Synthesis and equilibrium multistate of new pyrano-3-deoxyanthocyanin-type pigments in aqueous solutions

Catechol versus carboxyl linkage impact on DSSC performance of synthetic pyranoflavylium salts

“…Furthermore, pyranoanthocyanins have been shown to display higher color intensity and stability at a wider pH range comparatively to their anthocyanin precursors. 23,24 In fact, while anthocyanins practically lose their red color between pH 1 and 5, as a result of the formation of colorless hemiketals, pyranoanthocyanins practically do not change their color intensity. 23,24 For these reasons, these dyes are interesting for a wide range of potential applications namely as food colorants, hair dyes, laser dyes, as well as photosensitizers for medical applications namely in photodynamic therapy and for energy applications such as DSSCs.…”

“…23,24 In fact, while anthocyanins practically lose their red color between pH 1 and 5, as a result of the formation of colorless hemiketals, pyranoanthocyanins practically do not change their color intensity. 23,24 For these reasons, these dyes are interesting for a wide range of potential applications namely as food colorants, hair dyes, laser dyes, as well as photosensitizers for medical applications namely in photodynamic therapy and for energy applications such as DSSCs. 25,26 However, these natural occurring dyes develop through Nature's evolution process, optimizing and rearranging according to its needs.…”

3‐Deoxyanthocyanidin Colorant: Nature, Health, Synthesis, and Food Applications

“…In addition, pyrano‐3‐deoxyanthocyanidin (Figure G), a novel derivative, was synthesized from the cycloaddition between 3‐deoxyanthocyanidin and double bond containing molecules such as acetaldehyde, pyruvic acid, carboxylic acid, and vinylcatechin (Cruz, Sousa, Marinho, Mateus, & de Freitas, ; Sousa et al., , ). Pyrano‐3‐deoxyanthocyanidin has an additional fourth pyranic ring that enhances electron delocalization of the system which makes it more stable against pH variations and bleaching by SO 2 than its homologous 3‐deoxyanthocyanidins and anthocyanins (Sousa et al., ).…”

“…Such a simple structural difference confers 3‐deoxyanthocyanidins with distinct chemical and biochemical properties, which include their higher stability to pH and temperature conditions (Awika, Rooney, & Waniska, ), better color stability (Awika, ), and the fact that they are more cytotoxic to cancer cells (Shih et al., ) in comparison to their anthocyanin analogs. 3‐Deoxyanthocyanidins present an exciting opportunity for exploitation as potential commercial natural colorants in foods, in particular in the search for new and novel natural colorants with high stability and other functional properties (Al Bittar, Mora, Loonis, & Dangles, ; Sousa et al., ; Sousa, Araújo, Mateus, & de Freitas, ).…”

“…better color stability (Awika, 2008), and the fact that they are more cytotoxic to cancer cells (Shih et al, 2007) in comparison to their anthocyanin analogs. 3-Deoxyanthocyanidins present an exciting opportunity for exploitation as potential commercial natural colorants in foods, in particular in the search for new and novel natural colorants with high stability and other functional properties (Al Bittar, Mora, Loonis, & Dangles, 2016;Sousa et al, 2017;Sousa, Araújo, Mateus, & de Freitas, 2013). In some crop plants, such as sorghum and sugarcane, 3deoxyanthocyanidins are important phytoalexins excreted in response to pathogen and environmental stress (Chopra et al, 2002;Hipskind, Hanau, Leite, & Nicholson, 1990;Kumar, Viswanathan, Malathi, Nandakumar, & Sundar, 2015;Viswanathan, Mohanraj, Padmanaban, & Alexander, 1996a).…”