Molecular Structure and Antioxidant Properties of Alkali Metal Salts of Rosmarinic Acid. Experimental and DFT Studies

Renata Świsłocka , Ewa Krystyna Regulska , Joanna Karpińska , Grzegorz Świderski , Włodzimierz Lewandowski

Abstract

The molecular structure of alkali metal rosmarinates was studied in comparison to rosmarinic acid using FT-IR, FT-Raman, 1H and 13C NMR spectroscopy, as well as density functional theory (DFT) calculations. The B3LYP/6-311+G(d,p) method was used to calculate optimized geometrical structures of studied compounds, atomic charges, dipole moments, energies, as well as the wavenumbers and intensities of the bands in vibrational and NMR spectra. Theoretical parameters were compared to experimental data. Antioxidant activity was determined using two spectrophotometric methods: (i) Assessing the ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) stable radical and (ii) assay of antioxidant power of ferric ions reducing (FRAP). The linear correlations were found between HOMO–LUMO (highest occupied molecular orbital–lowest unoccupied molecular orbital) energy gap and the reducing power expressed as FRAP (R = 0.77) as well as between IC50 values (the ability of quenching DPPH radicals) and Δνas-s(COO) in IR spectra (differences between asymmetric and symmetric stretching vibrations bands) (R = 0.99). Photochemical properties of studied compounds were also evaluated. The influence of alkali metal on the electronic system of the rosmarinic acid molecule was discussed.
Author Renata Świsłocka (FCEE / DCBB)
Renata Świsłocka,,
- Department of Chemistry, Biology and Biotechnology
, Ewa Krystyna Regulska (FCEE / DCBB)
Ewa Krystyna Regulska,,
- Department of Chemistry, Biology and Biotechnology
, Joanna Karpińska
Joanna Karpińska,,
-
, Grzegorz Świderski (FCEE / DCBB)
Grzegorz Świderski,,
- Department of Chemistry, Biology and Biotechnology
, Włodzimierz Lewandowski (FCEE / DCBB)
Włodzimierz Lewandowski,,
- Department of Chemistry, Biology and Biotechnology
Journal seriesMolecules, ISSN 1420-3049, (N/A 100 pkt)
Issue year2019
Vol24
No14
Pages1-22
Publication size in sheets1.05
ASJC Classification1605 Organic Chemistry
DOIDOI:10.3390/molecules24142645
URL https://www.mdpi.com/1420-3049/24/14/2645
Internal identifierROC 19-20
Languageen angielski
LicenseJournal (articles only); published final; Uznanie Autorstwa (CC-BY); with publication
Score (nominal)100
Score sourcejournalList
ScoreMinisterial score = 100.0, 12-02-2020, ArticleFromJournal
Publication indicators Scopus SNIP (Source Normalised Impact per Paper): 2017 = 1.146; WoS Impact Factor: 2018 = 3.06 (2) - 2018=3.38 (5)
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