Design,Synthesis, and Biological Evaluation of Novel Dihydropyridine and Pyridine Analogs as Potent Human Tissue Nonspecific Alkaline Phosphatase Inhibitors with Anticancer Activity: ROS and DNA Damage-Induced Apoptosis

Small molecules with nitrogen-containing scaffolds have gained much attention due to their biological importance in the development of new anticancer agents. The present paper reports the synthesis of a library of new dihydropyridine and pyridine analogs with diverse pharmacophores. All compounds were tested against the human tissue nonspecific alkaline phosphatase (h-TNAP) enzyme. Most of the compounds showed excellent enzyme inhibition against h-TNAP, having IC₅₀ values ranging from 0.49 ± 0.025 to 8.8 ± 0.53 µM, which is multi-fold higher than that of the standard inhibitor (levamisole = 22.65 ± 1.60 µM) of the h-TNAP enzyme. Furthermore, an MTT assay was carried out to evaluate cytotoxicity against the HeLa and MCF-7 cancer cell lines. Among the analogs, the most potent dihydropyridine-based compound 4d was selected to investigate pro-apoptotic behavior. The further analysis demonstrated that compound 4d played a significant role in inducing apoptosis through multiple mechanisms, including overproduction of reactive oxygen species, mitochondrial dysfunction, DNA damaging, and arrest of the cell cycle at the G1 phase by inhibiting CDK4/6. The apoptosis-inducing effect of compound 4d was studied through staining agents, microscopic, and flow cytometry techniques. Detailed structure–activity relationship (SAR) and molecular docking studies were carried out to identify the core structural features responsible for inhibiting the enzymatic activity of the h-TNAP enzyme. Moreover, fluorescence emission studies corroborated the binding interaction of compound 4d with DNA through a fluorescence titration experiment.     

Isospin-breaking corrections in the pion–deuteron scattering length

It is shown that isospin-breaking corrections to the pion–deuteron scattering length can be very large, because of the vanishing of the isospin-symmetric contribution to this scattering length at leading order in chiral perturbation theory. We further demonstrate that these corrections can explain the bulk of the discrepancy between the recent experimental data on pionic hydrogen and pionic deuterium. We also give the first determination of the electromagnetic low-energy constant f₁$f_1$.     

Automated derivatization and analysis of malondialdehyde using column switching sample preparation HPLC with fluorescence detection

Analyte derivatization is advantageous for the analysis of malondialdehyde (MDA) as a biomarker of oxidative stress in biological samples. Conventionally, however, derivatization is time consuming, error-prone and has limited options for automation. We have addressed these challenges for the solid phase analytical derivatization of MDA from small volume tissue homogenate samples. A manual derivatization method was first developed using Amberlite XAD-2 (12 mg) as the solid phase. Subsequently an automated column switching process was developed that provided simultaneous derivatization and extraction of the MDA-DH hydrazone product on a cartridge packed with XAD-2, followed by quantitative elution of the product to an analytical LC column (Waters NovoPak C18, 3.9 x 150 mm). The LOD was 0.02 microg/mL and recovery was quantitative. The method was linear (r(2) >0.999) with precision < 5% from the LOQ (0.06 microg/mL) to at least 35 microg/mL. The method was successfully applied to the analysis of small volume (30 microL) mouse tissue homogenate samples. Endogenous levels of MDA in the tissues ranged from 20 to 40 nmol/g tissue (ca. 0.1-0.2 microg/mL homogenate). Compared to conventional MDA analyses, the current method has advantages in automation, selectivity, precision and sensitivity for analysis from very small sample volumes.     

Nonsolvent application of ionic liquids: organo-catalysis by 1-alkyl-3-methylimidazolium cation based room-temperature ionic liquids for chemoselective N-tert-butyloxycarbonylation of amines and the influence of the C-2 hydrogen on catalytic efficiency

1-Alkyl-3-methylimidazolium cation based ionic liquids efficiently catalyze N-tert-butyloxycarbonylation of amines with excellent chemoselectivity. The catalytic role of the ionic liquid is envisaged as "electrophilic activation" of di-tert-butyl dicarbonate (Boc(2)O) through bifurcated hydrogen bond formation with the C-2 hydrogen of the 1-alkyl-3-methylimidazolium cation and has been supported by a downfield shift of the imidazolium C-2 hydrogen of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][NTf(2)]) from δ 8.39 to 8.66 in the presence of Boc(2)O in the (1)H NMR and a drastic reduction of the catalytic efficiency with 1-butyl-2,3-dimethylimidazolium ionic liquids that are devoid of the C-2 hydrogen. The differential time required for reaction with aromatic and aliphatic amines has offered means for selective N-t-Boc formation during inter and intramolecular competitions. Preferential N-t-Boc formation with secondary aliphatic amine has been achieved in the presence of primary aliphatic amine. Comparison of the catalytic efficiency for N-t-Boc formation with a common substrate revealed that [bmim][NTf(2)] is superior to the reported Lewis acid catalysts.     

