Evaluation of the melanin synthesis-inhibitory potential of Morus alba L. leaf extract for the development of a natural anti-hyperpigmentation formulation

Background: Although Morus alba (white mulberry) has long been used in traditional skin care, the scientific evidence for its leaf extract in anti-hyperpigmentation applications remains limited, particularly regarding its incorporation into topical formulations. This study investigated the melanin-synthesis-inhibitory, tyrosinase-inhibitory, and antioxidant activities of M. alba leaf extract and evaluated its potential in a stable topical gel formulation. Methodology: Melanin suppression was assessed in IBMX-stimulated B16F10 melanocytes using microscopic observation, pellet analysis, and quantitative melanin measurement. Tyrosinase inhibition was examined with a mushroom tyrosinase assay, while antioxidant capacity was evaluated via DPPH radical scavenging. A topical gel containing M. alba extract was developed and assessed for physicochemical properties, phenolic retention, bioactivity, and stability. Result and Discussion: The extract showed strong tyrosinase inhibition (IC₅₀ = 5.70 ± 0.28 µg/mL) and antioxidant activity (IC₅₀ = 16.22 ± 0.6 µg/mL), and significantly reduced melanin synthesis in B16F10 cells without cytotoxicity (≤ 200 µg/mL). The formulated gel maintained phenolic content, exhibited moderate tyrosinase inhibition, and demonstrated stable appearance, pH, spreadability, and bioactivity during storage. Conclusion: Morus alba leaf extract possesses potent anti-melanogenic and antioxidant properties and can be successfully incorporated into a stable topical gel, supporting its potential as a natural ingredient for anti-hyperpigmentation products. However, these findings are based on in vitro assays and preliminary formulation studies; further in vivo and clinical evaluations are needed to confirm its efficacy and safety in humans.