Anticancer Properties of Novel 4‐methylene‐1,2‐diphenylpyrazolidin‐3‐ones

The limited success of the currently used antitumor therapies is the driving force for organic chemists to seek new lead structures with anticancer potential. Two α‐methylene‐γ‐lactams with an additional nitrogen atom in the lactam ring, 5‐vinyl‐1,2‐diphenyl‐4‐methylenepyrazolidin‐3‐one ( 2a ) and 5‐phenyl‐1,2‐diphenyl‐4‐methylenepyrazolidin‐3‐one ( 2b ) have been synthesized. Their anticancer activity was assessed in MCF‐7 cells. Both compounds inhibited cell proliferation and induced DNA damage and apoptosis, with 2a being the more potent analog. Synergistic effects of 2a used in combination with known anticancer drugs, 5‐fluorouracil, taxol, and oxaliplatin were evaluated. Compound 2a significantly enhanced the antitumor action of oxaliplatin and 5‐fluorouracil, but not taxol.     

Potent hypolipidemic activity of mimetic amides of fibrates based on the 2‐methoxy‐4‐(2‐propenyl)phenoxyacetic scaffold

A series of bioisosteric analogues of fibrates, such as clofibrate ( 2 ) and bezafibrate ( 3 ), was designed, considering the pharmacophore potential of phenoxyacetic derivatives 4 related to α‐asarone ( 1 ) in their structure. Thus, the hypolipidemic activity of the series of amides 5a‐5j , 6a‐6d , and 7a‐7c , amines 8b‐8d , and amino acids 9a‐9e has been evaluated. A significant decrease in serum cholesterol was observed in mice for a number of these compounds. Some of them also showed a lowering of low‐density lipoprotein cholesterol, and a few had an effect on increasing the high‐density lipoprotein cholesterol levels, and on reducing the triglyceride serum contents. Phenoxyacetic, phenoxyethyl‐amido and ‐amino moieties, as well as the presence of a chlorine atom in their aromatic rings, were identified as potential pharmacophores. Unexpectedly, derivatives 9a‐9e , bearing an amino acid group, did not exhibit any hypolipidemic activity under a similar pharmacological protocol. Drug Dev. Res. 61:19–36, 2004. © 2004 Wiley‐Liss, Inc.     

Synthesis and kinetics studies of N′‐(2‐(3,5‐disubstituted‐4H‐1,2,4‐triazol‐4‐yl)acetyl)‐6/7/8‐substituted‐2‐oxo‐2H‐chromen‐3‐carbohydrazide derivatives as potent antidiabetic agents

A novel series of N′‐(2‐(3,5‐disubstituted‐4H‐1,2,4‐triazol‐4‐yl)acetyl)‐6/7/8‐substituted‐2‐oxo‐2H‐chromen‐3‐carbohydrazides were synthesized and studied for their α‐glucosidase inhibition activity. Most of the synthesized compounds exhibited potential α‐glucosidase inhibition activity with IC₅₀ values ranging from 0.96 ± 0.02 to 32.86 ± 0.73 µg/ml. Among them, compounds 3e and 4e , having a methoxy group on the coumarin ring, proved to be the most potent ones, showing an enzyme inhibition activity with IC₅₀ = 0.96 ± 0.02 and 1.44 ± 0.06 µg/ml, respectively. The kinetic study through Lineweaver–Burk plots revealed that the inhibition mechanism of the most active compounds 3d, 3e, 4d , and 4e , on the α‐glucosidase activity, was found to be in the competitive mode.     

Improved solid‐phase synthesis of α,α‐dialkylated amino acid‐rich peptides with antimicrobial activity*

Abstract: A homologous series of nonapeptides and their acetylated versions were successfully prepared using solid‐phase synthetic techniques. Each nonapeptide was rich in α,α‐dialkylated amino acids [one 4‐aminopiperidine‐4‐carboxylic acid (Api) and six α‐aminoisobutyric acid (Aib) residues] and also included lysines or lysine analogs (two residues). The incorporation of the protected dipeptide 9‐fluorenylmethyloxycarbonyl (Fmoc)‐Aib‐Aib‐OH improved the purity and overall yields of these de novo designed peptides. The helix preference of each nonapeptide was investigated in six different solvent environments, and each peptide's antimicrobial activity and cytotoxicity were studied. The 3₁₀‐helical, amphipathic design of these peptides was born out most prominently in the N‐terminally acetylated peptides. Most of the peptides exhibited modest activity against Escherichia coli and no activity against Staphylococcus aureus. The nonacetylated peptides (concentrations ≤100 μm ) and the acetylated peptides (concentrations ≤200 μm ) did not exhibit any significant cytotoxicity with normal (nonactivated) murine macrophages.     

