Chemical alterations of hyaluronic acid and dermatan sulfate detected in aging human skin by infrared spectroscopy

Age-mediated deacetylation of hyaluronic acid and dermatan sulfate, and shift of sulfate ester configuration were indicated by infrared spectroscopy. Hyaluronic acid and the three dermatan sulfates (DS18, DS18 and DS35), sequentially precipitated from adult skin with 18%, 28% and 35% ethanol, were analyzed at varying ages. At age 75 years, loss of infrared bands in the 1650-1600 cm−1 region, at 1380 cm−1 and 1320 cm−1 and appearance of a band at 1560 cm−1 were characteristic of hyaluronic acid and DS35,·moreover, in DS28 and DS35 the intensities of the bands at 840 cm−1 and 860 cm− were, respectively, decreased and increased. A low intensity band in the 805-785 cm−1 region was observed in the spectra of DS18 (19–35 years), DS28 (70–80 years) and DS35 (all ages). It intensified in DS28 of the 80-years-olds. In the 75±5-year-old group. ninhydrin-positive material of hyaluronic acid and DS35 increased, while reducing GlcNAc of hyaluronic acid decreased. The data demonstrated hyaluronic acid and DS35 deacetylation and suggested a decrease of equatorial sulfates with infrared band at 840 cm−1 and an incrase of axial sulfates with band at 860 cm−1 in DS28 and DS35 of the 75±5-yearl-old set. Equatorial sulfates with band in the 805±785 cm−1 region apparently decreased in DS18 after 35 years and increased in DS28 of the oldest group.