REGULATION OF EXTRACELLULAR MATRIX BY NICOTINAMIDE AND ITS DERIVATIVES 51 to those on non-irradiated fi broblasts, except for the lack of regulation of fi brillin expres- sion by 0.01% nicotinamide and 2,6-dihydroxynicotinamide. Relative to UVA-radiated controls, the expression of elastin protein/promoter was stimu- lated by nicotinamide, 2,6-dihydroxynicotinamide, 2,4,5,6-tetrahydroxynicotinamide, and 3-hydroxypicolinamide upto 348/268%, 365/708%, 230/547%, and 221/214%, respec- tively ( p 0.05) (Figure 2A and B). The expression of fi brillin-1/fi brillin-2 protein levels was stimulated by nicotinamide, 2,6-dihydroxynicotinamide, 2,4,5,6-tetrahydroxynicotinamide, and 3-hydroxypicolinamide upto 524/482%, 859/563%, 347/312%, and 253/227% of UVA-radiated controls, respectively ( p 0.05) (Figure 2C and D). DIRECT INHIBITION OF MMP-1, MMP-3, MMP-9, AND ELASTASE ACTIVITIES BY NICOTINAMIDE, 2,6-DIHYDROXYNICOTINAMIDE, 2,4,5,6-TETRAHYDROXYNICOTINAMIDE, AND 3-HYDROXYPICOLINAMIDE The MMP-1 and MMP-3 activities were signifi cantly inhibited by nicotinamide and 2,6-dihydroxynicotinamide MMP-9 activity by nicotinamide, and elastase activity by nicotinamide, 2,6-dihydroxynicotinamide, 2,4,5,6-tetrahydroxynicotinamide, and 3-hydroxypicolinamide ( p 0.05) (Figure 3). The MMP-1/MMP-3 activities were significantly inhibited by nicotinamide upto 43/36%, and by 2,6-dihydroxynicotinamide upto 70/57%, of respective controls ( p 0.05) Figure 2 . Stimulation of elastin protein (A), elastin promoter activity (B), fi brillin-1 protein (C), and fi brillin-2 protein (D) by nicotinamide (green line), 2,6-dihydroxynicotinamide (red line), 2,4,5,6-tetrahydroxynicotin- amide (violet line), and 3-hydroxypicolinamide (blue line) in UVA-radiated dermal fi broblasts * = p 0.05, relative to UVA radiated control cells, error bars (A–D) represent standard deviation, n = 4.

JOURNAL OF COSMETIC SCIENCE 52 (Figure 3A). There was direct stimulation of MMP-3 activity by 3-hydroxypicolinamide upto 329% of control, respectively ( p 0.05) (Figure 3B). The MMP-9 activity was signifi cantly inhibited only by nicotinamide, upto 44% of con- trol ( p 0.05) (Figure 3C). The elastase activity was inhibited by nicotinamide, 2,6-dihydroxynicotinamide, 2,4,5,6-tetrahydroxynicotinamide and 3-hydroxypicolinamide at 1–40%, 72%, 70%, and 66% of control, respectively ( p 0.05) (Figure 3D). DISCUSSION Nicotinamide, with an amide linked to an aromatic ring has UV absorptive, anti- infl ammatory properties, cellular metabolic, and antiapoptotic properties. The hypothesis of this research was that nicotinamide and its derivatives, 2,6-dihydroxynicotinamide, 2,4,5,6-tetrahydroxynicotinamide, and 3-hydroxypicolinamide would stimulate elastin and fi brillin in nonirradiated, and UVA radiated dermal fi broblasts, and exhibit direct antiproteolytic activity on the ECM proteins. The elastin fi bers, composed of elastin and fi brillin microfi brils, give skin its fi rmness and elasticity (1–4,15–18). The formation of the elastin fi bers in the dermis is directed by the microfi brils, composed primarily of fi brillin-1 and fi brillin-2. The microfi brils also form at the epidermal–dermal junction (15). There is loss of elastin and fi brillin with intrinsic aging, and in addition elastotic deposits occur in photoaged skin (1–4,15–18). Nicotinamide Figure 3. Direct regulation of MMP-1 activity (A), MMP-3 activity (B), MMP-9 activity (C), and elastase activity (D) by nicotinamide (green line), 2,6-dihydroxynicotinamide (red line), 2,4,5,6-tetrahydroxynico- tinamide (violet line), and 3-hydroxypicolinamide (blue line) * = p 0.05, relative to control, error bars (A–D) represent standard deviation, n = 4.