Comparative effects of 1α‐hydroxyvitamin D3 and 1,25‐dihydroxyvitamin D3 on transporters and enzymes in fxr(+/+) and fxr(‐/‐) mice

Previous studies have shown that 1α,25‐dihydroxyvitamin D₃ [1,25(OH)₂D₃] treatment in mice resulted in induction of intestinal and renal Cyp24a1 and Trpv6 expression, increased hepatic Cyp7a1 expression and activity, as well as higher renal Mdr1/P‐gp expression. The present study compared the equimolar efficacies of 1α‐hydroxyvitamin D₃ [1α(OH)D₃] (6 nmol/kg i.p. q2d × 4), a lipophilic precursor with a longer plasma half‐life that is converted to 1,25(OH)₂D₃, and 1,25(OH)₂D₃ on vitamin D receptor (VDR) target genes. To clarify whether changes in VDR genes was due to VDR and not secondary, farnesoid X receptor (FXR)‐directed effects, namely, lower Cyp7a1 expression in rat liver due to increased bile acid absorption, wildtype [fxr(+/+)] and FXR knockout [fxr(‐/‐)] mice were used to distinguish between VDR and FXR effects. With the exception that hepatic Sult2a1 mRNA was increased equally well by 1α(OH)D₃ and 1,25(OH)₂D₃, 1α(OH)D₃ treatment led to higher increases in hepatic Cyp7a1, renal Cyp24a1, VDR, Mdr1 and Mrp4, and intestinal Cyp24a1 and Trpv6 mRNA expression in both fxr(+/+) and fxr(‐/‐) mice compared to 1,25(OH)₂D₃ treatment. A similar induction in protein expression and microsomal activity of hepatic Cyp7a1 and renal P‐gp and Mrp4 protein expression was noted for both compounds. A higher intestinal induction of Trpv6 was observed, resulting in greater hypercalcemic effect following 1α(OH)D₃ treatment. The higher activity of 1α(OH)D₃ was explained by its rapid conversion to 1,25(OH)₂D₃ in tissue sites, furnishing higher plasma and tissue 1,25(OH)₂D₃ levels compared to following 1,25(OH)₂D₃‐treatment. In conclusion, 1α(OH)D₃ exerts a greater effect on VDR gene induction than equimolar doses of 1,25(OH)₂D₃ in mice. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis of 1,4‐Anthracene‐9,10‐dione Derivatives and Their Regulation of Nitric Oxide,IL‐1β and TNF‐α in Activated RAW264.7 Cells

Mitoxantrone is an anthracenedione antineoplastic and immunosuppressive agent approved for multiple sclerosis treatment. Novel mono‐ and disubstituted anthraquinone derivatives, analogues of mitoxantrone, were synthesized through the addition of lipophilic amino alcohols and evaluated for their effect on IL‐1β, TNF‐α and nitric oxide production by LPS/IFN‐γ‐stimulated RAW264.7 cells. The disubstituted 1,4‐anthracene‐9,10‐dione 10 showed significant inhibition of nitric oxide, TNF‐α and IL‐1β production at the concentration of 5 μg/mL, with a much lower cytotoxicity than mitoxantrone. The monosubstituted 3 , 4 , 11, 12 and 13 also displayed a moderate to good inhibitory capacity on IL‐1β production. However, the methylated compounds 11, 12 and 13 failed to inhibit the TNF‐α production, and compound 13 was the only one to decrease the production of nitric oxide. None of these derivatives was toxic at the tested concentrations. Compounds 10 and 13 had better inhibitory capacity of the inflammatory mediators analyzed, with reliable viability of the cells.     

