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CARBOCATALYTIC SYNTHESIS OF AZINES BY OXIDIZED MULTIWALLED CARBON NANOTUBES

INTRODUCTION

Azines (R-C=N-N=C-R´) have gather increasing attention since they find application in several fields. They are usually synthetized by aggressive methods frequently metal-catalysed. Furthermore, a general process for the synthesis of symmetric (R=R´) and asymmetric (R≠R´) azines is still lacking till this work, which introduces mild-oxidized multiwalled carbon nanotubes (oxMWNT) as versatile azine’s metal-free catalyst.

RESULTS AND DISCUSSION

HNO3-medidated oxidation of MWNT yielded the sample oxMWNT whose oxygen surface chemistry, especially as epoxides and carboxylic acids (25% of the sample) was deployed. oxMWNT promoted the condensation of benzaldehyde and hydrazine to diphenyl azine 3a in 3h. We detected the transformation of the self-formed hydrazone into the azine monitoring the reaction by NMR. Control sample based on non-oxidized MWNT only reached 60% conversion of 3a in 3h, while overoxidized sample oxMWNT* finished the reaction in 10 min. Therefore, the surface oxygen chemistry behaved as solid Lewis acid and catalysed the azine formation. oxMWNT also showed high selectivity for aromatic aldehydes (higher than 98%) with a fully recyclable behaviour.

With this excellent catalyst in hand, 15 examples of symmetric azines with different functionalities, including heterocycles and gram-scale performance, were achieved in yields 66-94%. We also synthetized 6 asymmetric examples under similar reaction conditions with 40-92% yields. Two antifungal and antibacterial molecules were obtained with this procedure too, and thanks to the inherent oxMWNT oxidative power able to promote redox reactions, we also developed the one-pot synthesis of azines from benzyl alcohols (7 examples, total yield 47-79%).

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  • 9 Reads
Computational Approaches for Molecular Characterization and Structure-based Functional Elucidation of the Matrix Protein from Nipah henipavirus
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Nipah henipavirus is an emerging RNA virus that poses a danger to world safety due to its high fatality rate. The Nipah virus has caused several illness epidemics in South and Southeast Asia. The matrix protein of Nipah henipavirus plays a crucial function in linking the viral envelope to the virus core. Connecting the viral envelope to the virus core is critical for virus assembly. Through analyses of structural and functional protein explanations, bioinformatics tools can aid in our comprehension of the protein. This study intends to provide structural and functional annotations to proteins. Using in-silico approaches, the analysis also assigns the protein's physicochemical properties, three-dimensional structure, and functional annotation. The in silico research validated the protein’s hydrophilic nature and alpha (α) helix-dominated secondary structure. The protein's tertiary structure model is generally consistent based on various quality evaluation approaches. The functional explanation claimed that the protein is a structural protein that connects the viral envelope to the virus core, a protein that is necessary for virus assembly. This study reveals the importance of the matrix protein as a functional protein needed by Nipah henipavirus.

  • Open access
  • 18 Reads
Supramolecular Drug-Cyclodextrin Inclusion Complexes Entrapped Nanofibrous Biosystems for Biomedical Applications
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Cyclodextrins (CDs) are macrocyclic oligosaccharides, containing six to eight alpha(1→ 4) linked glucopyranose. CDs have a hydrophobic cone-shaped internal cavity and a hydrophilic exterior surface. It forms non-covalent inclusion complexes (ICs) with various drugs by trapping the full or partial inclusion in their cavity. Supramolecular ICs gained interest in engineering entrapped performance due to their potential to protect and modify the physicochemical properties of entrapped lipophilic and volatile drugs. However, the poor structural and mechanical properties of pure CD-ICs could restrict their application and the need for a suitable carrier system. Electrospun nanofibers have been the center of interest for biomedical applications due to their tunable physicochemical properties. Recent studies highlighted that entrapment of drug/CD-based ICs into nanofibers is an active research area since it facilitates high encapsulation, modulate the release profile of guest, integrates multi-type drugs, and leads to a synergistic effect. This mini-review first summarized the potential benefits and shortcomings of drug/CD-ICs and nanofibers and then discussed advancements in fabrication and characteristics of CD-ICs embedded nanofibers, along with some practical suggestions for potential biomedical application.

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  • 6 Reads
Development of new effective methods for the synthesis of lembehynes A–C exhibiting cytotoxic and neuritogenic activity

The report presents data on our studies on the preparation of the precursor lembehyne A and the complete stereoselective synthesis of natural lembehynes B and C, which have cytotoxic and neuritogenic activity. All methods and approaches to the synthesis of the above-mentioned lembehynes presented in the report are based on the use of the catalytic cross-cyclomagnesiation of 1,2-dienes (Dzhemilev reaction) at the key stage of the synthesis.

  • Open access
  • 8 Reads
Synthesis of 1,3-diyne derivatives of lembehyne B with antitumor and neuritogenic activity.

The report presents data on our studies on obtaining lembehyne B derivatives with cytotoxic and neuritogenic activity. The methods and approaches to the synthesis of the above-mentioned lembehynes presented in the report are based on the use of the catalytic cross-cyclomagnesiation of 1,2-dienes (the Dzhemilev reaction) at the key stage of the synthesis.

