New insight into erythema reduction induced by quercetin metal ions chelates

In dermatology, chelates play a significant role in skin care and treatment of skin diseases. Chelates involve coordination bonding between metal ions and organic molecules such as flavonoids. Quercetin ( Q ) is an extensively studied natural flavonoid with proven safety and anti-inflammatory properties. This study shows the role of two biocompatible metal ions, Iron ( Fe 2+ ) and Copper ( Cu 2+ ) in coordination bonding with Q in 2-Propanol 50% and 80% at 1:1 stoichiometry. Our results show that chelation involves the hydroxyl groups and occurs by coordination of Cu 2+ to Q for the Ring A-B (Benzoyl group) resulting in a fluorescence emission peak at 530nm from the Ring B-C (Cinnamoyl group). This chelates Q+Cu 2+ reduces mechanically induced erythema in the skin (Tanned type). A similar effect was observed in the chelate Q+Fe 2+ where the coordination of Fe 2+ to Q occurs for the cinnamoyl group resulting in an emission peak at 425nm from Benzoyl group of Q . The statistical analysis shows significant differences in the effects of Q+Cu 2+ (p-value = 0.00001), Q+Fe 2+ (p-value = 0.0003) respect to Q as well as between them (p-value =0.0029). Our results suggest that the interaction between Q and metal ions plays a central role in the inflammatory pathway. We conclude that the anti-inflammatory properties of Q were enhanced by both Q+Fe 2+ and Q+Cu 2+ chelates, highlighting the effect of Q+Fe 2+ where the hydroxyl groups available in the cinnamoyl group of the Q molecule are the main intermediates to interact with Fe 2+ , which is a requirement to trigger the anti-inflammatory molecular events of Q molecules.