The Study on the Effects of Psoralen Derivatives on Epidermal Melanocytes in C57 BL Mice after Topical Photochemotherapy

BACKGROUND: Monofunctional psoralens plus UVA radiation are not severely phototoxic and have less mutagenic activity than bifunctional psoralens plus UVA radiation. OBJECTIVE: The purpose of this study was to evaluate pigment producing effect using various concentrations(0.02%, 0.1%, 0.5%) of monofunctional psoralens such as angelicin, khellin and comparing it's effect with TMP in topical photochemotherapy. METHOD: Ninty three C57BL mice were painted with either angelicin, khellin or TMP solution in concentrations of 0.02%, 0.1% and 0.5% each and were UVA irradiated. Skin biopsies were performed at 1,3,5 weeks after UVA irradiation. The pigment producing effects were measured by the number, area and perimeter of the melanocytes after topical PUVA. RESULTS: The comparison of melanocyte numbers between different psoralens after five weeks of photochemotherapy showed a significant difference in decreasing order of TMP, khellin and angelicin. The area and perimeter of melanocytes were larger in the TMP group after five weeks photochemotherapy than the other group. However in the khellin and angelicin group, the area and perimeter of melanocytes were not increased by increasing the frequency of the UVA irradiation. CONCLUSION: The number, area and perimeter of melanocytes after topical PUVA increased in the TMP group compared to angelicin or khellin group. We expect the clinical application of angelicin and khellin in vitiligo is possible considering the result of the study of pigment producing effect with a higher concentration and higher dose of UVA.

A Study on the Effect of Various Dosage of Khellin on Epidermal Melanocytes and a Comparison with Trimethylpsoralen in Systemic Photochemotherapy / 대한피부과학회지

Ninety black C 57 BL mice were divided into control and photochemotherapy groups. Control group was subdivided into a UVA 1rradiation only subgroup and a khellin only administration subgroup, while the phototherapy group was subdivided into one TMP and two khellin administration subgroups with dosages of 1.5mg/kg, 5mg/kg and 20mg/kg, respectivly. UVA was administered three thimes a week in a dose of 4J/cm for 4 weeks. Skin biopsies were taken at 0, l, 2, 3 and 4 weeks and the split DOPA stain was employed to observe pigment production. The number, size and circumference of the melanocytes were assessed. In summary, our results inclicate that khellin, which is slightly less effective than TMP at the same effective dose, is quite effective for pigment production and the degree of the production is dose related.