Glyceraldehyde Is Present in Rat Lens and Its Level Is Increased in Diabetes Mellitus

Abstract

Purpose: OP-lysine, a glycation product of lysine residues of proteins, has been reported to be formed with glyceraldehyde and glycolaldehyde as precursors in the lens, and has been suggested to play a role in senile cataracts. However, there has been no reliable information regarding the content of glyceraldehyde in tissues. This study determined the glyceraldehyde levels in the lenses of normal and diabetic rats. Methods: Glyceraldehyde was derivatized to a fluorescent compound, and the compound was then quantified by high-performance liquid chromatography. Results: The lens glyceraldehyde levels in normal and diabetic rats were 0.75 ± 0.06 and 1.26 ± 0.21 nmol/g wet weight (means ± standard deviations of 6 animals, p < 0.01), respectively. Isolated rat lenses accumulated a higher level of glyceraldehyde when cultured for 6 days in 25.5 mM glucose than when cultured in 5.5 mM glucose. Conclusions: Glyceraldehyde was found to be present in the lens and was increased in diabetes mellitus. OP-lysine is thus likely to be a potential risk factor for senile and diabetic cataracts.

Aldose Reductase Inhibitory Activity of Compounds from Zea maysL.

“…Lenses from each group were minced in 150  μ L of phosphate-buffered saline on ice, homogenized by sonication, and centrifuged at 22.000 g for 10 min at 4°C. The supernatant was filtered through a membrane filter (Ultrafree-MC, nominal molecular weight limit 10,000; Millipore, Bedford, MA, USA) to remove proteins [25]. HPLC analysis for sugar alcohol in lens was performed with this filtrate after being benzoylated [26].…”

“…The supernatant was neutralized with 2.5 M K 2 CO 3 at 4°C and used for galactitol determination [27]. HPLC analysis for sugar and sugar alcohol in blood was performed with this supernatant of red blood cell homogenate after being benzoylated [25]. …”

Development of a Method for Quantitation of Glyceraldehyde in Various Body Compartments of Rodents and Humans

“…Glyceraldehyde is a major intermediary compound in carbohydrate metabolism and is a precursor of toxic AGEs. − ,− Therefore, the measurement of the physiological levels of glyceraldehyde is paramount to a deeper understanding of its role in glycation. However, to the best of our knowledge, only three studies have measured physiological glyceraldehyde levels. − In the first study, glyceraldehyde levels were measured in animal lenses on the basis of an enzyme reaction followed by spectrophotometric determination; however, the absorbance signal was considerably weak for reliable measurement . In another study, glyceraldehyde levels were measured in human urine and serum samples using gas chromatography–mass spectrometry after ethyloxime–trimethylsilyl derivatization under strong alkaline conditions .…”

“…However, our preliminary experiments indicated that high concentrations of NaOH, such as those used in the study mentioned above, reduced glyceraldehyde stability. In the final study, glyceraldehyde levels were measured using HPLC after derivatization with 4-( N , N -dimethylaminosulfonyl)-7-hydra-zino-2,1,3-benzoxadiazole (DBD-H) in rat lenses . However, the chromatogram showed a poor resolution of the glyceraldehyde derivative from other compounds, indicating low specificity of detection using HPLC.…”

“…Methylglyoxal and glyoxal levels have been measured in numerous studies by derivatization with compounds such as 2,3-diaminonaphthalene (DAN), which can specifically react with dicarbonyl compounds, such as methylglyoxal and glyoxal. However, to the best of our knowledge, only three studies have measured glyceraldehyde levels in biological samples. − In our preliminary experiment, we were unable to measure low plasma glyceraldehyde contents in humans using previously reported methods. After the publication of these studies, new and more sensitive measuring devices have become widely available.…”