Bioactivity-Guided Synthesis: In Silico and In Vitro Studies of ß-Glucosidase Inhibitors to Cope with Hepatic Cytotoxicity.

The major cause of hyperglycemia can generally be attributed to ß-glucosidase as per its involvement in non-alcoholic fatty liver disease. This clinical condition leads to liver carcinoma (HepG2 cancer). The phthalimides and phthalamic acid classes possess inhibitory potential against glucosidase, forming the basis for designing new phthalimide and phthalamic acid analogs to test their ability as potent inhibitors of ß-glucosidase. The study also covers in silico (molecular docking and MD simulations) and in vitro (ß-glucosidase and HepG2 cancer cell line assays) analyses. The phthalimide and phthalamic acid derivatives were synthesized, followed by spectroscopic characterization. The mechanistic complexities associated with ß-glucosidase inhibition were identified via the docking of the synthesized compounds inside the active site of the protein, and the results were analyzed in terms of the best binding energy and appropriate docking pose. The top-ranked compounds were subjected to extensive MD simulation studies to understand the mode of interaction of the synthesized compounds and binding energies, as well as the contribution of individual residues towards binding affinities. Lower RMSD/RMSF values were observed for 2c and 3c, respectively, in the active site, confirming more stabilized, ligand-bound complexes when compared to the free state. An anisotropic network model was used to unravel the role of loop fluctuation in the context of ligand binding and the dynamics that are distinct to the bound and free states, supported by a 3D surface plot. An in vitro study revealed that 1c (IC50 = 1.26 µM) is far better than standard acarbose (2.15 µM), confirming the potential of this compound against the target protein. Given the appreciable potential of the candidate compounds against ß-glucosidase, the synthesized compounds were further tested for their cytotoxic activity against hepatic carcinoma on HepG2 cancer cell lines. The cytotoxicity profile of the synthesized compounds was performed against HepG2 cancer cell lines. The resultant IC50 value (0.048 µM) for 3c is better than the standard (thalidomide: IC50 0.053 µM). The results promise the hypothesis that the synthesized compounds might become potential drug candidates, given the fact that the ß-glucosidase inhibition of 1c is 40% better than the standard, whereas compound 3c holds more anti-tumor activity (greater than 9%) against the HepG2 cell line than the known drug.

Development of AIEE active fluorescent and colorimetric probe for the solid, solution, and vapor phase detection of cyanide: smartphone and food applications.

Apart from environmental implications, the extreme toxicity of cyanide can lead to sudden human death upon prolonged exposure to it. Hence, rapid and low-level on-site detection of cyanide has earned paramount significance in the present era. Therefore, an AIEE active and piezofluorochromic Schiff base (probe 2) was synthesized which exhibited highly selective fluorescence enhancement based nanoscale (LOD; 6.17 nM) detection of CN-. The interaction mode was attributed to the deprotonation of the probe by the cyanide that was confirmed through 1H NMR titration, pH, theoretical studies, and switchable fluorescence response upon the addition of HCl. Advantageously, probe 2 displayed solid and vapor phase recognition of cyanide which is the first of its kind as far as we know. The excellent sensing potential of the probe was satisfactorily applied for the detection of cyanide in food, natural soil, and industrial wastewater. Additionally, probe 2 showed an immediate colorimetric response towards cyanide which was favorably integrated through a smartphone. Finally, the switchable fluorescence response of the probe was used to design an INHIBIT logic gate. Therefore, the multifunctional probe 2 displayed excellent practical potential for cyanide detection which was the ultimate goal of our work.

Three New Acrylic Acid Derivatives from Achillea mellifolium as Potential Inhibitors of Urease from Jack Bean and α-Glucosidase from Saccharomyces cerevisiae.

