“Coordination of Cu(II) increases radical scavenging efficiency of luteolin especially at low pH, while decreases efficiency of apigenin both at low and higher pH as studied by ABTS•+ radical scavenging.”
“For di-coordinated apigenin the coordination symmetry balances an electron withdrawl effect of Cu(II) resulting in a decrease of phenol acidity and less radical scavenging efficiency compared to parent apigenin.”