Ultrasound-assisted-one-pot synthesis and antiplasmodium evaluation of 3-substituted-isoindolin-1-ones.

As the attempts to control malaria through chemotherapy strategies are restricted, we have prepared a small library of 3-substituted-isoindolinones from (Z)-3-benzylideneisobenzofuran-1(3H)-ones in one-pot fashion under ultrasound irradiation. The one-pot reaction was scalable and efficiently produced the desired products (1a-m) in high yields in a short reaction time. Evaluation of their in vitro antiplasmodium assay against the 3D7 (chloroquine-sensitive) and FCR3 (chloroquine-resistant) strains of Plasmodium falciparum demonstrated that they displayed moderate to strong antiplasmodium activities (the IC50 values ranging from 4.21-34.80 µM) and low resistance indices. The in silico prediction of ADME and physicochemical properties showed that the synthesized compounds met the drug-likeliness requirements and featured low toxicity effects. Based on the evaluation of the antiplasmodium profiles, 3-substituted-isoindolinone derivatives of 1a, 1d, 1h, and 1l may become potential antiplasmodium candidates.

Facile fabrication of chitosan Schiff bases from giant tiger prawn shells (Penaeus monodon) via solvent-free mechanochemical grafting.

Fabrication of chitosan Schiff bases (ChSB) from giant tiger prawn shells (Penaeus monodon) using an environmentally friendly method has been conducted successfully. Transformation of Prawn Shells (PS) as raw material into chitin then chitosan was executed under ambient temperature. Later, three Ch Schiff bases (ChSB-A, ChSB-S, and ChSB-V) were successfully synthesized for the first time via solvent-free mechanochemical grafting with 2-hydroxy benzaldehyde, 4-methoxy benzaldehyde, and 3-methoxy-4-hydroxy benzaldehyde, respectively. Synthesis was carried out with Shaker Mill-Ultimate Gravity equipped with a Teflon jar with zirconia balls; then the product was characterized. FTIR analysis proved the conversion of free amine to imine groups. The degree of substitution (DS) and crystallinity index (CrI) were determined by elemental analysis and X-ray diffraction. The DS values obtained were about 0.343, 0.795, and 0.055 for ChSB-A, ChSB-S, and ChSB-V, respectively. The CrI of ChSB-A, ChSB-S, and ChSB-V was 53.3, 51.7, and 46.9 %, respectively. The thermal gravimetric analysis showed that the mechanochemical grafting of Ch improves the thermal stability of ChSB. This developed method provides a novel potential technique to convert PS into ChSB products by solvent-free mechanochemical grafting.

Utilization of vanillin to prepare sulfated Calix[4]resorcinarene as efficient organocatalyst for biodiesel production based on methylation of palmitic acid and oleic acid.

Recently, biodiesel production from palm oils has been thoroughly investigated to substitute crude oil due to its scarcity. However, the biodiesel production process is time-consuming due to its slow kinetics; thus, concentrated sulfuric acid has been used to fasten the reaction process in some industries. Unfortunately, sulfuric acid is a toxic, corrosive, and non-environmentally friendly catalyst. In this study, we prepared sulfated Calix[4]resorcinarene derived from vanillin as an efficient organocatalyst to replace sulfuric acid. The catalytic activity of sulfated Calix[4]resorcinarenes was evaluated through the methylation of palmitic acid and oleic acid as model compounds due to their abundant amounts in palm oil. The Calix[4]resorcinarene and sulfated Calix[4]resorcinarenes have been obtained through a one-pot reaction in 71.8-98.3% yield. Their chemical structures were confirmed by using FTIR, NMR and HRMS spectrometry analyses. The results showed that the sulfated Calix[4]resorcinarene exhibited high catalytic activity for methyl palmitate and methyl oleate productions in 94.8 ± 1.8 and 97.3 ± 2.1% yield, respectively, which was comparable to sulfuric acid (96.3 ± 1.8 and 95.9 ± 2.5%). The optimum condition was achieved by using 0.020 wt equivalent of organocatalyst for 6 h reaction process at 338 K. The methylation of palmitic acid and oleic acid fits well with the first-order kinetic model (R2 = 0.9940-0.9999) with a reaction rate constant of 0.6055 and 1.1403 h-1, respectively. Further investigation reveals that the hydroxyl group of vanillin plays a pivotal role in the organocatalytic activity of sulfated Calix[4]resorcinarene.

Ultrasonic-assisted-synthesis of isoindolin-1-one derivatives.

