Five new compounds from Rhododendron mariae Hance

Abstract

Five new compounds (–)-(7R,8S,7′R,8′S)-4,9,4′,9′-tetrahydroxy-3,3′-dimethoxy-7,7′-epoxylignan 9-O-β-d-xylopyranoside (1), (–)-(7′R,8′S)-5′-methoxyl(dimeric coniferyl acetate) (2), (+)-(1R,2S)-1,2-bis(4-hydroxy-3-methoxyphenyl)-3-acetyl-1,3-propanediol (3), (–)-3-((2R,3R)-2-ethoxy-3-(hydroxymethyl)-7-methoxy-2,3-dihydrobenzofuran-5-yl)propan-1-ol (4), and (+)-3-((2S,3S)-2-ethoxy-3-(hydroxymethyl)-7-methoxy-2,3-dihydrobenzofuran-5-yl)propan-1-ol (5), together with 12 known compounds, were isolated from an ethanol extract of the dried stems of Rhododendron mariae Hance. Their structures were elucidated by NMR, HR-MS, CD, ORD experiments and chemical methods. Compounds 2, 3, 6, and 17 exhibited significant inhibitory effects on the nitric oxide production in lipopolysaccharide activated C57BL6/J mouse macrophages.

Keywords::

• Rhododendron mariae
• chemical constituents
• biological activities

Acknowledgments

This work was financially supported by grants from the Natural Science Foundation of China (Nos 201072234, 21132009), the National Science and Technology Project of China (No. 2012ZX09301002-002), and PCSIRT (No. IRT1007). The authors are grateful to the Department of Instrumental Analysis of our institute for the UV, IR, NMR, and MS measurements.