-o-glucopyranosyl ester, 3-O-j3-o-xylopyranosyl-hederagenin-28-O-jl-o-glucopyranosyl (1-+ 2)­[Jl-o-glucopyranosyl (l-+6)]-J3-o-glucopyranosyl ester, hederagenin-28-O-j3-o-glucopyranosyl (l-+2)-[.8-o-glu­copyranosyl (1--6)]-j3-o-glucopyranosyl ester, 23-O-acetyl-3-O-j3-o-xylopyranosyl-pomolic acid-28-O-j3-o-gluco­pyranosyl ester, and 23-O-acetyl-pomolic acid-3-O-j3-o-xylopyranoside, along with eleven structurally diverse compounds. The structural characterizations of the isolated compounds were determined using physical data, comprehensive 1D and 2D Nuclear Magnetic Resonance (NMR) spectral analysis, and High-resolution electrospray ionisation mass spectrometry (HRESIMS). All isolated saponins are hederagenin or pomolic acid glycosides conjugated with differentiable sugar units bound to C-3 and/or C-28 of the aglycone through ether and/or ester glycosidic linkages, respectively. Structural diversity of these isolated secondary metabolites would have a great impact on the future chemosystematic studies of this plant. Four saponins, obtained in good yield were evaluated for their anti-inflammatory activities in a rat model using the carra­geenan-induced paw edema protocol. Two of these exhibited significant anti-inflammatory activities demon­strated through inhibition of the paw edema by 64 and 60%.