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UBC Theses and Dissertations

Studies on plant cell cultures of Podophyllum Peltatum and Tripterygium Wilfordii for biosynthesis of biologically active compounds Kuri-Brena, Francisco


This thesis investigates the use of plant cell cultures in combination with synthetic chemistry to provide new routes to biologically active compounds. The first chapter consists of approaches to the lignan podophyllotoxin (4), by means of enzyme catalyzed ring closure reactions of dibenzylbutyrolactone intermediates 56 and 57 mediated by Podophyllum peltatum cells. The substrates 56 and 57 studied were synthesized from readily available aromatic aldehydes employing a "one pot", 1,4addition- enolate alkylation sequence, as the key step. Semi-continuous biotransformation experiments performed with 56 illustrate the potential of the technique yielding the ring-closed products 75 and 76. A possible mechanism for the ring closure in vivo is provided, as well as suggestions to alter the stereochemical outcome of the process. The second chapter of this thesis concerns the attempts to oxidize dehydroisoabietanolide (132) with crude enzyme preparations (CFEs) from Tripterygium wilfordii, as part of an ongoing study regarding the biogenesis of the diterpcne triepoxides tripdiolide (5) and triptolide (91). The 12-hydroxy analogue of 132, isotriptophenolide (190), is also studied. Both compounds were prepared in gram quantities from dehydroabietic acid (122). The results from the biotransformation experiments, suggest that triptophenolide (163), an isomer of 190 and bearing a phenolic group at C-14, is a likely candidate for future biotransformation experiments. The present studies also suggest that an "activated" diterpene, that is, a substrate bearing a hydroxyl group in the aromatic ring (190 or an isomer), is a biogenetic precursor for the triepoxide system present in 5 and 91.

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