Protective effects of Carica papaya leaf against skin photodamage by blocking production of matrix metalloproteinases and collagen degradation in UVB-irradiated normal human dermal fibroblasts

Carica papaya is one of the most popular plants around the world. Various parts of Carica papaya have been used as ingredients in traditional medicine. However, no skin photoaging-related research has been performed with Carica papaya leaf (CPL). In the present study, Carica papaya leaf was investigated for its skin anti-aging effects in UVB-irradiated normal human dermal fibroblasts (NHDFs). Carica papaya leaf significantly suppressed UVB-induced activation of mitogen-activated protein kinases (MAPKs) and activator protein-1 (AP-1) signaling by scavenging reactive oxygen species (ROS) generation. Furthermore, our results indicated that CPL prevented degradation of Type I procollagen by positively modulating transforming growth factor-β1 (TGF-β1) activity and negatively regulating matrix metalloproteinases (MMPs) expression. Thus, the synthesis of Type I procollagen, a major component of extracellular matrix (ECM) was increased. In addition, a combination of both active compounds suggests they were active compounds of CPL. Taken together, the results suggest that Carica papaya leaf is promising for further investigation and development of a cosmetic product for the treatment of various skin conditions, including photoaging.