Identification of the convulsant opiate thebaine in mammalian brain.

The convulsant opiate thebaine, an intermediate of morphine biosynthesis, was purified from bovine brain to homogeneity by gel filtration and high-performance liquid chromatography (HPLC) monitored by a radioimmunoassay. The immunoreactive material behaved identically to standard thebaine in two HPLC systems and was confirmed to be thebaine by combined gas chromatography/mass spectrometry. To our knowledge, the presence of thebaine in mammalian tissue has not been demonstrated previously. Codeine and morphine were also found to exist in ovine brain. The presence of thebaine in ovine brain provides strong evidence that morphine and codeine, in various mammalian tissues, are of endogenous origin and actually biosynthesized from a precursor.