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

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-beta-D-[6 '-O-syringoylglucopyranosyl]-2-methoxy-7,8,9-trihydroxyphenylpropane (1), (7,8-threo)-8-O-(2 ''-methoxyacetophenone-1 ''-yl)-1-O-beta-D-glucopyranosyl-2-methoxy-7,9-dihydroxyphenylpropane (2), 1-O-beta-D-glucopyranosyl-2-O-(2 ''-methoxy-4 ''-acetylphenyl)-3-hydroxypropane (3), (-)-isolariciresinol 4-O-beta-D-glucopyranoside (4), (-)-isolarisiresinol 9 '-O-beta-D-glucopyranoside (5), (+ )-lyoniresinol 9 '-O-beta-D-glucopyranoside (6), (+ )-isolarisiresinol 9 '-O-beta-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 mu M, similar to those of the positive control, N-G-monomethyl-L-arginine acetate (IC50 32.51 +/- 3.70 mu M).