Synthesis and preliminary evaluation of pharmacological properties of some piperazine derivatives of xanthone

The Subtype Selectivity in Search of Potent Hypotensive Agents among 5,5-Dimethylhydantoin Derived α1-Adrenoceptors Antagonists

In order to find new hypotensive drugs possessing higher activity and better selectivity, a new series of fifteen 5,5-dimethylhydantoin derivatives (1-15) was designed. Three-step syntheses, consisting of N-alkylations using standard procedures as well as microwaves, were carried out. Crystal structures were determined for compounds 7-9. All of the synthesized 5,5-dimethylhydantoins were tested for their affinity to α1-adrenergic receptors (α1-AR) using both in vitro and in silico methods. Most of them displayed higher affinity (Ki < 127.9 nM) to α1-adrenoceptor than urapidil in radioligand binding assay. Docking to two subtypes of adrenergic receptors, α1A and α1B, was conducted. Selected compounds were tested for their activity towards two α1-AR subtypes. All of them showed intrinsic antagonistic activity. Moreover, for two compounds (1 and 5), which possess o-methoxyphenylpiperazine fragments, strong activity (IC50 < 100 nM) was observed. Some representatives (3 and 5), which contain alkyl linker, proved selectivity towards α1A-AR, while two compounds with 2-hydroxypropyl linker (11 and 13) to α1B-AR. Finally, hypotensive activity was examined in rats. The most active compound (5) proved not only a lower effective dose than urapidil but also a stronger effect than prazosin.

Self-assembly of new cobalt complexes based on [Co (SCN)4], synthesis, empirical, antioxidant activity, and quantum theory investigations

The cobalt (II) complexes have been synthesized from the reaction of the cationic entities (3,4-dimethylaniline (1) and histamine (2)) with metallic salt CoCl2⋅6H2O and thiocyanate ion (SCN-) as a ligand in H2O/ethanolic solution and processing by the evaporation crystal growth method at room temperature to get crystals. The synthesized complex has been fully characterized by single-crystal X-ray diffraction. UV-Visible, FTIR spectroscopy, TGA analysis, and DFT circulations were also performed. The crystal structural analysis reveals that the solid (1) {[Co(SCN)4] (C8H12N)3}·Cl crystallizes in the monoclinic system with the space group P21/n and the solid (2) {[Co(SCN)4](C5H11N3)2}·2Cl crystallizes in the monoclinic space group P21/m. Metal cations are joined into corrugated chains parallel to the b-axis direction in (1) and (2) by four thiocyanate anions. The crystal structures of (1) and (2) were calculated using XRPD data, indicating that they are closely connected to the DRX mono-crystal results. Different interactions pack the system into a ring formed by N-H⋯Cl and N-H⋯S hydrogen bonds. C-H⋯π and the π⋯π stacking of anilinuim ring for (1) and N-H⋯S intermolecular interactions for (1) and (2) increase the crystals' robustness. Hirshfeld surface analysis cum 2D fingerprint plots visualize the main intermolecular interactions with their contributions in the solid-state phase. The molecular geometries of both complexes obtained from the crystal structure were used for quantum chemical calculation. Here, frontier orbital analysis and electrostatic potential illustrate the chemical reactivities of metal-organic complexes. QTAIM and NCI analysis reveal the strength of interactions at the electronic level.

Piperazine skeleton in the structural modification of natural products: a review

Piperazine moiety is a cyclic molecule containing two nitrogen atoms in positions 1 and 4, as well as four carbon atoms. Piperazine is one of the most sought heterocyclics for the development of new drug candidates with a wide range of applications. Over 100 molecules with a broad range of bioactivities, including antitumor, antibacterial, anti-inflammatory, antioxidant, and other activities, were reviewed. This article reviewed investigations regarding piperazine groups for the modification of natural product derivatives in the last decade, highlighting parameters that affect their biological activity.

