Phenolic constituents from Rhopalocnemis phalloides with DPPH radical scavenging activity

Abstract

The 80% aqueous acetone extract of the whole plant of Rhopalocnemis phalloides Jungh. (Balanophoraceae) showed obvious radical scavenging activity (SC₅₀ = 32.1 μg/mL) on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical assay. Further chemical investigation of the extract led to the isolation of 12 phenolic compounds (1–12). Among these, bis-6,8’-catechinylmethane (2), a flavan-3-ol dimer, was first isolated as a natural product from Rhopalocnemis phalloides. The full NMR assignments of bis-catechinylmethanes (1 and 2) are reported for the first time, on the basis of detailed spectroscopic analysis. The DPPH assay showed that flavan-3-ol dimers (1–3) had remarkable free radical scavenging activity, while flavonoid aglycones (4 and 9) presented stronger activities than those of their glycosides (5–8 and 10).

Keywords::

• Balanophoraceae
• Rhopalocnemis phalloides
• flavan-3-ol dimer
• DPPH radical

Acknowledgements

The authors are grateful to the staff of the analytical group at the State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, for measuring the spectral data. This work was supported by the “West Light” Foundation of the Chinese Academy of Sciences.

Declaration of interest: The authors report no conflicts of interest.