Design, synthesis and antiproliferative activity of raloxifene/histone deacetylase inhibitor hybrids in breast cancer.

Antiestrogen/histone deacetylase inhibitor (HDACi) hybrids were designed by merging structures of raloxifene with suberoylanilide hydroxamic acid, incorporating the HDACi unit into the phenolic ring of the antiestrogen. These hybrids were synthesized with a range of HDACi chain lengths and assessed for bifunctionality. Four hybrids, 21 (YW471), 22 (YW490), 27(YW486), and 28 (YW487) showed good potency both as antiestrogens in a BRET assay and in a fluorometric HDACi assay. The antiproliferative activity of the hybrids was demonstrated in both ER+ MCF7 and ER- MDA-MB-231 breast cancer cell lines.

Design, synthesis, and biological evaluation of new raloxifene analogues of improved antagonist activity and endometrial safety.

Raloxifene agonism of estrogen receptor (ER) in post-menopausal endometrium is not negligible. Based on a rational drug design workflow, we synthesized 14 analogues of raloxifene bearing a polar group in the aromatic ring of the basic side chain (BSC) and/or changes in the bulkiness of the BSC amino group. Analogues with a polar BSC aromatic ring and amino group substituents of increasing volume displayed increasing ER antagonism in Ishikawa cells. Analogues with cyclohexylaminoethoxy (13a) or adamantylaminoethoxy BSC (13b) lacking a polar aromatic ring displayed high ER-binding affinity and ER antagonism in Ishikawa cells higher than raloxifene and similar to fulvestrant (ICI182,780). The endometrial surface epithelium of immature female CD1 mice injected with 13b was comparable to that of vehicle-treated mice, while that of mice treated with estradiol, raloxifene or 13b in combination with estradiol was hyperplastic. These findings indicate that raloxifene analogues with a bulky BSC amino group could provide for higher endometrial safety treatment of the menopausal syndrome.

In-situ forming chitosan implant-loaded with raloxifene hydrochloride and bioactive glass nanoparticles for treatment of bone injuries: Formulation and biological evaluation in animal model.

In-situ forming implants receive great attention for repairing serious bone injuries. The aim of the present study was to prepare novel chitosan in-situ forming implants (CIFI) loaded with bioactive glass nanoparticles and/or raloxifene hydrochloride (RLX). Incorporating raloxifene hydrochloride (RLX) as a selective estrogen receptor modulator was essential to make use of its anti-resorptive properties. The prepared formulae were tested for their in-vitro gelation time, drug release, injectability, rheological properties, erosion rate and morphological properties. Results revealed that the formulation composed of 1% (w/v) chitosan with 2% (w/v) NaHCO3 and 1% (w/v) bioactive glass nanoparticles (CIFI-BG) possessed the most sustained drug release profile which extended over four months with low burst release effect compared to the same formulation lacking bioactive glass nanoparticles (CIFI). Selected formulations were tested for their ability to enhance bone regeneration in induced puncture in rate tibia. Results declared that these formulations were able to enhance bone regeneration after 12 weeks in comparison to the untreated tibial punctures and that containing bioactive glass could be considered as novel approach for treatment of serious bone injuries which require long term treatment and internal mechanical bone support during healing.

Synthesis, biological evaluation, and docking studies of new raloxifene sulfonate or sulfamate derivatives as inhibitors of nucleotide pyrophosphatase/phosphodiesterase.

A new series of raloxifene sulfonate/sulfamate derivatives were designed and synthesized. The target compounds were tested for inhibitory effect against nucleotide pyrophosphatase/phosphodiesterase-1 and -3 (NPP1 and NPP3) enzymes. Furthermore, all the ten target compounds were subjected to cytotoxic studies on various cancer cell lines, and the most potent derivatives were explored for their potency against these cancer cell lines as well as F180 fibroblasts to investigate the selectivity indexes. Compound 1f exerted the highest potency against HT-29 colon cancer cell line (IC50 = 1.4 µM) with 8.43-fold selectivity towards HT-29 than F180 fibroblasts. Compound 1f exerted sub-micromolar IC50 values against NPP1 and NPP3 (IC50 = 0.29 µM and 0.71 µM, respectively). The most potent inhibitors were docked in developed homology model of NPP1 and crystal structure of NPP3. All the docked analogues manifested remarkable interactions within the active pocket of NPP1 and NPP3.

Facile Synthesis of Chitosan Capped Mesoporous Silica Nanoparticles: A pH Responsive Smart Delivery Platform for Raloxifene Hydrochloride.