The antidepressant-like activity of chiral xanthone derivatives may be mediated by 5-HT1A receptor and β-arrestin signalling

BACKGROUND

Our previous studies showed that xanthone derivatives with N-(2-methoxyphenyl)piperazine fragment have an affinity to the 5-HT1A receptor and show antidepressant-like properties in rodents. In this study, we tested three xanthone derivatives, HBK-1 (R, S) and its enantiomers, in which we increased the distance between the piperazine and xanthone fragments by using a hydroxypropoxy linker. We hypothesized that this would increase the binding to the 5-HT1A receptor and consequently, pharmacological activity.

AIMS

We aimed to assess the in vitro and in vivo pharmacological activity of the xanthone derivatives.

METHODS

We evaluated the in vitro affinity for serotonin 5-HT1A and 5-HT2A receptors and serotonin transporter. We also determined the intrinsic activity at the 5-HT1A receptor. We investigated the antidepressant-like properties and safety after acute administration (dose range: 1.25-20 mg/kg) using the forced swim, tail suspension, locomotor activity, rotarod and chimney tests in mice. We also evaluated the basic pharmacokinetic parameters.

RESULTS

Our results indicated that the compounds showed a high affinity for the 5-HT1A receptor but very weak antagonistic properties in the Ca²⁺ mobilization assay; however, they showed significant agonistic properties in the β-arrestin recruitment assay. In both behavioural tests the studied xanthone derivatives showed antidepressant-like activity. Pre-treatment with p-chlorophenylalanine or WAY-100635 abolished their antidepressant-like activity. None of the compounds caused motor impairments at antidepressant-like doses. The racemate penetrated the blood-brain barrier and had a relatively high bioavailability after intraperitoneal administration.

CONCLUSIONS

Xanthone derivatives with N-(2-methoxyphenyl)piperazine fragment and hydroxypropoxy linker show increased binding to the 5-HT1A receptor and may represent an attractive putative treatment candidate for depression.

Crystal structure of 1-(3-chlorophenyl)-4-(4-(((2,3-dihydro-1H-inden-5-yl)oxy)methyl)phenethyl)piperazine, C28H31ClN2O

C28H31ClN2O, monoclinic, P1̄ (no. 2), a = 21.9309(11) Å, b = 9.9648(5) Å, c = 11.0049(7) Å, β = 93.403(6)°, V = 2400.7(2) Å3, Z = 4, R gt(F) = 0.0566, wR ref(F 2) = 0.1355, T = 293 K.

Synthesis and pharmacological evaluation of naftopidil-based arylpiperazine derivatives containing the bromophenol moiety

BACKGROUND

Prostate cancer (PCa) is the most common malignancy in men and in the absence of any effective treatments available.

METHODS

For the development of potential anticancer agents, 24 kinds of naftopidil-based arylpiperazine derivatives containing the bromophenol moiety were synthesized and characterized by using spectroscopic methods. Their pharmacological activities were evaluated against human PCa cell lines (PC-3 and LNCaP) and a₁-adrenergic receptors (a₁-ARs; α_1a, α_1b, and α_1d-ARs). The structure-activity relationship of these designed arylpiperazine derivatives was rationally explored and discussed.

RESULTS

Among these derivatives, 3c, 3d, 3h, 3k, 3o, and 3s exhibited the most potent activity against the tested cancer cells, and some derivatives with potent anticancer activities exhibited better a₁-AR subtype selectivity than others did (selectivity ratio > 10).

CONCLUSION

This work provided a potential lead compound for the further development of anticancer agents for PCa therapy.

Recent advances in the synthesis of xanthones and azaxanthones

A useful chemical toolbox for (aza)xanthones from 2012 to 2020 that covers the optimization of known procedures and novel methodologies.

