Synthesis of a new class of antimicrobial agents incorporating the indolin-2-one moiety

Synthesis of Novel 3-(4-tert-Butylphenyl)-5-Cylopropyl-4H-1,2,4-Triazole Derivatives with Antioxidative and Antimicrobial Activities

Background:

In this work, new heterocyclic compounds containing 3-(4-tertbutylphenyl)- 5-cyclopropyl-4H-1,2,4-triazole ring were synthesized, starting from iminoester hydrochlorides and 4-tert-butylbenzhyrazide.

Methods:

Ethyl N-[(4-tert-butylphenyl)carbonyl]cyclopropanecarbohydrazonoate was used to synthesize 4-amino-3-(4-tert-butylphenyl)-5-cyclopropyl-4H-1,2,4-triazole, 3-(4-tert-butylphenyl)-5- cyclopropyl-4-(arylmethyleneamino)-4H-1,2,4-triazole, 3-(4-tert-butylphenyl)-5-cyclopropyl-4- (arylmethylamino)-4H-1,2,4-triazole and their phthalonitrile derivatives sequentially.

Results:

Seventeen new 3-(4-tert-butylphenyl)-5-cyclopropyl-4H-1,2,4-triazole derivatives were synthesized and their antioxidant and antimicrobial activities were determined.

Conclusion:

Imine and amine derivatives were better antioxidants than phthalonitrile derivatives. Doubly fluorination compounds appeared to result in higher activity. The compounds tested with five microorganisms showed better activity against B. subtilis with the antimicrobial activity of two far exceeding that of ampicillin. Imine and amine derivatives were better antimicrobials than phthalonitrile derivatives.

Indolin-2-one compounds targeting thioredoxin reductase as potential anticancer drug leads

Several compounds bearing the indolinone chemical scaffold are known to possess anticancer properties. For example, the tyrosine kinase inhibitor sunitinib is an arylideneindolin-2-one compound. The chemical versatility associated with structural modifications of indolinone compounds underlies the potential to discover additional derivatives possessing anticancer properties. Previously synthesized 3-(2-oxoethylidene)indolin-2-one compounds, also known as supercinnamaldehyde (SCA) compounds in reference to the parent compound 1 [1-methyl-3(2-oxopropylidene)indolin-2-one], bear a nitrogen-linked α,β-unsaturated carbonyl (Michael acceptor) moiety. Here we found that analogs bearing N-substituents, in particular compound 4 and 5 carrying an N-butyl and N-benzyl substituent, respectively, were strongly cytotoxic towards human HCT 116 colorectal and MCF-7 breast carcinoma cells. These compounds also displayed strong thioredoxin reductase (TrxR) inhibitory activity that was likely attributed to the electrophilicity of the Michael acceptor moiety. Their selectivity towards cellular TrxR inhibition over related antioxidant enzymes glutathione reductase (GR), thioredoxin (Trx) and glutathione peroxidase (GPx) was mediated through targeting of the selenocysteine (Sec) residue in the highly accessible C-terminal active site of TrxR. TrxR inhibition mediated by indolin-2-one compounds led to cellular Trx oxidation, increased oxidative stress and activation of apoptosis signal-regulating kinase 1 (ASK1). These events also led to activation of p38 and JNK mitogen-activated protein kinase (MAPK) signaling pathways, and cell death with apoptotic features of PARP cleavage and caspase 3 activation. In conclusion, these results suggest that indolin-2-one-based compounds specifically targeting TrxR may serve as novel drug leads for anticancer therapy.

New pyrano[2,3-c]pyridazine derivatives with antimicrobial activity synthesized using piperidine as the organocatalyst

A simple and efficient method for the synthesis of highly diverse pyrano[2,3-c]pyridazines was achieved by a one pot multicomponent reaction using piperidine as the organocatalyst. The synthesis of a series of heterocyclic derivatives with varying functionality (e.g. thiazine, tetrazole and pyrimidine) incorporating the pyrano[2,3-c]pyridazine moiety were achieved via reaction of 2a-e with different reagents. The structures of the synthesized derivatives were elucidated by FTIR, MS, (1)H and (13)C NMR spectroscopy. A number of the newly synthesized targeted compounds 2b-e, 3a-c and 4a-c were evaluated for their in vitro antibacterial activity and were compared with chloramphenicol and nystatin as broad spectrum reference standard antibiotics. Tests were carried out against Staphylococcus aureus (MTCC3160) and Enterococcusi fecalis as Gram-positive bacteria, and Escherichia coli (MTCC1652) and Klebsiella pneumonia as Gram-negative bacteria. Antifungal potential against Candida albicans, and Aspergillus albicans strains were also evaluated. The results revealed that compounds 3a and 3c showed strong significant activity relative to the reference against these bacterial and fungal strains.