Inhibitory effect of some selected nutraceutic herbs on LDL glycation induced by glucose and glyoxal

Anti-LDL glycative agents were investigated using aqueous extracts of Psidium guajava L. (PE), Toona sinensis Roem. (TE), Momordica charantia L. (ME) and Graptopetalum paragugayene E. Walther (GE). Concentrations of extracts 0.01-0.625 mg/mL, low density lipoprotein (LDL; 100 μg protein/mL) and inducers glucose (400 mM) and glyoxal (2.5 mM) were incubated at 37 °C. Evaluation parameters involved the thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD), relative electrophoretic mobility (REM), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capability and total polyphenolic content. Results for anti-TBARS efficiency (in%) were PE (75.77), TE (75.10), ME (68.81) and GE (19.81) at 0.5 mg/mL, respectively, when induced by glucose; 36.68, 35.60, 32.62 and inactive, respectively, by glyoxal. The lag times for CD formation (in min) were: 289 and 125 by PE and TE, respectively, comparing to the control (45). REM was 1.6 with respect to PE (0.1 mg/mL) compared to the control (4.2). PE at 0.01 mg/mL effectively inhibited with 63.45% efficiency on AGEs induced by glucose. We conclude that PE virtually is a potent antiglycative agent, which can be of great value in the preventive glycation-associated cardiovascular and neurodegenerative diseases.