RESUMO
An original method is described for detecting the photosensitizing ability of a compound. The principle of this method is based on the analysis of variations in the consumption of oxygen by Bacillus subtilis (measured with Warburg's apparatus or an oxygenometric cell), induced by irradiation of the test compound added to the bacterial culture medium. This methodology was applied to 7 substances: 5 known photosensitizers (8-MOP, chlorpromazine, 5-fluorouracil, Vitamin A acid and benzoyl peroxide) and 2 products without any photoactive properties (aspirin and erythromycin). The comparison of results obtained with the method of photo-patch tests and the analysis of the photophysical properties of the compounds confirm the reliability, reproducibility and the quantitative nature of this method.
Assuntos
Bacillus subtilis/metabolismo , Consumo de Oxigênio/efeitos dos fármacos , Transtornos de Fotossensibilidade/induzido quimicamente , Aspirina/farmacologia , Aspirina/efeitos da radiação , Aspirina/toxicidade , Peróxido de Benzoíla/farmacologia , Peróxido de Benzoíla/efeitos da radiação , Peróxido de Benzoíla/toxicidade , Clorpromazina/farmacologia , Clorpromazina/efeitos da radiação , Clorpromazina/toxicidade , Eritromicina/farmacologia , Eritromicina/efeitos da radiação , Eritromicina/toxicidade , Fluoruracila/farmacologia , Fluoruracila/efeitos da radiação , Fluoruracila/toxicidade , Luz , Metoxaleno/farmacologia , Metoxaleno/efeitos da radiação , Metoxaleno/toxicidade , Testes do Emplastro , Tretinoína/farmacologia , Tretinoína/efeitos da radiação , Tretinoína/toxicidadeRESUMO
Variations in individual sunburn sensitivity have been studied using erythema as the photobiologic criterion. The minimal erythema dose (MED), the minimal dose necessary to elicit an intense erythema (MED++), and an edema (MOD), were determined by Saidman's method. The irradiation was performed with a 2,500-W xenon arc solar simulator fitted with a water filter and WG 305 Schott filter. The high correlation between MED, MED++, and MOD and the existence of saturation phenomenon confirm that determination of MED is the best photobiologic criterion. The average MED and the pathologic threshold for total light spectrum irradiation are, respectively, 889 mJ/cm2 and 347 mJ/cm2. A statistically significant variation in MED as a function of age, sex, complexion, eye color, hair color, and Fitzpatrick skin type has been established. Finally, complexion has been shown to be the best clinical criterion for the characterization of sunburn sensitivity and a new classification of the epidermis for UV therapy and artificial photoprotection is proposed.