In silico studies of piperazine derivatives as potent anti-proliferative agents against PC-3 prostate cancer cell lines

Quantitative Structure Activity Relationship studies were carried out on arylpiperazine derivatives to investigate their anti-proliferate activity against prostate PC-3 cancer cell lines. The built model with statistical parameters; R2 = 0.8483, R2 adj = 0.8078, Q2 cv = 0.7122 and external validation (R2 test) 0.6682 revealed that the anti-proliferate activities were strongly dependent on the descriptors: MATS7c, MATS3e, maxwHBa and WPSA-3. The Variance Inflation Factor of the descriptors were all greater than one but less than two and all descriptors were poorly correlated (r < 0.4). A graph of the experimental activities and predicted activities showed a high correlation and a William's plot showed the presence of only one outlier compound. These results are similar to those reported for stable and robust models with high predicting power. Molecular docking studies of compounds 5 (1-phenyl-4-(4-(2-(p-tolyloxy)ethyl)benzyl)piperazine) and 17 (4-(4-((4-phenylpiperazin-1-yl)methyl)phenethoxy)benzonitrile) with the androgen receptor gave binding affinities of -7.5 and -7.1 kcal/mol respectively. Compound 5 formed a more stable complex having hydrogen, electrostatic and hydrophobic bond interactions while compound 17 had hydrogen and hydrophobic bond interactions only. This study provides a roadmap to the design of more potent anti-prostate cancer compounds.

Crystal structure of 2-(3-(2-(4-phenylpiperazin-1-yl)ethyl)benzyl)isoindoline-1,3-dione, C27H27N3O2

C27H27N3O2, triclinic, P1̄ (no. 2), a = 6.9263(4) Å, b = 10.0832(7) Å, c = 17.3531(10) Å, α = 75.708(5)°, β = 87.142(5)°, γ = 74.935(6)°, V = 1133.92(13) Å3, Z = 2, Rgt(F) = 0.0605, wRref(F2) = 0.1661, T = 290(1) K.

Design, synthesis and evaluation of activity and pharmacokinetic profile of new derivatives of xanthone and piperazine in the central nervous system

Searching for CNS active cyclic amines derivatives containing heterocyclic xanthone core we designed and synthesized a set of fourteen novel 2- or 4-methylxanthone substituted by alkyl- or aryl-piperazine moieties. The compounds were evaluated in vivo for their potential antidepressant-like activity (in the forced swim test) and anxiolytic-like activity (four-plate test) and their inhibitory effect against rat 5-HT₂ receptor was checked. The pharmacokinetic analysis of active compounds done by a non-compartmental approach have shown a rapid absorption of all studied molecules from intraperitoneal cavity and good penetration the blood-brain barrier after i.p. administration with brain to plasma ratios varied from 2.8 to 31.6. Genotoxicity and biotransformation of active compounds were studied. Compound 19 interactions with major classes of GPCRs, uptake systems and ion channels were tested and results indicated that it binds to 5-HT_2A, 5-HT_2B receptors and sodium channels.

Synthesis, biological evaluation and molecular docking of 4-Amino-2H-benzo[h]chromen-2-one (ABO) analogs containing the piperazine moiety

Prostate cancer (PCa) is a major cause of cancer-related male death in worldwide. To develop of potential anti-prostate cancer agents, 22 kinds of 4-Amino-2H-benzo[h]chromen-2-one analogs were designed and synthesized as potent androgen receptor (AR) antagonist through rational drug modification leading to the discovery of a series of novel antiproliferative compounds. Analogs (3, 4, 5, 7, 8, 10, 11, 12, 16, 18, 21, 23, and 24) exhibited potent antagonistic potency against AR (inhibition >50%), and exhibited potent AR binding affinities as well as displayed the higher activities than finasteride toward LNCaP cells (AR-rich) versus PC-3 cells (AR-deficient). Moreover, the docking study suggested that the most potent antagonist 23 mainly bind to AR ligand binding pocket (LBP) site through Van der Waals' force interactions. The structure-activity relationship (SAR) of these designed 4-Amino-2H-benzo[h]chromen-2-one analogs was rationally explored and discussed. Collectively, this work provides a potential lead compound for anticancer agent development related to prostate cancer therapy, and took a step forward towards the development of novel and improved AR antagonists.