An encapsulation of model drug raloxifene hydrochloride (RAL) inside the chitosan decorated pH responsive mesoporous system has a greater potential for accumulating in the tumor cells. The present study involves synthesis of surface modified mesoporous silica nanoparticles (MSN) with the aim of achieving pH sensitive drug delivery system. A silanol skeleton of MSN has been productively modified to amine intermediate which served as a firm platform to adapt chitosan grafted assembly and systematically evaluated. RAL incorporation inside the featured mesopores was performed employing novel immersion solvent evaporation methodology and evaluated further. The pH responsive behavior of formulated nano framework was studied at three different pH of a phosphate buffer saline individually. The in vitro cell viability assay on MCF-7 breast carcinoma cells was performed in time and concentration dependent manner. Finally, the hemolysis assay of designed nanoparticle was accomplished to envisage the hemocompatibility. The outcome of characterization details unveiled a perfect 2D hexagonal spherical structure gifted with higher surface area and optimum pore size for designed nanoparticles. The higher percentage grafting of amine and chitosan residue, i.e., 4.01 and 28.51% respectively along with 31.89 and 33.57% RAL loading efficiency made MSNs more attractive and applicable. Eventually, in vitro release study exhibited higher RAL release in acidic media for extended time periods confirming successful formation of pH responsive nanoparticle having controlled release property. Conclusively potential of designed nanosystem to serve efficient anti-cancer remedy was confirmed by superior behaviour of chitosan grafted MSN towards MCF-7 cells with supreme hemocompatibility.

Synthesis and evaluation of raloxifene derivatives as a selective estrogen receptor down-regulator.

Estrogen receptors (ERs) play a major role in the growth of human breast cancer cells. A selective estrogen receptor down-regulator (SERD) that acts as not only an inhibitor of ligand binding, but also induces the down-regulation of ER, would be useful for the treatment for ER-positive breast cancer. We previously reported that tamoxifen derivatives, which have a long alkyl chain, had the ability to down-regulate ERα. With the aim of expanding range of the currently available SERDs, we designed and synthesized raloxifene derivatives, which had various lengths of the long alkyl chains, and evaluated their SERD activities. All compounds were able to bind ERα, and RC10, which has a decyl group on the amine moiety of raloxifene, was shown to be the most potent compound. Our findings suggest that the ligand core was replaceable, and that the alkyl length was important for controlling SERD activity. Moreover, RC10 showed antagonistic activity and its potency was superior to that of 4,4'-(heptane-4,4-diyl)bis(2-methylphenol) (18), a competitive antagonist of ER without SERD activity. These results provide information that will be useful for the development of promising SERDs candidates.

Inhibition of xanthine oxidase by the aldehyde oxidase inhibitor raloxifene: implications for identifying molybdopterin nitrite reductases.

Sources of nitric oxide alternative to nitric oxide synthases are gaining significant traction as crucial mediators of vessel function under hypoxic inflammatory conditions. For example, capacity to catalyze the one electron reduction of nitrite (NO2-) to ·NO has been reported for hemoglobin, myoglobin and molybdopterin-containing enzymes including xanthine oxidoreductase (XOR) and aldehyde oxidase (AO). For XOR and AO, use of selective inhibition strategies is therefore crucial when attempting to assign relative contributions to nitrite-mediated ·NO formation in cells and tissue. To this end, XOR inhibition has been accomplished with application of classic pyrazolopyrimidine-based inhibitors allo/oxypurinol or the newly FDA-approved XOR-specific inhibitor, Uloric® (febuxostat). Likewise, raloxifene, an estrogen receptor antagonist, has been identified as a potent (Ki=1.0 nM) inhibitor of AO. Herein, we characterize the inhibition kinetics of raloxifene for XOR and describe the resultant effects on inhibiting XO-catalyzed ·NO formation. Exposure of purified XO to raloxifene (PBS, pH 7.4) resulted in a dose-dependent (12.5-100 µM) inhibition of xanthine oxidation to uric acid. Dixon plot analysis revealed a competitive inhibition process with a Ki=13 µM. This inhibitory process was more effective under acidic pH; similar to values encountered under hypoxic/inflammatory conditions. In addition, raloxifene also inhibited anoxic XO-catalyzed reduction of NO2- to NO (EC50=64 µM). In contrast to having no effect on XO-catalyzed uric acid production, the AO inhibitor menadione demonstrated potent inhibition of XO-catalyzed NO2- reduction (EC50=60 nM); somewhat similar to the XO-specific inhibitor, febuxostat (EC50=4 nM). Importantly, febuxostat was found to be a very poor inhibitor of human AO (EC50=613 µM) suggesting its usefulness for validating XO-dependent contributions to NO2- reduction in biological systems. Combined, these data indicate care should be taken when choosing inhibition strategies as well as inhibitor concentrations when assigning relative NO2- reductase activity of AO and XOR.

Recent advances in the synthesis of raloxifene: a selective estrogen receptor modulator.

