A Review on the Antimicrobial Activity of Schiff Bases: Data Collection and Recent Studies

Schiff bases (SBs) have extensive applications in different fields such as analytical, inor‐ ganic and organic chemistry. They are used as dyes, catalysts, polymer stabilizers, luminescence chemosensors, catalyzers in the fixation of CO2 biolubricant additives and have been suggested for solar energy applications as well. Further, a wide range of pharmacological and biological applica‐ tions, such as antimalarial, antiproliferative, analgesic, anti‐inflammatory, antiviral, antipyretic, an‐ tibacterial and antifungal uses, emphasize the need for SB synthesis. Several SBs conjugated with chitosan have been studied in order to enhance the antibacterial activity of chitosan. Moreover, the use of the nanoparticles of SBs may improve their antimicrobial effects. Herein, we provide an ana‐ lytical overview of the antibacterial and antifungal properties of SBs and chitosan‐based SBs as well as SBs‐functionalized nanoparticles. The most relevant and recent literature was reviewed for this purpose

Antimicrobial and antioxidant properties and quantitative screening of phytochemicals of Fraxinus excelsior L. and Eschscholtzia californica Cham. mother tinctures

The antioxidant and antimicrobial activities of Fraxinus excelsior L. and Eschscholtzia californica Cham. mother tinctures against a range of foodborne bacteria were investigated to determine the major components and to analyse the action spectrum and antimicrobial effectiveness of the extracts. Results demonstrated a significant antioxidant activity of Fraxinus excelsior L. and a lower activity of Eschscholtzia californica Cham. and a good chemical phenolic composition with the highest content of flavonoids. The Fraxinus excelsior L. and Eschscholtzia californica Cham. mother tinctures demonstrated a middle-high antimicrobial activity against, respectively, 66.67% and 43.33% of all tested bacteria. The inhibitory activity showed a moderate effect on the growth of the sensitive strains in presence of extracts minimum inhibitory concentration. The synergistic actions of bioactive compounds detected in the extracts might be on the basis of antioxidant and biological activities observed and should be used in pharmaceutical, food preservation, alternative medicine and natural therapies fields

Carbazoles: Role and Functions in Fighting Diabetes

Carbazole derivatives have gained a lot of attention in medicinal chemistry over the last few decades due to their wide range of biological and pharmacological properties, including antibacterial, antitumor, antioxidant, and anti-inflammatory activities. The therapeutic potential of natural, semi-synthetic or synthetic carbazole-containing molecules has expanded considerably owing to their role in the pathogenesis and development of diabetes. Several studies have demonstrated the ability of carbazole derivatives to reduce oxidative stress, block adrenergic hyperactivation, prevent damage to pancreatic cells and modulate carbohydrate metabolism. In this survey, we summarize the latest advances in the synthetic and natural carbazole-containing compounds involved in diabetes pathways

Synthesis of sericin-based conjugates by click chemistry: enhancement of sunitinib bioavailability and cell membrane permeation

Sericin is a natural protein that has been used in biomedical and pharmaceutical fields as raw material for polypeptide-based drug delivery systems (DDSs). In this paper, it has been employed as pharmaceutical biopolymer for the production of sunitinib–polypeptide conjugate. The synthesis has been carried out by simple click reaction in water, using the redox couple l-ascorbic acid/hydrogen peroxide as a free radical grafting initiator. The bioconjugate molecular weight (50 kDa < Mw < 75 kDa) was obtained by SDS-PAGE, while the spectroscopic characteristics have been studied in order to reveal the presence of grafted sunitinib. In both FT-IR and UV/Vis spectra, signals corresponding to sunitinib functional groups have been identified. Since sunitinib is an anticancer drug characterized by low bioavailability and low permeability, the bioconjugation aimed at their enhancement. In vitro studies demonstrated that bioavailability has been increased to almost 74%, compared with commercial formulation. Also cell membrane permeability has been augmented in in vitro tests, in which membrane models have been used to determine the lipid membrane/physiological fluid partition coefficient (Kp). The log(Kp) value of the bioconjugate was increased to over 4. This effect resulted in a three-fold decrease of IC50 value against MCF-7 cells

Target Therapy in Cancer Treatment: mPGES-1 and PARP

Target therapy is an approach focusing on specific protein or signaling pathways. This therapy is directly aimed to a molecular target such as a receptor, growth factor or enzyme in cancer cells. These targets are used by the tumor cells themselves to obtain uncontrolled proliferation, resistance to traditional therapies and to increase the number of blood vessels in the tissue of origin (neoangiogenesis). A purpose of target therapy may be to counteract the growth and proliferation of cancer cells through the use of drugs or monoclonal antibodies capable of inhibiting the receptor for the epidermal growth factor (EGFR), that is crucial in the process of neo-angiogenesis, protein kinases (PKs), as regulators of cell growth signals and human epidermal growth factor type 2 (HER2), which is essential in stimulating growth and proliferation of cancer cells. Among anticancer drugs, Bevacizumab, a humanised monoclonal antibody produced by recombinant DNA technique, is used for the first-line treatment of metastatic breast cancer, as it inhibits EGFR and the vascular endothelial cell growth factor (VEGF). Abemaciclib, a protein kinase inhibitor drug, is also used for the treatment of the same cancer. In 20-30% of primary breast tumors, the excessive expression of HER2 is observed; thus, HER2 inhibitors may represent another plausible therapy. A potent HER2 inhibitor is the recombinant humanized igG1 monoclonal antibody Trastuzumab, which was first tested in 1992 and is currently used for the treatment of HER2 positive breast cancer. Unfortunately, despite the numerous advances in finding new therapies, patients treated with these drugs often suffer from severe undesirable side effects. Therefore, the search for new therapeutic targets may be desirable. In this paper we analyse particularly two targets studied quite recently: the microsomal prostaglandin E2 synthase type 1 (mPGES-1) and poly (ADP-ribose) polymerase (PARP) proteins

Benzothiazole-Containing Analogues of Triclocarban with Potent Antibacterial Activity

Triclocarban (TCC) is a polychlorinated, aromatic, antimicrobial agent commercially used since the 1950s in personal care products for the prevention of spoilage and infections. Humans are frequently exposed to TCC due to its widespread use, leading to its substantial release into the aquatic environment. With the recent ban of TCC from some personal care products, implemented in 2016, many replacement antimicrobial compounds have been studied by researchers. Herein, we report the synthesis and biological activity of a series of diarylureas, analogues of TCC that bear the benzothiazole nucleus as one of the two aryl moieties. Among the studied compounds, 2bF and 2eC showed the highest antimicrobial activity against Staphylococcus aureus, being also more active than TCC, with MIC values of 8 µg/mL versus 16 µg/mL of TCC. Moreover, compound 2bB was much more active than TCC against Enterococcus faecalis, a Gram-positive bacterium that is, unfortunately, strongly responsible for nosocomial infections. Finally, interesting results were found for compound 2bG that, even though less active than the others, exerts an interesting bactericidal action