ABSTRACT
Kojic acid derivative 2 was synthesized by joining two pyrone rings through an ethylene linkage by Horner-Emmons reaction of phosphonate 6 with aldehyde 7. The intermediates 6 and 7 were derived from kojic acid. The tyrosinase inhibitory activity of 2 was about 8 times more potent (IC(50) = 3.63 microM) than that of kojic acid (IC(50) = 30.61 microM). Compound 2 also exhibited potent melanin synthesis inhibitory activity (19.53% inhibition at 5 mug) indicating that the connection of two pyrone rings of kojic acid through a suitable linker can be an useful strategy for identification of potent tyrosinase inhibitors.
Subject(s)
Enzyme Inhibitors/chemical synthesis , Monophenol Monooxygenase/adverse effects , Pyrones/chemical synthesis , Animals , Enzyme Inhibitors/pharmacology , Humans , Melanins/biosynthesis , Melanins/physiology , Melanoma, Experimental/enzymology , Melanoma, Experimental/metabolism , Mice , Pyrones/pharmacology , Skin Pigmentation/drug effects , Structure-Activity Relationship , Tumor Cells, Cultured/drug effects , Tumor Cells, Cultured/metabolismABSTRACT
Vogt-Koyanagi-Harada (VKH) disease is an ocular inflammatory disease and is considered to be a cell-mediated, autoimmune disease against melanocytes. To learn more about the mechanisms involved in VKH disease, the identification of the antigens specific to the disease and the development of an animal model are critically important. We have expressed and purified the melanocyte specific proteins, tyrosinase-related protein 1 (TRP1) and 2 (TRP2). Lewis rats developed an ocular and extraocular inflammatory disease 12 days after immunization with TRP1 or TRP2 that was characterized clinically by the infiltration of inflammatory cells and accumulation of massive fibrin in the anterior and posterior chambers of the eye. Histologically, inflammatory cells were found in the anterior and posterior chambers, iris, ciliary body, the choroid, subretinal space and vitreous body. In severe cases, a serous detachment of the retina was observed. In mild cases, focal inflammatory lesions surrounded by normal chorioretinal architecture were observed and the inflammation persisted for more than 42 days after the injection. Some eyes showed accumulation of epithelioid cells in the choroid or the retinal pigment epithelium which were similar to the Dalen-Fuchs nodules found in patients with VKH disease. The alterations of the photoreceptor outer segment and the outer nuclear layer were less severe than in experimental autoimmune uveitis induced by retinal antigens. Extraocular manifestations such as skin lesions and meningitis were also observed. The clinical course and histological findings in these rats resembled the changes in patients with VKH disease.
Subject(s)
Immunization , Monophenol Monooxygenase/adverse effects , Uveomeningoencephalitic Syndrome/immunology , Animals , Electrophoresis , Electrophoresis, Polyacrylamide Gel , Melanocytes/immunology , Pigment Epithelium of Eye/cytology , Pigment Epithelium of Eye/immunology , Rats , Rats, Inbred Lew , Transfection , Uvea/cytology , Uvea/immunology , Uveomeningoencephalitic Syndrome/chemically induced , Uveomeningoencephalitic Syndrome/pathologyABSTRACT
This phase II study was performed to determine the induction of a specific T-cell response, the clinical response rate, and toxicity of vaccination with different HLA class I-binding peptide epitopes derived from the melanocyte differentiation antigen tyrosinase in patients with stage IV melanoma. The study population consisted of 16 patients with metastatic disease and two patients who were macroscopically free of disease at study entry after resection of recurrent skin lesions. Patients received intradermal injections of 200 microgram [corrected] peptide corresponding to their HLA type on day 3, and 75 or 150 microg granulocyte-macrophage colony-stimulating factor on days 1 to 4. Vaccinations were repeated at weeks 2, 4, 6, 10, and 14. Monitoring of peptide-specific T-cell frequencies in the peripheral blood was performed using an interferon gamma ELISPOT assay. Eleven of the 16 patients with metastatic disease went off the protocol within the first 10 weeks because of tumor progression. Of the five patients with metastatic disease who received all six vaccinations, one patient showed a mixed response with regression of some lung metastases; two patients with progressive disease before vaccination had stable disease for 6 and 18+ months; and two patients had progression of their disease. The two patients who had all their metastases resected before vaccination did not have relapses for 6 and 12+ months after vaccination. Induction of tyrosinase-reactive T cells was found in these two patients and in two others with metastatic disease, including the one who achieved a mixed response and one with stable disease. This study shows limited clinical and immunologic activity of HLA class 1-peptide vaccination in combination with granulocyte-macrophage colony-stimulating factor in stage IV melanoma patients.
