title: Inhibitory activities of proanthocyanidins from persimmon against oxidative stress and digestive enzymes related to diabetes.
abstract: The present study was carried out to evaluate the promising potential of polymers and oligomers from proanthocyanidins of persimmon peel as antioxidants and therapeutic agents for diabetes. Both polymers and oligomers showed the scavenging effect of 2,2-diphenyl-l-picrylhydrazyl, with IC50 values of 4.35 and 2.41 microg/mL, respectively, and they also showed a protective activity against protein oxidation induced by 2,2'-azobis (2-amidinopropane) dihydrochloride. In particular, oligomers exerted a stronger activity against free radicals than polymers. In addition, to investigate their protective potential against diabetes-related pathological conditions, their inhibitory activities on digestive enzymes and advanced glycation endproduct (AGE) formation were evaluated. Polymers showed a strong inhibitory activity against alpha-amylase, while oligomers had a relatively weak effect. This suggests that the inhibition of alpha-amylase activity would probably depend on the degree of polymerization. On the other hand, against alpha-glucosidase activity and AGE formation, oligomers exerted a stronger protective effect than polymers. The present study suggests that polymers and oligomers from proanthocyanidins of persimmon peel could play a role as antidiabetic agents with antioxidative effects. Moreover, oligomers rather than polymers from proanthocyanidins of persimmon peel may be expected to be a more promising antioxidative and antidiabetic agent in relation to utilization in biological systems.
authors.affiliation: Institute of Natural Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
authors.forename: Young A
authors.initials: YA
authors.lastname: Lee
authors.forename: Eun Ju
authors.initials: EJ
authors.lastname: Cho
authors.forename: Takashi
authors.initials: T
authors.lastname: Tanaka
authors.forename: Takako
authors.initials: T
authors.lastname: Yokozawa
mesh_terms: D000975:Antioxidants / Q000737:chemistry* / Q000302:isolation & purification; D003920:Diabetes Mellitus / Q000201:enzymology*; D029788:Diospyros / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry; D017127:Glycation End Products, Advanced / Q000737:chemistry; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010936:Plant Extracts / Q000737:chemistry; D044945:Proanthocyanidins / Q000737:chemistry* / Q000302:isolation & purification; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013997:Time Factors; D000516:alpha-Amylases / Q000737:chemistry; D000520:alpha-Glucosidases / Q000737:chemistry
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D017127:Glycation End Products, Advanced; D010936:Plant Extracts; D044945:Proanthocyanidins; C081628:advanced glycation end products-bovine serum albumin; D012710:Serum Albumin, Bovine; D000516:alpha-Amylases; D000520:alpha-Glucosidases