Synthesis, antibacterial and antioxidant activities of new 1-alkyl-4-(1-alkyl-4-oxo-1,4-dihydroquinolin-2-yl)pyridinium bromides

Synthesis and biological evaluation of new 2,4,6-trisubstituted pyrimidines and their N-alkyl derivatives

A series of new 2,4,6-trisubstituted pyrimidines and their N-alkyl bromide derivatives were prepared based upon methoxy substituted azachalcones as the starting materials. All newly synthesized compounds were screened for their anti-proliferative, cytotoxic, antibacterial activities and DNA/protein binding affinity. In vitro cell proliferation inhibitory and cell cytotoxic effects of 2,4,6-trisubstituted pyrimidines (1-9) and their N-alkyl bromide derivatives (2a-c, 3a-c,5a-c,6a-c, 8a-c, 9a-c) were obtained with the help of the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) cell proliferation, LDH cytotoxicity detection, and microdilution assays. The antimicrobial activity for these compounds was also evaluated following the European Pharmacopoeia 8.0 protocol. The interactions of these compounds with DNA or bovine serum albumin were investigated by the spectrophotometric titration method. When the cytotoxic analysis and anticancer properties of the compounds were examined, most of the compounds significantly exhibited an anti-proliferative potency on cancer cells (IC₅₀ ∼ 2-10 µg/mL) and caused a cytotoxic effect as low as control drugs, 5-fluorouracil, and cisplatin (∼7-15%). Because the compound-DNA adducts are hyperchromic or hypochromic, they caused variations in their spectra. This situation shows they can be linked to DNA by the groove binding mode at a binding constant range of 2.0 × 104 and 2.4 × 105 M^-1. The antimicrobial screening results revealed that our new compounds for some human Gram(+) and Gram(-) pathogen bacteria showed remarkable activity with MIC values between <7.81 and 125 µg/mL. Overall, incorporation of alkyl chain to pyrimidines in the generation of N-alkyl bromides has resulted in showing differences in DNA/protein binding affinity, along with anti-proliferative and cytotoxic activity in favor of new compounds.

Antibacterial and antioxidant activities for natural and synthetic dual-active compounds

Antimicrobial resistance is widely recognized as a grave threat to global health in the 21st century, since the past decades have seen a dramatic increase in human-pathogenic bacteria that are resistant to one or multiple antibiotics. New antimicrobial agents are urgently required, particularly in the treatment of chronic infections such as cystic fibrosis, often associated with persistent colonization by drug-resistant pathogens and epithelial damage by pulmonary oxidative stress. In such events, it would be favourable to find agents that could have antioxidant and antibacterial activities combined in one molecule. The discovery of compounds that can show a dual-target activity considerably increased in the last years, reflecting the growing confidence that this new approach could lead to better therapeutic solutions for complex multigenic diseases. The aim of this review is to report those natural and synthetic compounds displaying significant antioxidant and antibacterial activities. In recent years there has been a growing attention on plant-derived antimicrobials as an alternative to antibiotics, for their efficacy and low tendency in developing bacterial resistance. Moreover, it was found that some natural products could enhance the activity of common antibiotics displaying a synergistic effect. We then report some selected synthetic compounds with an in-built capacity to act on two targets or with the combination in a single structure of two pharmacophores with antioxidant and antibacterial activities. Recent literature instances were screened and the most promising examples of dual-active antibacterial-antioxidant molecules were highlighted.

4-Quinolone derivatives and their activities against Gram positive pathogens

Gram-positive bacteria are responsible for a broad range of infectious diseases, and the emergency and wide spread of drug-resistant Gram-positive pathogens including MRSA and MRSE has caused great concern throughout the world. 4-Quinolones which are exemplified by fluoroquinolones are mainstays of chemotherapy against various bacterial infections including Gram-positive pathogen infections, and their value and role in the treatment of bacterial infections continues to expand. However, the resistance of Gram-positive organisms to 4-quinolones develops rapidly and spreads widely, making them more and more ineffective. To overcome the resistance and reduce the toxicity, numerous of 4-quinolone derivatives were synthesized and screened for their in vitro and in vivo activities against Gram-positive pathogens, and some of them exhibited excellent potency. This review aims to outlines the recent advances made towards the discovery of 4-quinolone-based derivatives as anti-Gram-positive pathogens agents and the critical aspects of design as well as the structure-activity relationship of these derivatives. The enriched SAR paves the way to the further rational development of 4-quinolones with a unique mechanism of action different from that of the currently used drugs to overcome the resistance, well-tolerated and low toxic profiles.

An efficient one-pot approach for the regio- and diastereoselective synthesis of trans-dihydrofuran derivatives: cytotoxicity and DNA-binding studies

A facile one-pot, three component strategy has been developed for the construction oftrans-2,3-dihydrofuran derivatives. All the synthesized compounds have been evaluated for their cytotoxic activity.

Benzoquinoline amines - Key intermediates for the synthesis of angular and linear dinaphthonaphthyridines

A systematic study on the condensation reaction of 2,4-dichlorobenzo[h]quinoline and naphth-1-ylamine in the presence of CuI as catalyst to functionalised mono- and di-substituted (naphthalen-1-yl)benzo[h]quinoline amines was described. Subsequently these mono- and di-substituted amines on polyphosphoric acid catalysed cyclisation reaction with aromatic/heteroaromatic carboxylic acids led to the construction of angular and linear aromatic/heteroaromatic substituted dinaphthonaphthyridines in good yields.

Spectroscopic studies on the in vitro antioxidant capacity of isopentyl ferulate

Essential oils have played a prominent role in research on natural products, due to the high level of bioactive constituents, which include those derived from phenylpropanoids or terpenoids. This study aimed to evaluate the antioxidant capacity of isopentyl ferulate (IF) employing in vitro experimental models for elimination of the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS+), hydroxyl (OH) and nitric oxide (NO), as well as its capacity to electron transfer by reducing potential and inhibition of lipid peroxidation by TBARS (thiobarbituric acid reactive substances) method. In all in vitro antioxidants protocols, isopentyl ferulate showed to be potent in a concentration of 54.4 nM, presenting a percentage inhibition of 91.29±0.57, 92.63±0.28, 83.62±0.18, 77.07±0.72 and 79.51±0.32% for DPPH, ABTS+, hydroxyl, nitric oxide and TBARS level, respectively. The increase of absorbance at 700 nm in the concentrations of 3.4, 6.8, 13.6, 27.2 and 54.4 nM shows the reducing potential of IF. Similar results were obtained with Trolox (559 nM), a hydrophilic synthetic analogue of α-tocopherol, which is widely used as a standard antioxidant. The present study demonstrated that isopentyl ferulate has an antioxidant activity in vitro experimental models, suggesting that this compound could enhance the development of a new product with antioxidant properties. However, further in vivo studies are needed to assign possible implications in the treatment of diseases related with free radicals.