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.

Fluorenone-Based Fluorescent and Colorimetric Sensors for Selective Detection of I- Ions: Applications in HeLa Cell Imaging and Logic Gate.

Fluorenone-based fluorescent and colorimetric sensors 1 and 2 have been developed that displayed selective detection of iodide ions in the presence of interferences. Sensors displayed the fluorescence emission enhancement response toward I- with detection limits of 8.0 and 11.0 nM, respectively, which is accomplished through inhibition of intramolecular charge transfer and C=N isomerization. Excellent sensitivity and unique fluorescence enhancement response of sensors toward I- make them superior because most of the previously reported iodide sensors are based on the fluorescence quenching mechanism and are less sensitive. The sensing potential of sensors toward I- ions was investigated through 1H NMR titration, dynamic light scattering, Job's plots, and density functional theory analysis. Further, sensors displayed reversible behavior by the alternate addition of I- and Cu2+ ions that substantiate their role as recyclable sensors for the on-site detection of I- ions. Advantageously, fluorescence enhancement response of sensors was favorably used for fluorescence imaging of I- in live HeLa cells and the design of the logic gate. These sensors were successfully applied in diversified applications such as the preparation of sensors' coated paper strips and the determination of I- ions in blood serum, food, and real water samples.

Fluorene-Based Fluorometric and Colorimetric Conjugated Polymers for Sensitive Detection of 2,4,6-Trinitrophenol Explosive in Aqueous Medium.

Nitroaromatic explosives are a class of compounds that are responsible for various health hazards and terrorist outrages. Among these, sensitive detection of 2,4,6-trinitrophenol (TNP) explosive has always been highly desirable considering public health and national security. In this regard, three fluorene-based conjugated polymers (CP 1, CP 2, and CP 3) were synthesized through the Suzuki-Miyaura coupling reaction and were found to be highly sensitive for fluorescence detection of TNP with detection limits of 3.2, 5.7, and 6.1 pM, respectively. Excellent selectivity of CPs toward TNP was attributed to their unique π-π interactions based on fluorescence studies and density functional theory (DFT) calculations. The high sensitivity of CPs to TNP was attributed to the static quenching mechanism based on the photoinduced electron transfer process and was evaluated by fluorescence, UV-visible absorption, dynamic light scattering, Job's plots, the Benesi-Hildebrand plots, and DFT calculations. CPs were also used for colorimetric and real-water sample analysis for the detection of TNP explosive. Meanwhile, sensor-coated test strips were fabricated for on-site detection of TNP, which makes them convenient solid-supported sensors.

Synthesis and Tetraphenylethylene-Based Aggregation-Induced Emission Probe for Rapid Detection of Nitroaromatic Compounds in Aqueous Media.

Tetraphenylethylene (TPE) can be used to construct fluorescent probes with typical aggregation-induced emission (AIE) behavior for next-generation sensing applications. McMurry coupling and Suzuki cross coupling strategies provided the desired sensor thiophene-substituted tetraphenylethylene (THTPE). The synthesized TPE analogues were characterized by NMR spectroscopy and mass spectrometry. Maximum AIE of THTPE was observed in 90% water (H2O/THF) content due to extensive formation of aggregates. The AIE properties of THTPE have been utilized for facile detection of nitroaromatic compounds (NACs) (1.0 nM) through a fluorescence quenching mechanism. A paper strip adsorbed with the AIE-based THTPE fluorophore is developed for rapid and convenient detection of NAC-based analytes. Further, interaction of THTPE with analytes is also studied via Gaussian software at the DFT/B3LYP/6-31G(d) level of theory. Interaction energy, frontier molecular orbitals (FMOs), and non-covalent interaction (NCI) analyses are studied by using the same method. Computational results revealed that nitrobenzene (NB) has the strongest interaction while 1,3-dinitrobenzene (DNB) exhibits the least interaction with the sensor molecule. These computational results clearly demonstrate good agreement with experimental data.

Quinazolinones as Competitive Inhibitors of Carbonic Anhydrase-II (Human and Bovine): Synthesis, in-vitro, in-silico, Selectivity, and Kinetics Studies.

