Biosynthesis begins with decarboxylation of ornithine by ornithine decarboxylase (ODC) to produce putrescine. In wine, histamine, cadaverine, phenylethylamine, putrescine, and tyramine have all been detected. The biosynthesis of hyoscine begins with the decarboxylation of L-ornithine to putrescine by ornithine decarboxylase. The odor commonly associated with bacterial vaginosis has been linked to cadaverine and putrescine. GABA can also be synthesized from putrescine by diamine oxidase and aldehyde dehydrogenase. They are structurally and biosynthetically related to the diamines putrescine and cadaverine. In animals, however, the urea cycle derives putrescine from ornithine. The separate pathways of converting ornithine to putrescine in plants and animals have converged. Ornithine then undergoes a pyridoxal phosphate-dependent decarboxylation to form putrescine. Spermidine synthase (SPDS) catalyzes its formation from putrescine. Ornithine then undergoes a PLP-dependent decarboxylation to form putrescine. These include acetic, lactic and succinic acids, and putrescine. Spermidine synthase uses putrescine and "S"-adenosylmethioninamine (decarboxylated "S"-adenosyl methionine) to produce spermidine. Furthermore, some polyamines like putrescine inhibit biosynthetic activities in plants. Spermidine is synthesized from putrescine, using an aminopropyl group from decarboxylated "S"-adenosyl-L-methionine (SAM).