JOURNAL OF COSMETIC SCIENCE 128 Relative to the control (0 at 100%), xanthohumol at 0.001%, 0.01%, 0.1%, and 1%, respectively, signifi cantly inhibited elastase activity to 50%, 48%, 23%, and 0.2% of control and inhibited MMP-9 activity to 76%, 68%, 26%, and 3% of control (p0.05) (Figure 1a,d). Xanthohumol at 0.1%, and 1% signifi cantly inhibited MMP-1 activity to 84% and 4% of control, and MMP-2 activity to 70% and –17% of control, respectively (p0.05) (Figure 1b,c). The effects of xanthohumol at the higher concentrations were similar to those of the positive controls ascorbic acid, PMSF or EDTA, and protease Figure 1. Inhibition of elastase (a), MMP-1 (b), MMP-2 (c), and MMP-9 (d) activities by 0.001-1% xan- thohumol (xan within arrows, a-d), PMSF (a), EDTA (b-d), ascorbic acid (AA, a-d), or protease inhibitor (PI, a, b, d). The effect of additives is represented as % of control (0, no additives), represented at 100% *=p0.05, relative to control. Error bars represent standard deviation (n=4).

REGULATION OF ECM REMODELING BY XANTHOHUMOL 129 inhibitor, which signifi cantly inhibited the activities of elastase and each of the MMPs (Figure 1a–d). STIMULATION OF EXPRESSION OF TYPES I, III, AND V COLLAGENS, ELASTIN, FIBRILLIN-1, AND FIBRILLIN-2 The identifi cation of natural products that inhibit MMPs and elastase, and simultaneously stimulate collagen and elastin fi ber formation, is ideal to counteract skin aging, which is Figure 2. Stimulation of expression of types I, III, and V collagens (a) and elastin, fi brillin-1, and fi brillin-2 (b) by 0.01%, 0.1%, and 1% xanthohumol or ascorbic acid (AA). Effect of xanthohumol or ascorbic acid is represented as % of control (0, no additives), represented at 100% *=p0.05, relative to control. Error bars represent standard deviation (n=4).