To investigate the efficacy of the ingestion of vinegar in aiding recovery from fatigue, we examined the effect of dietary acetic acid, the main component of vinegar, on glycogen repletion in rats. Rats were allowed access to a commercial diet twice daily for 6 d. After 15 h of food deprivation, they were either killed immediately or given 2 g of a diet containing 0 (control), 0.1, 0.2 or 0.4 g acetic acid/100 g diet for 2 h. The 0.2 g acetic acid group had significantly greater liver and gastrocnemius muscle glycogen concentration than the control group (P < 0.05). The concentrations of citrate in this group in both the liver and skeletal muscles were >1.3-fold greater than in the control group (P > 0.1). In liver, the concentration of xylulose-5-phosphate in the control group was significantly higher than in the 0.2 and 0.4 g acetic acid groups (P < 0.01). In gastrocnemius muscle, the concentration of glucose-6-phosphate in the control group was significantly lower and the ratio of fructose-1,6-bisphosphate/fructose-6-phosphate was significantly higher than in the 0.2 g acetic acid group (P < 0.05). This ratio in the soleus muscle of the acetic acid fed groups was <0.8-fold that of the control group (P > 0.1). In liver, acetic acid may activate gluconeogenesis and inactivate glycolysis through inactivation of fructose-2,6-bisphosphate synthesis due to suppression of xylulose-5-phosphate accumulation. In skeletal muscle, acetic acid may inhibit glycolysis by suppression of phosphofructokinase-1 activity. We conclude that a diet containing acetic acid may enhance glycogen repletion in liver and skeletal muscle.

To clarify the possibility of a preventive effect of dietary vinegar on blood pressure, long-term administration of vinegar or the acetic acid to SHR was examined. As a result, it was observed that acetic acid itself, the main component of vinegar, significantly reduced both blood pressure (p<0.05) and renin activity (p<0.01) compared to controls given no acetic acid or vinegar, as well as vinegar. There were no significant differences in angiotensin I-converting enzyme activity in various organs. As for the mechanism of this function, it was suggested that this reduction in blood pressure may be caused by the significant reduction in renin activity and the subsequent decrease in angiotensin II. From this study, it was also suggested that the antihypertensive effect of vinegar is mainly due to the acetic acid in it.

Particulate alcohol dehydrogenase of acetic acid bacteria that is mainly participated in vinegar fermentation was purified to homogeneous state from Gluconobacter suboxydans IFO 12528. Solubilization of enzyme from the bacterial membrane fraction by Triton X-100 and subsequent fractionation on DEAE-Sephadex A-50 and hydroxylapatite was successful in enzyme purification. A cytochrome c-like component was tightly bound to the dehydrogenase protein and existed as an enzyme-cytochrome complex. It was also confirmed that the alcohol dehydrogenase is not a cytochrome component itself. The molecular weight of the enzyme was determined to be 150,000, and gel electrophoresis showed the presence of three subunits having a molecular weight of 85,000, 49,000 and 14,400. The smallest subunit was corresponded to the cytochrome c-like component. Ethanol was oxidized in the presence of dyes in vitro but NAD or NADP were not required as hydrogen acceptor. Unlike NADlinked alcohol dehydrogenase in yeast or liver and other primary alcohol dehydrogenases in methanol utilizing bacteria, the enzyme from the acetic acid bacteria showed its optimum pH at fairly acidic pH.

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Membrane-bound alcohol dehydrogenase (ADH) was purified from the membrane fraction of an industrial-vinegar-producing strain, A. polyoxogenes sp. nov. NBI1028 by solubilization using Triton X-100 and subsequent column chromatography on DEAE-Sepharose CL-6B and hydroxyapatite. The purified enzyme was homogeneous on polyacrylamide disc gel electrophoresis (PAGE). Upon sodium dodecyl sulphate-PAGE, the enzyme showed the presence of two subunits with a molecular mass of 72 000 daltons and 44000 daltons, respectively. The small subunit was identified as cytochrome c. In addition, absorption and fluorescence spectra showed the the presence of pyrroloquinoline quinone in the purified ADH. The A D H preferentially oxidized aliphatic alcohols with a straight carbon chain except for methanol. Formaldehyde and acetaldehyde were also oxidizable substrates. The apparent Km for ethanol was 1.2 mM. The optimum pH and temperature were 5.0-6.0 and 40 ° C, respectively, p-Chloromercuribenzoic acid and heavy metals such as CuSO4 were inhibitory to the enzyme activity. Ferricyanide was effective as an electron acceptor.

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