Piperidine Ring Research Articles

Synthesis and biological evaluation of conformationally restricted GluN2B ligands derived from eliprodil

N-Methyl-d-aspartate (NMDA) receptors containing one or two GluN2B subunits play a crucial role in a variety of neurodegenerative diseases, such as Alzheimer's and Huntington's disease. In order to increase selectivity for GluN2B NMDA receptors, the piperidine ring of eliprodil (2) was conformationally restricted by introduction of an ethano bridge across C-2 and C-6 resulting in a tropane scaffold. Benzylidenetropanes 15 and 16 and benzyltropanes 17 and 18 were prepared by nucleophilic opening of enantiomerically pure phenyloxiranes 13 and 14 with racemic secondary amines (Z/E)-11 and diastereomeric mixtures (r/s)-12. The diastereomers were separated by preparative HPLC to obtain enantiomerically pure test compounds 15–18. The absolute and relative configuration of the products were determined by X-ray crystal structure analysis. Benzylidenetropanes 15 and 16 as well as benzyltropanes 17 and 18 display very high GluN2B affinity in receptor binding studies. Benzylidinetropanes with the phenyl moiety oriented towards C-5 of the tropane system showed higher GluN2B affinity than their analogs with the phenyl moiety oriented towards C-1. In benzyltropanes endo-configured stereoisomers exhibit higher GluN2B affinity than exo-configured diastereomers. Unfortunately, tropanes 15–18 show also high σ1 and σ2 affinity with the same trends for the stereoisomers as for GluN2B affinity. The high-affinity GluN2B ligand (R,r)-17b was able to inhibit the ion flux in two-electrode voltage clamp experiments using GluN1a/GluN2B expressing oocytes.

Chiral Bicyclic Imidazole-Catalyzed Direct Enantioselective C -Acetylation of Indolones

Chiral Bicyclic Imidazole-Catalyzed Direct Enantioselective <i>C</i> -Acetylation of Indolones

New Prospective Phosphodiesterase Inhibitors: Phosphorylated Oxazole Derivatives in Treatment of Hypertension.

Purpose: One of the promising chemical groups for the development of new antihypertensive medicines, the action of which is associated with the inhibition of phosphodiesterase III (PDE3) activity, are phosphorylated oxazole derivatives (OVPs). This study aimed to prove experimentally the presence of the OVPs antihypertensive effect associated with decreasing of PDE activity and to justify its molecular mechanism. Methods: An experimental study of the effect of OVPs on phosphodiesterase activity was performed on Wistar rats. Determination of PDE activity was performed by fluorimetric method using umbelliferon in blood serum and organs. The docking method was used to investigate the potential molecular mechanisms of the antihypertensive action of OVPs with PDE3. Results: The introduction of OVP-1 50 mg/kg, as a leader compound, led to the restoration of PDE activity in the aorta, heart and serum of rats with hypertension to the values observed in the intact group. This may indicate the possibility of the development of vasodilating action of OVPs by the influence of the latter on the increase in cGMP synthesis due to inhibition of PDE activity. The calculated results of molecular docking of ligands OVPs to the active site of PDE3 showed that all test compounds have a common type of complexation due to phosphonate groups, piperidine rings, side and terminal phenyl and methylphenyl groups. Conclusion: The analysis of the obtained results both in vivo and in silico showed that phosphorylated oxazole derivatives represent a new platform for further studies as phosphodiesterase III inhibitors with antihypertensive activity.

Novel 7-Aryliden-3,3a,4,5,6,7-(hexahydro-5-(2-ethoxyethyl)-2-phenyl-3-aryl-2H-pyrazolo[4,3-c]pyridine Hydrochloride: Synthesis and Structure

A Claisen-Schmidt type reaction of 1-(2-ethoxyethyl)piperidin-4-one with differ¬ent aromatic aldehydes led to corresponding dienones with a yield of 65‒71%. 7-Arylidene-3,3a,4,5,6,7-(hexahydro-5-(2-ethoxyethyl)-2-phenyl-3-aryl-2H-pyrazolo[4,3-c]pyridines were synthesized by heterocyclization of 3,5-dia¬rylidene-piperidin-4-ones with phenylhydrazine hydrochloride in methanol at 70 °C over 4‒6 h. The X-ray crystal structure determination of 7-(p-methoxy¬benzyliden)-3,3a,4,5,6,7-(hexahydro-5-(2-ethoxyethyl)-2-phenyl-3-(p-methoxy¬phenyl)-2H-pyrazolo[4,3-c]pyridine hydrochloride (the deposition number is CCDC 862410) was completed. The piperidine and pyrazoline rings are close to a chair and envelope conformations, respectively.

