RESUMEN
The in vivo assessment of sunscreen protection does not include the photogenotoxicity of UVA or UVB solar radiation. Using the comet assay we have developed a simple and rapid technique to quantify sunscreen efficacy against DNA damage induced by UV light. Cutaneous human melanocytes from primary cultures were embedded in low-melting point (LPM) agarose and exposed to UVA (0.8 J/cm2) or to UVB (0.06 J/cm2) through a quartz slide covered with 10 microL volumes of sunscreens. DNA single-strand breaks induced directly by UVA at 4 degrees C and indirectly through nucleotide excision repair by UVB following a 35 min incubation period at 37 degrees C were quantified using the comet assay. Tail moments (TM) (tail length x %tail DNA) of 100 cells/sample were determined by image analysis. DNA damage was evaluated with a nonlinear regression analysis on the normalized distribution frequencies of TM using a chi 2 function. The coefficients of genomic protection (CGP) were defined as the percentage of inhibition of DNA lesions caused by the sunscreens. Twenty-one sunscreens were evaluated, and the calculated CGP were compared with the in vivo sun protective factor (SPF) and with the protection factor UVA (PFA). Nonlinear relationships were found between SPF and CGPUVB and between PFA and CGPUVA.
Asunto(s)
Melanocitos/efectos de los fármacos , Melanocitos/efectos de la radiación , Protectores Solares/farmacología , Rayos Ultravioleta/efectos adversos , Células Cultivadas , Ensayo Cometa/métodos , Daño del ADN , Reparación del ADN , Relación Dosis-Respuesta en la Radiación , Evaluación Preclínica de Medicamentos , Humanos , Melanocitos/metabolismo , FotobiologíaRESUMEN
The study of the metabolism of iridoid glycosides from Harpagophytum procumbens and Harpagophytum zeyheri by human intestinal bacteria, was realized in order to elucidate compounds responsible for the pharmacological activities of Harpagophytum. Harpagide, harpagoside and 8-O-p-coumaroyl-harpagide were transformed into the pyridine monoterpene alkaloid aucubinine B by human fecal flora and by bacteria isolated from this flora. Aucubinine B was also prepared from harpagide, harpagoside and 8-O-p-coumaroylharpagide, by beta-glucosidase in the presence of NH4+.
Asunto(s)
Alcaloides/síntesis química , Bacterias/metabolismo , Ácidos Cumáricos/metabolismo , Glicósidos , Intestinos/microbiología , Plantas/metabolismo , Piranos/metabolismo , Piridinas/síntesis química , Ácidos Cumáricos/química , Humanos , Glicósidos Iridoides , Espectroscopía de Resonancia Magnética , Nitrógeno/química , Piranos/químicaRESUMEN
The curative action of mezlocillin on 10 severe experimental infections in mice was determined and expressed as effective dose 50 (ED50). The ED50 against infections produced by 5 strains of Gram-positive bacteria was distinctly lower than the ED50 against infections produced by 5 strains of Gram-negative bacteria. Infections due to Proteus mirabilis and Klebsiella pneumoniae were the least susceptible to mezlocillin. The determination of MICs and MBCs of mezlocillin against the strains used in the experiments showed a linear relationship between MBC and ED50 for Listeria spp., E. coli spp., S. typhimurium and Pr. mirabilis. For strains of 3 species (S. pyogenes, S. pneumoniae and E. insidiosa) with very low MBCs, the ED50 was related to virulence. The diversity of the results shows that various types of experimental infections should be used when testing an antibiotic.