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In the urine of rats as metabolites of the theophylline-derivative 7-[2-hydroxy - 3 - (N-methyl-N-2-hydroxyethyl)-amino-propyl]-1,3-dimethylxanthine (xantinol), the two stereoisomeric 2-coffeinyl-N-methyl-6-hydroxy-morpholines were found. These compounds represented about 7 to 8 percent of the eliminated xantinol and can be described structurally as semiacetals of a terminal aldehyde formed from Xantinol. Their structure has been elucidated by combined NMR- and mass-spectrometry. After oral application of xantinol-nicotinate in therapeutic doses to male test subjects, the same substances were detected by thin-layer chromatography. Both compounds could be synthetized by treatment of 7-[2,3-epoxypropyl]-theophylline or 7-[2-hydroxy-3-chloro-propyl]-theophylline with methylami-noacetaldehyde-dimethylacetal and subsequent hydrolysis of the reaction product with hydrochloric acid.

5-Methylpyrazole-3-carboxylic acid forms salts with basically substituted adenine bases of type (4) or (5), which have significantly more lipolysis inhibitory activity than the free acid itself. The substance tested, 6-amino-9-[2-hydroxy-3-(N-methyl-N-2-hydroxyethyl)-aminopropyl]-purine-5-methyl pyrazole-3-carboxylate (16), causes a significant reduction of serum FFA levels in fasted rats, even at the very low dosage of 0.150 mg/kg b.w., whereas the free 5-methylpyrazole-3-carboxylic-acid shows significant activity in this model only at doses of 2 mg/kg b.w. and above. The salt also shows similar activity on serum triglycerides. The effect on FFA, triglyceride and cholesterol levels, respectively, in fasted rats lasts for at least 8 h.