Methyl-Hispolon from Phellinus lonicerinus (Agaricomycetes) Affects Estrogen Signals in MCF-7 Breast Cancer Cells and Premature Aging in Rats.

We studied Phellinus lonicerinus to determine the cytotoxic effect and the dual estrogenic activities of methyl-hispolon and their relation to estrogen signals in vivo and in vitro. The Glide scores of methyl-hispolon-estrogen receptor α (ERα) and methyl-hispolon-ERß docked complexes were -7.29 kcal/mol and -6.68 kcal/mol in docking simulations. Methyl-hispolon had a significant antiproliferative effect for estrogen-sensitive ER(+) MCF-7 cells in the absence of estrogen, and it exhibited dual estrogen activities. Methyl-hispolon increased the serum E2 in rats with premature ovarian failure and fulfilled the estrogenic function in the uterus and ovary. Methyl-hispolon significantly inhibited the expression of Ras, API, ERα, C-myc, and cyclinDl, as well as their gene transcription in RL95-2 cells. The phosphorylation of ERK1/2 was inhibited by methyl-hispolon. Thus, methyl-hispolon has potential use in treating estrogen deficiency-related diseases, with good antitumor effects and estrogenic activity.

2D-NMR investigation and in vitro evaluation of antioxidant, antigenotoxic and estrogenic/antiestrogenic activities of strawberry grape.

Strawberry grape is considered beneficial due to its extensive phytochemical properties. To expand the knowledge about the chemical constituents and the biological activities of the whole plant, 2D-NMR investigation has been carried out on pulp, peel, seeds, stalks and leaves. Catechin and epicatechin were identified as the main constituents of the seed extract, quercetin and ferulic acid were detected in the leaves and malvidin and cyanidin glucopyranoside in the peels. The leaf, stalk and seed extracts were found to be very rich in phytochemicals and were tested for their ability to reduce the mutagenicity and genotoxicity of standard agents via Salmonella mutagenicity assay and SOS chromotest, respectively. Moreover, the estrogen/antiestrogen-like activity was evaluated on the MCF-7 estrogen-responsive cells. Seed and stalk extracts had an elevated antimutagenic/antigenotoxic activity. Stalk extracts highly reduced the proliferative effect of natural estrogen, 17ß-estradiol.

Design and Synthesis of Some Novel Estrogen Receptor Modulators as Anti-Breast Cancer Agents: In Vitro & In Vivo Screening, Docking Analysis.

A series of novel coumarin-chalcone hybrids have been synthesized in good yields and evaluated for their in vitro & in vivo anticancer activity. Cytotoxicity study was done against MCF-7 and Zr-75-1 human cancer cell lines. All compounds exhibited significant antiproliferative properties on both cell lines. The most active ER modulators found in in vitro screening are subjected for in vivo screened using methyl nitrosourea (MNU) induced mammary carcinoma in female spraque dawley rats. The Glide XP docking was performed for designed scaffold to optimize its structural requirement for ER-α inhibition.

Antiproliferative and Antiestrogenic Activities of Bonediol an Alkyl Catechol from Bonellia macrocarpa.

The purpose of this study was to investigate antiproliferative activity of bonediol, an alkyl catechol isolated from the Mayan medicinal plant Bonellia macrocarpa. Bonediol was assessed for growth inhibition of androgen-sensitive (LNCaP), androgen-insensitive (PC-3), and metastatic androgen-insensitive (PC-3M) human prostate tumor cells; toxicity on normal cell line (HEK 293) was also evaluated. Hedgehog pathway was evaluated and competitive 3H-estradiol ligand binding assay was performed. Additionally, antioxidant activity on Nrf2-ARE pathway was evaluated. Bonediol induced a growth inhibition on prostate cancer cell lines (IC50 from 8.5 to 20.6 µM). Interestingly, bonediol binds to both estrogen receptors (ERα (2.5 µM) and ERß (2.1 µM)) and displaces the native ligand E2 (17ß-estradiol). No significant activity was found in the Hedgehog pathway. Additionally, activity of bonediol on Nrf2-ARE pathway suggested that bonediol could induce oxidative stress and activation of detoxification enzymes at 1 µM (3.8-fold). We propose that the compound bonediol may serve as a potential chemopreventive treatment with therapeutic potential against prostate cancer.