Carbonic anhydrase-II (CA-II) is associated with glaucoma, malignant brain tumors, and renal, gastric, and pancreatic carcinomas and is mainly involved in the regulation of the bicarbonate concentration in the eyes. CA-II inhibitors can be used to reduce the intraocular pressure usually associated with glaucoma. In search of potent CA-II inhibitors, a series of quinazolinones derivatives (4a-p) were synthesized and characterized by IR and NMR spectroscopy. The inhibitory potential of all the compounds was evaluated against bovine carbonic anhydrase-II (bCA-II) and human carbonic anhydrase-II (hCA-II), and compounds displayed moderate to significant inhibition with IC50 values of 8.9-67.3 and 14.0-59.6 µM, respectively. A preliminary structure-activity relationship suggested that the presence of a nitro group on the phenyl ring at R position contributes significantly to the overall activity. Kinetics studies of the most active inhibitor, 4d, against both bCA-II and hCA-II were performed to investigate the mode of inhibition and to determine the inhibition constants (Ki). According to the kinetics results, 4d is a competitive inhibitor of bCA-II and hCA-II with Ki values of 13.0 ± 0.013 and 14.25 ± 0.017 µM, respectively. However, the selectivity index reflects that the compounds 4g and 4o are more selective for hCA-II. The binding mode of these compounds within the active sites of bCA-II and hCA-II was investigated by structure-based molecular docking. The docking results are in complete agreement with the experimental findings.

Synthesis, molecular docking and anti-diabetic studies of novel benzimidazole-pyrazoline hybrid molecules.

Pyrazoline and benzimidazoles derivatives have been widely studied due to their potential applications in the medicinal field. In this research project, we have hybridized these two heterocyclic systems in the same molecule. A new series of compounds, 2-((3,5-diaryl-4,5-dihydro-1H-pyrazol-1-yl)methyl)-1H-benzo[d]imidazole (5a-i) were synthesized through a multistep reaction. In the first step, chalcones 3a-i were prepared by coupling of various acetophenones and benzaldehydes under alkaline conditions. These chalcones were cyclized with hydrazine hydrate to form a series of pyrazolines which were finally coupled with 2-chloromethyl-1H-benzimidazole to get a new series of titled hybrid molecules. The structures of these compounds were elucidated by spectral (1H NMR and 13C NMR) analysis. The anti-diabetic potential of these compounds was studied by screening them for their α-glucosidase inhibition activity. The SAR was established through molecular docking analysis. Compound 5d appeared as effective inhibitor with IC50 = 50.06µM as compared to reference drug (acarbose) having IC50 = 58.8µM.

Synthesis, evaluation of thymidine phosphorylase and angiogenic inhibitory potential of ciprofloxacin analogues: Repositioning of ciprofloxacin from antibiotic to future anticancer drugs.

Over expression of thymidine phosphorylase (TP) in various human tumors compared to normal healthy tissue is associated with progression of cancer and proliferation. The 2-deoxy-d-ribose is the final product of thymidine phosphorylase (TP) catalyzed reaction. Both TP and 2-deoxy-d-ribose are known to promote unwanted angiogenesis in cancerous cells. Discovery of potent inhibitors of thymidine phosphorylase (TP) can offer appropriate approach in cancer treatment. A series of ciprofloxacin 2, 3a-3c, 4a-4d, 5a-5b, 6 and 7 has been synthesized and characterized using spectroscopic techniques. Afterwards, inhibitory potential of synthesized ciprofloxacin 2, 3a-3c, 4a-4d, 5a-5b, 6 and 7 against thymidine phosphorylase enzyme was assessed. Out of these twelve analogs of ciprofloxacin nine analogues 3a-3c, 4a-4c, 5a-5b and 6 showed good inhibitory activity against thymidine phosphorylase. Inhibitory activity as presented by their IC50 values was found in the range of 39.71 ± 1.13 to 161.89 ± 0.95 µM. The 7-deazaxanthine was used as a standard inhibitor with IC50 = 37.82 ± 0.93 µM. Furthermore, the chick chorionic allantoic membrane (CAM) assay was used to investigate anti-angiogenic activity of the most active ciprofloxacin-based inhibitor 3b. To enlighten the important binding interactions of ciprofloxacin derivatives with target enzyme, the structure activity relationship and molecular docking studies of chosen ciprofloxacin analogues was discussed. Docking studies revealed key π-π stacking, π-cation and hydrogen bonding interactions of ciprofloxacin analogues with active site residues of thymidine phosphorylase enzyme.