Design,Synthesis, and Evaluation of 3‐Aryl‐4‐pyrrolyl‐maleimides as Glycogen Synthase Kinase‐3β Inhibitors

A series of 3‐aryl‐4‐pyrrolyl‐maleimides were designed, synthesized, and evaluated for their glycogen synthase kinase‐3β (GSK‐3β) inhibitory activity. Most compounds exhibited potent activity against GSK‐3β. Among them, compounds 11a , 11c , 11h , 11i , and 11j significantly reduced Aβ‐induced Tau hyperphosphorylation, showing the inhibition of GSK‐3β at the cellular level. Structure–activity relationships were discussed based on the experimental data obtained.     

Synthesis and Evaluation of 3‐(furo[2,3‐b]pyridin‐3‐yl)‐4‐(1H‐indol‐3‐yl)‐maleimides as Novel GSK‐3β Inhibitors and Anti‐Ischemic Agents

A series of novel 3‐(furo[2,3‐b]pyridin‐3‐yl)‐4‐(1H‐indol‐3‐yl)‐maleimides were designed, synthesized, and biologically evaluated for their GSK‐3β inhibitory activities. Most compounds showed favorable inhibitory activities against GSK‐3β protein. Among them, compounds 5n , 5o , and 5p significantly reduced GSK‐3β substrate tau phosphorylation at Ser396 in primary neurons, indicating inhibition of cellular GSK‐3β activity. In the in vitro neuronal injury models, compounds 5n , 5o , and 5p prevented neuronal death against glutamate, oxygen–glucose deprivation, and nutrient serum deprivation which are closely associated with cerebral ischemic stroke. In the in vivo cerebral ischemia animal model, compound 5o reduced infarct size by 10% and improved the neurological deficit. The results may provide new insights into the development of novel GSK‐3β inhibitors with potential neuroprotective activity against brain ischemic stroke.     

Design,Synthesis, Antioxidant,and Anti‐Breast Cancer Activities of Novel Diethyl(alkyl/aryl/heteroarylamino)(4‐(pyridin‐2‐yl)phenyl)methylphosphonates

A series of new diethyl(alkyl/aryl/heteroarylamino)(4‐(pyridine‐2‐yl)phenyl)methylphosphonates ( 4a–t ) were synthesized via three‐component Kabachnik–Field's reaction of 4‐(pyridin‐2‐yl)benzaldehyde, diethylphosphite and various primary amines, catalyzed by cupric acetate monohydrate [Cu(OAc)₂ · H₂O] under solvent‐free and microwave irradiation conditions. Their computational docking analysis supported them as good therapeutic agents to the breast cancer aromatase enzyme and ascertained 4a , 4h , 4m , 4n , and 4t as potential molecules with good binding affinities varying from ?9.0 to ?9.6 kcal/mol and containing the 4‐(pyridine‐2‐yl)phenyl moiety as a pharmacophore. Their in vitro screening performed for the anti‐cell proliferation activity against MBC‐MCF7 cells by MTT and Trypan blue assays confirmed 4m , 4n , and 4q as promising compounds to sustain a low percentage of cell viability at 20 µg/mL concentration. These compounds were also evaluated for their antioxidant activity by the DPPH method and the results established that compounds 4m , 4n , and 4q show around 10% higher activity than the standard antioxidant ascorbic acid.     

Synthesis and Cytotoxic Evaluation of 6‐(3‐Pyrazolylpropyl) Derivatives of 1,4‐Naphthohydroquinone‐1,4‐diacetate

Several new 6‐(3‐pyrazolylpropyl) derivatives of 1,4‐naphthohydroquinone‐1,4‐diacetate (NHQ‐DA) have been prepared by chemical modifications of the Diels–Alder adduct of α‐myrcene and 1,4‐benzoquinone. All these new compounds and precursors have been evaluated in vitro for their cytotoxicity against cultured human cancer cells of MB‐231 breast‐adeno carcinoma, A‐549 lung carcinoma, and HT‐29 colon carcinoma. GI₅₀ values ranged in and below the micromolar concentration level.     

