Quantum-mechanical characteristics of apigenin: Antiradical, metal chelation and inhibitory properties in physiologically relevant media

Organic–Mineral Interactions under Natural Conditions: A Computational Study of Flavone Adsorption on Smectite Clay

“…Apigenin (Api), like other aglycone flavonoids, is poorly soluble in water, while its solubility increases significantly in mild alkaline environments. , The acid–base dissociation constants for Api are close to each other, and multispecies mixtures are often found, making the experimental identification of p K a values difficult. Nevertheless, both experimental and computational studies agree that the hydroxyl group at C7 is most readily deprotonated (see Figure ), with the reported p K a 1 values in the range of 6.6 to 7.4. ,, The next p K a 2 is between 8.1 and 9.3, and can be attributed to the deprotonation at C4’ or C5 positions, it is also possible that there is an overlap of two dianion forms. ,, The last p K a 3 , producing trianion, is rarely measured and is reported to be above 10.5, or even 11.5 . In this work, we analyze interactions of four Api species, a neutral form and three anions, which are present at more than 15% across the pH range.…”

“…The chelation of the redox-active metals, such as Cu II and Fe II/III , minimizes the radical-generating Fenton reaction within the organism. Still, the chelation of trivalent cations by apigenin was again reported to be more prominent than divalent …”

Theoretical Insights into the Oxidative Stress-Relieving Properties of Pinocembrin─An Isolated Flavonoid from Honey and Propolis

“…The presented data demonstrates that pinocembrin exhibits significantly lower reactivity than other antioxidants, for example apigenin, where deprotonation led to an increased rate constants. The rates are even more implausible when compared to commonly used reference substances, such as Trolox or vitamin C .…”

Computational assessment of the primary and secondary antioxidant potential of alkylresorcinols in physiological media

“…53,54 Similar methodology has been used in the previous work. 8 The chelating potential was determined by the mean of Gibbs free energy of complexation ðDG f Þ for a reaction with a general scheme:…”

“…53,54 Similar methodology has been used in the previous work. 8 The chelating potential was determined by the mean of Gibbs free energy of complexation for a reaction with a general scheme:[M(H 2 O) 6 ] n + A m ⇄ [M(H 2 O) 4 A] n − m + 2H 2 Owhere M denotes the metal, n its charge, A describes the antioxidant, and m the charge of the antioxidant species. The apparent equilibrium constants ( K app i ) were then calculated according to the set of formulas: K II i = K f × m f i K app i = ∑ K II i where K f is the equilibrium constant at the studied complexation site of a given species, K II i equals the equilibrium constant corrected by the molar fraction, m f i , of the considered i species under the studied conditions.…”