Studies On Chemical Constituents Of Radix Polygoni Multiflori Praeparata

Radix Polygoni Multiflori, the dried roots of Polygonum multiflorum Thunb.(Polygonaceae) have long been used as detoxifying and purgative agents, while RadixPolygoni Multiflori Praeparata, the processed roots have been used in the preparationof tonics and as nutritional supplements. Compounds isolated from the roots of P.multiflorum are reported to be anthraquinones, stilbenoids, flavonoids, and others. Toinvestigate the chemical alterations after processing, we conducted a chemical studyon Radix Polygoni Multiflori Praeparata and supplemented a comparison of thechemical constituents in processed and unprocessed roots of P. multiflorum by HPLCand HPLC-MS.Thirty-five compounds were isolated from the EtOH extract of Radix PolygoniMultiflori Praeparata employing solvent extraction, repetitive columnchromatography and recrystallization. On the basis of various modern spectroscopicanalysis and classical chemical methods, the stuctures of twenty-nine compoundswere elucidated as: citreorosein (PMPE-1), aloe emodin (PMPE-2), pyrogallol(PMPE-3), daucosterol (PMPE-4), emodin-8-O--D-glucopyranoside (PMPE-5),(E)-2,3,5,4′-tetrahydroxystilbene-2-O--D-glucoside (PMPE-6), catechin (PMPE-7),(E)-2,3,5,4′-tetrahydroxystilbene-2-O--D-(6’’-acetyl)-glucopyranoside (PMPE-8),(E)-2,3,5,4′-tetrahydroxystilbene-2-O--D-(2’’-galloyl)-glucopyranoside (PMPE-9),gallic acid (PMPE-10), N-trans-feruloyl tyramine (PMPE-11), polygonumoside A(PMPB30-1), polygonimitin B (PMPB30-2), polygonumoside D (PMPB30-3),polygonumoside C (PMPB30-4),(E)-2,3,5,4′-tetrahydroxystilbene-2-O--D-(6’’-O--D-glucopyranosyl)-glucopyranoside (PMPB30-7), polygonimitin (PMPB30-8),polygonumoside B (PMPB30-11), physcion-8-O--D-glucopyranoside (PMPB30-12),trycin-7-O--D-glucopyranoside (PMPB30-13), butyl-1-O--D-fructopyranoside(PMPB30-14), epicatechin (PMPB30-16),2-(2-hydroxylpropyl)-5-methylchromone-7-O--D-glucopyranoside (PMPB30-18), lyoniresinol-3-O--D-glucopyranoside(PMPB30-19), polygonumoside E (PMPB30-20), physcion (PMPC-1), emodin(PMPC-2),2,5-dimethyl-7-hydroxychromenone (PMPC-3) and sitosterol (PMPP-1).Among these compounds, polygonumosides A-E (PMPB30-1, PMPB30-11,PMPB30-4, PMPB30-3and PMPB30-20) are new compounds. Polygonumoside A and polygonumoside B, possessing an unprecedented2H-benzo[c]furo[2,3-f]chromen-7(3H)-one tetracyclic skeleton, while polygonumoside C andpolygonumoside D were the first diastereomeric stilbene glucopyranoside dimersisolated from the roots of P. multiflorum.2,5-dimethyl-7-hydroxychromenone(PMPC-3),2-(2-hydroxylpropyl)-5-methylchromenone-7-O--D-glucopyranoside(PMPB30-18), trycin-7-O--D-glucopyranoside (PMPB30-13) and pyrogallol(PMPE-3), were reported for the first time from this plant.Comparison of HPLC and HPLC-MS chromatograms led to a conclusion thatthe content of stilbene glycoside PMPE-6decreased while the content of otherstilbene derivatives PMPE-8, PMPE-9, PMPB30-8, and the new compoundspolygonumosides A-D increased in the processed roots. The content of combinedathraquinone PMPE-5decreased and the content of free athraquinones increased inthe processed roots.Compounds PMPE-7, PMPC-2, PMPE-1, PMPE-2, PMPE-5, and PMPE-6showed phytoestrogenic activity. The new compouds polygonumoside A andpolygonumoside B displayed significant activities of scavengining DPPH free radicals,while polygonumoside C and polygonumoside D showed poor activities.Studies on chemical constituents and bioactivities of P. multiflorum were alsosummarized.