Design,synthesis, and biological evaluation of thieno[3,2‐d]pyrimidine derivatives as potential simplified phosphatidylinositol 3‐kinase alpha inhibitors

A series of thieno[3,2‐d]pyrimidine derivatives as phosphatidylinositol 3‐kinase (PI3K) inhibitors was designed using the combination strategy. The synthesis and biological evaluation of the derivatives demonstrated their potent inhibition of PI3K, culminating in the discovery of 7 and 21 . Determination of a co‐crystal structure of 7 complexed with PI3Kα provided the structural basis for the high enzymatic activity. Furthermore, cellular investigation of compounds 7 and 21 revealed that they efficiently suppressed cancer cell lines proliferation through inhibition of intracellular PI3K/AKT/mammalian target of rapamycin pathway. The results provided potent simplified inhibitors of PI3K with a promising overall profile and a chemical series for further optimization to progress into vivo experiments.     

Two novel lupane triterpenoids from Paullinia pinnata L. with fibroblast stimulatory activity

Objectives Novel lupane triterpenoids from Paullinia pinnata L., a Ghanaian plant traditionally used for wound healing, were examined for in‐vitro fibroblast stimulatory activity using the 142BR cell line. Methods Bioactivity‐guided isolation of the crude extract of P. pinnata L. was carried out in order to determine the nature of the compounds responsible for the stimulation of fibroblast proliferation. Key findings Two novel compounds were isolated and characterised, namely, 6β‐(3′‐methoxy‐4′‐hydroxybenzoyl)‐lup‐20(29)‐ene‐one ( 1 ) and 6β‐(3′‐methoxy‐4′‐hydroxybenzoyl)‐lup‐20(29)‐ene‐ol ( 2 ), together with three known compounds, friedelin ( 3 ), β‐sitosterol ( 4 ) and β‐sitosterol‐3‐d ‐glucoside ( 5 ). The methanol extract of the roots of P. pinnata caused a significant in‐vitro increase (94%) in 142BR cell line proliferation at 20 µg/ml compared with the control. Conclusions Compounds 1 and 2 , which were isolated from the active chloroform fraction, have not previously been reported and showed a dose‐dependent increase in proliferation of 142BR cells up to 3 µm ; compounds 3 , 4 and 5 had no effect on the 142BR cell line at the concentrations tested.     

A topographically and conformationally constrained,spin‐labeled, α‐amino acid: crystallographic characterization in peptides*

Abstract: 2,2,6,6‐Tetramethylpiperidine‐1‐oxyl‐4‐amino‐4‐carboxylic acid (TOAC) is a topographically and conformationally restricted, nitroxide containing, C^α‐tetrasubstituted α‐amino acid. Here, we describe the molecular and crystal structures, as determined by X‐ray diffraction analyses, of a TOAC terminally protected derivative, the cyclic dipeptide c(TOAC)₂·1,1,1,3,3,3‐hexafluoropropan‐2‐ol (HFIP) solvate, and five TOAC‐containing, terminally protected, linear peptides ranging in length from tetra‐ to hepta‐peptides. Incipient and fully developed, regular or distorted 3₁₀‐helical structures are formed by the linear peptides. A detailed discussion on the average geometry and preferred conformation for the TOAC piperidine ring is also reported. The X‐ray diffraction structure of an intramolecularly cyclized side product resulting from a C‐activated TOAC residue has also been determined.     

Third‐generation dihydropyridine‐type calcium channel blocker labedipinedilol‐B displays α/β‐adrenoceptor blocking activities

