Spectrophotometric study of anthocyan copigmentation reactions .4. Malvin and apigenin 7-glucoside

The existence of a copigmentation reaction was established between malvin chloride (malvidin 3,5-diglucoside) and apigenin 7-glucoside (5,4'-dihydroxyflavone 7-glucoside), and optimal conditions for its taking place were defined. Dependencies of the process on parameters such as the pH value of the solution, molecular concentration, and temperature were also determined. The kinetic and thermodynamic parameters obtained (K=137 M-1, Delta G degrees=-12.2 kJ/mol, Delta H=-37.4 kJ/mol, Delta S=-84.6 J/K mol) were correlated with the structure of the flavone used.