Water-induced isomerism of salicylaldehyde and 2-acetylpyridine mono- and bis-(thiocarbohydrazones) improves the antioxidant activity: spectroscopic and DFT study
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2019
Authors
Assaleh, Mohamed H.Božić, Aleksandra R.

Bjelogrlić, Snežana

Milošević, Milena D.

Simić, Milena R.

Marinković, Aleksandar D.

Cvijetić, Ilija

Article (Published version)

Springer
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Thiocarbohydrazones (TCHs) and structurally related molecules are versatile organic compounds which exert antioxidant, anticancer, and other beneficial health effects. The combination of UV/Vis, NMR spectroscopy, and quantum chemical calculations was used to rationalize the experimentally observed increase in the radical scavenging activity upon the addition of water in DMSO solution of TCHs. Mono- and bis(salicylaldehyde) TCHs (compounds 1 and 2) undergo water-induced E-to-Z isomerization which is followed by disruption of intramolecular hydrogen bond, ground state destabilization, and 11 kcal/mol decrease in the bond dissociation enthalpy (BDE). Electron spin delocalization is more pronounced in Z-isomers of 1 and 2. On the other hand, 2-acetylpyridine TCHs (compounds 3 and 4) undergo thione-to-thiol tautomerism which also decreases the BDE and facilitates the hydrogen atom transfer to 2,2-diphenyl-1-picrylhydrazyl radical (DPPH∙). The appearance of thiolic –SH group as another react...ive site toward free radicals improves the antioxidant activity of 3 and 4. The spin density of 3- and 4-thiol radicals is delocalized over the entire thiocarbohydrazide moiety compared to more localized spin of thione radicals. Additional stabilization of thiol radicals corroborates with the increased antioxidant activity. This study provides the new insights on the solution structure of TCHs, and also highlights the importance of solution structure determination when studying the structure-antioxidant relationships of isomerizable compounds.
Keywords:
Thiocarbohydrazones / E/Z isomerism / Tautomerism / Antioxidantactivity / Bonddissociationenthalpy / Spindensity distributionSource:
Structural Chemistry, 2019, 30, 2447-2457Publisher:
- Springer
Funding / projects:
- Study of the Synthesis, Structure and Activity of Natural and Synthetic Organic Compounds (RS-172013)
- Rational design and synthesis of biologically active and coordination compounds and functional materials, relevant for (bio)nanotechnology (RS-172035)
- Interactions of natural products, their derivatives and coordination compounds with proteins and nucleic acids (RS-172055)
DOI: 10.1007/s11224-019-01371-4
ISSN: 1040-0400
WoS: 000494698700034
Scopus: 2-s2.0-85068185532
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Institution/Community
IHTMTY - JOUR AU - Assaleh, Mohamed H. AU - Božić, Aleksandra R. AU - Bjelogrlić, Snežana AU - Milošević, Milena D. AU - Simić, Milena R. AU - Marinković, Aleksandar D. AU - Cvijetić, Ilija PY - 2019 UR - https://cer.ihtm.bg.ac.rs/handle/123456789/3037 AB - Thiocarbohydrazones (TCHs) and structurally related molecules are versatile organic compounds which exert antioxidant, anticancer, and other beneficial health effects. The combination of UV/Vis, NMR spectroscopy, and quantum chemical calculations was used to rationalize the experimentally observed increase in the radical scavenging activity upon the addition of water in DMSO solution of TCHs. Mono- and bis(salicylaldehyde) TCHs (compounds 1 and 2) undergo water-induced E-to-Z isomerization which is followed by disruption of intramolecular hydrogen bond, ground state destabilization, and 11 kcal/mol decrease in the bond dissociation enthalpy (BDE). Electron spin delocalization is more pronounced in Z-isomers of 1 and 2. On the other hand, 2-acetylpyridine TCHs (compounds 3 and 4) undergo thione-to-thiol tautomerism which also decreases the BDE and facilitates the hydrogen atom transfer to 2,2-diphenyl-1-picrylhydrazyl radical (DPPH∙). The appearance of thiolic –SH group as another reactive site toward free radicals improves the antioxidant activity of 3 and 4. The spin density of 3- and 4-thiol radicals is delocalized over the entire thiocarbohydrazide moiety compared to more localized spin of thione radicals. Additional stabilization of thiol radicals corroborates with the increased antioxidant activity. This study provides the new insights on the solution structure of TCHs, and also highlights the importance of solution structure determination when studying the structure-antioxidant relationships of isomerizable compounds. PB - Springer T2 - Structural Chemistry T1 - Water-induced isomerism of salicylaldehyde and 2-acetylpyridine mono- and bis-(thiocarbohydrazones) improves the antioxidant activity: spectroscopic and DFT study VL - 30 SP - 2447 EP - 2457 DO - 10.1007/s11224-019-01371-4 ER -
@article{ author = "Assaleh, Mohamed H. and Božić, Aleksandra R. and Bjelogrlić, Snežana and Milošević, Milena D. and Simić, Milena R. and Marinković, Aleksandar D. and Cvijetić, Ilija", year = "2019", abstract = "Thiocarbohydrazones (TCHs) and structurally related molecules are versatile organic compounds which exert antioxidant, anticancer, and other beneficial health effects. The combination of UV/Vis, NMR spectroscopy, and quantum chemical calculations was used to rationalize the experimentally observed increase in the radical scavenging activity upon the addition of water in DMSO solution of TCHs. Mono- and bis(salicylaldehyde) TCHs (compounds 1 and 2) undergo water-induced E-to-Z isomerization which is followed by disruption of intramolecular hydrogen bond, ground state destabilization, and 11 kcal/mol decrease in the bond dissociation enthalpy (BDE). Electron spin delocalization is more pronounced in Z-isomers of 1 and 2. On the other hand, 2-acetylpyridine TCHs (compounds 3 and 4) undergo thione-to-thiol tautomerism which also decreases the BDE and facilitates the hydrogen atom transfer to 2,2-diphenyl-1-picrylhydrazyl radical (DPPH∙). The appearance of thiolic –SH group as another reactive site toward free radicals improves the antioxidant activity of 3 and 4. The spin density of 3- and 4-thiol radicals is delocalized over the entire thiocarbohydrazide moiety compared to more localized spin of thione radicals. Additional stabilization of thiol radicals corroborates with the increased antioxidant activity. This study provides the new insights on the solution structure of TCHs, and also highlights the importance of solution structure determination when studying the structure-antioxidant relationships of isomerizable compounds.", publisher = "Springer", journal = "Structural Chemistry", title = "Water-induced isomerism of salicylaldehyde and 2-acetylpyridine mono- and bis-(thiocarbohydrazones) improves the antioxidant activity: spectroscopic and DFT study", volume = "30", pages = "2447-2457", doi = "10.1007/s11224-019-01371-4" }
Assaleh, M. H., Božić, A. R., Bjelogrlić, S., Milošević, M. D., Simić, M. R., Marinković, A. D.,& Cvijetić, I.. (2019). Water-induced isomerism of salicylaldehyde and 2-acetylpyridine mono- and bis-(thiocarbohydrazones) improves the antioxidant activity: spectroscopic and DFT study. in Structural Chemistry Springer., 30, 2447-2457. https://doi.org/10.1007/s11224-019-01371-4
Assaleh MH, Božić AR, Bjelogrlić S, Milošević MD, Simić MR, Marinković AD, Cvijetić I. Water-induced isomerism of salicylaldehyde and 2-acetylpyridine mono- and bis-(thiocarbohydrazones) improves the antioxidant activity: spectroscopic and DFT study. in Structural Chemistry. 2019;30:2447-2457. doi:10.1007/s11224-019-01371-4 .
Assaleh, Mohamed H., Božić, Aleksandra R., Bjelogrlić, Snežana, Milošević, Milena D., Simić, Milena R., Marinković, Aleksandar D., Cvijetić, Ilija, "Water-induced isomerism of salicylaldehyde and 2-acetylpyridine mono- and bis-(thiocarbohydrazones) improves the antioxidant activity: spectroscopic and DFT study" in Structural Chemistry, 30 (2019):2447-2457, https://doi.org/10.1007/s11224-019-01371-4 . .