Chemically Synthesized Glycosides of Hydroxylated Flavylium Ions as Suitable Models of Anthocyanins: Binding to Iron Ions and Human Serum Albumin, Antioxidant Activity in Model Gastric Conditions

Abstract

. Both pigments inhibit heme-induced lipid peroxidation in mildly acidic conditions (a model of postprandial oxidative stress in the stomach), the colorless (chalcone) forms being more potent than the colored forms. Finally, P1 and P2 are moderate ligands of human serum albumin (HSA), their likely carrier in the blood circulation, with chalcones having a higher affinity for HSA than the corresponding colored forms.

Complexation of common metal cations by cyanins: Binding affinity and molecular structure

“…In particular, our results indicate a larger stability of the metal‐cyanin complex with Cu(II), Δ b E = −52.04 kcal mol −1 /Δ b G = −37.59 kcal mol −1 , than with Zn(II), Δ b E = −31.74 kcal mol −1 /Δ b G = −19.65 kcal mol −1 , in agreement with what has been observed experimentally . Also, it has been found that binding to Fe(II) goes more slowly than with Fe(III) and that complexation with the latter goes faster than with Al(III), which can be pretty well correlated with our results.…”

“…[9] However, some of our kcal mol −1 , in agreement with what has been observed experimentally. [33] Also, it has been found [29] that binding to Fe(II) goes more slowly than with Fe(III) and that complexation with the latter goes faster than with Al(III), which can be pretty well correlated with our results.…”

“…Indeed, this has been corroborated, previously, by some of us . In addition, synthetic analogues of anthocyanins, lacking O‐glucose groups at C3 and C5 positions, have been shown as a useful model system for metal‐anthocyanin complexation studies, pointing to that the replacement of the glucose by a methyl group is expected not to play any relevant role on metal complexation . Therefore, cyanin is modeled replacing the glucose groups attached to O3 and O5 by methyl ones (Scheme ).…”

“…[20] In addition, synthetic analogues of anthocyanins, lacking O-glucose groups at C3 and C5 positions, have been shown as a useful model system for metal-anthocyanin complexation studies, pointing to that the replacement of the glucose by a methyl group is expected not to play any relevant role on metal complexation. [29] Therefore, cyanin is modeled replacing the glucose groups attached to O3 and O5 by methyl ones (Scheme 1). The methyl groups are orientated so that the aglycon is in the same disposition determined for the glycosyl groups in the X-ray diffraction study of the protocyanin crystal.…”

Natural Solutions for Blue Colors in Food

“…Whereas anthocyanins rapidly bind to aluminum and ferric ions, they weakly interact with ferrous ions promoting their autoxidation to Fe III (Bayer et al, 1966;Bittar et al, 2014). Under slightly acidic conditions, a huge excess of aluminum ions (metal to anthocyanin ratio of >100:1) is required to achieve blue hues (Sigurdson and Giusti, 2014).…”