Insights into eutectic formation and photodynamic therapeutic effects produced by folic acid on wound healing by an allantoin-fructose system

An insight has been provided into the eutectic formation and cutaneous wound healing potential of a binary allantoin/β-D-fructose system (AF). The system was blended with folic acid for light-aided wound therapy. Solid–liquid binary phase diagram showed a differential melting depression of 88°C from the ideal line and the existence of eutectic at X1 = X2 = 0.5. Simulations of molecular mechanics showed the involvement of hydantoin C=O and ureido –NH in hydrogen bonding with hydroxyl or hydroxymethyl groups of fructose. In the eutectic-folic acid blend (AFF), H-bonds were present between =N of pterin ring A and hydantoin –NH. Additionally, pi-sigma interactions involving pterin rings and pyranose moiety were revealed. The bulk density variations showed the disruption of the allantoin template after eutectic formation. An in-depth attenuated total reflectance infrared spectroscopic analysis endorsed the findings of other investigations and vibrational frequencies of interacting functionalities were shifted to different extents. The thermal stability of the eutectic mixture was markedly compromised after the addition of folic acid. Differential scanning calorimetry indicated the presence of co-crystal in addition to eutectic. Eutectic and its blend produced nearly the same healing effects in non-infected cutaneous wounds in rabbit models under normal and photodynamic wound therapy.