Anti‑melanogenic activity of the novel herbal medicine, MA128, through inhibition of tyrosinase activity

Background: Recently, our research group developed MA128, a novel herbal medicine, and demonstrated that MA128 is effective for the treatment of asthma and atopic dermatitis (AD). In particular, postinflammatory hyper‑pigmentation in AD mice was improved with MA128 treatment. Thus, in this study, we determined the effect of MA128 on melanogenesis and its underlying mechanism in murine B16F10 melanoma cells. Materials and Methods: After treatment with MA128 at 100 and 250 µg/mL and/or alpha‑melanocyte stimulating hormone (α‑MSH) (1 µM), cellular melanin content and tyrosinase activity in B16F10 cells were measured. Using western blotting, expression levels of tyrosinase, tyrosinase‑related protein‑1 (TRP‑1), TRP‑2, microphthalmia‑associated transcription factor (MITF), and activation of c‑AMP‑dependent protein kinase (PKA), c‑AMP‑related element binding protein (CREB) and mitogen‑activated protein kinases (MAPKs) were examined. Results: MA128 significantly inhibited melanin synthesis and tyrosinase activity in a resting state as well as α‑MSH‑stimulating condition, and significantly decreased the expression of tyrosinase, TRP‑1, TRP‑2 and MITF. In addition, phosphorylation of PKA and CREB by α‑MSH stimulation was efficiently blocked by MA128 pretreatment. Moreover, MA128 as an herbal mixture showed synergistic anti‑melanogenic effects compared with each single constituent herb. Conclusion: MA128 showed anti‑melanogenic activity through inhibition of tyrosinase activity mediated by p38 MAPK and PKA signaling pathways in B16F10 cells. These results suggest that MA128 may be useful as an herbal medicine for controlling hyper‑pigmentation and as a skin‑whitening agent.