Synthetic Chiral Derivatives of Xanthones: Biological Activities and Enantioselectivity Studies

Many naturally occurring xanthones are chiral and present a wide range of biological and pharmacological activities. Some of them have been exhaustively studied and subsequently, obtained by synthesis. In order to obtain libraries of compounds for structure activity relationship (SAR) studies as well as to improve the biological activity, new bioactive analogues and derivatives inspired in natural prototypes were synthetized. Bioactive natural xanthones compromise a large structural multiplicity of compounds, including a diversity of chiral derivatives. Thus, recently an exponential interest in synthetic chiral derivatives of xanthones (CDXs) has been witnessed. The synthetic methodologies can afford structures that otherwise could not be reached within the natural products for biological activity and SAR studies. Another reason that justifies this trend is that both enantiomers can be obtained by using appropriate synthetic pathways, allowing the possibility to perform enantioselectivity studies. In this work, a literature review of synthetic CDXs is presented. The structures, the approaches used for their synthesis and the biological activities are described, emphasizing the enantioselectivity studies.

Chiral Derivatives of Xanthones with Antimicrobial Activity

According to the World Health Organization, the exacerbated use of antibiotics worldwide is increasing multi-resistant infections, especially in the last decade. Xanthones are a class of compounds receiving great interest in drug discovery and development that can be found as natural products or obtained by synthesis. Many derivatives of xanthones are chiral and associated with relevant biological activities, including antimicrobial. The aim of this review is to compile information about chiral derivatives of xanthones from natural sources and their synthesized examples with antimicrobial activity.

Synthesis and biological evaluation of estrone 3-O-ether derivatives containing the piperazine moiety

A series of new estrone derivatives were designed and synthesized, and their structures were confirmed by spectroscopic methods. All new estrone derivatives were investigated for their in vitro cytotoxic efficacies against a panel of three human prostate cancer cell lines (PC-3, LNCaP, and DU145). The derivatives 6, 7, 10, 15, 16, 20, 21, 22, 24 and 26 showed important cytotoxic actions against individual carcinoma cell line collections. Moreover, antagonistic activities of compounds (7, 15, 16 and 21) towards a₁-ARs (α_1A, α_1B, and α_1D) were further evaluated using dual-luciferase reporter assays, and the compounds 16 and 21 exhibited better a₁-ARs subtype selectivity. The structure-activity relationship (SAR) suggested that the substitute's type and position on the phenyl group leads to the interesting variations within pharmacological effects of resultant molecular systems.

Design, synthesis and cardiovascular evaluation of some aminoisopropanoloxy derivatives of xanthone

A series of aminoisopropanoloxy derivatives of xanthone has been synthesized and their pharmacological properties regarding the cardiovascular system has been evaluated. Radioligand binding and functional studies in isolated organs revealed that title compounds present high affinity and antagonistic potency for α₁-(compound 2 and 8), β-(compounds 1, 3, 4, 7), α₁/β-(compounds 5 and 6) adrenoceptors. Furthermore, compound 7, the structural analogue of verapamil, possesses calcium entry blocking activity. The title compounds showed hypotensive and antiarrhythmic properties due to their adrenoceptor blocking effect. Moreover, they did not affect QRS and QT intervals, and they did not have proarrhythmic potential at tested doses. In addition they exerted anti-aggregation effect. The results of this study suggest that new compounds with multidirectional activity in cardiovascular system might be found in the group of xanthone derivatives.

Crystal structure of 1-(4-((benzo[d][1,3]dioxol-5-yloxy)methyl)phenethyl)-4-(3-chlorophenyl) piperazin-1-ium chloride, C26H28Cl2N2O3

C26H28Cl2N2O3, monoclinic, P21/c (no. 14), a = 13.422(3) Å, b = 7.0011(14) Å, c = 26.249(5) Å, β = 101.06(3)°, V = 2420.8(9) Å3, Z = 4, R gt(F) = 0.0516, wR ref(F 2) = 0.1370, T = 296 K.

