Benzofuran ε-caprolactam glucosides, amides and phenylpropanoid derivatives with anti-inflammatory activity from Oxybaphus himalaicus

• Published in: Phytochemistry (Oxford) 2021-11, Vol.191, p.112905-112905, Article 112905
• Main Authors: Qiu, Yan, Yang, Xuedong, Xu, Jun, Liu, Bo, Li, Xiaoxue
• Format: Article
• Language: English
• Subjects: Amides; Anti-inflammatory activity; Nyctaginaceae; Oxybaphus himalaicus; Phenylpropanoid glycosides; Structure elucidation
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/j.phytochem.2021.112905

(+)-(2S,3S)- and (−)-(2R,3R)-Oxybaphuslactam A glucosides are two undescribed benzofuran ε-caprolactams featuring a unique 7/6/5 fused tricyclic framework with p-glucosyl-O-phenyl unit. They were isolated from the root of Tibetan medicinal plant Oxybaphus himalaicus along with an undescribed sucrose ester, 3-O-feruloyl sucrose, an undescribed lignan glucoside, (7′R,8R,8′S)-3,3′,5,5′-tetramethoxy-7′,9-epoxylignan-9′-ol-7-one 4,4′-di-O-β-D-glucopyranoside and ten known amides and phenylpropanoid derivatives. Based on the spectral analyses, X-ray crystallography and comparison of experimental and TD-DFT calculated ECD spectra, the structures of these compounds were determined. The anti-inflammatory assay showed the undescribed compounds had significant inhibitory effects on the formation of NO, TNF-α and IL-6, which were evaluated by LPS induced RAW 264.7 cell model. Two undescribed benzofuran ε-caprolactams featuring a unique 7/6/5 fused tricyclic framework with p-glucosyl-O-phenyl unit and two undescribed phenylpropanoid glycosides were isolated from Oxybaphus himalaicus with potential anti-inflammatory activities. [Display omitted] •Two undescribed benzofuran ε-caprolactam glucosides and two undescribed phenylpropanoid glycosides from Oxybaphus himalaicus.•First report of benzofuran ε-caprolactams featuring a unique 7/6/5 fused tricyclic framework.•Plausible biosynthetic pathways of undescribed benzofuran ε-caprolactam glucosides were proposed.