A small library of 3-hydroxyisoindolin-1-ones has been prepared from 3-alkylidenephtalides under ultrasonic irradiation. This practical synthesis is featured by group tolerance, high efficiency and yields. The reaction can also be performed in multigram scale and be further extended to access other motifs of isoindolin-1-ones in a one-pot fashion.

Novel luminescent Schiff's base derivative with an azo moiety for ultraselective and sensitive chemosensor of Fe3+ ions.

Chemosensors with ultrasensing capabilities for detection of metal ions have received particular attention when using luminescent organic compounds. Even though hundreds of chemosensor agents have been reported for Fe3+ ion sensing, the designs of those molecules have been complicated and time consuming, in addition to having limited application for aquatic samples due to their poor hydrophilicity. Here, we synthesized a novel azo-imine derivative (L2) that showed ultrasensitive and selective sensing for Fe3+ ions. L2 exhibited ultraselective detection of Fe3+ ions with a turn-off of its emission intensity at 341 nm in H2 O:MeOH (4:1 v/v) aqueous medium. This quenching phenomenon was in good agreement with its colour change from orange-yellowish to colourless. Its capability was shown due to its very low limit of detection and limit of quantification values of 0.31 and 1.04 µM, respectively. The interference study showed that L2 is ultraselective for the detection of Fe3+ ions without a significant reduction in its sensing capability even in competitive metal mixtures. Furthermore, direct Fe3+ quantification of tap and drinking water showed that L2 gave good recovery percentages. These findings demonstrated that the Schiff's base with an azo fluorophore derivative is a potential chemosensor agent for Fe3+ ions sensing applications in aqueous media.

Antibacterial and Antifungal Activity of Three Monosaccharide Monomyristate Derivatives.

Microbial infections remains a serious challenge in food industries due to their resistance to some of the well-known antibacterial and antifungal agents. In this work, a novel monomyristoyl ester (fructosyl monomyristate) and two other derivatives (i.e., glucosyl and galactosyl monomyristates) were successfully synthesized from myristic acid and monosaccharides in two-step reactions. First, the myristic acid was converted to myristoyl chloride, and then the myristoyl chloride was reacted with fructose, glucose and galactose separately to produce the corresponding monosaccharide monomyristate derivatives. The structures of the synthesized products were confirmed by Fourier transform infrared (FTIR), proton and carbon nuclear magnetic resonance (1H- and 13C-NMR), and mass spectral (MS) data. The monomyristates esters were obtained in reaction yields of 45.80%-79.49%. The esters were then evaluated for their antimicrobial activity using the disc diffusion test. It was found that the esters exhibited a medium antibacterial activity against gram-positive bacteria; however, they showed a weak antibacterial activity against gram-negative bacteria. Amongst the esters, galactosyl myristate yielded the highest antibacterial activity against Salmonella typhimurium, Staphylococcus aureus and Bacillus subtilis, while glucosyl monomyristate exhibited the highest antibacterial activity only against Escherichia coli. Additionally, all products showed remarkable antifungal activity against Candida albicans. These findings demonstrate that monosaccharide monomyristate derivatives are promising for use as biocompatible antimicrobial agents in the future.

Synthesis and biological activity of novel bis-indole inhibitors of bacterial transcription initiation complex formation.

The increasing resistance of bacteria against clinically approved antibiotics is resulting in an alarming decrease in therapeutic options for today's clinicians. We have targeted the essential interaction between bacterial RNA polymerase and σ(70)/σ(A) for the development of lead molecules exhibiting a novel mechanism of antibacterial activity. Several classes of structurally related bis-indole inhibitors of bacterial transcription initiation complex formation were synthesized and their antimicrobial activities were evaluated. Condensation of indole-7- and indole-2-carbohydrazides with 7- and 2-trichloroacetylindoles or indole-7- and indole-2-glyoxyloyl chlorides resulted in the successful synthesis of 7,7'-, 2,2'-, 2,7'- and 3,2'-linked bis-indole derivatives with -CO-NH-NH-CO- and -CO-CO-NH-NH-CO- linkers. Indole-7-glyoxyloyl chlorides were reacted with hydrazine hydrate in different ratios to afford respective -CO-CO-NH-NH-CO-CO- bis-indole or hydrazide derivatives. The resulting compounds were found to be active against the ß'-CH-σ(70)/σ interaction in ELISA assays and inhibited the growth of both Gram-positive and Gram-negative bacteria. Structure-activity relationship (SAR) studies were performed in order to identify the structural features of the synthesized inhibitors required for biological activity.