The pharmacological properties of labedipinedilol‐B {N‐[4‐[2‐hydroxy‐3‐(2‐methoxy‐1‐oxyethylaminobenzene) propoxy]‐benzyl]‐2,6‐dimethyl‐3,5‐dicarbomethoxy‐1,4‐dihydropyridine} were investigated in vivo and in vitro in comparison with labedipinedilol‐A. Intravenous labedipinedilol‐B (0.5, 1.0, and 3.0 mg kg^–1), produced dose‐dependent hypotensive and bradycardia responses in pentobarbital‐anesthetized Wistar rats. Pretreatment with labedipinedilol‐B (1.0 mg kg^–1, iv) also inhibited phenylephrine (10 μg kg^–1)‐induced hypertensive and (–)isoproterenol (0.5 μg kg^–1)‐induced tachycardia effects. In the isolated Wistar rat right and left atria and guinea pigs tracheal strips experiments, labedipinedilol‐B (10^–7, 10^–6, and 10^–5 M) competitively antagonized the (–)isoproterenol‐induced positive chronotropic and inotropic effects and tracheal relaxation responses in a concentration‐dependent manner. The parallel shift to the right of the concentration–response curve of (–)isoproterenol suggested that labedipinedilol‐B was a β₁/β₂‐adrenoceptor competitive antagonist. Labedipinedilol‐B (10^–7, 10^–6, and 10^–5 M) also prevented the rate‐increasing effects of increased extracellular Ca²⁺ (3.0–9.0 mM) in a concentration‐dependent manner. In the isolated rat aorta, labedipinedilol‐B (10^–7, 10^–6, and 10^–5 M) competitively antagonized the CaCl₂ and norepinephrine‐induced contractions with pKCa^–1 and pA₂ values of 8.02 ± 0.04 and 7.55 ± 0.05 in a concentration‐dependent manner. The parallel shift to the right of the concentration–response curves of norepinephrine suggested that labedipinedilol‐B was an α‐adrenoceptor competitive antagonist. Furthermore, labedipinedilol‐B, in an equal antagonist activity, inhibited norepinephrine‐induced phasic and tonic contraction. In the isolated rat aorta, labedipinedilol‐B also competitively antagonized CaCl₂‐induced contractions and made the parallel shift to the right of the concentration–response curve of CaCl₂. In cultured blood vessel smooth muscle cells (A7r5 cell lines), Bay K 8644‐induced intracellular calcium changes were decreased after application of labedipinedilol‐B, suggesting that the compound was a calcium channel blocker. The binding characteristics of labedipinedilol‐B were evaluated in [³H]CGP‐12177 binding to ventricle and lung and [³H]prazosin binding to brain membranes in rats. Labedipinedilol‐B also was evaluated in [³H]nitrendipine binding to brain membranes in rats. These results indicated that labedipinedilol‐B, similar to labedipinedilol‐A, has α‐adrenoceptor blocking, β‐adrenoceptor blocking, and calcium entry blocking activities in a single compound. We suggest that these two compounds represent a new generation of 1,4‐dihydropyridine‐type calcium channel blockers. Drug Dev. Res. 52:462–474, 2001. © 2001 Wiley‐Liss, Inc.     

β‐eudesmol suppresses allergic reactions via inhibiting mast cell degranulation

The regulatory effect of β‐eudesmol, which is an active constituent of Pyeongwee‐San (KMP6), is evaluated for allergic reactions induced by mast cell degranulation. Phorbol 12‐myristate 13‐acetate (PMA) plus calcium ionophore A23187‐stimulated human mast cell line, HMC‐1 cells, and compound 48/80‐stimulated rat peritoneal mast cells (RPMCs) are used as the in vitro models; mice models of systemic anaphylaxis, ear swelling, and IgE‐dependent passive cutaneous anaphylaxis (PCA) are used as the in vivo allergic models. The results demonstrate that β‐eudesmol suppressed the histamine and tryptase releases from the PMA plus calcium ionophore A23187‐stimulated HMC‐1 cells. β‐eudesmol inhibits the expression and activity of histidine decarboxylase in the activated HMC‐1 cells. In addition, β‐eudesmol inhibits the levels of histamine and tryptase released from the compound 48/80‐stimulated RPMCs. Furthermore, β‐eudesmol decreases the intracellular calcium level in the activated RPMCs. β‐eudesmol also decreases the compound 48/80‐induced mortality and ear swelling response. β‐eudesmol suppresses the serum levels of histamine, IgE, interleukin (IL)‐1β, IL‐4, IL‐5, IL‐6, IL‐13, and vascular endothelial growth factor (VEGF) under PCA mice as well as PCA reactions. Therefore, the results from this study indicate the potential of β‐eudesmol as an anti‐allergic drug with respect to its pharmacological properties against mast cell‐mediated allergic reactions.     