Stereoselective Synthesis and Applications of Pinane-Based Chiral 1,4-Amino Alcohol Derivatives

AbstractA new library of pinane-based 1,4-amino alcohols was synthesised and utilised as chiral ligands in enantioselective diethylzinc addition to benzaldehyde. Aldol condensation of (+)-nopinone, derived from (–)-β-pinene, with 2-pyridinecarboxaldehyde gave the key intermediate α,β-unsaturated ketone, which was transformed in diastereoselective reduction, followed by hydrogenation, resulting in 1,4-amino alcohols. On the other hand, epoxidation of the α,β-unsaturated ketone, followed by reduction and then hydrogenation of the pyridine ring, afforded a mixture of 4-amino-2,3-epoxy-1-ols. Stereoselective hydride reduction of the epoxy ketone and subsequent condensation of the resulting products with substituted benzyl bromides provided quaternary ammonium salts, which were subjected to hydride reduction and then hydrogenation, affording 4-amino-2,3-epoxy-1-ol derivatives containing an N-benzylpiperidine moiety. The inhibition of nucleophile-initiated opening of the oxirane ring was interpreted by a systematic series­ of comparative Hartree–Fock modelling study using the 6-31+G(d,p) basis set. The antiproliferative activities of 4-amino-2,3-epoxy­-1-ol derivatives were examined, and structure–activity relationships were studied from the aspects of the stereochemistry of the oxirane ring, saturation, and substituent effects on the piperidine ring system.

Synthesis, crystal structure, computational, and molecular docking studies of bis {1,1'-[1,3,5-Trimethyl-1,3-phenylenebis(methylene)]di-1H-piperidinium}tetrabromide tri hydrate

Recently synthesized crystal of Bis {1,1'-[1,3,5-Trimethyl-1,3-phenylenebis(methylene)]di-1H-piperidinium}tetrabromide trihydrate (PD1Br) crystallizes in the monoclinic space group P21/c. The piperidine ring as a whole adopted chair conformation. Hirshfeld surface technique is useful for determining molecular nature and visualizing intermolecular relations in crystal structures. The molecular configuration, frontier theory of orbitals, and thermodynamic character of the label molecule were examined via density functional theory (DFT) computations make use of the B3LYP method with the 6-311++G (d,p) basis set. On the report of molecular docking investigation, the chemical binds efficiently to protein, resulting in a significant anticancer property.

Enhanced Dehydrogenative H2 Release from N-Containing Amphicyclic LOHC Boosted by Pd-Supported Nanosheet MFI Zeolites Having Strong Acidity and Large Mesoporosity

The amount and rate of H2 discharge from 2-[(n-methylcyclohexyl)methyl]piperidine (H12-MBP), an amphicyclic liquid organic hydrogen carrier (LOHC) having two cycle moieties (cyclohexane and piperidine) with different reactivities, are determined by dehydrogenation of a cyclohexane ring with less reactivity. To realize high H2 yields with rapid kinetics, the cyclohexane ring in the partially dehydrogenated 2-[n-methylcyclohexyl]methyl)pyridine (H6-MBP) that is generated as the intermediate species should be fully dehydrogenated to 2-(n-methylbenzyl)pyridine (H0-MBP). This is approached using Pd-supported nanosheet zeolites having mesoporous structures bearing high concentrations of strongly acidic sites on external surfaces, which can not only enhance the diffusion of bulky H12-MBP but also strongly bind the basic piperidine ring in H12-MBP and H6-MBP. The H2 yields and rate constants are correlated with the acidity, mesoporosity, and adsorption behaviors of the LOHCs. As these factors are strengthened, H2 yield and rate constants increased dramatically within the ranges of 16.0–64.7% and 0.0001–0.0013 min–1, respectively. The results prove that mesoporous zeolites can be used for constructing supported Pd catalysts achieving high H2 yields with rapid kinetics from N-containing amphicyclic LOHCs.