Chiral Derivatives of Xanthones: Investigation of the Effect of Enantioselectivity on Inhibition of Cyclooxygenases (COX-1 and COX-2) and Binding Interaction with Human Serum Albumin

Searching of new enantiomerically pure chiral derivatives of xanthones (CDXs) with potential pharmacological properties, particularly those with anti-inflammatory activity, has remained an area of interest of our group. Herein, we describe in silico studies and in vitro inhibitory assays of cyclooxygenases (COX-1 and COX-2) for different enantiomeric pairs of CDXs. The evaluation of the inhibitory activities was performed by using the COX Inhibitor Screening Assay Kit. Docking simulations between the small molecules (CDXs; known ligands and decoys) and the enzyme targets were undertaken with AutoDock Vina embedded in PyRx—Virtual Screening Tool software. All the CDXs evaluated exhibited COX-1 and COX-2 inhibition potential as predicted. Considering that the (S)-(−)-enantiomer of the nonsteroidal anti-inflammatory drug ketoprofen preferentially binds to albumin, resulting in lower free plasma concentration than (R)-(+)-enantiomer, protein binding affinity for CDXs was also evaluated by spectrofluorimetry as well as in in silico. For some CDXs enantioselectivity was observed.

The antidepressant- and anxiolytic-like activities of new xanthone derivative with piperazine moiety in behavioral tests in mice

Objectives:

Xanthones are flavonoids with numerous activities, including antioxidant, antidepressant., or anxiolytic-like. Therefore, the aim of our study was to determine antidepressant- and anxiolytic-like properties of four xanthone derivatives (3-chloro-5-[(4-methylpiperazin-1-yl)methyl]-9H-xanthen-9-one dihydrochloride [HBK-5], 6-methoxy-2-[(4-methylpiperazin-1-yl) methyl]-9H-xanthen-9-one dihydrochloride, 2-[(4-benzylpiperazin-1-yl) methyl]-6-methoxy-9H-xanthen-9-one dihydrochloride, 2-{[4-(2-methoxyphenyl) piperazin-1-yl] methyl}-9H-xanthen-9-one hydrochloride), as well as the influence on cognitive and motor function of active compounds, using animal models.

Materials and Methods:

To determine the antidepressant-like activity, we used forced swim test (FST) and tail suspension test (TST) in mice. We evaluated anxiolytic-like properties in the four-plate test in mice. We studied the influence on cognitive and motor function in passive avoidance step-through and chimney tests, respectively.

Results:

The antidepressant-like activity (in both FST and TST) showed only HBK-5. Moreover, the compound was also active in the four-plate test, which suggests that it possessed anxiolytic-like properties. HBK-5 did not cause any cognitive and motor deficits in mice at antidepressant- and anxiolytic-like doses.

Conclusions:

HBK-5 may have potential in the treatment of depression or anxiety disorders, but this issue needs further studies.

Cardiovascular activity of the chiral xanthone derivatives

A series of 6 derivatives of xanthone were synthesized and evaluated for cardiovascular activity. The following pharmacological experiments were conducted: the binding affinity for adrenoceptors, the influence on the normal electrocardiogram, the effect on the arterial blood pressure, the effect on blood pressor response and prophylactic antiarrhythmic activity in adrenaline induced model of arrhythmia (rats, iv). Two compounds revealed nanomolar affinity for α1-adrenoceptor which was correlated with the strongest cardiovascular (antiarrhythmic and hypotensive) activity in animals' models. They were enantiomers of previously described (R,S)-4-(2-hydroxy-3-(4-(2-methoxyphenyl)piperazin-1-yl)propoxy)-9H-xanthen-9-one hydrochloride and revealed similar antiarrhythmic potential in adrenaline induced model of arrhythmia in rats after intravenous injection (ED50=0.53 mg/kg and 0.81 mg/kg, respectively). These values were lower than values obtained for reference drug urapidil. These compounds were more active in this experiment than urapidil (ED50=1.26 mg/kg). The compound 5 administered iv at doses of 0.62-2.5 mg/kg at the peak of arrhythmia prevented and/or reduced the number of premature ventricular beats in a statistically significant manner. The ED50 value was 1.20 mg/kg. The S-enantiomer (6) given at the same doses did not show therapeutic antiarrhythmic activity in this model. These compounds significantly decreased the systolic and diastolic blood pressure throughout the whole observation period in anesthetized, normotensive rats. The studied enantiomers showed higher toxicity than urapidil, but imperceptibly higher that another cardiovascular drugs, that is, carvedilol or propranolol. They were also evaluated for mutagenic potential in the Ames (Salmonella) test. It was found that at the concentrations tested the compounds were non mutagenic when compared to solvent control. Results were quite promising and suggested that in the group of xanthone derivatives new potential antiarrhythmics and hypotensives might be found.

