Alstonia scholarisR. Br. Significantly Inhibits Retinoid-Induced Skin IrritationIn VitroandIn Vivo

Abstract

Topical retinoids inhibit matrix metalloproteinases and accelerate collagen synthesis, thereby triggering antiaging effects in the skin. However, topical retinoids can cause severe skin reactions, including scaling, erythema, papules, and inflammation. The present study demonstrates that the ethanolic bark extract ofAlstonia scholarisR. Br. can significantly inhibitall-transretinoic acid-induced inflammation in human HaCat keratinocyte cells. Furthermore, two representative retinoid-induced proinflammatory cytokines, monocyte chemoattractant protein-1 and interleukin-8, were significantly suppressed byA. scholarisextract (by 82.1% and 26.3% at 100 ppm, and dose-dependently across the tested concentrations)in vitro. In a cumulative irritation patch test,A. scholarisextract decreased retinol-induced skin irritation, while strengthening the ability of retinoids to inhibit matrix metalloproteinase-1 expression, which is strongly associated with aging effects. These results suggest thatA. scholarisis a promising compound that may increase the antiaging function of retinoids while reducing their ability to cause skin irritation.