Theoretical and Experimental Studies of the Antioxidant and Antinitrosant Activity of Syringic Acid

Abstract

Syringic acid (SA) is a natural phenolic acid found in vegetables, fruits, and other plant-based foods. A range of biological activities were proposed for this compound including anticancer, antimicrobial, anti-inflammation, and anti-diabetic activities, as well as antioxidant and antinitrosant properties. In this study, the focus is on the latter two. The HO • , HOO • , NO, and NO 2 scavenging activities of SA were evaluated in physiological environments by kinetic and thermodynamic calculations. The computed rate constants of the HO • radical scavenging of SA were 4.63 × 10 9 and 9.77 × 10 7 M −1 s −1 in polar and nonpolar solvents, respectively. A comparison with the experimentally determined rate constant in aqueous solution yields a k calculated /k experimental ratio of 0.3, thus the computed kinetic data are reasonably accurate. SA exhibited excellent HOO • and NO 2 scavenging activity in water (k overall (HOO • ) = 1.53 × 10 8 M −1 s −1 and k overall (NO 2 ) = 1.98 × 10 8 M −1 s −1 ), whereas it did not show NO scavenging activity in any of the studied environments. In lipid medium, SA exhibited weak activity. Thus, in polar environments, the HOO • radical scavenging of SA is 1.53 times higher than that of ascorbic acid. Consistently, SA is a promising antioxidant and antinitrosant agent in polar environments.

A metabolomics comparison of plant-based meat and grass-fed meat indicates large nutritional differences despite comparable Nutrition Facts panels

“…Several other compounds were found exclusively (31 metabolites total) or in greater quantities (67 metabolites total) in the plant-based meat alternative when compared to beef (Supplemental Table 1 ) (all, p < 0.05). Nutrients only found in the plant-based meat alternative included 2-hydroxy-3-methylvaleric acid (pentanoic acids; flavor) 22 , 3-hydroxyanthranilic acid (phenolic; anti-oxidant) 23 , aconitic acid (carboxylic acid; flavor) 24 , ascorbate (vitamin C; anti-oxidant) 25 , beta-sitosterol (phytosterol; anti-carcinogenic) 26 , campesterol (phytosterol; anti-carcinogenic) 26 , loganin (terpenoid phenolic; anti-inflammatory) 27 , melezitose or similar disaccharides (flavor) 28 , monolaurin (glyceride; anti-microbial) 29 , phenylacetic acid (phenylacetates; anti-oxidant) 30 , sorbic acid (unsaturated fatty acid; food preservative) 31 , sulfurol (phenolic; flavor) 32 , syringic acid (phenolic; anti-oxidant) 33 , trilaurin (glyceride; anti-microbial) 29 , and tyrosol (phenolic; anti-oxidant) 34 . A full list of annotated metabolites, their respective pathway classification (KEGG-identified) 11 , and their potential bioactivates/health effects (FoodDB and PubChem-identified) can be found in Supplemental Table 1 .…”

Is natural fraxin an overlooked radical scavenger?

“…Previous studies suggested that in aromatic antioxidants, the phenolic O-H bond is the most likely deprotonation site in the gas phase. 17,18,29,64 Therefore the PA values were computed for the O7-H bond only, yielding PA ¼ 327.0 kcal mol À1 . The computed IE value is 175.4 kcal mol À1 .…”

“…9,22,23 Solvent effects of water and pentyl ethanoate were modelled by solvation model density (SMD) method. 10,[24][25][26][27][28][29] The bond dissociation enthalpy (BDE), proton affinity (PA) and ionization energy (IE) were calculated as follows. 17,30…”

“…in gas phase, pentyl ethanoate or water. The rate constant (k) was calculated using the conventional transition state theory (TST) and 1 M standard state at 298.15 K. 28,29,[31][32][33][34][35][36]…”

The hydroperoxyl radical scavenging activity of sulfuretin: insights from theory

“…Computer calculations offer a convenient way to predict the antioxidant activity of organic compounds in physiological media [16][17][18][19][20][21][22][23]. In this context and as a continuation of our previous studies [18,24,25], we set out in this work to evaluate the HOO • antiradical activity of SFR by a combination of thermodynamic and kinetic calculations. This study also considered the effects of solvents on the antioxidant properties of SFR in comparison with some typical antioxidants.…”