Absorption, metabolism, and excretion of [14C]YY-20394, a highly selective PI3K-Delta inhibitor in humans

YY-20394, a highly selective PI3Kδ inhibitor, is under NDA submission for treating follicular lymphoma in China. The absorption, metabolism, and excretion of YY-20394 were evaluated in healthy Chinese male subjects following a single oral dose of 80 mg [14C]YY-20394 (100 µCi). Within 264 h post-dose, 92.1% of the administered dose was recovered, with 58.1% from urine and 34.0% from faeces. YY-20394 was rapidly absorbed in humans, and the peak plasma concentrations occurred at 1.0 h. The absorbed drug fraction was at least 58.1% according to urine recovery. In addition to the parent drug, nine metabolites were identified in plasma, urine, and faeces. Unchanged YY-20394 was the predominant drug-related component in plasma (accounting for 68.4% of the total radioactivity), urine (accounting for 90.0% of the urinary radioactivity) and faeces (accounting for 41.7% of the faecal radioactivity). In humans, the major metabolic sites were the morphine ring and side chains of piperidine rings. The major metabolic pathways involved N-dealkylation, O-dealkylation, glucuronidation and acetylation. Overall, renal elimination played a significant role in the disposition of YY-20394, and the morphine ring and the side chain of the piperidine ring was the predominant metabolic sites.

Thiazole inhibitors of α-glucosidase: Positional isomerism modulates selectivity, enzyme binding and potency of inhibition

Isomerism plays a key role in determining potency, selectivity and type of inhibition exhibited by enzyme inhibitors. We present 20 new benzylidene-hydrazinyl-thiazole inhibitors of α-glucosidase featuring positional isomerism of the methyl group at 3 and 4 positions of their piperidine ring. This structural property helped understand their potency and selectivity to the enzyme yielding new clues to α-glucosidase inhibition. The isomerism was pivotal to improving or deteriorating enzyme binding and potency of inhibition shown by the target compounds. Data from enzyme kinetics experiments were in agreement with docking and molecular dynamics simulations revealing a direct influence of isomerism on enzyme-inhibitor molecular interactions. Generally, the 4-methyl derivatives showed more selectivity toward the enzyme since they established more and stronger molecular contacts with the enzyme than their 3-methyl counterparts. However, the isomerism did not significantly affect the type of inhibition since majority of the compounds exhibited noncompetitive enzyme inhibition except for one. Our work provides essential and interesting clues to understanding α-glucosidase inhibition by thiazole isomers that would help explore new avenues to designing and developing better α-glucosidase inhibitors as antidiabetic drugs.

Hexafluoroisopropyl Carbamates as Selective MAGL and Dual MAGL/FAAH Inhibitors: Biochemical and Physicochemical Properties.

A series of hexafluoroisopropyl carbamates with indolylalkyl‐ and azaindolylalkyl‐substituents at the carbamate nitrogen was synthesized and evaluated for inhibition of the endocannabinoid degrading enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL). The synthesized derivatives with butyl to heptyl spacers between the heteroaryl and the carbamate moiety were inhibitors of both enzymes. For investigated compounds in which the alkyl chain was partially incorporated into a piperidine ring, different results were obtained. Compounds with a methylene spacer between the piperidine ring and the heteroaromatic system were found to be selective MAGL inhibitors, while an extension of the alkyl spacer to two to four atoms resulted in dual inhibition of FAAH/MAGL. The only small change in enzyme inhibitory activity with variation of the heteroaromatic system indicates that the reactive hexafluoroisopropyl carbamate group is mainly responsible for the strength of the inhibitory effect of the compounds. Selected derivatives were also tested for hydrolytic stability in aqueous solution, liver homogenate and blood plasma as well as for aqueous solubility and for permeability in a Caco‐2 cell model. Some compounds showed a slightly higher MAGL inhibitory effect than the known selective MAGL inhibitor ABX‐1431 and also partly surpassed this substance with regard to certain physicochemical and biochemical properties such as water solubility and cell permeability.

