- BERBERINE SYNTHASE, THE METHYLENEDIOXY GROUP FORMING ENZYME IN BERBERINE SYNTHESIS
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An Fe(2+) containing enzyme responsible for the formation of the methylenedioxy group in berberine was discovered, purified to homogeneity and characterized; it acts on columbamine as a substrate rather than on (S)-tetrahydrocolumbamine as previously assumed.
- Rueffer, M.,Zenk, M. H.
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- Method for synthesizing benzophenanthridine and protoberberine alkaloids through modular diversity regulation and control
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The invention discloses a method for synthesizing benzophenanthridine and protoberberine alkaloids through modular diversity regulation and control. The method comprises the following steps: improving a substituent group of a high-iodine salt leaving group, generating pyridine alkyne under the action of relatively mild potassium tert-butoxide, and carrying out [4 + 2] cycloaddition reaction on the pyridine alkyne and diene to obtain polysubstituted isoquinoline ring precursor compounds. Ring opening and aromatization of the isoquinoline ring precursor are realized by developing a novel iridium-catalyzed cross-coupling method, polysubstituted isoquinoline ring compounds with connecting capacity are efficiently synthesized, and then the polysubstituted isoquinoline ring compounds are coupled with a high-activity polysubstituted cyclic boric acid to obtain 3-aryl isoquinoline high-grade intermediates. Through application of two different chemical principles, regulation and control of the 3-aryl isoquinoline high-grade intermediates are realized, and benzophenanthridine and protoberberine alkaloids are modularly, diversely and efficiently synthesized.
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- Characterization of a flavoprotein oxidase from opium poppy catalyzing the final steps in sanguinarine and papaverine biosynthesis
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Benzylisoquinoline alkaloids are a diverse class of plant specialized metabolites that includes the analgesic morphine, the antimicrobials sanguinarine and berberine, and the vasodilator papaverine. The two-electron oxidation of dihydrosanguinarine catalyzed by dihydrobenzophenanthridine oxidase (DBOX) is the final step in sanguinarine biosynthesis. The formation of the fully conjugated ring system in sanguinarine is similar to the four-electron oxidations of (S)-canadine to berberine and (S)-tetrahydropapaverine to papaverine. We report the isolation and functional characterization of an opium poppy (Papaver somniferum) cDNA encoding DBOX, a flavoprotein oxidase with homology to ( S)-tetrahydroprotoberberine oxidase and the berberine bridge enzyme. A query of translated opium poppy stem transcriptome databases using berberine bridge enzyme yielded several candidate genes, including an (S)-tetrahydroprotoberberine oxidase-like sequence selected for heterologous expression in Pichia pastoris. The recombinant enzyme preferentially catalyzed the oxidation of dihydrosanguinarine to sanguinarine but also converted (RS)-tetrahydropapaverine to papaverine and several protoberberine alkaloids to oxidized forms, including (RS)-canadine to berberine. The Km values of 201 and 146 μM for dihydrosanguinarine and the protoberberine alkaloid (S)-scoulerine, respectively, suggested high concentrations of these substrates in the plant. Virus-induced gene silencing to reduce DBOX transcript levels resulted in a corresponding reduction in sanguinarine, dihydrosanguinarine, and papaverine accumulation in opium poppy roots in support of DBOX as a multifunctional oxidative enzyme in BIA metabolism.
- Hagel, Jillian M.,Beaudoin, Guillaume A. W.,Fossati, Elena,Ekins, Andrew,Martin, Vincent J. J.,Facchini, Peter J.
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p. 42972 - 42983
(2013/03/13)
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