Piperlongosides A–C, Three New Phenolic Constituents From Piper longum L.

Abstract

Phytochemical study on the methanolic extract of the aerial parts of this plant led to the isolation of 7 phenolic compounds (1-7), including 3 new ones (1-3). Their chemical structures were determined to be (7,8- threo)-1 -O-β-D-[6′ -O-syringoylglucopyranosyl]-2-methoxy-7,8,9-trihydroxyphenylpropane (1), (7,8- threo)-8 -O-(2′′-methoxyacetophenone-1′′-yl)-1 -O-β-D-glucopyranosyl-2-methoxy-7,9-dihydroxyphenylpropane (2), 1 -O-β-D-glucopyranosyl-2 -O-(2′′-methoxy-4′′-acetylphenyl)-3-hydroxypropane (3), (−)-isolariciresinol 4 -O-β-D-glucopyranoside (4), (−)-isolarisiresinol 9′ -O-β-D-glucopyranoside (5), (+ )-lyoniresinol 9′ -O-β-D-glucopyranoside (6), (+ )-isolarisiresinol 9′ -O-β-D-glucopyranoside (7) by the spectroscopic data and in comparison with those reported in the literature. Compounds 3 to 7 significantly inhibited NO production in LPS-activated RAW264.7 cells with IC50 values ranging from 32.09 ± 3.34 to 38.16 ± 1.35 µM, similar to those of the positive control, NG-monomethyl-L-arginine acetate (IC50 32.51 ± 3.70 µM).