Design and syntheses of 7-nitro-2-aryl-4H-benzo[d][1,3]oxazin-4-ones as potent anticancer and antioxidant agents.

A group of new nitro substituted benzoxazinones (3a-k) were synthesized from easily available 4-nitroanthranilic acid. All the synthesized compounds were characterized by FT-IR, 1H NMR, 13C NMR, mass spectrometry and elemental analysis. Anti-proliferative and pro-apoptotic potential of all the synthesized compounds (3a-k) was evaluated by MTT and Hoechst 33258 staining assay respectively whereas their antioxidant properties were determined via DPPH free radical scavenging assay. The most active compounds (3a, 3c and 3k) showed significant cytotoxic potential against HeLa cells with an inhibition of cell viability that ranged between 28.54 and 44.67% (P < 0.001). Albeit statistically different, the anti-proliferative effect of 3c was in close match with that of the reference drug doxorubicin. Likewise, the test compounds showed profound pro-apoptotic potential with an apoptotic index that ranged between 52.86 and 75.61%. Besides, the docking studies revealed a higher efficiency for compounds (3a and 3h) owing to their better affinity and inhibition constant (Ki = 4.397 and 3.713 nmol) respectively. The antioxidant potential of synthesized benzoxazinones (3a-k) was in close agreement with the experimental anticancer results with a percent inhibition from 34.45 to 85.93% as compared to standard (90.56%).

5-Endo-dig cyclizations in organic syntheses.

The favorability of ring closure reactions as per Baldwin rules has gained immense importance recently. This is evident from the current literature such as research articles, reviews, and books that have been published in this area. This review covers the recent applications of 5-endo-dig cyclization in organic synthesis focusing in the last two decades. A variety of 5-membered heterocycles as well as carbocycles could be synthesized via 5-endo-dig cyclization reactions. The important applications of 5-endo-dig cyclization in organic synthesis covering different aspects have been summarized in this review.

Identification of 1,2,4-triazoles as new thymidine phosphorylase inhibitors: Future anti-tumor drugs.

Thymidine phosphorylase (TP) is over expressed in several solid tumors and its inhibition can offer unique target suitable for drug discovery in cancer. A series of 1,2,4-triazoles 3a-3l has been synthesized in good yields and subsequently inhibitory potential of synthesized triazoles 3a-3l against thymidine phosphorylase enzyme was evaluated. Out of these twelve analogs five analogues 3b, 3c, 3f, 3l and 3l exhibited a good inhibitory potential against thymidine phosphorylase. Inhibitory potential in term of IC50 values were found in the range of 61.98 ±â€¯0.43 to 273.43 ±â€¯0.96 µM and 7-Deazaxanthine was taken as a standard inhibitor with IC50 = 38.68 ±â€¯4.42 µM. Encouraged by these results, more analogues 1,2,4-triazole-3-mercaptocarboxylic acids 4a-4g were synthesized and their inhibitory potential against thymidine phosphorylase was evaluated. In this series, six analogues 4b-4g exhibited a good inhibitory potential in the range of 43.86 ±â€¯1.11-163.43 ±â€¯2.03 µM. Angiogenic response of 1,2,4-triazole acid 4d was estimated using the chick chorionic allantoic membrane (CAM) assay. In the light of these findings, structure activity relationship and molecular docking studies of selected triazoles to determine the key binding interactions was discussed. Docking studies demonstrate that synthesized analogues interacted with active site residues of thymidine phosphorylase enzyme through π-π stacking, thiolate and hydrogen bonding interactions.

Technetium-99m radiolabeling and biological study of epirubicin for in vivo imaging of multi-drug-resistant Staphylococcus aureus infections via single photon emission computed tomography.