Biofunctional studies of new 2-methoxyphenylpiperazine xanthone derivatives with α₁-adrenolytic properties

BACKGROUND

The aim of this study was to assess the selectivity of the studied xanthone derivatives for α1-adrenoceptor subtypes (α1A, α1B, α1D, α1L) in functional experiments in order to verify if they possess any selectivity for a distinct subtype of α1-adrenoceptor. Moreover, several pharmacological tests were carried out to assess whether they reveal other than α1-adrenoceptor blocking properties such as: antagonistic for 5-HT2 receptors, vasorelaxant or spasmolytic.

METHODS

The influence on α1A-adrenoceptors was examined in biofunctional studies employing isolated rat vas deferens, on α1B-adrenoceptors in guinea-pig spleen, on α1D-adrenoceptors in rat aorta, and on α1L-adrenoceptors in rabbit spleen. Affinity for 5-HT2 receptors was measured in radioligand binding assay, whereas antagonistic potency for 5-HT2 receptors was studied on isolated rat aorta. Vasorelaxant effect of tested compounds was assessed in functional study employing rat aorta, whereas direct spasmolytic activity was investigated using the isolated rabbit small intestine.

RESULTS

The present study provides evidences that the tested 2-methoxyphenylpiperazine xanthone derivatives are non-selective α1-adrenoceptor blockers. However, at higher concentrations the direct spasmolytic effect could enhance their hypotensive activity. The obtained results indicate that the studied xanthones possessed weak calcium entry blocking activity, as well as antagonistic properties for 5-HT2A receptors.

CONCLUSIONS

The results of the present study support the idea that the hypotensive activity of the studied compounds is related to their α1-adrenolytic properties.

Synthesis and cytotoxic activity evaluation of novel arylpiperazine derivatives on human prostate cancer cell lines

A series of novel arylpiperazine derivatives was synthesized. The in vitro cytotoxic activities of all synthesized compounds against three human prostate cancer cell lines (PC-3, LNCaP, and DU145) were evaluated by a CCK-8 assay. Compounds 9 and 15 exhibited strong cytotoxic activities against LNCaP cells (IC₅₀ < 5 μM), and compound 8 (IC₅₀ = 8.25 μM) possessed the most potent activity against DU145 cells. However, these compounds also exhibited cytotoxicity towards human epithelial prostate normal cells RWPE-1. The structure–activity relationship (SAR) of these arylpiperazine derivatives was also discussed based on the obtained experimental data.

Preliminary assessment of mutagenic and anti-mutagenic potential of some aminoalkanolic derivatives of xanthone by use of the Vibrio harveyi assay

The Vibrio harveyi assay was used to evaluate mutagenic and anti-mutagenic effects of four new aminoalkanolic derivatives of xanthone with anticonvulsant activity, to select the potentially safe compounds for further in vivo studies in animal models. The study showed that at a concentration of 40 ng/ml the test compounds were not mutagenic. Additionally, two of the investigated compounds, namely the (R,S)-N-methyl-1-amino-2-propanol derivative of 6-methoxyxanthone (compound III) and the (R)-N-methyl-2-amino-1-butanol derivative of 7-chloroxanthone (compound IV) were strong inhibitors of the mutagenicity induced by 4-nitroquinoline-N-oxide (4-NQO) in V. harveyi strains BB7M and BB7XM. The inhibition percentages for compound IV were 49 (in BB7M) and 69 (in BB7XM), whereas for compound III these percentages were 47 (in BB7M) and 42 (in BB7XM), respectively. The present study demonstrates that four bioactive derivatives of xanthone display no mutagenic activity in the V. harveyi assay. In addition, compounds III and IV demonstrated considerable anti-mutagenic activity in this test. Based on the results obtained here, these compounds could be selected for further studies in animal models, while compounds III and IV should be tested further for their anti-mutagenic properties.