Chlorination diversifies Cimicifuga racemosa triterpene glycosides.

Extracts from the roots and rhizomes of black cohosh (Cimicifuga racemosa) are widely used as dietary supplements to alleviate menopausal symptoms. State-of-the-art quality control measures involve phytochemical fingerprinting of the triterpene glycosides for species identification and chemical standardization by HPLC. In the course of developing materials and methods for standardization procedures, the major C. racemosa triterpene glycoside (1) was isolated and initially thought to be cimicifugoside (2). Detailed HR-LC-MS and 1D and 2D NMR analysis of 1 and 2 unambiguously revealed that 1 is the chlorine-containing derivative of 2, namely, 25-chlorodeoxycimigenol-3-O-beta-d-xyloside. Accordingly, HPLC profiles of black cohosh preparations require revision of the assignments of the chlorinated (1) and nonchlorinated (2) pair. Besides explaining the substantial shift in polarity (DeltatR[RP-18] ca. 20 min), 25-deoxychlorination opens a new pathway of structural diversification in triterpene glycoside chemistry. As chemical conversion of 2 into 1 could be demonstrated, deoxychlorination may be interpreted as artifact formation. Simultaneously, however, it is a potentially significant pathway for the gastric in vivo conversion ("nature's prodrug") of the relatively polar triterpene glycosides into significantly less polar chlorinated derivatives with altered pharmacological properties.

Black cohosh (Actaea racemosa, Cimicifuga racemosa) behaves as a mixed competitive ligand and partial agonist at the human mu opiate receptor.

Black cohosh is a commonly used botanical dietary supplement for the treatment of climacteric complaints. Because the opiate system in the brain is intimately associated with mood, temperature, and sex hormonal levels, the activity of black cohosh extracts at the human mu opiate receptor (hMOR) expressed in Chinese hamster ovary cells was investigated. The 100% methanol, 75% ethanol, and 40% 2-propanol extracts of black cohosh effectively displaced the specific binding of [3H]DAMGO to hMOR. Further studies of the clinically used ethanol extract indicated that black cohosh acted as a mixed competitive ligand, displacing 77 +/- 4% [3H]DAMGO to hMOR (Ki = 62.9 microg/mL). Using the [35S]GTPgammaS assay, the action of black cohosh was found to be consistent with an agonist, with an EC50 of 68.8 +/- 7.7 microg/mL. These results demonstrate for the first time that black cohosh contains active principle(s) that activate hMOR, supporting its beneficial role in alleviating menopausal symptoms.

Cimipronidine, a cyclic guanidine alkaloid from Cimicifuga racemosa.

A new cyclic guanidine alkaloid, cimipronidine (1), together with the known compound fukinolic acid (2), was isolated from the n-BuOH-soluble fraction of Cimicifuga racemosa roots that showed 5-HT7 receptor binding activity. Structure elucidation of 1, a minor constituent, presented unique challenges based on its polarity, but was accomplished with the use of a combination of one- and two-dimensional NMR as well as MS analyses. The relative configuration was established by analyzing the H,H-coupling constants and the results of the 2-D gradient NOESY spectrum. The previously reported serotonergic (5-HT7), highly polar, n-BuOH-soluble fraction was characterized by HPLC-ELSD and was shown to be a mixture containing the following compounds: cimicifugic acids A, B, and F, fukinolic acid, ferulic acid, isoferulic acid, and compound 1, potentially significant as a marker compound of C. racemosa.

Synthesis of cimiracemate B, a phenylpropanoid found in Cimicifuga racemosa.

The synthesis of the rare bioactive phenylpropanoid ester known as cimiracemate B (1) from black cohosh, Cimicifuga racemosa, is described. The procedure employs a coupling method using 1, l'-carbonyldiimidazole and methyltrifluoromethanesulfonate as coupling reagents in the presence of N-methylmorpholine.

Black cohosh acts as a mixed competitive ligand and partial agonist of the serotonin receptor.

