In skin aging, from intrinsic factors or exposure to ultraviolet (UV) radiation, there is loss of structural fibrillar collagen and regulatory heat shock proteins. Phenolic compounds, with hydroxyl groups attached to an aromatic ring, have antioxidative and anti-inflammatory properties. Nicotinamide is an amide derivative of niacin or vitamin B3, with an amide linked to an aromatic ring, with UV absorptive, antioxidant, anti-inflammatory and anti-cell death/apoptosis properties. The goal of

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... research was to investigate the anti-skin aging mechanism of nicotinamide and its derivatives, 2,6-dihydroxynicotinamide, 2,4,5,6-tetrahydroxynicotinamide, and 3-hydroxypicolinamide (collectively niacin derivatives), through the stimulation of fibrillar collagens (type I, III and V, at protein and/or promoter levels) and the expression of heat shock proteins (HSP)-27, 47, 70, and 90 in non-irradiated or UVA radiated dermal fibroblasts; and from its direct antioxidant activity. UVA radiation inhibited the expression of types I and III collagen, and HSP-47 in dermal fibroblasts. The niacin derivatives significantly and similarly stimulated the expression of types I (transcriptionally), III and V collagens in non-irradiated, and UVA radiated fibroblasts indicating predominant effects. The 2,6-dihydroxynicotinamide had greater stimulatory effect on types I and III collagen in the non-irradiated, and UVA OPEN ACCESS Cosmetics 2015, 2 147 radiated fibroblasts, as well as greater direct antioxidant activity than the other niacin derivatives. The niacin derivatives, with a few exceptions, stimulated the expression of HSP-27, 47, 70 and 90 in non-irradiated, and UVA radiated fibroblasts. However, they had varied effects on the expression of the different HSPs in non-irradiated, and UVA radiated fibroblasts indicating non-predominant, albeit stimulatory, effect. Overall, nicotinamide and its derivatives have anti skin aging potential through the stimulation of fibrillar collagen and HSPs.