Undescribed Lignanamide and Flavone C-Glucoside Isolated from the Aerial Parts of Piper Samentosum with NO Production Inhibitory Activity in LPS Activated RAW 264.7 Cells

Abstract

In this study, two undescribed compounds (1 and 2), together with eight known compounds (3-10) were isolated from the aerial parts of Piper samentosum by various chromatography methods. Their chemical structures were determined to be 7'''-oxolyciumamide N (1), vitexin 2''-O-β-D-(6'''-feruloyl)-glucopyranoside (2), 1,2-dihydro-6,8-dimethoxy-7-hydroxy-1-(3,4-dihydroxyphenyl)-N¹,N²-bis-[2-(-hydroxyphenyl)ethyl]-2,3-napthalene dicarboamide (3), vitexin 6''-O-β-D-glucopyranoside (4), vitexin 2''-O-α-L-rhamnopyranoside (5), methyl 2-hydroxybenzoate-2-O-β-D-apiofuranosyl-(1→2)-O-β-D-glucopyranoside (6), ficuside G (7), methyl 2-O-β-D-glucopyranosylbenzoate (8), methyl 2,5-dihydroxybenzoate-5-O-β-D-glucopyranoside (9), and 3,7-dimethyloct-1-ene-3,6,7-triol 6-O-β-D-glucopyranoside (10) by spectroscopic data analysis including HR-ESI-MS, 1D-, and 2D-NMR spectra. Compounds 1-5 inhibited nitric oxide production in LPS-stimulated RAW264.7 macrophages with the IC₅₀ values of 27.62, 74.03, 38.54, 70.39, and 44.95 μM, respectively. The NMR data of 9 were firstly reported herein.

Keywords: C-flavone glycoside; Piper sarmentosum; Piperaceae; lignanamide; nitric oxide inhibition activity.