SYNTHESIS, CHEMICAL CHARACTERIZATION, AND BIOLOGICAL INVESTIGATION OF NATURALLY ISOLATED HESPERIDIN AND ITS METAL COMPLEXES

This study was conducted to investigate the ability of hesperidin (HES) to form metal-complexes (HES-M) by chelation with transition metals such iron(III), copper(II), zinc(II), and silver(I), in addition to screen the antioxidant activity (DPPH free radical scavenging and phosphomolybdenum reduction potential methods PRP), anti-Alzheimer activity [(acetylcholinesterase (AChE)] inhibition assay) and coagulant activity (prothrombin time PT assay). The results indicated that HES could form a 1:1 complex with the studied metals in methanolic solution. The complex has been synthesized and characterized by physicochemical methods. Complexing of hesperidin with metals leads to increase in the antioxidant activity by 15.4-33%. Also, the total antioxidant capacities of HES-M complexes were increased by 13.8-251%. Cu-complex revealed the most increasing antioxidant activity by 33% for DPPH scavenging activity and 251% for PRP activity. The inhibition capacity of the HES, as well as of the HES-M complexes on the enzyme AChE, was revealed that only HES-Zn complex has higher anti-Alzheimer activity (IC(50 )1.18 mg/mL). HES and HES-M complexes led to accelerate the clotting time by 28.9-67.3%, where HES-Zn complex was the most accelerating clotting time by 67.3%. The high increase in total antioxidant activity of hesperidin after chelating with copper (251%) opens the door for further research.