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SUMMARY The normal level of human serum alcohol dehydrogenase (EC l.l.l.l) (ADH) activity which is not measurable by conventional methods was found to be within the range 0·07-0·56 VII when measured by a sensitive method based on a coenzyme recycling reaction. In different liver diseases the normal upper limit of serum ADH activity was found to be exceeded up to 70 times.Although ADH activity under pathological conditions usually parallels that of other enzymes, e.g., sorbitol dehydrogenase (EC 1.l.l.l4) (SDH) and alanine transaminase (EC 2.6.1.2) (ALT), its relative elevation above the upper normal limit is generally greater, particularly in the early stages of viral hepatitis. Observations on some patients also suggested that very early stages of liver damage, caused by drugs or secondary malignancy, could be detected by increases of serum ADH activity when the activities of some other liver specific enzymes were still within their normal values.A pilot experiment on rats, intoxicated with carbon tetrachloride, showed that serum ADH activity could reflect acute liver parenchymal damage more sensitively than SDH and ALT activity.Alcohol dehydrogenase (alcohol: NAD+ oxidoreductase, Ee 1.1.1.1) (ADH) has broad substrate specificity-in man and is confined almost exclusively to the liver. From the data of Moser et al. 2 it can be calculated that only 5 %or less of the total activity is spread in other organs. Accordingly, ADH is a highly 'liver tissue specific' enzyme. 3 Since the majority of the total ADH content of liver cells was found in the cytosol;' it could be expected to leak out into the circulation after hepatocellular damage.It has been known for a long time that ADH activity in serum from normals is undetectable, whereas some activity could be detected in liver diseases." The relative insensitivity of the conventional ADH assay method," which is based on optical measurement of the rate ofNADH formation, is inherent in the enzyme and is related primarily to its low molecular activity.' It was this that prevented the ADH assay from becoming one of the biochemical parameters of liver function. Recently, the semisynthetic thio-analogue ofNAD+ was suggested" for routine ADH activity measurements. With this modified coenzyme, ADH exhibits considerably higher activity towards ethanol than with NAD+. Also, performing the conventional ADH assay at tPennanent address: Department of Biochemistry, Faculty of Science, University J. E. Purkyne, Brno, Czechoslovakia. elevated temperatures? enhances the activity of minute amounts of the enzyme normally present in serum to a detectable level. In this study, we tried to examine the usefulness for clinical practice of another sensitive method" for ADH activity determination.The method is based on a coupled reaction in which the enzyme is offered two substrates at once. The first one, n-butanol, is oxidised, and the second one (artificial aldehyde-like substrate) p-nitroso -N, N-dimethyl aniline (NDMA) is reduced, while the coenzyme recycles between its oxidised and reduc...

Ricinine-3,5-"C (N-methyl-3-cyano-4-methoxy-2-pyridone) administered to senescent leaves of Ricinus communis L. was translocated to all other tissues of the plant. Developing fruit and especially seeds were found to be labeled the most rapidly.Young growing leaves and other developing tissues of the plant imported ricinine from the senescent leaves much more quickly than mature leaves. Relative intensities of the radioactive ricinine imported and deposited in various tissues indicate a possible functional role of ricinine in the castor bean plant.Data on N-demethyl ricinine presented here may stimulate interest in the possible physiological role of the ricinine to Ndemethyl ricinine interconversion.A biological function for alkaloids in plants is not yet well established in spite of the extensive knowledge of their biosynthetic pathways (4,5,7,11). The increasing evidence for catabolic reactions of alkaloids (8,9,12) indicates that some cannot be considered merely as final products of nitrogen metabolism. Information on the role of a particular alkaloid in the plant can be obtained by studying its catabolic reactions, translocation, and distribution in the parent plant. Only a few reports on the translocation of alkaloids in plants have appeared (1, 5).Intensive catabolism of ricinine in Ricinus cominunis L. has been proven (9,12). The appearance in immature seeds of radioactive ricinine which had been administered to the plant before it bloomed (12) indicated translocation of the alkaloid into the seed from other tissues. Rapid demethylation of ricinine in senescent leaves (9) posed the question of a possible role of N-demethyl ricinine in the translocation of ricinine. Experiments (14) and had the specific radioactivity given in "Results." Immediately before use it was purified, using both preparative thin layer and paper chromatography (9, 14) and only one radioactive spot was observed in each system.Administration of Labeled Compound. Labeled ricinine was administered by injecting an aqueous solution of the compound into the veins and petioles of senescent leaves using a 50-,ud syringe (9).Isolation Procedure. Fresh parts of the plants were stored at -18 C and extracted by repeated homogenization of the frozen material with acetone at room temperature using a Sorvall Omnimixer until the residue was completely free of chlorophyll. At this stage the extraction of ricinine was 90 to 95% complete. The debris was weighed and extracted three more times with 80% (v/v) ethanol which resulted in an extraction efficiency greater than 98% for ricinine and the more polar compounds. The pooled acetone extracts were evaporated to dryness under reduced pressure. After addition of a small amount of water to the residue, the chlorophyll and lipids were removed by extraction with ether; the colored ether layer was re-extracted with water to minimize possible loss of ricinine. The combined aqueous phases were evaporated under reduced pressure, combined with the ethanol extract mentioned above, and used for chromatog...

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