Design,Synthesis, and Antiviral Activity of Novel Ribonucleosides of 1,2,3‐Triazolylbenzyl‐aminophosphonates

A novel series of ribonucleosides of 1,2,3‐triazolylbenzyl‐aminophosphonates was synthesized through the Kabachnik–Fields reaction using I₂ as catalyst followed by copper‐catalyzed cycloaddition of the azide–alkyne reaction (CuAAC). All structures of the newly prepared compounds were characterized by ¹H NMR, ¹³C NMR, and HRMS spectra. The structures of 2e , 2f , 3d , and 3g were further confirmed by X‐ray diffraction analysis. These compounds were tested against various strains of DNA and RNA viruses; compounds 4b and 4c showed a modest inhibitory activity against respiratory syncytial virus (RSV) and compound 4h displayed modest inhibitory activity against Coxsackie virus B4.     

The synthetic cathinone psychostimulant α‐PPP antagonizes serotonin 5‐HT2A receptors: In vitro and in vivo evidence

Synthetic cathinones (SCs) are β‐keto analogs of amphetamines. Like amphetamines, SCs target monoamine transporters; however, unusual neuropsychiatric symptoms have been associated with abuse of some SCs, suggesting SCs might possess additional pharmacological properties. We performed radioligand competition binding assays to assess the affinities of nine SCs at human 5‐HT_2A receptors (5‐HT_2AR) and muscarinic M₁ receptors (M₁R) transiently expressed in HEK293 cells. None of the SCs exhibited affinity at M₁R (minimal displacement of [~K_d] [³H]scopolamine up to 10 μM). However, two SCs, α‐pyrrolidinopropiophenone (α‐PPP) and 4‐methyl‐α‐PPP, had low μM K_i values at 5‐HT_2AR. In 5‐HT_2AR–phosphoinositide hydrolysis assays, α‐PPP and 4‐methyl‐α‐PPP displayed inverse agonist activity. We further assessed the 5‐HT_2AR functional activity of α‐PPP, and observed it competitively antagonized 5‐HT_2AR signaling stimulated by the 5‐HT₂R agonist (±)‐2,5‐dimethoxy‐4‐iodoamphetamine (DOI; K_b = 851 nM). To assess in vivo 5‐HT_2AR activity, we examined the effects of α‐PPP on the DOI‐elicited head‐twitch response (HTR) in mice. α‐PPP dose‐dependently blocked the HTR with maximal suppression at 10 mg/kg (P < 0.0001), which is a moderate dose used in studies investigating psychostimulant properties of α‐PPP. To corroborate a 5‐HT_2AR mechanism, we also tested 3,4‐methylenedioxy‐α‐PPP (MDPPP) and 3‐bromomethcathinone (3‐BMC), SCs that we observed had 5‐HT_2AR K_is > 10 μM. Neither MDPPP nor 3‐BMC, at 10 mg/kg doses, attenuated the DOI HTR. Our results suggest α‐PPP has antagonist interactions at 5‐HT_2AR in vitro that may translate at physiologically‐relevant doses in vivo. Considering 5‐HT_2AR antagonism has been shown to mitigate effects of psychostimulants, this property may contribute to α‐PPPs unpopularity compared to other monoamine transporter inhibitors.     

Synthesis and Biological Evaluation of Novel 5,8‐Disubstituted‐2‐methyl‐2,3,4,5‐tetrahydro‐1H‐pyrido[4,3‐b] indoles as 5‐HT6 and H1 Receptors Antagonists

Synthesis, biological evaluation, and structure‐activity relationships (SAR) for a series of novel γ‐carboline analogues of Dimebon are described. Among the studied compounds, tetrahydro‐γ‐carboline 5b (2,8‐dimethyl‐5‐[cis‐2‐pyridin‐3‐ylvinyl]‐2,3,4,5‐tetrahydro‐carboline) has been identified as the most potent small molecule antagonist, in particular against histamine H₁ and serotonin 5‐HT₆ receptors (IC₅₀ < 0.45 μM and IC₅₀ = 0.73 μM, respectively). A thorough comparative SAR study performed for the tested compounds has revealed significant correlations between the nature of side substituents and the related antagonistic activity.