Extracts of the rhizome of black cohosh [Actaea racemosa L., formerly called Cimicifuga racemosa (L.) Nutt.] were evaluated for potential mechanisms of action in the alleviation of menopausal hot flashes. Ovariectomized Sprague-Dawley rats were administered a 40% 2-propanol extract of black cohosh [4, 40, and 400 mg/(kg.day)] by gavage for 2 weeks with or without estradiol [50 microg/(kg.day)] to determine if black cohosh could act as an estrogen or antiestrogen on the basis of an increase in uterine weight or vaginal cellular cornification. No effects were observed on uterine weight or on vaginal cellular cornification in rats treated with black cohosh alone or in combination with 17beta-estradiol, indicating this black cohosh extract had no estrogenic or antiestrogenic properties in the ovariectomized rat model. To evaluate other potential pathways by which black cohosh might reduce menopausal hot flashes, serotonin activity was first assessed by the inhibition of radioligand binding to cell membrane preparations containing recombinant human serotonin receptor (5-HT) subtypes. A 40% 2-propanol extract of black cohosh was tested against 10 subtypes of the serotonin receptor, revealing the presence of compounds with strong binding to the 5-HT(1A), 5-HT(1D), and 5-HT(7) subtypes. Subsequent binding studies were carried out using 5-HT(1A) and 5-HT(7) receptors because of their association with the hypothalamus, which has been implicated in the generation of hot flashes. The black cohosh 40% 2-propanol extract inhibited [(3)H]lysergic acid diethylamide (LSD) binding to the human 5-HT(7) receptor (IC(50) = 2.4 +/- 0.4 microg/mL) with greater potency than binding of [(3)H]-8-hydroxy-2-(di-N-propylamino)tetralin to the rat 5-HT(1A) receptor (IC(50) = 13.9 +/- 0.6 microg/mL). Analysis of ligand binding data indicated that components of a black cohosh methanol extract functioned as a mixed competitive ligand of the 5-HT(7) receptor. In addition, a black cohosh methanol extract elevated cAMP levels in 293T-5-HT(7)-transfected HEK cells, suggesting the extract acted as a partial agonist at the receptor. The elevation in cAMP mediated by the black cohosh extract could be reversed in the presence of the antagonist methiothepin, indicating a receptor-mediated process. These data suggest that reductions in hot flashes in some women taking black cohosh may not be due to estrogenic properties. This study identifies other possible biological targets of black cohosh that could account for reported biological effects.

Black cohosh (Cimicifuga racemosa L.) protects against menadione-induced DNA damage through scavenging of reactive oxygen species: bioassay-directed isolation and characterization of active principles.

The roots/rhizomes of Cimicifuga racemosa L. (Nutt.) (black cohosh) have traditionally been used to treat menopausal symptoms through an unknown mechanism of action. In an effort to determine if black cohosh had additional health benefits, methanol extracts were investigated for their potential to scavenge reactive oxygen species and to protect against menadione-induced DNA damage. These extracts effectively scavenged 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals. In addition, the extracts showed dose-dependent decreases in DNA single-strand breaks and oxidized bases induced by the quinone menadione using the comet (single-cell gel electrophoresis assay) and fragment length associated repair enzyme assays, respectively. Bioassay-directed fractionation of the methanolic extracts using the DPPH assay as a monitor led to the isolation of nine antioxidant active compounds: caffeic acid (1), methyl caffeate (2), ferulic acid (3), isoferulic acid (4), fukinolic acid (5), cimicifugic acid A (6), cimicifugic acid B (7), cimicifugic acid F (8), cimiracemate A (9), and cimiracemate B (10). Six of these antioxidants were found to reduce menadione-induced DNA damage in cultured S30 breast cancer cells with the following order of potency: methyl caffeate (2) > caffeic acid (1) > ferulic acid (3) > cimiracemate A (9) > cimiracemate B (10) > fukinolic acid (5). These data suggest that black cohosh can protect against cellular DNA damage caused by reactive oxygen species by acting as antioxidants.

Cimiracemosides I-P, new 9,19-cyclolanostane triterpene glycosides from Cimicifuga racemosa.

Eight new and 13 known triterpene glycosides, along with the known compounds glyceryl-1-palmitate and daucosterol-6'-linoleate were isolated from the roots/rhizomes of Cimicifuga racemosa. The new compounds, designated as cimiracemosides I-P (1, 3-9), were determined by spectral analysis to be 7-dehydro-23-epi-12,26-dideoxyacteol-3-O-beta-D-xylopyranoside (1), 12-O-acetyl-25-anhydrocimigenol-3-O-alpha-L-arabinopyranoside (3), 12-O-acetyl-25-anhydrocimigenol-3-O-beta-D-xylopyranoside (4), 4',23-O-diacetylshengmanol-3-O-beta-D-xylopyranoside (5), 4',23-O-diacetylshengmanol-3-O-alpha-L-arabinopyranoside (6), 23-epi-acetylacteol-3-O-alpha-L-arabinopyranoside (7), 4'-O-acetyl-26-deoxyactein (8), and 16beta:23;24:25-diepoxy-12beta-O-acetyl-3beta-hydroxy-9,19-cyclolanost-23,26-olide-O- beta-D-xylopyranoside (9).

Cimiracemates A-D, phenylpropanoid esters from the rhizomes of Cimicifuga racemosa.

Four phenylpropanoid esters, cimiracemates A-D (1-4), along with three known compounds, isoferulic acid, ferulic acid and methyl caffeate were isolated from the EtOAc fraction of the rhizome of Cimicifuga racemosa. The structures of the esters were elucidated by means of spectral data, including 2D NMR spectroscopy.

Isolation, structure elucidation, and absolute configuration of 26-deoxyactein from Cimicifuga racemosa and clarification of nomenclature associated with 27-deoxyactein.

A new triterpene glycoside, 26-deoxyactein (1), along with two known compounds, 23-epi-26-deoxyactein (2), previously designated as "27-deoxyactein", and actein (3), were isolated from the roots/rhizomes of Cimicifuga racemosa. The structures and absolute stereochemistry of 1 and 2 were established by spectroscopic methods (FABMS, (1)H and (13)C NMR) and single-crystal X-ray data analysis.