Objectives: Glycation is a non-enzymatic reaction between reducing sugars and the amino groups of proteins and lipids. This reaction produces advanced glycation end products (AGEs). AGEs are involved in diabetic complications, and plants containing iridoids are reported to prevent diabetes complications. However, it is unknown if these increase AGE degradation. In this study, the abilities of extracts from iridoid containing plants (Morinda citrifolia, Cornus officinalis and Olea europaea) to prevent AGE formation were tested with three model proteins (Human serum albumin, collagen and keratin). Further, the
AGE degrading activity of these extracts was determined by examining their impact on the α-diketone structure of 1-phenyl-1,
2-propanedione (PPD).
Method: To measure the inhibition of AGE formation, each model protein was incubated with glucose and samples at 60℃. Changes in detectable fluorescent AGEs (excitation wavelength 370 nm, detection wavelength 440 nm) were used to determine the percent inhibition of AGE formation of each sample. Determination of AGE degradation activity involved reacting PPD
solution with samples at 37℃, for 8 h. Changes in measured benzoic acid content (by HPLC), produced from cleavage of the α-diketone structure, was used to calculate AGE degrading activity.
Result: Morinda citrifolia seed extract was the most active sample in preventing AGE formation in all model proteins. The other extracts were also active. But inhibition intensity differed by protein type. At 1 mg/mL, Cornus officinalis fruit juice extract was the strongest AGE breaker (degradation rate; 29.8%), followed by Olea europaea leaf extract (26.5%) and Morinda citrifolia seed extract (18.2%).
Conclusion: The results demonstrate that iridoid containing plants may prevent AGE formation, as well as degrade existing AGEs.
... Olea europaea leaves (OEL), grown in Morocco, were extracted with ethanol. Reagents Deacetylasperulosidic acid (DAA) was purchased from Chengdu Biopurify Phytochemicals Ltd. (Sichuan, China). Loganin was purchased from Tokyo Chemical Industry Co., Ltd. ...
