New hydroxylated metabolites of 4-monochlorobiphenyl in whole poplar plants

Two new monohydroxy metabolites of 4-monochlorobiphenyl (CB3) were positively identified using three newly synthesized monohydroxy compounds of CB3: 2-hydroxy-4-chlorobiphenyl (2OH-CB3), 3-hydroxy-4-chlorobiphenyl (3OH-CB3) and 4-hydroxy-3-chlorobiphenyl (4OH-CB2). New metabolites of CB3, including 2OH-CB3 and 3OH-CB3, were confirmed in whole poplars (Populus deltoides × nigra, DN34), a model plant in the application of phytoremediation. Furthermore, the concentrations and masses of 2OH-CB3 and 3OH-CB3 formed in various tissues of whole poplar plants and controls were measured. Results showed that 2OH-CB3 was the major product in these two OH-CB3s with chlorine and hydroxyl moieties in the same phenyl ring of CB3. Masses of 2OH-CB3 and 3OH-CB3 in tissues of whole poplar plants were much higher than those in the hydroponic solution, strongly indicating that the poplar plant itself metabolizes CB3 to both 2OH-CB3 and 3OH-CB3. The total yield of 2OH-CB3 and 3OH-CB3, with chlorine and hydroxyl in the same phenyl ring of CB3, was less than that of three previously found OH-CB3s with chlorine and hydroxyl in the opposite phenyl rings of CB3 (2'OH-CB3, 3'OH-CB3, and 4'OH-CB3). Finally, these two newly detected OH-CB3s from CB3 in this work also suggests that the metabolic pathway was via epoxide intermediates. These five OH-CB3s clearly showed the complete metabolism profile from CB3 to monohydroxylated CB3. More importantly, it's the first report and confirmation of 2OH-CB3 and 3OH-CB3 (new metabolites of CB3) in a living organism

Structure and Function of Enzymes Involved in the Biosynthesis of Tropane Alkaloids

Tropane alkaloids are found in a scattered distribution among the angiosperm families including members within the Solanaceae, Erythroxylaceae, Convolvulaceae, and Brassicaceae. Recent studies regarding the origins of tropane production provide strong evidence for a polyphyletic origin, suggesting that novel enzymes from different gene families have been recruited during the course of flowering plant evolution. Tropane alkaloid biosynthesis is best documented on the molecular genetic and biochemical level from solanaceous species. Regardless of the system chosen, there are currently gaps in the knowledge of enzyme structure-function relationships and how they influence tropane alkaloid biosynthesis. Obtaining insights on structure-function relationships of tropane biosynthetic enzymes is critical to understanding regulation, turnover, and flux of metabolites through the pathway. In this review, we discuss the current state of knowledge regarding structure-function relationships of the known steps involved in tropane biosynthesis.This is a post-peer-review, pre-copyedit version of a chapter published as Kim, Neill, Benjamin Chavez, Charles Stewart, and John C. D’Auria. "Structure and Function of Enzymes Involved in the Biosynthesis of Tropane Alkaloids." In Tropane Alkaloids (Srivastava V., Mehrotra S., Mishra S., eds.) 2021: 21-50. The final authenticated version is available online at DOI: 10.1007/978-981-33-4535-5_2. Posted with permission.</p