title: Kinetic analysis on the sensitivity of glucose- or glyoxal-induced LDL glycation to the inhibitory effect of Psidium guajava extract in a physiomimic system.
abstract: Experimentation with a physiomimic system and kinetic analysis exhibited four distinct reaction phases in LDL glycation despite of the type of inducer: glucose or glyoxal. LDL glycation was more sensitive to a status of hyperglycemia (such as 400 mg glucose/100 mL) as evidenced by the reaction order of 0.53. Glucose reacted intensively in the Initial Phase (reaction period 0-2h) which was identified to result from a parallel mechanism involving both the direct Schiff's product formation and the auto-oxidative cleavages. In contrast, a physiological level of glyoxal revealed merely a reaction order of only 0.09, implicitly indicating a far less sensitive glycation which can be attributed to a mechanism proceeding simply through a molecular Schiff's reaction. On treatment with Psidium guajava L. aqueous extract (PE) (0.01-0.625 mg/mL), a rather unique and significant inhibitory characteristic on LDL glycation was observed with a dose-dependent manner. We attributed such an effect of PE to its distinct abundance of polyphenolic content (165.61+/-10.39 mggallic acid equivalent (GAE)/g). Conclusively, PE is an excellent anti-LDL glycative agent whose potential therapeutic uses can be extended to the prevention of a variety of cardiovascular and neurodegenerative diseases associated with glycations.
authors.affiliation: Research Institute of Biotechnology, HungKuang University, No. 34, Chung-Chie Rd., Shalu County, Taichung Hsien 433, Taiwan.
authors.forename: Chiu-Lan
authors.initials: CL
authors.lastname: Hsieh
authors.forename: Ming-Hua
authors.initials: MH
authors.lastname: Yang
authors.forename: Charng-Cherng
authors.initials: CC
authors.lastname: Chyau
authors.forename: Chun-Hon
authors.initials: CH
authors.lastname: Chiu
authors.forename: Hui-Er
authors.initials: HE
authors.lastname: Wang
authors.forename: Yuh-Charn
authors.initials: YC
authors.lastname: Lin
authors.forename: Wen-Ta
authors.initials: WT
authors.lastname: Chiu
authors.forename: Robert Y
authors.initials: RY
authors.lastname: Peng
mesh_terms: D005947:Glucose / Q000494:pharmacology; D017127:Glycation End Products, Advanced / Q000378:metabolism; D006031:Glycosylation / Q000187:drug effects; D006037:Glyoxal / Q000494:pharmacology; D006801:Humans; D006943:Hyperglycemia / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008077:Lipoproteins, LDL / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D008954:Models, Biological; D010936:Plant Extracts / Q000494:pharmacology; D031647:Psidium; D049490:Systems Biology; D000093844:Glycated Proteins
chemical_list: D005947:Glucose; D017127:Glycation End Products, Advanced; D006037:Glyoxal; D008077:Lipoproteins, LDL; D010936:Plant Extracts; C031797:glycated lipoproteins, LDL; D000093844:Glycated Proteins