Phenolic Thiazoles with Antioxidant and Antiradical Activity. Synthesis, In Vitro Evaluation, Toxicity, Electrochemical Behavior, Quantum Studies and Antimicrobial Screening

Abstract

Oxidative stress represents the underlying cause of many chronic diseases in human; therefore, the development of potent antioxidant compounds for preventing or treating such conditions is useful. Starting from the good antioxidant and antiradical properties identified for the previously reported Dihydroxy-Phenyl-Thiazol-Hydrazinium chloride (DPTH), we synthesized a congeneric series of phenolic thiazoles. The radical scavenging activity, and the antioxidant and chelation potential were assessed in vitro, a series of quantum descriptors were calculated, and the electrochemical behavior of the synthesized compounds was studied to evaluate the impact on the antioxidant and antiradical activities. In addition, their antibacterial and antifungal properties were evaluated against seven aerobic bacterial strains and a strain of C. albicans, and their cytotoxicity was assessed in vitro. Compounds 5a-b, 7a-b and 8a-b presented remarkable antioxidant and antiradical properties, and compounds 5a-b, 7a and 8a displayed good Cu+2 chelating activity. Compounds 7a and 8a were very active against P. aeruginosa ATCC 27853 compared to norfloxacin, and proved less cytotoxic than ascorbic acid against the human keratinocyte cell line (HaCaT cells, CLS-300493). Several phenolic compounds from the synthesized series presented excellent antioxidant activity and notable anti-Pseudomonas potential.

Antioxidant Activity Evaluation and Assessment of the Binding Affinity to HSA of a New Catechol Hydrazinyl-Thiazole Derivative

“…In our previous report using in silico techniques, we have identified in the resorcinol hydrazinyl-thiazoles for the ortho phenol BDE ranging from 65.9 to 70.2 kcal/mol, whereas for the para phenol we identified BDE ranging from 80.8 to 81.1 kcal/mol [ 17 ]. Applying the same computational protocol, for the new CHT compound from the current study, the BDE for the meta phenol was computed to be 69.9 kcal/mol, whereas the BDE for the para phenol was computed to be 77.2 kcal/mol.…”

“…Synthesis of compound 5 (CHT) was performed using a previously reported protocol [ 8 , 17 ]. Briefly, in a round-bottom glass flask, 5 mmol (1.05 g) of compound 3 were dissolved in 30 mL of boiling anhydrous acetone and 5.05 mmol (0.467 g) of chloropropanone (compound 4 ) were added.…”

“…The decrease in the absorbance of the resulted solutions was determined spectrophotometrically at λ = 734 nm, against a blank sample. DPPH • radical scavenging assay was performed using a protocol previously reported by our group [8,17].…”

Synthesis of New Phenolic Derivatives of Quinazolin-4(3H)-One as Potential Antioxidant Agents—In Vitro Evaluation and Quantum Studies

“…The esters 2a-d were In vitro spectrophotometric techniques are the most commonly used assays, because they are easily accessible, fast and simple. According to the literature, multiple quantum and thermodynamical parameters can describe the antioxidant activity of the compounds [12][13][14][15].…”

“…The LUMO describes the ability of a molecule to accept an electron, and in this context, the lowest possible energy level in this orbital is wanted. Therefore, a lower HOMO-LUMO gap indicates that the molecule has a higher antiradical effect [12,14,39].…”