(1) Background: Achillea mellifolium belongs to a highly reputed family of medicinal plants, with plant extract being used as medicine in indigenous system. However, limited data is available regarding the exploitation of the medicinal potential of isolated pure compounds from this family; (2) Methods: A whole plant extract was partitioned into fractions and on the basis of biological activity, an ethyl acetate fraction was selected for isolation of pure compounds. Isolated compounds were characterized using different spectroscopic techniques. The compounds isolated from this study were tested for their medicinal potential using in-vitro enzyme assay, coupled with in-silico studies; (3) Results: Three new acrylic acid derivatives (1-3) have been isolated from the ethyl acetate fraction of Achillea mellifolium. The characterization of these compounds (1-3) was carried out using UV/Vis, FT-IR, 1D and 2D-NMR spectroscopy (1H-NMR, 13C-NMR, HMBC, NOESY) and mass spectrometry. These acrylic acid derivatives were further evaluated for their enzyme inhibition potential against urease from jack bean and α glucosidase from Saccharomyces cerevisiae, using both in-silico and in-vitro approaches. In-vitro studies showed that compound 3 has the highest inhibition against urease enzyme (IC50 =10.46 ± 0.03 µΜ), followed by compound 1 and compound 2 with percent inhibition and IC50 value of 16.87 ± 0.02 c and 13.71 ± 0.07 µΜ, respectively, compared to the standard (thiourea-IC50 = 21.5 ± 0.01 µΜ). The investigated IC50 value of compound 3 against the urease enzyme is two times lower compared to thiourea, suggesting that this compound is twice as active compared to the standard drug. On the other hand, all three compounds (1-3) revealed mild inhibition potential against α-glucosidase. In-silico molecular docking studies, in combination with MD simulations and free energy, calculations were also performed to rationalize their time evolved mode of interaction inside the active pocket. Binding energies were computed using a MMPBSA approach, and the role of individual residues to overall binding of the inhibitors inside the active pockets were also computed; (4) Conclusions: Together, these studies confirm the inhibitory potential of isolated acrylic acid derivatives against both urease and α-glucosidase enzymes; however, their inhibition potential is better for urease enzyme even when compared to the standard.

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.

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.

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.

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%).

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.

Aggregation enhanced excimer emission (AEEE) of benzo[ghi]perylene and coronene: multimode probes for facile monitoring and direct visualization of micelle transition.

We report benzo[ghi]perylene (BzP) and coronene (Cron) as multimode fluorescent probes for accurate monitoring and direct visualization of monomer-micelle transitions in surfactants for the first time. The probe molecules formed self-assembled nanoparticles in an aqueous solution and displayed strong aggregation-enhanced excimer emission (AEEE). During the process of surfactant monomer-micelle transition, the probe nanoparticles dissolved, and the observation of excimer-monomer emission transition clearly indicated the formation of micelles. The ratiometric changes in excimer-monomer emission (IE/IM) were used for the precise determination of critical micelle concentration (CMC) of various surfactants. The monomer-micelle transition process was directly observed under a UV lamp, and the visual determination of CMC became possible. The CMC value determination using the excimer/monomer ratio (IE/IM), UV-vis, lifetime and visual assessment clearly suggests that BzP and Cron are excellent multimode probes for monitoring the micelle structural transitions of amphiphiles.

Fluorescence turn-on detection of alkaline phosphatase activity based on controlled release of PEI-capped Cu nanoclusters from MnO2 nanosheets.

A fluorescence turn-on assay for alkaline phosphatase (ALP) activity is developed through the controlled release of polyethyleneimine-capped copper nanoclusters (PEI-capped CuNCs) from the MnO2 nanosheets. In an aqueous solution, the positively charged PEI-capped CuNCs could be adsorbed onto the surface of the negatively charged MnO2 nanosheets. Such adsorption through favorable electrostatic interactions could efficiently quench the nanocluster fluorescence emission via resonance energy transfer from the PEI-capped CuNCs to the MnO2 nanosheets. 2-Phospho-L-ascorbic acid (AAP) could be hydrolyzed to L-ascorbic acid (AA) in the presence of ALP. AA could reduce MnO2 into Mn2+ and trigger the disintegration of the MnO2 nanosheets. As a result, the CuNCs were released and the quenched fluorescence was recovered efficiently. The detection strategy is simple, inexpensive, sensitive, selective, with low toxicity, and has better biocompatibility. The newly fabricated biosensor for ALP activity will potentially make it a robust candidate for numerous biological and biomedical applications.

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.

Antioxidant, antibacterial and antiproliferative activities of pumpkin (cucurbit) peel and puree extracts - an in vitro study.

Natural resources right from the beginning of the human civilization has paved the way to human being to combat different challenges. The big challenge was to safe the human being from diseases and shortage of food. Plants helped the man in both areas very efficiently. No doubt when plants are used as food actually we are also taking lot of compounds of medicinal values in an excellent combination which naturally reduce the risk of diseases. Extraction and purification of several medicinally important compounds also gave the way to develop pharmaceutical industry in addition to its own therapeutic effects against different lethal diseases. Pumpkin is one of the several medicinal important vegetables used in different way on the behalf of its admirable power to combat different diseases. Antioxidant and biological studies showed very important results. A good coherence was found among extraction yield (10.52 to 18.45%), total phenolics (1.13 to 6.78 mg GAE/100g), total flavonoids (0.23 to 0.72mg CE/100g) and antioxidant potential (≻70%). Antibacterial assays of peel and puree extracts advocated good potential to stop the growth and division of pathogenic bacteria. Further biological activity study was carried out using MDBK cancer cell line. The growth inhibitory effect on cancer cell line using MTT assay showed methanol extracts of peel and puree both remained efficient to inhibit growth (≻35%) and cell division of cancer cells. Our results showed that extracts of pumpkin puree and its waste, peel, may be utilize to prepare functional food against pathogenic born diseases and most active compounds may also be extracted, concentrated and converted into tablets or suspension form for therapeutic purposes.

