Effect of Non-Enzymatic Glycosylation and Heating on Browning of Human Stratum corneum and Nail

Abstract

The purpose of the present study was to examine the effect of non-enzymatic glycosylation and subsequent heating on the browning of the plantar stratum corneum and the finger-nail, and to elucidate the pathogenesis of the yellow skin and the yellow nail seen in diabetic subjects. We incubated stratum corneum and nail from non-diabetics in 0 (control) 10 (only nail) 20 (only nail) 100 and 250 mM glucose buffer at 37°C for 5 days. These glycosylated samples were dialysed against distilled water for 96 h. Distilled water was changed every 24 h. Then samples were dried for 24 h. The extent of non-enzymatic glycosylation was measured by furosine content. Each 5 mg of sample was hydrolysed by 6 N HCl and processed for measurement of furosine by high-performance liquid chromatography. The rest of each sample was stored at 37, 42 (only nail), 47 and 52 °C for 14 days. Browning of the stratum corneum was assessed macroscopically and that of the nail by spectrophotometry. Based on their spectrophotometric reflectances, Munsell’s scores (H = hue score V = lightness score C = saturation score) and (H + C)/V were calculated for objective evaluation of browning. Incubation of the stratum corneum and nail with glucose buffer increased their non-enzymatic glycosylation (furosine) dose dependently. Macroscopically, the browning of the stratum corneum was enhanced in proportion to the glucose concentration and storage temperature. However, samples incubated in 10 and 20 mM glucose and stored at 42 °C did not show visible browning. Munsell’s score of the nail samples treated by glycosylation and heating showed increased hue and saturation but reduced lightness. (H + Q/V values of these nail samples were significantly higher than those of the control. We could not detect any fluorescence with Wood light in the browned samples. The present in vitro study demonstrated that the browning of the stratum corneum and the nail depended on the extent of both non-enzymatic glycosylation and storage temperature. We suggested a hypothesis that the non-enzymatic glycosylation and the storage temperature of the stratum corneum and the nail might be a contributory factor in the development of yellow skin and yellow nail in diabetic patients.

Niacinamide

“…This leads to increased glycation and visibly more yellow appearance, described as "yellow skin syndrome" and "yellow nail syndrome." [19][20][21][22][23] There is thus potential for glycation to have a significant role in the aging-induced changes in skin appearance (eg, yellowing or sallowness). Niacinamide has been reported to have antiglycation effects, preventing this oxidative process likely via its role as a precursor to the endogenous antioxidant NAD(P)H. 24,25 For antiwrinkling, two mechanisms may apply.…”

Skin signs in diabetes mellitus

“…The yellow coloration is probably caused by the effect of non-enzymatic glycation, similar to the yellow skin in diabetic patients. 99,100 Onychomycosis may be considered as differential diagnosis.…”

Investigation of diabetic patient’s fingernail quality to monitor type 2 diabetes induced tissue damage

“…The HbA1c is a reliable representation of long-standing uncontrolled blood glucose (hyperglycemia) 8 . The long-standing hyperglycemia is prone to increase the non-enzymatic reactions (Maillard reactions) and form advanced glycation end-products (AGEs) 9–12 . The AGEs are a category of post-translation modification 13 , and they are highly cross-linked & slightly soluble 9 .…”