Glycosides of polygalacic acid from the stem barks of Piper guineense Schum and Thonn

• Published in: Carbohydrate research Vol. 507; p. 108374
• Main Authors: Le Doux Kamto, Eutrophe, Noté, Olivier Placide, Kinyok, Mc Jesus, Wilhelm, Anke, Mbing, Joséphine Ngo, Antheaume, Cyril, de Théodore Atchadé, Alex, Pegnyemb, Dieudonné Emmanuel, Ndinteh, Derek Tantoh, Haddad, Mohamed, Bonnet, Susan L.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01-09-2021; Elsevier
• Subjects: Glycosides - chemistry; Glycosides - isolation & purification; Guineenosides; Life Sciences; Magnetic Resonance Spectroscopy; NMR; Piper guineense; Piperaceae; Plant Bark - chemistry; Plant Stems - chemistry; Saponins - chemistry; Saponins - isolation & purification; Triterpenoid saponins; Piperaceae; NMR; Piper guineense; Triterpenoid saponins; Guineenosides
• ISSN: 0008-6215; 1873-426X; 1873-426X; 0008-6215
• DOI: 10.1016/j.carres.2021.108374

In a continuation of our study on constituents of P. guineense now focusing on the search for saponins, phytochemical investigation of the n-BuOH fraction of P. guineense stem bark led to the isolation of three previously undescribed triterpenoid saponins, named guineenosides A─C (1─3). Their structures were established on the basis of extensive analysis of 1D and 2D NMR (1H, 13C NMR, DEPT, COSY, TOCSY, NOESY, HSQC, HSQC-TOCSY and HMBC) and HRESIMS experiments, and by chemical evidence as 3-O-{α-l-rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl-(1 → 2)-α-l-arabinopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 3)-[α-l-arabinofuranosyl-(1 → 4)]-α-l-rhamnopyranosyl-(1 → 3)-β-d-fucopyranosyl} polygalacic acid 28-O-α-l-rhamnopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl ester (1), 3-O-{α-l-rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl-(1 → 2)-α-l-arabinopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 3)-[α-l-arabinofuranosyl-(1 → 4)]-α-l-rhamnopyranosyl-(1 → 3)-β-d-fucopyranosyl} polygalacic acid 28-O-β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl ester (2), and 3-O-{α-l-rhamnopyranosyl-(1 → 2)-β-d-xylopyranosyl-(1 → 3)-β-d-fucopyranosyl} polygalacic acid 28-O-[α-l-rhamnopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl ester (3). This is the first report of triterpenoid saponins from P. guineense.
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•Three new triterpenoid saponins, named guineenosides A─C were isolated from the stem bark of Piper guineense.•Their structures were established on the basis of extensive analysis of 1D and 2D NMR experiments.•These saponins possess a long glycosidic chain consisting of three to seven sugar moieties at C-3 of polygalacic acid.