Synthesis, Insecticidal Evaluation of Novel 1,3,4-Thiadiazole Chrysanthemamide Derivatives formed by an EDCI/HOBt Condensation

Cyclodextrins-Peptides/Proteins Conjugates: Synthesis, Properties and Applications

Cyclodextrins (CDs) are a family of macrocyclic oligosaccharides mostly composed of six, seven, or eight α-D-glucopyranose units with α-1,4-glycosidic bonds to form toroidal structures. The CDs possess a hydrophilic exterior and hydrophobic interior with the ability to form an inclusion complex, especially with hydrophobic molecules. However, most existing studies are about conjugation CDs with peptide/protein focusing on the formation of new systems. The CD-peptide/protein can possess new abilities; particularly, the cavity can be applied in modulation properties of more complexed proteins. Most studies are focused on drug delivery, such as targeted delivery in cell-penetrating peptides or co-delivery. The co-delivery is based mostly on polylysine systems; on the other hand, the CD-peptide allows us to understand biomolecular mechanisms such as fibryllation or stem cell behaviour. Moreover, the CD-proteins are more complexed systems with a focus on targeted therapy; these conjugates might be controllable with various properties due to changes in their stability. Finally, the studies of CD-peptide/protein are promising in biomedical application and provide new possibilities for the conjugation of simple molecules to biomolecules.

Asymmetric Mannich Reaction: Synthesis of Novel Chiral 5-(substituted aryl)-1,3,4-Thiadiazole Derivatives with Anti-Plant-Virus Potency

A series of novel chiral 5-(substituted aryl)-1,3,4-thiadiazole derivatives was synthesized in an enantioselective three-component Mannich reaction using cinchona alkaloid squaramide catalyst with excellent enantioselectivities (up to >99% enantiomeric excess (ee)). The bioassay results showed that these derivatives possessed good to excellent activities against tobacco mosaic virus (TMV).

Synthesis of Thymol Derivatives as Potential Non-Irritant Antimicrobial and Insecticidal Agents

Background:

Thymol has been reported to have a variety of antimicrobial and insecticidal activities but it has irritation side effect due to its phenolic nature.

Methods:

A new series of potential non-irritant non-phenolic thymol derivatives were designed to hybridize the well-known biologically active thymol scaffold with various five membered heterocyclic antimicrobial and insecticidal pharmacophores like 1,3,4-oxadiazole, 1,3,4-thiadiazole, 1,2,4-triazole, thiazole and 4-thiazolidinone through different spacers. The target compounds were biologically evaluated for their in vitro antibacterial, antifungal and insecticidal activities.

Results:

Compounds 4b and 9c showed weak antibacterial activity against S. aureus and B.subtilis with the inhibition zone diameters ranging from 2 to 7 mm and 4 mm respectively compared with ciprofloxacin with the inhibition zone diameter of 21 mm. Compounds 9a, 7d and 13b showed weak antibacterial compounds against B. subtilis with inhibition zone diameters 4, 4 and 6 mm respectively. Compounds 12b, 9c and 7a showed 20% insecticidal activity at a concentration of 0.157 mg/cm2 for each compound against Tribolium castaneum (Herbst) and Sitophilus oryzae (L.). Compound 6 showed moderate larvicidal activity against Culex pipiens with 40% mortality at a concentration of 1000 ppm.

Conclusion:

Compound 9c showed weak dual antimicrobial and insecticidal activities.

Oxidative Reactivities of 2-Furylquinolines: Ubiquitous Scaffolds in Common High-Throughput Screening Libraries

High-throughput screening (HTS) was employed to discover APOBEC3G inhibitors, and multiple 2-furylquinolines (e.g., 1) were found. Dose-response assays with 1 from the HTS sample, as well as commercial material, yielded similar confirmatory results. Interestingly, freshly synthesized and DMSO-solubilized 1 was inactive. Repeated screening of the DMSO aliquot of synthesized 1 revealed increasing APOBEC3G inhibitory activity with age, suggesting that 1 decomposes into an active inhibitor. Laboratory aging of 1 followed by analysis revealed that 1 undergoes oxidative decomposition in air, resulting from a [4 + 2] cycloaddition between the furan of 1 and (1)O2. The resulting endoperoxide then undergoes additional transformations, highlighted by Baeyer-Villager rearrangements, to deliver lactam, carboxylic acid, and aldehyde products. The endoperoxide also undergoes hydrolytic opening followed by further transformations to a bis-enone. Eight structurally related analogues from HTS libraries were similarly reactive. This study constitutes a cautionary tale to validate 2-furylquinolines for structure and stability prior to chemical optimization campaigns.

Synthesis and characterization of a series of novel amino β-cyclodextrin-conjugated poly(ε-lysine) derivatives

Soluble poly(ε-lysine)s bearing β-cyclodextrin (β-CD) moieties were prepared by three amino β-CD derivatives and N-succinylated poly(ε-lysine), in which the poly(ε-lysine) and amino β-CD derivatives were bonded covalently to the end carboxyl groups of succinic acid by peptide bonds. 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDCI) and N-hydroxysuccinimide (NHS) were chosen to assist the reaction. The three poly(ε-lysine) derivatives were characterized by 1H nuclear magnetic resonance (1H NMR) and Fourier transform infrared (FT-IR). The synthesis process is simple, feasible and has strong practicability. The target polymers can serve as new polymer biomaterial for use in the biotechnology area.

Multinuclear magnetic resonance studies of 2-aryl-1,3,4-thiadiazoles

The (1) H, (13) C and (15) N spectra of aryl-substituted 1,3,4-thiadiazoles were recorded. The results obtained were correlated with Hammett coefficients. The experimental results were compared with DFT-calculated chemical shifts. The results obtained were compared with those for 1,3,4-oxadiazoles and 1,3,4-selenadiazoles.