title: Quantitative determination by bioassay of photoactive 8-methoxypsoralen in serum.
abstract: Photoactive 8-methoxypsoralen (8-MOP) levels in human and animal sera were determined by bioassay with Staphylcoccus aureus serving as the test organism. 8-MOP was extracted from sera with as 9:1 (V/V) ethyl acetate-n-hexane mixture and reconstituted in an aqueous medium following evaporation of the extractant. Bacterial suspensions containing extracted 8-MOP were irradiated for predetermined intervals with longwave ultraviolet light (UVA) at an intensity of 2.1 mw/cm2. Cultures containing known amounts of 8-MOP were used as standards and cytotoxicity (i.e., drug levels) determined by colony counts. The detection limit for 8-MOP was 5 ng/ml with an accuracy of +/- 10% above 10 ng/ml. Concomitant determinations of 8-MOP levels by high pressure liquid chromatography (HPLC) were in excellent agreement with the bioassay results.
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000379:methods*; D002853:Chromatography, Liquid; D004285:Dogs; D006801:Humans; D008730:Methoxsalen / Q000032:analysis*; D010949:Plasma / Q000032:analysis; D011829:Radiation Dosage; D051381:Rats; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D008730:Methoxsalen