Structure simplification of the Securinine skeleton reveals the importance of BCD ring system for the cytotoxic activity on HCT116 and HL60 cell lines

Function-oriented molecular editing of the polycyclic scaffold of securinine led to the preparation of a library of simplified analogs that have been evaluated for their cytotoxicity potential against HCT116 and HL60 human cell lines. Chemical diversity at the C14 position (securinine numbering) was generated through the site-selective γ-iodination followed by Pd-catalyzed Sonogashira and Suzuki-Miyaura reactions. To explain the selectivity in the iodination step, a reaction mechanism has been proposed. Surprisingly, the piperidine ring (ring A) of the securinine skeleton has been found to be irrelevant for the cytotoxic activity. Based on this finding, the pharmacophoric core of securinine could be simplified to the key BCD motif. The nature of the substituent at the nitrogen can vary from a methyl or an isobutyl group to a benzyl or a carbamate moiety. Interestingly, the N-benzyl substituted simplified analog exhibited the same cytotoxic activity as the parent compound securinine. This functional group tolerance paves the way for the installation of reactive handles for the synthesis of molecular probes for target identification.

Syntheses, crystal structures, antibacterial activities and non-linear optical properties based on DFT calculation of two substituted benzyl piperidinium salts tetrahalogenated copper(II)

This paper presents the syntheses, composition analysis and structural characterization of two ionic complexes, [4NO2BzPid]2[CuX4] ([4-NO2BzPid]+= 4-nitro-1-benzylpiperidinium, X = Cl(1) and Br(2)). Two complexes crystallize in chiral space group P6(4)(No. 172), and comprise two [4NO2BzPid]+cations and a [CuX4]2– anion in which the piperidine ring shows a boat structure while the [CuX4]2– anion exhibits a tetrahedron geometry. The intermolecular energy, the energy gap between the HOMO and LUMO orbitals, and the first hyperpolarizability were carried out based on the DFT calculation. The low energy gap (2.24 ev for 1 and 2.01 ev for 2) explains the eventual charge transfer interactions taken place between the [CuX4]2−anion and [4NO2BzPid]+cation. The first hyperpolarisability (βtot) of two salts is 9.3 and 16.0 times greater than that of the standard KDP crystal showing that two complexes are good materials for NLO application. The results of antibacterial experiments show that two complexes exhibit good bactericidal activity for S. aureus and E. coli.

Proton Affinity Values of Fentanyl and Fentanyl Analogues Pertinent to Ambient Ionization and Detection.

Proton affinity is a major factor in the atmospheric pressure chemical ionization of illicit drugs. The detection of illicit drugs by mass spectrometry and ion mobility spectrometry relies on the analytes having greater proton affinities than background species. Evaluating proton affinities for fentanyl and its analogues is informative for predicting the likelihood of ionization in different environments and for optimizing the compounds' ionization and detection, such as through the addition of dopant chemicals. Herein, density functional theory was used to computationally determine the proton affinity and gas-phase basicity of 15 fentanyl compounds and several relevant molecules as a reference point. The range of proton affinities for the fentanyl compounds was from 1018 to 1078 kJ/mol. Fentanyl compounds with the higher proton affinity values appeared to form a bridge between the oxygen on the amide and the protonated nitrogen on the piperidine ring based on models and calculated bond distances. Experiments with fragmentation of proton-bound clusters using atmospheric flow tube-mass spectrometry (AFT-MS) provided estimates of relative proton affinities and showed proton affinity values of fentanyl compounds >1000 kJ/mol, which were consistent with the computational results. The high proton affinities of fentanyl compounds facilitate their detection by ambient ionization techniques in complex environments. The detection limits of the fentanyl compounds with AFT-MS are in the low femtogram range, which demonstrates the feasibility of trace vapor drug detection.

Crystal structure, DFT and Hirshfeld surface analysis of N-acetyl-t-3-methyl-r-2,c-6-di-phenyl-piperidine.

In the title compound [systematic name: 1-(3-methyl-2,6-diphenylpiperidin-1-yl)ethanone], C20H23NO, the piperidine ring adopts a distorted boat conformation, while the phenyl rings subtend a dihedral angle 65.1 (2)°. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds into chains extending along the b-axis direction. The DFT/B3LYP/6-311 G(d,p) method was used to determine the HOMO-LUMO energy levels. A Hirshfeld surface analysis was conducted to verify the contributions of the different inter-molecular inter-actions, indicating that the important contributions to the crystal packing are from H⋯H (73.2%), C⋯H (18.4%) and O⋯H (8.4%) inter-actions.

