Photoprotective and Antimelanogenic Properties of Carica papaya Leaf Extract: A Molecular Perspective on Skin Aging Prevention

Introduction: Skin hyperpigmentation disorders, such as melasma and post-inflammatory pigmentation, pose aesthetic and psychological concerns. These conditions are aggravated by ultraviolet B (UVB) radiation, which induces oxidative stress, DNA damage, and chronic inflammation in skin cells. Interest in plant-based antioxidants is rising. Carica papaya L. leaves, rich in flavonoids, phenolics, and bioactive compounds, offer promising antioxidant, anti-inflammatory, and wound-healing benefits that may help regulate melanogenesis and combat photoaging. This review aims to evaluate the therapeutic potential and molecular mechanisms of papaya leaf extract and its active compounds in managing UVB-induced pigmentation and inflammation based on findings from the last decade. Methods: This is a narrative review synthesizes findings from in vitro and in vivo studies between 2014–2024 on the effects of papaya leaf extract and its active compounds on UVB-induced skin damage and pigmentation. References were gathered using academic databases including Google Scholar, PubMed, ScienceDirect, SpringerLink, and Garuda. The analysis focused on molecular pathways involving oxidative stress responses and melanogenic signaling mechanisms. Results and Discussion: Papaya leaf extract was shown to neutralize reactive oxygen species (ROS), suppress matrix metalloproteinases (MMPs), and reduce inflammation. UVB exposure activates melanocytes via POMC-derived α-MSH and the cAMP-MITF-tyrosinase axis, contributing to hyperpigmentation. Among the bioactive constituents, caffeic acid and rutin demonstrate potent antioxidant and anti-inflammatory activity. Caffeic acid modulates NF-κB and MAPK signaling, reducing pro-inflammatory cytokines and enzymes such as COX-2 and iNOS. Rutin inhibits AP-1 transcription factors, suppressing MMP production and protecting collagen integrity. Both compounds contribute to restoring skin barrier function, reducing pigmentation irregularities, and slowing photoaging. Conclusion: Carica papaya L. leaf extract presents a natural alternative for managing hyperpigmentation and preventing skin aging. Its multitarget effects on oxidative stress, inflammation, collagen maintenance, and melanogenesis suggest promising applications in cosmeceutical formulations. Further clinical research is warranted to validate its therapeutic potential.