New Pyranoanthocyanins Synthesized from Roselle (Hibiscus sabdariffa L.) Anthocyanins

Abstract

Six new pyranoanthocyanins were synthesized through the reaction between dephinidin-3-sambubioside and cyanidin-3-sam-bubioside, extracted from roselle calyxes, with 4-vinylphenol, acetone and 2-butanone. The reaction products were characterized by liquid chromatography coupled to mass spectrometry (HPLC-TOF-MS), ul-traviolet-visible spectroscopy (UV/Vis) and high-performance liquid chromatography. Those new pigments belong to the families of pino-tins and methylpyranoanthocyanins and show a hypsochromic shift, which results in a more orange colour compared to the red hue of the original anthocyanins. Therefore, these compounds could be used to obtain new colorants more stable against certain factors such as pH.

Stabilization of Anthocyanins from Coffee (Coffea arabica L.) Husks and In Vivo Evaluation of Their Antioxidant Activity

“…A gradient was established using acetonitrile (A) and 4.5% formic acid (B): isocratic 9:91 (A:B) for 25 min, 26–28 min, 100:0 (A:B) and 28–30 min, 9:91 (A:B) at a flow rate of 1.5 mL/min. Detection was carried out using a Waters 996 PDA detector at 520 nm [ 66 , 82 , 83 ].…”

Improved Synthesis of Analogues of Red Wine Pyranoanthocyanin Pigments

“…Over the last several years, various synthetic approaches have been developed to prepare pyranoflavylium cation analogues of the naturally occurring pyranoanthocyanin pigments of wine. ,− As in the case of anthocyanins, for which the synthetic analogues containing the 7-hydroxyflavylium cation chromophore successfully mimic the ground- and excited-state chemistry of naturally occurring anthocyanin pigments, − , synthetic analogues with the pyranoflavylium cation chromophore can also be expected to reproduce the reactivity patterns of their natural counterparts . Moreover, they could eventually serve as a novel source of synthetic cationic dyes with tunable colors or as chromophores in dye-sensitized solar cells .…”

“…Moreover, they could eventually serve as a novel source of synthetic cationic dyes with tunable colors or as chromophores in dye-sensitized solar cells . The principal synthetic routes reported to date in the literature include (a) the reaction of a 5,7-dihydroxyflavylium cation or, as presumably occurs in red wine, of a natural anthocyanin with a substrate containing an enolizable keto group (Scheme ) or a vinylbenzene derivative; ,,, (b) reaction of either of these with hydroxy- or dimethylamino-substituted cinnamic acids; ,, (c) reaction of methyl or carboxy pyranoanthocyanins (analogues of vitisin A or B) with a substituted cinnamaldehyde or cinnamic acid, respectively; , or (d) reaction of 5,7-dihydroxy-4-methylflavylium (DHMF) cations with electron-rich benzaldehydes ,, (Scheme ).…”