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Nitric oxide is a reactive endogenous molecule with multiple functions. In vitro experiments showed that de novo attachment of melanocytes to extracellular matrix (ECM) could be reduced in the presence of NO donors. Moreover, it is well recognized that NO plays important role in cellular signaling in melanocytic cells, that is mediated by activation of soluble isoform of guanylyl cyclase (sGC) accompanied by increased levels of intracellular cyclic GMP (cGMP). The orchestrated dual activities of NO and cGMP are associated with melanogenesis and also with the alteration of melanocytic cells. NO-induced perturbation in de novo melanocyte-ECM interaction could thus be an important cause for the disappearance of melanocytes in vitiliginous lesions.In the present study, we therefore have examined the possible involvement of cGMP in NO-induced detachment of cultured melanocytes from normal healthy donors and vitiligo patients from ECM component such as fibronectin. The direct NO donor PAPA/NO and the peroxynitriteproducing compound SIN-1 induced detachment of normal and vitiliginous melanocytes in a concentration-dependent manner. Inhibitors of sGC and cGMP-dependent proteinkinase partially reversed the effect of SIN-1 and PAPA/NO. The NO-induced detachment further appears to be a result of apoptotic cell death, since the process was completely blocked after SIN-1 treatment and partially after treatment with PAPA/NO in the presence of caspase inhibitors (Ac-YVAD-CHO and Ac-DEVD-CHO). This observation was also found by direct monitoring of cellular apoptosis. However, NO-induced apoptotic events were cGMP-independent. Taken together, our results imply the involvement of the cGMP pathway in NO-induced detachment of both normal and vitiliginous melanocytes from ECM. The finding that human melanocytes undergo NO-mediated anchorage-dependent apoptosis may indicate that NO-induced apoptosis is a general mechanism for melanocyte reduction during inflammation.Ultraviolet B (UVB 290320 nm) radiation in human keratinocytes induces an expression of IL-1a and IL-6 (Interleukin-1a and Interleukin-6). UVB induced IL-1a and IL-6 can be activated melanogenesis by signal transduction to melanocytes. In this research, Luteolin was isolated from the aqueous ethanolic extract of Zostera marina L. leaves. We have analyzed the inhibitory effect of luteolin on the tyrosinase activity. As compared with arbutin, luteolin showed have similar inhibitory effect on tyrosinase activity. Human keratinocytes HaCaT exposed to UVB produced IL-1a and IL-6 but it decreased by treatment of luteolin for 5 h. This inhibition was measured after 10 mJ UVB irradiation and the addition of the luteolin. The luteolin inhibited the production of IL-1a and IL-6 up to 15%, 30% at 35 lM, which were known as cytokines involved in melanogenesis. We experimented inhibition of melanogenesis using mouse melanocyte B16F1 cell line. Luteolin treatment (48 h) suppressed the biosynthesis of melanin up to 26% at 35 lM. Therefore we had been very clearly established that luteol...