The development of functional imaging is a promising strategy for diagnosis and treatment of infectious and cancerous diseases. In this study, epirubicin was developed as a [99m Tc]-labeled radiopharmaceutical for the imaging of multi-drug-resistant Staphylococcus aureus infections. The labeling was carried out using sodium pertechnetate (Na99m TcO4 ; ~370 MBq). The other parameters such as amount of ligand, reducing agent (SnCl2 .2H2 O), and pH were optimized. The highest labeling yield ≥96.98% was achieved when 0.3 mg epirubicin, 13 µg SnCl2 .2H2 O, and ~370 MBq Na99m TcO4 were incubated at pH 7 for 15 min in the presence of ascorbic acid at room temperature. Radiochemical purity, stability, charge, and glomerular filtration rate were studied to evaluate the biological compatibility for in vivo administration. Biodistribution investigations showed radiotracer uptake (13.89 ± 1.56% ID/gm organ) by liver and 7.79 ± 0.38% ID/gm organ by kidneys at 30 min post-injection which promisingly wash out at 24 hr post-injection. Scintigraphy study showed selective uptake in S. aureus-infected tissues in contrast to turpentine oil-induced inflamed tissues. Target-to-non-target ratio (6.7 ± 0.05) was calculated at 1 hr post-injection using SPECT gamma camera. The results of this study reveal that the [99m Tc]-epirubicin can be a choice of imaging and monitoring the treatment process of multi-drug resistant S. aureus bacterial infections.

Synthetic approaches toward stilbenes and their related structures.

Compounds belonging to the stilbene family have gained remarkable significance in pharmaceutical as well as material chemistry. The current review covers the various synthetic approaches for the syntheses of stilbene scaffold and related structures over last 30 years. In addition, this review also highlights the role of stilbene intermediates used in the synthesis of important molecules with diverse applications in the field of pharmaceutics and material science.

Compositional difference in antioxidant and antibacterial activity of all parts of the Carica papaya using different solvents.

BACKGROUND: Carica papaya is a well known medicinal plant used in the West and Asian countries to cope several diseases. Patients were advised to eat papaya fruit frequently during dengue fever epidemic in Pakistan by physicians. This study was conducted to establish Polyphenols, flavonoids and antioxidant potential profile of extracts of all major parts of the C. papaya with seven major solvents i.e. water, ethanol, methanol, n-butanol, dichloromethane, ethyl acetate, and n-hexane. RESULTS: TPC, TFC, antioxidant and antibacterial potential were determined using different aqueous and organic solvents in addition to the determination of trace element in leaves, pulp and peel of C. papaya. Total soluble phenolics and flavonoids were found in promising quantity (≈66 mg GAE/g) especially in case of methanol and ethanol extracts. Antioxidant activity using DPPH free radical scavenging assay indicated leaves, bark, roots and pulp extracts showed >75.0 % scavenging potential while leaves and pulp showed 84.9 and 80.9 % inhibition of peroxidation, respectively. Reducing power assay showed leaves, pulp and roots extracts active to reduce Fe(3+) to Fe(2+) ions. The antibacterial study showed pulp extract is the best to cope infectious action of bacteria. CONCLUSION: This study was conducted to test the medicinal profile of all parts of C. papaya by extracting secondary metabolites with organic and aqueous solvents. Ethanol and methanol both were found to be the best solvents of choice to extract natural products to get maximum medicinal benefits and could be used to medicinal formulation against different infectious diseases.Graphical abstractMedicinal evaluation of different parts of C. papaya.

Synthesis, thymidine phosphorylase inhibition and molecular modeling studies of 1,3,4-oxadiazole-2-thione derivatives.

Thymidine phosphorylase (TP) inhibitors have attracted great attention due to their ability to suppress the tumors formation. In our ongoing research, a series of 1,3,4-oxadiazole-2-thione (1-12) has been synthesized under simple reaction conditions in good to excellent yields (86-98%) and their TP inhibition potential has also been evaluated. The majority of synthesized compounds showed moderate thymidine phosphorylase inhibitory activity with IC50 values ranging from 38.24±1.28 to 258.43±0.43µM, and 7-deazaxanthine (7DX) was used as a reference compound (IC50 38.68±4.42). The TP activity was very much dependent on the C-5 substituents; among this series the compound 6 bearing 4-hydroxyphenyl group was found to be the most active with IC50 38.24±1.28µM. Molecular docking studies revealed their binding mode.

Antioxidant and antibacterial activities of Hibiscus Rosa-sinensis Linn flower extracts.

