Anthocyanin-Related Pigments: Natural Allies for Skin Health Maintenance and Protection

Abstract

Human skin is commonly described as a particularly dynamic and complex environment, with a physiological balance continuously orchestrated by numerous internal and external factors. Intrinsic aging, exposure to UV radiation and skin pathogens are some of the key players that account for dermatological alterations and ailments. In this regard, this study intended to explore the potential skin-health beneficial properties of a group of molecules belonging to the anthocyanin family: cyanidin- and malvidin-3-O-glucosides and some of their structurally related pigments, resulting in a library of compounds with different structural properties and color hues. The inclusion of both purified compounds and crude extracts provided some insights into their distinctive effects when tested as individual agents or as part of multicomponent mixtures. Overall, most of the compounds were found to reduce biofilm production by S. aureus and P. aeruginosa reference strains, exhibit UV-filter capacity, attenuate the production of reactive oxygen species in human skin keratinocytes and fibroblasts and also showed inhibitory activity of skin-degrading enzymes, in the absence of cytotoxic effects. Carboxypyranocyanidin-3-O-glucoside stood out for its global performance which, combined with its greater structural stability, makes this a particular interesting compound for potential incorporation in topical formulations. Results provide strong evidence of the skin protective effects of these pigments, supporting their further application for cosmeceutical purposes.

Pyranoanthocyanins Interfering with the Quorum Sensing of Pseudomonas aeruginosa and Staphylococcus aureus

“…Next, we have used a natural indicator strain, C. violaceum, for QSI screening, which involves the quantification of violacein produced by the strain. CarboxypyCy-3-glc inhibited violacein production in a dose dependent manner, which corroborates with the results of biofilm formation obtained by the crystal violet assay in P. aeruginosa ATCC 27853 [24]. However, interestingly, herein the carboxypyrano-ant extract stimulated violacein production (at both 64 and 256 µg/mL).…”

“…The carboxypyrano-ant extract and carboxypyCy-3-glc had previously not shown antibacterial activity against several Gram-positive and Gram-negative reference strains [24]. Now, in this study, the MIC and MBC values were obtained against the MDR isolates of P. aeruginosa and S. aureus (Pa3, PA004, SA007 and SA011), and are presented in Table 1.…”

“…Nevertheless, they both phenotypically hampered the biofilm formation by MRSA isolates, while not affecting the biofilm formation by MDR P. aeruginosa isolates. Given the fact that the biofilm formation of P. aeruginosa ATCC 27853 has been affected by the carboxypyrano-ant extract and carboxypyCy-3glc [24], these results may suggest that either the compounds' target is altered, inaccessible or absent, or regulated differently in MDR P. aeruginosa biofilms. Hypothesizing that the target of the compounds is the QS system, as we anticipate, and knowing that the QS mechanism involves the production, release, and detection of chemical signaling molecules, it is likely that differences between strains may occur in this system regulation upon the presence of these compounds [35][36][37].…”

“…Carboxypyranocyanidin-3-O-glucoside (carboxypyranocy-3-glc) (Figure 10) was hemisynthesized from the reaction of cyanidin-3-O-glucoside with pyruvic acid [58] and purified according to the procedure described in the literature [24]. The carboxypyranoanthocyanins extract (carboxypyrano-ant extract) was obtained from the reaction between anthocyanins present in a red wine extract with pyruvic acid according to the methodology described elsewhere [24]. The HPLC profile, at 520 nm, of the purified compound and the carboxypyrano-ant extract is present in Figure S1 of the Supplementary Materials.…”

“…The HPLC profile, at 520 nm, of the purified compound and the carboxypyrano-ant extract is present in Figure S1 of the Supplementary Materials. The full composition of the extract (phenolic compounds, sugar, proteins and was determined as already reported in the literature [24], and is shown in Table 2 Table 2. Full composition of the carboxypyrano-ant extract.…”