The estrogenic activity of isoflavones extracted from chickpea Cicer arietinum L sprouts in vitro.

Isoflavones have drawn attention due to their potential therapeutic use. Isoflavones are the important chemical components of the seeds and sprouts of chickpea and higher isoflavones in sprouts than in seeds. However, there have been no previous reports of the estrogenic activity of isoflavones extracted from chickpea Cicer arietinum L sprouts (ICS) in vitro. In this study, which incorporated several in vitro bioassays methods, we systematically evaluated the estrogenic properties of ICS. MTT assay showed that ICS at the low concentration ranges (10(-3)-1 mg/L) promoted MCF-7 cell growth, while at high concentrations, (>1 mg/L) inhibited cell proliferation, indicating ICS worked at a diphasic mechanism. Flow cytometric analysis further calculated the proliferation rate of ICS at low concentration (1 mg/L). ERα/Luc trans-activation assay and then semi-quantitative RT-PCR analysis indicated that ICS at low concentrations induced ERα-mediated luciferase activity in MCF-7 cells and promoted the ER downstream target gene pS2 and PR trans-activation. These effects were inhibited by ICI 182,780, a special antagonist of ER, indicating that an ER-mediating pathway was involved. Alkaline phosphatase (AP) expression in Ishikawa cells showed that ICS at low concentrations stimulated AP expression. Our current study is the first to demonstrate that ICS has significant estrogenic activity in vitro. ICS may be useful as a supplement to hormone replacement therapy and in dietary supplements.

Developing phytoestrogens for breast cancer prevention.

Breast cancer is one of the most common types of cancer in women, and is the second leading cause of cancer-related deaths in the United States. Chemoprevention using phytoestrogens (PEs) for breast cancer may be a valid strategy. PEs are phytochemicals with estrogen-like structures and can be classified into four types: isoflavones, lignans, stilbenes and coumestans. They are widely distributed in diet and herbs and have shown anti-cancer activity via mechanisms including estrogen receptor modulation, aromatase inhibition, and anti-angiogenesis. Genistein, daidzein and resveratrol are some of the most studied PE examples. Quality control in product manufacturing and clinical study design is a critical issue in developing them as clinically effective chemopreventive agents for breast cancer.

Development of 2,3,5-triaryl-1H-pyrroles as estrogen receptor†α selective ligands.

1-Alkyl-2,3,5-triaryl-1H-pyrroles (for which alkyl=methyl, ethyl, n-propyl, or 2-methylpropyl) were tested for stability, estrogen receptor (ER) binding, and inhibition of tumor cell growth. These pyrroles (type B) showed higher stability in aqueous solution than their 1,2,4-triaryl-1H-pyrrole congeners (type A pyrroles), exclusive ERα binding (no ERß interaction), and a hormonal profile of partial agonists at ERα. The most potent compound, 1-(2-methylpropyl)-2,3,5-tris(4-hydroxyphenyl)-1H-pyrrole (5 d), was less active than the lead structure 1,3,5-tris(4-hydroxyphenyl)-4-propyl-1H-pyrazole (PPT) in MCF-7 cells stably transfected with the plasmid EREwtcluc (MCF-7/2a), but more potent in U2-OS/α cells. Furthermore, 5 d showed weak anti-estrogenic properties (IC50=310 nM). An additional propyl chain at C4 decreased the stability and pharmacological effects.

Lignans as food constituents with estrogen and antiestrogen activity.

Phytoestrogens are plant-derived food ingredients assumed to contribute to the prevention of hormone-dependent cancers, osteoporosis, cardiovascular disease, and menopausal symptoms. Lignans occur in numerous food plants and various structures; they are common constituents of human diet, and estrogen activity has been assessed for lignan metabolites formed in the mammalian intestine. We examined natural lignans and semisynthetic norlignans for estrogen and antiestrogen activity. A transformed yeast strain (Saccharomyces cerevisiae) expressing the estrogen receptor alpha and a reporter system was applied as test system. Some plant lignans showed estrogen activity while others and the semisynthetic norlignans were moderately active antiestrogens. Docking of lignans to protein models of estrogen receptor alpha in the active and inactive form sustained the results of the yeast estrogen assay and supported the concept of plant lignans as phytoestrogens.