Antioxidant and antibacterial potential of different solvent extracts of locally grown Hibiscus rosa-sinensis Linn was evaluated. The antioxidant activity was assessed by estimation of total flavonoids contents, total phenolic contents, DPPH free radical scavenging activity and percentage inhibition of linoleic acid oxidation capacity. Agar disc diffusion method was used to assess antibacterial potential of crude extract of H. rosa-sinensis. The yield of the crude extracts (23.21 ± 3.67 and 18.36 ± 2.98% in 80% methanol and ethanol solvents was calculated, respectively. Methanol and ethanol extract of H. rosa-sinensis showed total phenolics 61.45 ± 3.23 and 59.31 ± 4.31 mg/100g as gallic acid equivalent, total flavonoids 53.28 ± 1.93 and 32.25±1.21 mg/100g as catechine equivalent, DPPH free radical scavenging activity 75.46±4.67 and 64.98 ± 2.11% and inhibition of linoleic acid oxidation potential 75.8 ±3.22 and 61.6 ± 2.01% respectively, was measured. Antibacterial study against three human pathogens such as staphlococus sp. Bacillus sp. and Escherichia coli showed growth inhibitory effect in the range of 12.75 ± 1.17 to 16.75 ± 2.10 mm. These results showed H. rosa-sinensis indigenous to Kallar Kahar and its allied areas bear promising medicinal values and could be used for developing herbal medicines to target oxidative stress and infectious diseases.

Design and Synthesis of New Dual Binding Site Cholinesterase Inhibitors: in vitro Inhibition Studies with in silico Docking.

Cholinesterases (ChEs) play a vital role in the regulation of cholinergic transmission. The inhibition of ChEs is considered to be involved in increasing acetylcholine level in the brain and thus has been implicated in the treatment of Alzheimer's disease. We have designed and synthesized a series of novel indole derivatives and screened them for inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Most of the tested compounds exhibited inhibitory activity against AChE and BChE. Among them 4f and 6e showed the highest AChE inhibitory activity with IC50 91.21±0.06 and 68.52±0.04 µM, respectively. However compound 5a exhibited the highest inhibitory activity against BChE (IC50 55.21±0.12 µM).

Synthesis and biological evaluation of novel oxadiazole derivatives: a new class of thymidine phosphorylase inhibitors as potential anti-tumor agents.

Based on the fact that the thymidine phosphorylase inhibitors are considered potential anti-tumor agents, a range of novel oxadiazole derivatives 3a-3u was designed and synthesized by a simple and facile synthetic route. The biological assay revealed that majority of compounds displayed modest inhibitory activity against thymidine phosphorylase at low micromolar concentrations (IC50 173.23±3.04 to 14.40±2.45µM). In the current study the most active compounds were 3h and 3q with IC50 values 14.40±2.45 and 17.60±1.07µM, respectively. Molecular docking studies were performed on the most active compounds (3h, 3k, 3o-3q) to show their binding mode.

Novel indium-111 labeled gastrin peptide analogues (MG-CL1-4): synthesis and quality control.

Radiolabeled neuropeptides are widely investigated to diagnose and therapy of tumors. These peptides get internalization after binding with particular receptors at the surface of cells and finally move to lysosome. Internalization into tumor cells helps in mapping the infected site. Minigastrin peptide analogues (MG-CL1-4) were synthesised and labeled with 111-In radioisotope under different sets of conditions for imaging CCk-2 receptor bearing tumors. Different parameters such as temperature (80-100°C), pH (4-12), incubation time (5-30 minutes) and dilution effect were investigated to get the maximum labeling yield and stability. The results indicated that MG-CL1-4 is successfully labeled with indium-111 at pH 4.5 with heating at 98°C for 15 minute. At these conditions i.e. heating, pH and incubation minimum oxidized and maximum labeling yield, more than 94 %, was obtained. The labeling stability was studied by incubating the radiolabeled complex for predefined time points in PBSA and blood serum. Results show that more than 90% radiolabeled MG-CL1-4 remained intact.

Synthesis of indene derivatives via electrophilic cyclization.

3-Iodo-1H-indene derivatives are synthesized by iodonium-promoted 5-endo-dig carbocyclization of 2-substituted ethynylmalonates. Various 2-substituted ethynylmalonates bearing aryl-, alkyl- and ether-protected propargyl alcohols were successfully converted to cyclized products. Their use in subsequent reactions as substrate and catalyst was investigated.

An expeditious and environmentally friendly synthesis of 3-substituted isocoumarins using microwave irradiation.

A microwave-assisted, environmentally friendly, high-yielding, time-saving synthesis of medicinally important 3-substituted isocoumarins was carried out in a single step by direct condensation of homophthalic acid with aryol and acyl chlorides under solvent-free conditions without any solid support. The synthesised isocoumarins were structurally characterised by microanalysis, 1H NMR, EI, IR and UV.