Pentosidine

Pentosidine is an advanced glycation end product (AGE) and a covalent crosslink that forms when a pentose sugar reacts with proteins. It creates a crosslink between lysine and arginine residues in neighboring protein chains and is inherently fluorescent, typically excited around 335 nm with emission near 385 nm. The molecule is widely used as a marker of nonenzymatic glycation and oxidative modification of proteins.

Formation of pentosidine occurs through a Maillard-type reaction in which pentose sugars, such as ribose, react with amino groups on proteins, followed by oxidative steps that culminate in the crosslink. The process is favored by higher sugar availability and oxidative stress and tends to accumulate over time in long-lived proteins.

Pentosidine accumulates in connective tissues rich in collagen and elastin, as well as in lenses, skins, and bones. Its buildup is associated with aging and with diabetic complications, including reduced tissue elasticity and vessel stiffness, contributing to vascular and ocular pathologies. Because it reflects both glycation and oxidative stress, pentosidine is studied as a biomarker of cumulative metabolic damage and aging.

Measurement and clinical relevance: pentosidine levels can be quantified in plasma, serum, urine, or tissue samples using fluorescence detection after chromatographic separation or by mass spectrometry. Elevated levels correlate with duration and intensity of hyperglycemia and with indices of oxidative stress, lending support to its use as a surrogate marker in aging and diabetes research. Diet can contribute to pentosidine exposure, but endogenous formation is the primary source in humans.