| Black cohosh (Actaea racemosa L.) is an important botanical dietary supplement for the treatment of menopausal symptoms in women. Despite the documented clinical efficacy of black cohosh, little is known of its active compounds. The phytochemistry of A. racemosa, as well as the other three closely related species, A. pachypoda, A. podocarpa, and A. rubra, was investigated.;Activity-guided fractionation of a standardized black cohosh powdered extract resulted in the isolation of two novel polyphenolic compounds, (3 S)-2-(3″,4″-dihydroxyphenylmethylene)-3-hydroxy-3-(3 ',4'-dihydroxybenzoyl)-gamma-butyrolactone (1) (2R, 3S)-2-O-(3',4'---dimethoxy-E-cinnamoyl)-3-hydroxy-3-[(3 ',4'-dihydroxyphenyl) methyl]-butanedioic acid (2), together with fifteen known polyphenols, namely protocatechuic acid, protocatechualdehyde, p-coumaric acid, caffeic acid, methyl caffeate, ferulic acid, ferulate-l-methyl-ester, isoferulic acid, 1-isoferuloyl-beta-D-glucopyranoside, fukinolic acid, cimicifugic acids A, B, D, E, and F. Compounds 1 and 2 displayed high antioxidant activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical assay with IC50 values of 26.94 and 37.40 muM, respectively. Also, compounds 1 and 2 were able to stimulate MCF-7 cell proliferation of 1.24-fold (14 muM) and 1.14-fold (10 muM), respectively, when compared with the untreated cells. The fifteen known polyphenolic compounds were tested in the DPPH assay and displayed activities ranging from IC50 values of 12.91 to 321.41 muM. Fukinolic acid had the highest antioxidant activity, while p-coumaric acid had the lowest activity.;A reversed-phase high-performance liquid chromatography (RP-HPLC) with diode array detection (DAD) method was developed and validated to quantify eight major polyphenols in the rhizomes and roots of four North American Actaea species, A. pachypoda, A. podocarpa , A. racemosa, and A. rubra. This validated method allowed for the identification and quantification of caffeic acid, ferulic acid, isoferulic acid, fukinolic acid, cimicifugic acids A, B, E, and F. The highest levels of the eight measured polyphenols were found in A. rubra, the second highest in A. podocarpa, the third highest in A. racemosa, and the lowest in A. pachypoda. The polyphenol levels corresponded with the antioxidant activities determined by the DPPH assay.;In summary, four North American Actaea species were analyzed for their phytochemical profiles with a new validated HPLC-DAD method, and two novel and fifteen polyphenolic compounds were identified and isolated from A. racemosa roots and rhizomes. |