  • Open access
  • 16 Reads
Development and Validation of RP-UHPLC Method for Determination of Sertraline in Bulk Drug and Dosage Form
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Objective: The new, rapid, sensitive, simple, precise and accurate Reversed- Phase Ultra High Performance Liquid Chromatography (RP-UHPLC) method was developed and validated for determination of Sertraline in bulk drug and Pharmaceutical dosage form. Methods: The UV Spectrum of Sertraline in diluent showed maximum wavelength at 273nm. In RP-UHPLC method separation achieved by Agilent C18 (75mm×3.9mm, 2µm particle size) column using Acetonitrile :( 0.1%OPA) Water (80:20v/v) as mobile phase at flow rate 0.7ml/min. Injection volume is 20µl. RP-UHPLC detection carried out at 273nm. Results: In RP-UHPLC method retention time was found to be 3.75min. The Calibration curve was found to be linear (r2=0.999) with concentration range of 10-50µg/ml. The Accuracy (% recovery) for Sertraline was found to be 99-100%. The % RSD (intra-day and inter precision) values are not more than 2% hence the developed methods are accurate and precise. The LOD and LOQ were found to be 0.2085µg/ml and 0.6321µg/ml respectively. Conclusion: The developed method was validated with respect to linearity, accuracy, precision, robustness, ruggedness, LOD and LOQ as per ICH guidelines. The proposed method was used for routine analysis of Sertraline in Bulk drug and Solid dosage Form.

  • Open access
  • 82 Reads
In Silico Comparison of Drug-likeness of Phytochemicals from Nine Herbal Plants against Asthma
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Asthma is a chronic obstructive pulmonary disease, affecting approximately 300 million people worldwide. Current therapies present disadvantages like side effects and high cost. Alternatively, herbal plants have been used for decades as focal medicine to cure asthma. The goal of this research was to make use of molinspiration and pkCSM in silico tools to determine the drug-likeness of nine phytochemicals (Mangiferonic acid, Withaferin A, Stigmasterol, 6-Shogaol, Rosmarinic acid, Glycyrrhizin, Alphitolic acid, Oleanic acid, and Kalambroside A) present in nine distinct herbal plants. These phytochemicals have reported anti-asthmatic properties. Currently, available fluticasone propionate drug was used as the positive control. Molinspiration findings showed that except for glycyrrhizin and Kamabroside A, all other phytochemicals obeyed Lipinski’s and Verber’s rules. Furthermore, all phytochemicals except glycyrrhizin and Kalambroside A exhibited considerable bioactivity for nuclear receptors (NRs) with bioactivity scores ranging from 0.20 to 0.96. The pkCSM results indicated that mangiferonic acid, withaferin A, 6-shogaol, and stigmasterol exhibit high intestinal absorption (>80%), high Caco-2 permeability (log Papp > 0.90 x 10-6 cm/s), high lethal dose (LD50 = 2.081 to 3.201 mol/kg), non-mutagenicity, and non-hepatotoxicity. Furthermore, these phytochemicals were non-inhibitors of cytochrome P450 enzymes. In conclusion, mangiferonic acid abundantly available in Pericampylus glaucus is regarded as the best phytochemical that can be developed into a drug against asthma. Since it had good bioavailability, considerable bioactivity towards NRs, and higher LD50 than the control drug. However, further wet-lab experiments need to be carried out to develop mangiferonic acid as a potent anti-asthmatic drug.

  • Open access
  • 7 Reads
Construction of Lipid-Drug Conjugates for Beclomethasone Dipropionate

Lipid-based nanoparticles (LBNs) are a new type of nanoparticulate drug delivery system, which have been gradually shown broad prospects in pulmonary drug delivery systems. However, the main disadvantage of these LBNs for inhalable drugs with limited lipophilicity is the low encapsulation capacity. Herein, this study anticipates establishing a technology platform to improve the loading capacity of low lipophilicity drugs in LBNs, for the therapy of lung diseases. A proof-of-concept was carried out using Beclomethasone dipropionate (BDP) as a model drug. BDP was conjugated with stearic acid (SA), a kind of the lipid matrix for LBN. The conjugate was characterized and the interactions between the conjugate and SA were investigated by molecular dynamics simulation. It is expected that the drug loading capacity of weak-lipophilic drugs in LBN can be increased by establishing the technology platform, and the application of LBNs in pulmonary delivery can be broadened.

  • Open access
  • 6 Reads
Ti-catalyzed reaction of β-pinene with BF3·THF

The reaction of β-pinene with BF3·THF in the presence of the catalytic system Cp2TiCl2/Mg was carried out for the first time to obtain a previously undescribed 1-fluoro-substituted boraspirane. The reaction proceeds stereoselectively, but is complicated by the rearrangement of the β-pinene under the Ti-catalyzed reaction conditions.

  • Open access
  • 6 Reads
In-silico computational strategies for structure-based characterization of the fusion protein of Nipah henipavirus

Throughout history, viral epidemics of varying frequency and intensity have been responsible for inducing panic and causing widespread damage. The Nipah virus has one of the highest rates of fatalities of any infectious disease in the world. There have been cases when severe respiratory distress has resulted in death, and it is known that these cases can cause encephalitis. The appearance of the virus and its ability to spread is affected by several factors. Several strategies have been created to raise awareness about the need for personal hygiene and enhance surveillance within the contaminated zone. This work aimed to determine the characteristics of a previously unidentified protein linked with the fusion of Nipah henipavirus particles. The protein's secondary structure comprises helix, sheet, turn, and secondary coil structures. The protein is a fusion protein. In addition, the estimated Ramachandran plot provided evidence of the accuracy of the modeled protein structure. This accuracy was then verified by the Z-score-based and local model quality evaluation methods. It is possible to think of the protein as a target for developing prospective therapeutic and vaccine candidates directed against the protein to fight viral infections.

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