General<unk>  is a structural analog of kainic<unk> , proline, and endogenous excitatory neurotransmitter glutamate. Ohfune and Tomita, who wanted to investigate its absolute stereochemistry, were the first and only to synthesize<unk>  in 1982. Biosynthesis In 1999, using 13C- and 14C-labelled precursors, the biosynthesis of<unk>  in the diatom genus Pseudo-nitzschia was examined. After addition of 1,2-13C2-acetate, NMR spectroscopy showed enrichment of every carbon in<unk> , indicating incorporation of the carbon isotopes. This enrichment was consistent with two biosynthetic pathways. The labeling pattern determined that<unk>  can be biosynthesized by an isoprenoid intermediate in combination with a tricarboxylic<unk>  (TCA) cycle intermediate. In 2018, using growth conditions known to induce<unk>  production in Pseudo-nitzschia multiseries, transcriptome sequencing successfully identified candidate<unk>  biosynthesis genes responsible for the pyrrolidine core. These<unk>  biosynthesis genes, or ‘Dab’ enzymes were heterologously expressed, characterized, and annotated as<unk> bA (terpene cyclase),<unk> bB (hypothetical protein),<unk> bC (α-ketoglutarate–dependent dioxygenase), and<unk> bD (CYP450).centerDomoic<unk>  biosynthesis begins with the<unk> bA-catalyzed geranylation of L-glutamic<unk>  (L-Glu) with geranyl pyrophosphate (GPP) to form N-geranyl-L-glutamic<unk>  (L-NGG).<unk> bD then performs three successive oxidation reactions at the 7′-methyl of L-NGG to produce 7′-carboxy-L-NGG, which is then cyclized by<unk> bC to generate the naturally occurring isodomoic<unk>  A. Finally, an uncharacterized isomerase could convert isodomoic<unk>  A to<unk> . Further investigation is needed to resolve the final isomerization reaction to complete the pathway to<unk> . Synthesis alt Using intermediates 5 and 6, a Diels-Alder reaction produced a bicyclic compound (7). 7 then underwent ozonolysis to open the six-membered ring leading to selenide (8). 8 was then deselenated to form 9 (E-9 and Z-9), lastly leading to the formation of (-)<unk> .
Domoic acid
Delta-Palutoxin
Bempedoic acid
Ricin
Maitotoxin
Psalmotoxin
Birtoxin
Phoneutria nigriventer toxin-3