Molecular characterization of the salutaridinol 7-O-acetyltransferase involved in morphine biosynthesis in opium poppy Papaver somniferum

Salutaridinol 7-O-acetyltransferase (EC ) catalyzes the conversion of the phenanthrene alkaloid salutaridinol to salutaridinol-7-O-acetate, the immediate precursor of thebaine along the morphine biosynthetic pathway. We have isolated a cDNA clone that corresponds to the internal amino acid sequences of the native enzyme purified from a cell suspension culture of opium poppy Papaver somniferum. The recombinant enzyme acetylated the 7-hydroxyl moiety of salutaridinol in the presence of acetyl-CoA. The apparent K(m) value for salutaridinol was determined to be 9 microm and 54 microm for acetyl-CoA. The gene transcript was detected in extracts from Papaver orientale and Papaver bracteatum in addition to P. somniferum. Genomic DNA gel blot analysis indicated that there is likely a single copy of this gene in the P. somniferum genome. The amino acid sequence of salutaridinol 7-O-acetyltransferase is most similar (37% identity) to that of deacetylvindoline acetyltransferase of Catharanthus roseus. Salutaridinol 7-O-acetyltransferase is the second enzyme specific to morphine biosynthesis for which we have isolated a cDNA. Taken together with the other cDNAs cloned encoding norcoclaurine 6-O-methyltransferase, (S)-N-methylcoclaurine 3'-hydroxylase, the cytochrome P-450 reductase, and codeinone reductase, significant progress has been made toward accumulating genes of this pathway to enable the end goal of a biotechnological production of morphinan alkaloids.

Concentricol, a taxonomically significant triterpenoid from Daldinia concentrica

In the course of a chemotaxonomic study of xylariaceous Ascomycetes, a major metabolite was isolated and identified from the ascostromata of Daldinia concentrica. The compound, for which the name concentricol is proposed, constitutes a highly oxidised squalene derivative. A survey of several Daldinia spp. from around the world (including several type materials), employing analytical HPLC-UV/Vis (with diode array detection) and positive electrospray HPLC-MS of stromatal MeOH extracts revealed that concentricol was omnipresent in the stromata of D. concentrica, as well as in those of several collections of the pantropical Daldinia eschscholzii. All other investigated Daldinia spp. were found devoid of concentricol but contained binaphthalenes, benzophenones and/or azaphilones as further taxonomically relevant main metabolites.