The biosynthesis of skimmianine starts from anthranilic acid,[3] which is very abundant in the family Rutaceae. By combining anthranilic acid acetate, anthraniloyl-CoA is formed as a starting unit and able to extend side chain by adding malonyl-CoA by Claisen condensation. Next, lactam is formed through the cyclization and generate a heterocyclic system, leading the dienol tautomer adopt the 4-hydroxy quinolone tautomer, which is 4-hydroxy-2-quinolone.
With the formation of quinolone, alkylation is happening at C-3 position by introducing dimethylallyl diphosphate. Another key step is the cyclization on the dimethylallyl sidechain, forming a new heterocyclic five-member-ring.[4] Platydesmine is then forming an intermediate through the oxidative cleavage reaction[5] by losing an isopropyl group to form dictamine. Finally, skimmianine is formed through the hydroxylation of dictamine.
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