Disaccharide analysis of human skin glycosaminoglycans in sun-exposed and sun-protected skin of aged people

The total amount of main disaccharide units of skin glycosaminoglycans was compared between sun-exposed ( n = 12) and sun-protected skin ( n = 14) of aged people using high performance liquid chromatography after labeling with 1-phenyl-3-methyl-5-pyrazolone. The total amount of main disaccharide units in sun-exposed skin was comparable to sun-protected skin presumably due to the diversity of individuals. Consequently, we compared sun-exposed skin with sun-protected skin in identical individuals ( n = 6). The total amount of main disaccharide units in sun-exposed skin was significantly greater than that in sun-protected skin ( P < 0.05). In addition, the ratio of ΔDi-HA (hyaluronic acid, HA)/ΔDi-4S (dermatan sulfate, DS) in sun-exposed skin showed a decreasing trend as compared with sun-protected skin in four of six individuals. These results are in agreement with our previous results obtained in animal experiments of photoaging, i.e., hairless mouse skin exposed to repeated UV irradiation showed an increase in total amount of main disaccharide units and a decrease in the ratio of ΔDi-HA(HA)/ΔDi-4S(DS). We could confirm similar changes in skin glycosaminoglycans both in human and murine photoaging supporting the appropriate rationale for using the hairless mouse as an animal model for photoaging. Again, disaccharide analysis should provide a useful method to examine the biochemical changes of skin glycosaminoglycans in human photoaging.