Royal jelly (RJ) is one of the most attractive functional foods that have been a commercial product, especially in dietetics and cosmetics in many countries. However, RJ has been evoked with dermatitis, acute asthma and anaphylaxis because of major RJ proteins. Therefore, to access water soluble royal jelly (WSRJ) that removed allergy-induced proteins as an effective whitening agent for cosmetics and potential external treatment for topical use, we investigated its ability to inhibit melanin biosynthesis. B16F1 cells were treated with 10 nM α-melanocyte-stimulating hormone (α -MSH) for 48hr, and then were treated with various doses of WSRJ for 36hr. WSRJ (1-10ug/ml) inhibited direct tyrosinase activity and cellular tyrosinase activity, which lead to the decrease of melanin synthesis in α-MSH stimulated B16F1 melanoma cells. In addition, we examined RT-PCR and Western blotting for melanogenesis-related genes such as tyrosinase, tyrosinase related protein 1 (TRP-1) and 2. WSRJ suppressed mRNA and protein expression of tyrosinase, tyrosinase related protein (TRP)-1 and TRP-2 in α-MSH stimulated B16F1 cells, and similar to positive control, arbutin. Our findings suggest that WSRJ induced the downregulation of melanogenesis by inhibiting tyrosinase, TRP-1 and 2 activations. It may serve as a new candidate in the new skin-whitening agents.

The objective of this study was to determine the effect of macrophages on growth of human colon cancer cells. The results showed that co-culture of colon cancer cells with macrophages inhibited the growth of colon cancer cells (HCT116 and SW620) depending on the number of macrophages, RAW 264.7 cells, and activated THP-1 cells accompanied by down regulation of pSTAT3 in cancer cells. We also found that expression and release of cancer cell growth inhibitory cytokines, IL-1 receptor antagonist (IL-1ra) and IL-10, was increased in macrophages. Blocking of the STAT3 pathway with specific inhibitor and siRNA of STAT3 abolished the growth of colon cancer cells and expression of IL-1ra and IL-10. In addition, neutralization of IL-1ra and IL-10 with antibodies resulted in reversal of macrophage-induced inhibition of cancer cell growth. These data showed that IL-1ra and IL-10 released from macrophages inhibit growth of colon cancer cells through inhibition of the STAT3 pathway.