Design and green synthesis of 1-(4-ferrocenylbutyl)piperazine chemically grafted reduced graphene oxide for supercapacitor application

In this paper, we report the green synthesis of 1-(4-ferrocenylbutyl)piperazine chemically grafted rGO (P.Fc/rGO) as a battery-type supercapacitor electrode material. For this purpose, initially, the ability of the aqueous Damson fruit extract is investigated in the reduction reaction of graphene oxide (GO). 1-(4-ferrocenylbutyl)piperazine (P.Fc) is synthesized via nucleophilic substitution reaction of piperazine with as-synthesized 4-chlorobutylferrocene. In continue, P. Fc is incorporated to GO by ring-opening reaction of epoxide groups on the GO surface. In the next step, the modified reduction method by aqueous Damson fruit extract was used to prepare the P.Fc/rGO from P.Fc/GO. The prepared materials were characterized by various techniques including FT-IR, Uv–vis, XRD, SEM, EDX, and BET. N₂ adsorption–desorption data of P.Fc/rGO nanocomposite shows that the surface area is 37.746 m² g⁻¹. The capability of P.Fc/rGO nanocomposite for using as an energy storage electrode material in battery-type supercapacitor was examined by investigation of its electrochemical behavior by CV, EIS, and GCD measurements. The charge storage capacity of 1,102 mAh g⁻¹ is achieved at 2.5 A g⁻¹. This nanocomposite shows 89% retention of charge storage capacity after 2000 CV cycles.     

Making and Breaking of C−N Bonds: Applications in the Synthesis of Unsymmetric Tertiary Amines and α-Amino Carbonyl Derivatives

An operationally simple process has been developed for the synthesis of unsymmetrical amines and α-amino carbonyl derivatives in the absence of a catalyst, ligand, oxidant, or any additives. Contrary to known reductive amination methods, this protocol is amenable to substrates containing other reducible groups. This process effectively results in consecutive cleavage and formation of C−N bonds. DFT studies and Hammett analysis provide useful insight into the mechanism. The role of noncovalent interactions as a stabilizing factor have been examined in the protocol. A wide range of alkyl-bromides have been coupled efficiently with a variety of dimethyl anilines to get unsymmetric tertiary amines with yields up to 90%. This methodology was further extended to the synthesis of α-amino carbonyl derivatives with yields up to 93%.     

Ultrastructural and Morphological Effects in T-Lymphoblastic Leukemia CEM-SS Cells Following Treatment with Nordamnacanthal and Damnacanthal from Roots of Morinda elliptica

Background: Morinda elliptica (family Rubiaceae), locally known as ‘mengkudu kecil’, has been used by the Malays for medicinal purposes. Anthraquinones isolated from the roots of Morinda elliptica, namely nordamnacanthal and damnacanthal, have been widely reported to exhibit anticancer and antioxidant properties in various cancer models in vitro and in vivo. Aim: This study analyzed the morphological and ultrastructural effects of damnacanthal and nordamnacanthal on T-lymphoblastic leukemia CEM-SS cells. Method: Light microscopy, Giemsa staining, Wright’s staining, scanning electron microscopy, and transmission electron microscopy were carried out to determine apoptosis, necrosis, and ultrastructural changes that occurred within the cells. Results: The outcomes showed that these compounds induced cell death by apoptosis and necrosis, specifically at higher doses of 10 and 30 μg/mL. Condensation and fragmentation of the nuclear chromatin, which further separated into small, membrane-bound vesicles known as apoptotic bodies, were observed in the nuclei and cytoplasm. The plasma membranes and cytoskeletons also showed marked morphological changes upon treatment with damnacanthal and nordamnacanthal, indicating apoptosis. Conclusion: Therefore, we report that damnacanthal and nordamnacanthal exhibit anticancer properties by inducing apoptosis and necrosis in CEM-SS cells, and they have potential as a drug for the treatment of T-lymphoblastic leukemia.