Current Organic Chemistry - Volume 22, Issue 27, 2018

The following review provides up to date information about the recent progress in synthetic approaches and chemical reactivities to α-(arylhydrazono)-β-ketoaldehydes, mainly using N,N-dimethyl-β-ketoenamines as an efficient starting material. These α - (arylhydrazono)-β-ketoaldehydes have assured to be of biological interest and furnish an inlet to a new class of biologically active heterocyclic compounds for biomedical implementations. The data published until the end of 2017 have been covered.

Efavirenz is an anti-HIV drug categorized under Non-Nucleoside Reverse Transcriptase Inhibitor (NNRTI). It is recognized as the first line drug of choice for treating HIV infections. Poor aqueous solubility of the drug (< 10 μg/mL) offers specific challenges in formulation design, leading to limited bioavailability of 40 to 50%. To address this issue, several drug delivery options have been adopted for Efavirenz with special emphasis on alternative routes of administration like buccal, rectal, vaginal and transdermal. The carrier-based delivery using vesicular systems, micro/nanoparticles, hydrogels, degradable systems, etc. was also designed through solvent evaporation, spray drying, double emulsification and ionic gelation techniques. The nanotechnology-based drug delivery approaches have been demonstrated with significant improvement in the solubility and bioavailability of Efavirenz. The objective of the review is to compile and present the comprehensive report of various researches highlighted for synthesizing nanoparticles of Efavirenz using different polymeric and nonpolymeric materials. We have discussed the range of materials utilized for the preparation of stable nanoparticles through the validated experimental protocol and their substantial selection of optimized formulation through significant results.

Thermal energy can be stored as sensible or latent heat. Phase change materials (PCMs) use latent heat storage, offering great energy density over a limited temperature range. Organic materials, such as paraffins, fatty acids, polymers, sugar alcohols and their eutectic mixtures can be used as PCMs for applications near room temperature, due to their high liquid-solid enthalpy. Inorganic salts and salts hydrates can also function as PCMs, although most of them suffer from incongruent crystallization. Pure PCMs exhibit some disadvantages, such as leakage, decreased thermal transfer and storage capacity during use, arising from their large change in molar volume upon phase transition. These drawbacks can be alleviated by impregnation in high porosity matrices. A promising class of porous matrices is represented by Mesoporous Silica Nanomaterials (MSN). MSN offer high pore volume and surface area, often in excess of 1 cm3/g and 1000 m2/g, respectively, monodisperse pores, high chemical and thermal stability and ease of tailoring their textural, morphological and surface properties through chemical synthesis. To date, the studies on nanocomposites phase change materials using mesoporous silica matrices have not been reviewed. The current review focuses on the various strategies for obtaining the MSN matrices and PCMs, their properties and the fundamental aspects pertaining to the difference in thermal properties between nanoconfinement in MSN and bulk. The monodisperse pores in the 2 – 50 nm range give rise to nanoconfinement effects, such as decreased melting and crystallization points with respect to bulk phases, hysteresis between melting and crystallization and existence of an interface, liquid-like layer between the silica surface and PCM molecules. The nanoconfinement effects on the PCM properties are discussed and insight into the materials and their applications is provided.

Biofilm is the advantageous mode of growth for microorganisms, where dynamic microbial communities are irreversibly attached to a solid substratum, as well as to each other. The residing bacterial cells in the biofilm embedded in a self-made matrix of extracellular polymeric substances, which makes the community up to 1,000-times more resistant to detergents and antibiotics than planktonic cells. Dental caries is a common oral infectious disease associated with pathogenic microbes, such as Streptococcus mutans, which integrated into a complex dental plaque biofilm on tooth surface. Streptococcus mutans has been shown to be one of the main pathologic organisms in the initiation and development of dental caries because of the following virulence attributes: producing glucosyltransferases, and synthesizing extracellular polysaccharides, which promote bacterial accumulation and biofilm formation, surviving at a low pH environment and rapidly producing organic acids. The extracellular polysaccharides matrix constitutes an external scaffold system that supports stable synergistic interactions between cariogenic bacteria and commensal. The increased prevalence of antibiotic resistance exhibited by biofilm bacteria prompts an emergent need to develop new drugs and to design novel strategies to identify effective drug targets. As the attachment of the cells to a surface is crucial for Streptococcus mutans biofilm formation, it became an attractive target for researchers to design successful small molecule inhibitors. Numerous small molecules and natural products, including marine alkaloid, flavonoids, anthraquinones, phenolic compounds, and other synthetic analogs have been characterized and shown to have anti-biofilm activity toward Streptococcus mutans. In this review, we briefly summarized their chemical properties, mode of action and biological efficacy of different small molecules reported.

Hantzsch pyridines are conspicuous nitrogen-holding heterocyclic compounds and different procedures have been worked out for their synthesis. Hantzsch pyridines have a variety of methods for their synthesis but according to the literature survey, two pot synthetic route is more developed than one pot due to a vast variety of catalysts becoming cheap, economical, eco-friendly and recyclable. However, researchers synthesized Hantzsch pyridines under different methodologies due to the molecule's reactivity and requirement of the chemist. An up-to-date first review related to the two pot and one pot synthetic methodologies of Hantzsch pyridines gives the most valuable basic skeleton to derive the biologically active compounds, which are frequently used in the pharmacological field. The main objective of this review is to explore all the synthetic modifications in its methodologies, which are fruitful, especially for the synthetic chemists and therapeutical industry.