Fluorescence turn-on detection of mercury ions based on the controlled adsorption of a perylene probe onto the gold nanoparticles.

A novel fluorescence turn-on strategy based on Au nanoparticles and a perylene probe for the sensing of Hg(2+) ions has been developed. It was observed that a perylene probe could be adsorbed onto the surface of Au NPs through strong electrostatic and hydrophobic interactions. Its fluorescence was efficiently quenched by the Au nanoparticles. However, in the presence of Hg(2+) and NaBH4, Hg(2+) was reduced and an Au/Hg amalgam was formed on the surface of the Au nanoparticles. The perylene probe could hardly be adsorbed and quenched by the Au/Hg amalgam. A turn on fluorescence signal was therefore detected. The assay is quite sensitive, and 5 nM Hg(2+) could be easily detected. It is also very selective, a number of metal ions were tested and no noticeable interference was observed. The assay was also successfully applied for the determination of Hg(2+) in lake water samples. A simple, fast, inexpensive, highly sensitive and selective Hg(2+) sensing strategy is therefore established.

Organocatalyzed Novel Synthetic Methodology for Highly Functionalized Piperidines as Potent α-Glucosidase Inhibitors.

An efficient atom-economic one-pot synthesis of highly functionalized piperidines was achieved by catalytic multicomponent reaction. A wide range of heterogeneous and homogenous catalysts were explored; however, promising results were achieved when a ß-keto-ester was reacted with selected aromatic aldehydes and anilines by using N-acetyl glycine (NAG) as catalyst. The implication of this methodology is straightforward since the products were precipitated out from the reaction solution, eliminating the need of column chromatography purifications. The synthesized piperidines were screened against α-glucosidase inhibition, which revealed that these compounds were very active inhibitors, and some of the compounds showed even better inhibition than the reference compound, at low micromolar concentrations. In silico molecular modeling was also performed to investigate the binding modes of the compounds into the active sites of the target protein.

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.

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 synthesis of dihydropyrimidines for α-glucosidase inhibition to treat type 2 diabetes: in vitro biological evaluation and in silico docking.

A convenient and efficient new method has been established for the synthesis of dihydropyrimidines by inexpensive and non-toxic N-acetyl glycine (NAG) catalysed reaction of aromatic aldehydes with ethyl acetoacetate and urea/thiourea. This method is applicable for various substituted aldehydes as well as urea and thiourea. It has also been used to synthesize bicyclic oxygen-bridged pyrimidine derivatives (4d, 4j). The biological assay revealed that the majority of compounds synthesized displayed modest inhibitory activity against α-glucosidase at low micro-molar concentrations. Molecular docking studies were also performed on the most active compound, 4f (with IC50 value 112.21±0.97 µM), to show the enzyme - inhibitor interactions.

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).

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.

A combined experimental and theoretical approach for doxycycline sensing using simple fluorescent probe with distinct fluorescence change in wide range of interferences.

Overuse of doxycycline (DOXY) can cause serious problems to human health, environment and food quality. So, it is essential to develop a new sensing methodology that is both sensitive and selective for the quantitative detection of DOXY. In our current research, we synthesized a simple fluorescent probe 4,4'-bis(benzyloxy)-1,1'-biphenyl (BBP) for the highly selective detection of doxycycline by through fluorescence spectroscopy. The probe BBP displayed ultra-sensitivity towards doxycycline due to Forster resonance energy transfer (FRET). Fluorescence spectroscopy, density functional theory (DFT), 1H NMR titration, UV-Vis, and Job's plot were used to confirm the sensing mechanism. The charge transfer between the probe and analyte was further examined qualitatively by electron density differences (EDD) and quantitively by natural bond orbital (NBO) analyses. Whereas the non-covalent nature of probe BBP towards DOXY was verified by theoretical non-covalent interaction (NCI) analysis as along with Bader's quantum theory of atoms in molecules (QTAIM) analysis. Furthermore, probe BBP was also practically employed for the detection of doxycycline in fish samples, pharmaceutical wastewater and blood samples.