Inhibitory Effect of Lotusine on Solar UV-Induced Matrix Metalloproteinase-1 Expression

Solar ultraviolet (sUV) radiation remains a major cause of skin aging. Nelumbo nucifera (lotus) is a well-known edible plant widely grown in Asia, including Korea, China, and Japan. The lotus consists of flowers, leaves, stems, and seeds, and all parts reportedly possess nutritional and medical values. Traditionally, lotus flowers, leaves, stems, and seeds have been used as antidiarrheal agents, diuretics, antipyretics, and antimicrobial and antihyperlipidemic agents. In addition, the Nelumbo nucifera lotus embryo has been shown to possess sedative and antipyretic properties and can relieve hemostatic thirst and treat eye diseases. Recently, Nelumbo nucifera lotus flower extract has been widely used in cosmetics due to its ability to reduce wrinkles and its whitening effects. Numerous cosmetics using Nelumbo nucifera lotus embryo extracts are commercially available. However, the active components of Nelumbo nucifera remain elusive. Lotusine is a phytochemical and soluble alkaloid found in lotus embryos. Herein, we examined the anti-wrinkle effect of lotusine using sUV-exposed human keratinocytes. We observed that lotusine reduced sUV-induced matrix metalloproteinase (MMP)-1 expression and modulated transcriptional activities of activator protein (AP)-1 and nuclear factor kappa B (NF-κB). sUV-induced AP-1 and NF-κB activity could be activated via multiple signal transduction cascades, including the p38 MAPK, JNK, ERK1/2, and Akt pathways in the skin. Lotusine inhibited the MEK1/2-ERK1/2-p90^RSK, MKK3/6-p38, and Akt-p70^S6K pathways. Overall, our findings suggest that lotusine has potential benefits related to MMP-1 expression and skin aging following sUV exposure. Hence, the lotus can be developed as a valuable functional food and cosmetic material.