Chemistry and biology of monoterpene indole alkaloid biosynthesis

Recent Advances in Transition-Metal-Catalyzed Functionalization of Unstrained Carbon–Carbon Bonds

The production of plant secondary metabolites by means of large-scale culture of plant cells in bioreactors is technically feasible. The economy of such a production is the major bottleneck. For some costly products it is feasible, but unfortunately some of the most interesting products are only in very small amounts or not all produced in plant cell cultures. Screening, selection and medium optimization may lead to 20- to 30-fold increase in case one has producing cultures. In case of phytoalexins, elicitation will lead to high production. But for many of the compounds of interest the production is not inducible by elicitors. The culture of differentiated cells, such as (hairy) root or shoot cultures, is an alternative, but is hampered by problems in scaling up of such cultures. Metabolic engineering offers new perspectives for improving the production of compounds of interest. This approach can be used to improve production in the cell culture, in the plant itself or even production in other plant species or organisms. Studies on the production of terpenoid indole alkaloids have shown that the overexpression of single genes of the pathway may lead for some enzymes to an increased production of the direct product, but not necessarily to an increased alkaloid production. On the other hand feeding of such transgenic cultures with early precursors showed an enormous capacity for producing alkaloids, which is not utilized without feeding precursors. Overexpression of regulatory genes results in the upregulation of a series of enzymes in the alkaloid pathway, but not to an improved flux through the pathway, but feeding loganin does result in increased alkaloid production if compared with wild-type cells. Indole alkaloids could be produced in hairy root cultures of Weigelia by overexpression of tryptophan decarboxylase and strictosidine synthase. Alkaloids could be produced in transgenic yeast overexpressing strictosidine synthase and strictosidine glucosidase growing on medium made out the juice of Symphoricarpus albus berries to which tryptamine is added. Metabolic engineering thus seems a promising approach to improve the production of a cell factory.

Biotechnology for the production of plant secondary metabolites

Flavonoids and their glycosides, including anthocyanins

Chemo- and stereoselective CH oxidations and epoxidations/cis-dihydroxylations with H2O2, catalyzed by non-heme iron and manganese complexes

Ethyl Cyanoacetate: A New Cyanating Agent for the Palladium-Catalyzed Cyanation of Aryl Halides

Total synthesis of (−)-Englerin A

In an effort to identify new immunosuppressive agents from natural sources, 12 new geranylated flavonoids, 5,7,4′-trihydroxy-3′-[7-hydroxy-3,7-dimethyl-2(E)-octenyl]isoflavone (1), a racemate of 5,7,2′,4′-tetrahydroxy-3′-[7-hydroxy-3,7-dimethyl-2(E)-octenyl]isoflavanone (2), 2′′(S)-5,7-dihydroxy-[2′′-methyl-2′′-(4-methyl-3-pentenyl)pyrano]-5′′,6′′:3′,4′-isoflavone (3), (2′′S,3′′R,4′′S)-5,7,3′′,4′′-tetrahydroxy[2′′-methyl-2′′-(4-methyl-3-pentenyl)pyrano]-5′′,6′′:3′,4′-isoflavone (4), a racemate of 3′-geranyl-5,7,2′,4′-tetrahydroxyisoflavanone (5), a racemate of 3′-geranyl-4′-methoxy-5,7,2′-trihydroxyisoflavanone (6), 3′-geranyl-5,7,4′,5′-tetrahydroxyisoflavone (8), 3′-geranyl-5,7,2′,5′-tetrahydroxyisoflavone (9), 3′-geranyl-4′-methoxy-5,7,2′-trihydroxyisoflavone (10), 2(R),3(R)-3′-geranyl-2,3-trans-5,7,4′-trihydroxyflavonol (12), (2R,3R)-6-methyl-3′-geranyl-2,3-trans-5,7,4′-trihydroxyflavonol (13), and 5,7-dihydroxy-4′-O-geranylisoflavone (14), were isolated from the roots of Campylotropis hirtella (Franch...

Geranylated Flavonoids from the Roots of Campylotropis hirtella and Their Immunosuppressive Activities

Hirtellanines A and B, a pair of isomeric isoflavonoid derivatives from Campylotropis hirtella and their immunosuppressive activities.

Preparation of TiO2 nanocapsules for loading and release of antimicrobial triclosan molecules

Zhengwu Shen

Papers

Ethyl Cyanoacetate: A New Cyanating Agent for the Palladium-Catalyzed Cyanation of Aryl Halides

Total synthesis of (−)-Englerin A

Geranylated Flavonoids from the Roots of Campylotropis hirtella and Their Immunosuppressive Activities

Hirtellanines A and B, a pair of isomeric isoflavonoid derivatives from Campylotropis hirtella and their immunosuppressive activities.

Preparation of TiO2 nanocapsules for loading and release of antimicrobial triclosan molecules