Synthesis of tropane-based σ1 receptor antagonists with antiallodynic activity

Following the concept of conformational restriction to obtain high affinity σ1 ligands, the piperidine ring of eliprodil was replaced by the bicyclic tropane system and an exocyclic double bond was introduced. The envisaged benzylidenetropanes 9 were prepared by conversion of tropanone 10 into the racemic mixture of (Z)-14 and (E)-14. Reaction of racemate (Z)-14/(E)-14 with enantiomerically pure (R)- or (S)-configured 2-phenyloxirane provided mixtures of diastereomeric β-aminoalcohols (R,Z)-9 and (R,E)-9 as well as (S,Z)-9 and (S,E)-9, which were separated by chiral HPLC, respectively. X-ray crystal structure analysis of (S,Z)-9 allowed the unequivocal assignment of the configuration of all four stereoisomers. In receptor binding studies with radioligands, (R,E)-9 and (S,Z)-9 showed subnanomolar σ1 affinity with eudismic ratios of 8.3 and 40. In both compounds the 4-fluorophenyl moiety is oriented towards (S)-configured C-5 of the tropane system. Both compounds display high selectivity for the σ1 receptor over the σ2 subtype but moderate selectivity over GluN2B NMDA receptors. In vivo, (R,E)-9 (Ki(σ1) = 0.80 nM) showed high antiallodynic activity in the capsaicin assay. The effect of (R,E)-9 could be reversed by pre-administration of the σ1 agonist PRE-084 confirming the σ1 antagonistic activity of (R,E)-9.

Exploratory studies on soluble small molecule CD4 mimics as HIV entry inhibitors

Several small molecule CD4 mimics, which inhibit the interaction of gp120 with CD4, have been developed. Original CD4 mimics such as NBD-556, which has an aromatic ring, an oxalamide linker and a piperidine moiety, possess significant anti-HIV activity but with their hydrophobic aromatic ring-containing structures are poorly soluble in water. We have developed derivatives with a halopyridinyl group in place of the phenyl group, such as KKN-134, and found them to have excellent aqueous solubility. Other leads that were examined are YIR-821, a compound with a cyclohexane group in a spiro attachment to a piperidine ring and a guanidino group on the piperidine nitrogen atom, and its PEGylated derivative, TKB-002. YIR-821 and TKB-002 retain potent anti-HIV activity. Here, new CD4 mimics, in which the phenyl group was replaced by a halopyridinyl group with the halogen atoms in different positions, their derivatives without a cyclohexane group on the piperidine ring and their hybrid molecules with PEG units were designed and synthesized. Some of these compounds show significantly higher aqueous solubility with maintenance of certain levels of anti-HIV activity. The present data should be useful in the future design of CD4 mimic molecules.

Crystal structure and Hirshfeld surface analysis of 3-(hy-droxy-meth-yl)-3-methyl-2,6-di-phenyl-piperidin-4-one.

A new synthesis of the title compound, C19H21NO2, was developed with good yield and purity using the reaction of 4-hy-droxy-3-methyl-2-butanone, benzaldehyde and ammonium acetate in glacial acetic acid as a solvent. The central piperidine ring adopts a chair conformation, and its least-squares basal plane forms dihedral angles of 85.71 (11) and 77.27 (11)° with the terminal aromatic rings. In the crystal, the mol-ecules are linked by O-H⋯O and C-H⋯O hydrogen bonds into double ribbons. The Hirshfeld surface analysis shows that the most important contributions are from H⋯H (68%), C⋯H/H⋯C (19%) and O⋯H/H⋯O (12%) inter-actions.

METHODS OF NITROPYRIDINE SYNTHESIS

Background. Pyridine derivatives are widely used in pharmaceuticals, agrochemistry, as well as in the production of new materials. The pyridine and piperidine rings are the main structural fragments of numerous natural alkaloids with a wide spectrum of biological activity. Many of these alkaloids have anticancer and anti-neurological and other medical activities and continue to be valuable research subjects to stimulate drug discovery. Highly efficient methods for the synthesis of various pyridine derivatives and piperidine enantiomers will continue to be in high demand. In this regard, the analysis and systematization of the main results of studies on the synthesis of nitropyridines is an urgent task.&#x0D; Purpose. To summarize and systematize the main methods for the synthesis of pyridine nitro derivatives from the beginning of the last century to the present.&#x0D; Materials and methods. To achieve this goal of the study, a review of the scientific literature on the main methods of obtaining nitropyridines was carried out.&#x0D; Results. This literature review presents the results of experimental studies on the synthesis of pyridine nitro derivatives starting from the first half of the 20th century and up to the present time.&#x0D; Conclusion. Thus, it was possible to summarize the scattered but rather extensive factual material accumulated to date on the preparation of pyridine nitro derivatives. Several main approaches to the synthesis are considered, starting from aliphatic compounds, by nitration of pyridine and its derivatives, as well as by oxidation of aminopyridines.

