Succinic acid from GABA

GABA is converted to succinic semialdehyde [via GABA transaminase (GABAT) + pyri-doxal phosphate] which is thence oxidized to succinic acid which is further oxidized via the TCA cycle. 4-Hydroxybenzaldehyde from Gastrodia elata (Orchidaceae), a plant with antiepileptic properties, is an inhibitor of GABAT, as is the synthetic antiepileptic valproic acid (2-propenylpropanoic acid) (Table 6.6). 

Valproic acid and its salts are a new group of antiepileptic drugs that differs from the known drugs both structurally and in terms of its mechanism of action. It is believed that it acts on the metabolism of the GABA system. Valproic acid has been shown to elevate the level of GABA in the brain by means of competitive inhibition of GABA transaminase and the dehydrogenase of succinic semialdehyde. 

Fig. 6.22. The (a) 1-D and (b) 2-D-DOSY spectrum of a mixture containing D2O, glucose, ATP and SDS micelles [50]. (Adapted with permission from ref. [50]. Copyright 1993 American Chemical Society), (c) 1-D and (d) 2D-DOSY spectrum of the perchloric acid extract of a gerbil brain in D2O. Selected assignments are ac — acetate ala — alanine cho — choline cr — creatinine etn — ethanolamine GABA — y-aminobutyric acid glu — glutamine CPC — glycerophospho-choline lac — lactate m-ino — myo-inositol NAA — N-acetylaspartate succ — succinate and tau = taurine [51]. (Adapted with permission from ref. [51]. Copyright 1997 Elsevier.)...

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