Effect of graded doses of Caesalpinia bonducella seed extract on ovary and uterus in albino rats.

Histological changes observed under light microscope illustrate follicular degeneration in ovary, vacuolation and mild disorganization of uterus on treatment with graded doses of alcohol seed extract of Caesalpinia bonducella. There was a significant decrease (p≤0.05) in duration of estrous cycle and mean ovarian weight. However, there were no uniform variations in mean uterine weight, serum estradiol and progesterone level. The results suggest that alcohol seed extract of C. bonducella has antiestrogenic property, possibly acting via inhibition of estrogen secretion.

Tibolone rapidly attenuates the GABAB response in hypothalamic neurones.

Tibolone is primarily used for the treatment of climacteric symptoms. Tibolone is rapidly converted into three major metabolites: 3 alpha- and 3beta-hydroxy (OH)-tibolone, which have oestrogenic effects, and the Delta 4-isomer (Delta 4-tibolone), which has progestogenic and androgenic effects. Because tibolone is effective in treating climacteric symptoms, the effects on the brain may be explained by the oestrogenic activity of tibolone. Using whole-cell patch clamp recording, we found previously that 17beta-oestradiol (E(2)) rapidly altered gamma-aminobutyric acid (GABA) neurotransmission in hypothalamic neurones through a membrane oestrogen receptor (mER). E(2) reduced the potency of the GABA(B) receptor agonist baclofen to activate G-protein-coupled, inwardly rectifying K(+) (GIRK) channels in hypothalamic neurones. Therefore, we hypothesised that tibolone may have some rapid effects through the mER and sought to elucidate the signalling pathway of tibolone's action using selective inhibitors and whole cell recording in ovariectomised female guinea pigs and mice. A sub-population of neurones was identified post hoc as pro-opiomelanocortin (POMC) neurones by immunocytochemical staining. Similar to E(2), we have found that tibolone and its active metabolite 3 beta OH-tibolone rapidly reduced the potency of the GABA(B) receptor agonist baclofen to activate GIRK channels in POMC neurones. The effects were blocked by the ER antagonist ICI 182 780. Other metabolites of tibolone (3 alpha OH-tibolone and Delta 4-tibolone) had no effect. Furthermore, tibolone (and 3 beta OH-tibolone) was fully efficacious in ER alpha knockout (KO) and ER beta KO mice to attenuate GABA(B) responses. The effects of tibolone were blocked by phospholipase C inhibitor U73122. However, in contrast to E(2), the effects of tibolone were not blocked by protein kinase C inhibitors or protein kinase A inhibitors. It appears that tibolone (and 3 beta OH-tibolone) activates phospholipase C leading to phosphatidylinositol bisphosphate metabolism and direct alteration of GIRK channel function. Therefore, tibolone may enhance synaptic efficacy through the G(q) signalling pathways of mER in brain circuits that are critical for maintaining homeostatic functions.

Discovery of thiochroman and chroman derivatives as pure antiestrogens and their structure-activity relationship.

In order to develop pure antiestrogens, a series of 7-hydroxy-3-(4-hydroxyphenyl)-3-methylchroman and 7-hydroxy-3-(4-hydroxyphenyl)-3-methylthiochroman derivatives with sulfoxide containing side chains at the 4-position were designed, synthesized, and evaluated. Among them, compounds 14b and 24b functioned as pure antiestrogens with the ability to downregulate ER, and their in vitro and in vivo antiestrogen activities were similar to those of ICI182,780. In addition, the structure-activity relationship indicated that the (3RS,4RS)-configuration between the 3- and 4-position, the methyl group at the 3-position, the 9-methylene chain between the scaffold and the sulfoxide moiety, and the terminal perfluoroalkyl moiety play an important role in increasing estrogen receptor binding and oral antiestrogen activities.

Estrogen receptors: molecular interactions, virtual screening and future prospects.