Poly(fluorene alkylene) Anion Exchange Membranes with Pendant Spirocyclic and Bis-Spirocyclic Quaternary Ammonium Cations

Anion exchange membranes (AEMs) functionalized with certain alicyclic quaternary ammonium cations show high alkaline stability, which is necessary for use in fuel cells and water electrolyzers. Here, we have prepared and studied a series of poly(fluorene alkylene)s incorporating N,N-dimethylpiperidinium (DMP) and 6-azoniaspiro[5.5]undecane (ASU) cations in spirocyclic and bis-spirocyclic arrangements, respectively. First, a new fluorene monomer carrying a piperidine ring attached in the C9 position was prepared in a cycloalkylation reaction with N-Boc-N,N-bis(2-chloroethyl)amine. After deprotection, this monomer was employed in superacid-mediated polyhydroxyalkylations with 2,2,2-trifluoroacetophenone (Ap) and 1,1,1-trifluoroacetone (Ac), respectively, to prepare piperidine-functional precursor polymers. Finally, the DMP and ASU cations were formed in quaternizations and cycloquaternizations of the piperidine groups in the polymers by using methyl iodide and 1,5-dibromopentane, respectively. Solvent-cast AEMs showed high thermal stability in combination with good mechanical properties and restricted water uptake as a result of the stiff polymer backbone and bulky cations. Still, the AEM prepared with Ac and carrying DMP cations reached high OH– conductivity, exceeding 80 mS cm–1 at 80 °C. At the same temperature, this AEM showed a high alkaline stability and retained more than 96% of the DMP cations after storage during 30 days in 1 M NaOH. Detailed NMR analysis revealed that ionic loss via Hofmann elimination dominated, but evidence of ring-opening and methyl substitution reactions was also found. Degradation of the ASU cation in the bis-spirocyclic arrangement occurred mainly through ring-opening reactions in the ring directly attached to the fluorene unit in the polymer backbone. These results provide valuable insights when it comes to molecular design of piperidinium-based cations in polycyclic arrangements toward alkali-stable and highly conductive AEMs.

Cytotoxic Tumour-Selective 1,5-Diaryl-3-Oxo-1,4-Pentadienes Mounted on a Piperidine Ring.

A series of 3,5-bis(benzylidene)-4-piperidones 2a–u were prepared as candidate cytotoxic agents. In general, the compounds are highly toxic to human gingival carcinoma (Ca9-22), human squamous carcinoma-2 (HSC-2) and human squamous carcinoma-4 (HSC-4) neoplasms, but less so towards non-malignant human gingival fibroblast (HGF), human periodontal ligament fibroblast (HPLF) and human pulp cells (HPC), thereby demonstrating tumour-selective toxicity. A further study revealed that most of the compounds in series 2 were more toxic to the human Colo-205 adenocarcinoma cell line (Colo-205), human HT29 colorectal adenocarcinoma cells (HT-29) and human CEM lymphoid cells (CEM) neoplasms than towards non-malignant human foreskin Hs27 fibroblast line (Hs27) cells. The potency of the cytotoxins towards the six malignant cell lines increased as the sigma and sigma star values of the aryl substituents rose. Attempts to condense various aryl aldehydes with 2,2,6,6-tetramethyl-4-piperidone led to the isolation of some 1,5-diaryl-1,4-pentadien-3-ones. The highest specificity for oral cancer cells was displayed by 2e and 2r. In the case of 2r, its selective toxicity exceeded that of doxorubicin and melphalan. The enones 2k, m, o have the highest SI values towards colon cancer and leukemic cells. Both 2e,r inhibited mitosis and increased the subG1 population (with a transient increase in G2/M phase cells). Slight activation of caspase-3, based on the cleavage of poly(ADP-ribose)polymerase (PARP) and procaspase 3, was detected.