Spectroscopic Methods in Evaluation of Antioxidant Potential, Enzyme Inhibition, Cytotoxicity, and Antimicrobial Activity of the Synthesized N3-Substituted Amidrazones

TL;DR

This paper reports the synthesis and biological evaluation of amidrazones, showing their antioxidant, enzyme inhibition, cytotoxicity, and antimicrobial properties.

Contribution

The study introduces new amidrazones with substituted moieties and demonstrates their diverse biological activities through experimental and multivariate analysis.

Findings

Compound 2d exhibited potent antioxidant activity with DPPH = 90.43% and FRAP = 4.73 mM FeSO4.

Compound 2d showed high inhibition of α-amylase (86.8%) and moderate inhibition of lipase and pepsin.

Unsupervised multivariate analysis confirmed that Ar1 and Ar2 substituents significantly influence amidrazone biological activity.

Abstract

Seven amidrazones containing a characteristic NH2–N=C(Ar1)–NHAr2 moiety, where Ar1, Ar2 are phenyl, 4-methylphenyl, 4-nitrophenyl, 2-pyridyl, and 4-pyridyl substituents, denoted as 2a–2g, were synthesized by the reactions between thioamides and hydrazine. Their molecular structures were confirmed by 1H, 13C, 1H-13C HMQC, 1H-13C HMBC, and 1H-15N HMBC NMR spectroscopy, with complete assignment of the detected signals, as well as by high-resolution mass spectra. The biological activity of all compounds was studied, exhibiting antioxidant properties determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) methods, inhibitory potential against digestive tract enzymes (α-amylase, lipase, pepsin), cytotoxicity (hemolysis), and antimicrobial activities (against Gram-positive and Gram-negative bacteria, and a fungus). The antioxidant activity of the studied amidrazones varied from 83.34% to 93.27% and 1.01–5.79 mM FeSO4 for the DPPH and FRAP methods, respectively. Moreover, these derivatives revealed inhibition potential against α-amylase (28.6–86.8%), lipase (28.0–60.0%), and pepsin (34.1–76.6%), which increased when increasing their concentrations from 0.2 to 1 mg/mL. Among them, compound 2d (possessing 2-pyridyl and 4-nitrophenyl substituents) stood out in particular, as a potent antioxidant (DPPH = 90.43%, FRAP = 4.73 Mm FeSO4) with the highest activity against Gram-positive bacteria: S. aureus (MIC = 64 μg/mL), G. rubripertincta (MIC = 64 μg/mL), and fungus: C. albicans (MIC = 32 μg/mL); high α-amylase (86.8%) inhibition at the highest concentration (1 mg/mL); and lipase (38.0%) and pepsin (43.8%) inhibition at the lowest concentration (0.2 mg/mL). The obtained results were analyzed by unsupervised multivariate techniques to confirm significant differences in the biological activity of amidrazones depending on the Ar1 and Ar2 substituents.

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