Determination of circular dichroism and ultraviolet spectral parameters ofnorgestimate- and other Delta(4)-3-ketosteroid oxime isomers via normal phase HPLC method

The oxime formation reaction of therapeutical progestogen (levonorgestrel, levonorgestrel acetate, norethisterone), androgen (methyltestosterone, test osterone phenylpropionate) and anabolic (nortestosterone phenylpropionate) Delta (4)-3-ketosteroids has been investigated. The ketosteroid-hydroxylami ne reaction was monitored by reversed phase HPLC system. It was established , that under the experimental conditions applied the oxime formation was co mplete within 2 h. The reaction leads to the formation of Z and E oxime iso mers. The isomers of norgestimate (levonorgestrel 17-acetate oxime) and oth er Delta (4)-3-ketosteroid oximes have been separated by a new normal phase HPLC method. The identification (elution order assignation) and determinat ion of the formation ratio of the isomers have been performed by H-1 NMR sp ectroscopy on the basis of the chemical shift differences of 4-H signals. T he on-line CD and UV spectra of the pure oxime isomers were recorded and th en molar ellipticities and absorbances of the isomers were calculated in th e wavelength range of 200-300 nm via parameter estimation method.