الفهرس 
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Abstract
Lomefloxacin phototoxic effect appears as an immediate inflammatory reaction resulting from cellular damage with skin leisons manifesting themselves as reddening and, when severe, with blistering and subsequent peeling. Such reactions are developed, in most individuals, if the cell is exposed to sufficient amounts of light together with the candidate drug. As a result, formation of reactive oxygen intermediates takes place.
• This study was done to evaluate the effect of different dose levels of GBE (25, 50, 100 and 200 mg/kg) against lomefloxacin induced phototoxicity. Lomefloxacin was given as a single oral dose of 200 mg/kg as this dose was reported as being a phototoxic dose. Mice were exposed to UVA radiation at a dose of 21.6 J/cm2 for 190 minutes.
• Twenty four hours after irradiation, animals were weighed and ears are examined for morphological parameters and then animals are sacrificed to estimate the biochemical and histological parameters.
Results
Set І: exposure to UVA radiation
The morphological Results:
• The dose of the emitted UVA radiation caused a moderate oxidative stress in the skin. This was manifested morphologically by a significant (p<0.05) increase in erythema score, ear pinna thickness, relative ear weight to body weight against negative control group. The different concentrations of GBE (25, 50, 100 and 200 mg/kg) have a partial protective effect against UVA induced oxidative skin stress shown as a non-significant decrease in erythema score, in ear pinna thickness and in relative ear weight to body weight.
• Administration of lomefloxacin 200 mg/kg showed morphological changes upon exposure to UVA radiation observed as a significant (p<0.05) increase in erythema score, in ear pinna thickness and in relative ear weight to body weight against control group.
• The exerted protection of different concentrations of GBE (25, 50 and 100 mg/kg) against lomefloxacin induced phototoxicity was in a dose related manner observed morphologically through significant (p<0.05) decrease in ear pinna thickness and relative ear weight to body weight.
• It was noted that GBE 200 mg/kg provided a better protective effect against lomefloxacin induced phototoxicity through significant (p<0.05) decrease in erythema score, the ear pinna thickness and the relative ear weight to body weight.
The Biochemical Results:
• The oxidative stress in the skin due to the emitted UVA radiation was also manifested biochemically by a significant (p<0.05) increase in tissue level of malondialdehyde, a significant (p<0.05) decrease in glutathione and zinc tissue levels against negative control group where no exposure to UVA radiation. Administration of GBE 100 and 200 mg/kg cause a significant (p<0.05) increase in tissue glutathione level.
• Lomefloxacin upon exposure to UVA radiation showed a significant (p<0.05) increase in tissue level of malondialdehyde, a significant (p<0.05) decrease in glutathione and zinc tissue levels against control group. Different concentrations of GBE (25, 50, 100 and 200 mg/kg) showed a partial protective effect against lomefloxacin induced phototoxicity through significant (p<0.05) increase in tissue GSH level.
Histopathological Resuts:
• Histopathological findings supported the morphological and biochemical results in this study, confirming the inflammatory reactions resulted in ear sections after receiving lomefloxacin 200 mg/kg followed by exposure to UVA radiation, also a progressive decrease in the produced inflammatory cells infiltrations and edema upon receiving different concentrations of GBE (25, 50, 100 and 200 mg/kg) following administration of lomefloxacin and exposure to UVA radiation.
Set ІІ: Without UVA exposure:
• We found that without exposure to UV radiation there was no significant change between groups receiving either drug treatment or vehicle or different concentration of GBE in either morphological, or biochemical, or histopathological parameters.
• In conclusion, the partial protective effect of GBE against lomefloxacin induced phototoxicity was in a dose related manner. This partial protective effect was more pronounced with GBE 200 mg/kg.