Identification of the Estrogen Receptor (ER) as a key mediator of the proliferation of breast cancer, and its involvement in pathways leading to osteoporosis and coronary heart disease, has resulted in a surge to discover and design compounds with the ability to modulate its actions (SERMs). Concurrently, a dramatic increase in the number of crystal structures of the ER has led to a more in depth understanding of the governing mechanisms involved in ER modulation. Entwining computational techniques with the availability of 3D structural data, has allowed not only the rational design of potent inhibitors of the ER, but also its incorporation in Virtual Screening (VS) in the search for novel chemotypes that can modulate the ER. An important initial step in the VS process is to filter towards molecules that occupy similar chemical space to a set of known actives prior to docking. We illustrate through Principal Component Analysis (PCA) of 145 descriptors the region of chemical space antiestrogens occupy compared with 'drug-like' space. We also review all available studies involving validation of several docking algorithms utilizing the ER, ultimately focusing on analysis of Enrichment (E) rates and False Positive (FP) rates to illustrate the successes attributed to each docking algorithm. Finally, we relate the recent discovery of non-genomic mechanisms of the ER and subsequently present a model involving a recently identified alternative, second binding-pocket of the ER in our laboratory through cavity analysis that suggests how the same receptor can invoke these, 'classical' and rapid responses concurrently.

Isoflavonoids with antiestrogenic activity from Millettia pachycarpa.

Three new isoflavonoids, named millewanins G (1) and H (2) and furowanin B (3), were isolated from the leaves of Millettia pachycarpa. Their structures were elucidated on the basis of spectroscopic analyses. The antiestrogenic activity in the yeast two-hybrid assay of these isoflavonoids was examined and shown to be comparable with that of 4-hydroxytamoxifen.

Isolation and structure elucidation of an isoflavone and a sesterterpenoic acid from Henriettella fascicularis.

A new isoflavone, 4',5,7-trihydroxy-6,8-dimethylisoflavone (1), and a new sesterterpenoic acid (2), together with five known compounds, lichexanthone (3), (-)-pinoresinol (4), betulinic acid, palmitic acid, and beta-sitosterol, were isolated from a dichloromethane extract of the branches of Henriettella fascicularis. Their structures were established by extensive spectroscopic methods. An attempt to determine the absolute stereochemistry of (2E,6S)-6-[(1R,5Z,3aS,9R,10Z,12aR)-1,2,3,3a,4,7,8,9,12,12a-decahydro-9-hydroxy-3a,6,10-trimethylcyclopentanocycloundecen-1-yl]-2-methylhept-2-enoic acid (2) was performed by single-crystal X-ray analysis, using Cu Kalpha radiation. Compound 1 showed significant competitive binding to estrogen receptor beta and moderate antiestrogenic activity with cultured Ishikawa cells.

Antiestrogenic activities of Cimicifuga racemosa extracts.

Despite the wide use of extracts from the rhizome of black cohosh (Cimicifuga racemosa) for the treatment of menopausal complaints, surprisingly little is known on their potential estrogenic properties, e.g. on estrogen dependent gene transcription. In addition, available informations on the effects on cell proliferation are contradictory. We therefore, tested for estrogenic and antiestrogenic effects of Cimicifuga racemosa extracts on proliferation of MCF-7 cells and on gene expression using ethanolic and iso-propanolic extracts of this medical plant. Estrogenic properties of plant extracts could neither be detected in proliferation assays, nor on gene expression using an estradiol-inducible yeast assay or the estrogen-inducible MVLN cells. In contrast, in all three experimental systems Cimicifuga racemosa antagonized estradiol induced activities. Estradiol induced stimulation of proliferation was inhibited by a dosage >1 microg/ml of extract concentration, gene expression was suppressed by doses of 100-1000 microg/ml of Cimicifuga racemosa extracts. From these results we conclude, that extracts from the rhizome of Cimicifuga racemosa contain compounds with antiestrogenic properties.

Furans with basic side chains: synthesis and biological evaluation of a novel series of antagonists with selectivity for the estrogen receptor alpha.

3-alkyl-2,4,5-triarylfurans with basic side-chain substituents were prepared as ligands for the estrogen receptor. Those analogues having the basic side chain on the C(4) phenol were high-affinity, ERalpha-selective antagonists.