Estrogens are a group of steroids that exert important effects on reproductive and many non-reproductive tissues. Selective estrogen receptor modulators (SERM) are a class of therapeutic agents widely prescribed for the treatment and prevention of breast cancer, osteoporosis, and postmenopausal symptoms. Raloxifene, an example of oral SERM is prescribed primarily for the treatment and prevention of postmenopausal disorders in woman. The current review provides an outline of practical methodologies used to access benzothiophenyl scaffolds of raloxifene and relevant structural analogs. The contents are discussed in five sections: (a) synthesis of raloxifene, (b) organometallic analogs, (c) radiolabelled analogs, (d) constrained raloxifene analogs, and (e) other oxygen, sulfur, and nitrogen based raloxifene analogs. In addition to the synthesis, biological activity of a few synthetic analogs has been discussed.

Efeito da terapia de reposição hormonal e do raloxifeno a curto prazo sobre o intervalo QTc e a dispersão de QTc em mulheres idosas com hipertensão arterial sistêmica / Short term effect of hormone replacement therapy and of raloxifene on QTc interval and QTc dispersion in elderly women with systemic arterial hypertension

Objetivo: Dados encontrados na literatura sugerem que a terapia de reposição hormonal (TRH) pode promover alteração de repolarização e taquicardia ventricular. Como consequência houve um interesse na terapia com raloxifeno (R), um modulador seletivo do receptor do estrogênio, em função do seu potencial em apresentar a maioria dos efeitos benefícios do estrogênio, enquanto evita a maioria dos seus efeitos adversos.Métodos: Este estudo randomizado, duplo-cego e cruzado teve o objetivo de comparar o efeito do R com o TRH, no intervalo QT no eletrocardiograma, em 30 mulheres hipertensas, com idade média de 69 anos após um período run-in com hidroclorothiazida 12,5 mg uma vez ao dia. O intervalo QT foi corrigido(QTc) para a frequência cardíaca e a dispersão do QT(QTd) foi definida como a diferença entre os intervalos QT máximo e mínimo em quaisquer 2 derivações. As medidas foram realizadas no período basal, após 8 semanas de TRH (estradiol transdérmico+noretisterona) e após 8 semanas de R (60mg), com um período de wash-out entre as duas terapias.Resultados: verificou-se que R e TRH aumentaram QTc numa mesma extensão quando comparado aos níveis basais (p menor 0,05), embora não haja diferença significativa entre eles apesar dos valores de QTd.Conclusão: Os resultados encontrados neste estudo sugerem que o R e o TRH exercem os mesmos efeitos no intervalo QTc em mulheres hipertensas, em pós menopausa, não demonstrando qualquer efeito no QTd. Tal resultado deve encorajar futuros estudos para avaliar o impacto em eventos clínicos

Benzothiophenes containing a piperazine side chain as selective ligands for the estrogen receptor alpha and their bioactivities in vivo.

The synthesis of benzothiophenes containing a piperazine side chain and their binding affinities for estrogen receptors are described. These compounds bearing piperazine side chains were identified to be high-affinity ligands with high selectivity for ER alpha subtype. They were also potent agonists in bone tissue.

Synthesis and binding affinities of fluoroalkylated raloxifenes.

Three fluoroalkylated derivatives (1-3) of the selective estrogen receptor modulator (SERM), raloxifene, have been synthesized. The key step in the synthesis is the C-C bond formation of benzo[b]thiophene and a substituted phenyl group (ring C) using a Stille reaction. The in vitro binding affinities of the substituted raloxifenes 1-3 are 45, 60, 89%, respectively, relative to the affinity of estradiol, which is higher than the affinity of raloxifene itself (25%). When labeled with the positron-emitting radionuclide, these compounds might be useful as PET imaging agents for estrogen receptor-positive breast tumors.

Synthesis of constrained raloxifene analogues by complementary use of Friedel-Crafts and directed remote metalation reactions.

New constrained heterocyclic analogues, 2a,b and 3, of Raloxifene (1) have been prepared by complementary Directed remote Metalation (DreM)/Friedel-Crafts cyclization approaches. Utilization of a benzylidene-thiolactone rearrangement was successfully implemented to construct benzothiophenes 13a-c in good yields. Selective deprotection of 13a and 13b induced by complexation followed by triflation gave 18 and 23, thereby allowing efficient Suzuki-Miyaura cross coupling with borolane 16 to give biaryls 19 and 24. Treatment of 19 with BCl(3) induced an intramolecular para Fridel-Crafts cyclization and concomitant double deprotection to furnish analogue 2a, a new 5,6,6,6-(C(4)S-C(6)-C(6)-C(6)) sulfur-containing heterocycle. Exposure of 25 with excess LDA induced a DreM cyclization delivering the ortho-substituted 5,6,6,6-(C(4)S-C(6)-C(6)-C(6)) heterocylic analogue 26 in 70% yield. Similar treatment of 13c and 27 afforded 30, representing the novel 5,5,6,6-(C(4)S-C(5)-C(6)-C(6)) ring system, which was subjected to Suzuki-Miyaura cross coupling with 16 to give the biaryl 31 in 93% yield; deprotection furnished the final constrained analogue 3.