It is desired to establish the relationship of the production of secondary natural products to the general metabolic reactions which are common to all biological systems. Specific problems which will be investigated include the following: 1. The origin of nicotinic acid in higher plants will be reinvestigated. In tobacco, where the """"""""aspartic acid-glyceraldehyde"""""""" route apparently operates, details of the intermediates involved will be sought. In other species (Orchidaceae) attempts will be made to substantiate the """"""""trytophan"""""""" route to this important human vitamin. 2. The mechanism whereby nicotinic acid is activated for condensation to yield the tobacco alkaloids (nicotine, anabasine, and anatabine) and disocorine will be examined by the synthesis of potential metabolites (e.g. 3,6-dihydronicotinic acid). 3. It is proposed that nicotine formation in tobacco may be related to the production of polyamines (spermine and spermidine) which are important in all living system (controlling the production of nucleic acids: DNA, RNA). 4. It may be possible to block the synthesis of nicotine and other secondary natural products by the administration of compounds (e.g. Alpha-difluoromethylornithine) which inhibit certain of the enzyme steps involved in nicotine formation. 5. It is proposed to examine the biosynthesis of nicotine and other alkaloids in cell-free systems at the enzyme level. 6. Other alkaloids and secondary natural products whose biosynthesis will be further investigated include cocaine, cuscohygrine, hygrine (in Erythroxylon coca), mimosine (in Mimosa pudica), hyoscyamine and scopolamine (in Datura innoxia), coniine and Gamma-coniceine (in Conium maculatum), Delta9-tetrahydrocannabinol (in Cannabis sativa). Extensive use will be made of precursors labled with two contiguous 13C atoms or 13C adjacent to 15N, since the incorporation of such species can often be readily established by 13C-NMR spectroscopy. 7. Biomimetic syntheses of the following natural products (or analogs) will be attempted: dioscorine, methoxatin, cocaine, sesbanine, macrostomine, and conhydritone. These natural product analogs and all intermediates obtained in these synthetic endeavors will be submitted for biological testing to the NCI.
| Leete, E (1990) Recent developments in the biosynthesis of the tropane alkaloids. Planta Med 56:339-52 |
| Leete, E (1987) 2,3-Dehydrococaine: not a direct precursor of cocaine in Erythroxylum coca. J Nat Prod 50:30-5 |
| Leete, E; Rana, J (1986) Synthesis of [3,5-14C]trachelanthamidine and [5-3H]isoretronecanol and their incorporation into the retronecine moiety of riddelliine in Senecio riddellii. J Nat Prod 49:838-44 |
