DETERMINATION METHODS FOR URINARY 3-METHOXY-4-HYDROXYMANDELIC ACID AND 3, 4-DIHYDROXY-MANDELIC ACID

Abstract

Within these several years, owing much to tracer experiments (1, 2), circulating metabolic pattern of catecholainine (CA), epinephrine (E) and norepinephrine (NE), has been clarified nearly completely. Most part of circulating CA undergoes O-methylation to yield metanephrine (MA) and normetanephrine (NMA) (3, 4), and a part of these is excreted in the urine in conjugated form but the rest part is further metabolized by monoamine oxidase (MAO) to give vanillylmandelic acid (VMA) (5), a stable final common metabolite of both E and NE, and without further metabolism and conjugate formation VMA is excreted in the urine. A lessor portion of circulating CA first undergoes deamination to make 3, 4-dihydroxymandelic acid (DOMA) and a part of which is excreted in free form and the rest is O-methylated to give VMA which is excreted in the urine. Since, according to Goodall and Kirshner (1, 2), infusion of dl-2-C¹⁴-E and dl-2-C¹⁴-NE makes the recovery of as much as 27 and 32%, respectively, of the infused radioactivity as VMA, determination of this compound together with VMA from endogenous metabolism is expected to afford a reasonable index of CA level in the organism. As for determination method for urinary VMA, there have been reported several representative ones besides vanilline (V) colorimetric method by Sandler et al. (6, 7). Two dimension paper chromatographical method by Armstrong et al. (8), high voltage paper electrophoresis by Studnitz et al. (9) and some others require difficult technique or elaborate apparatus. The authors improved Sandler's method and worked out a new method which can be employed in routine clinical examination with high specificity and reliability. Determination of urinary DOMA, however, has never been tried on the ground that this compound is less stable than VMA and regarded to be excreted far small amount as an intermediate metabolite of both E and NE. But determination of DOMA, like that of VMA, MA or NMA, is considered to give an index of the overall CA level in the organism and is still expected to make a better reflect of metabolic magnitude of endogenous CA than determination of VMA if there was a comparatively large route for endogenous CA metabolism to give DOMA, as reported by Crout (10) and supported by Johnson (11). In this respect the authors elaborated a determination method for urinary DOMA based on an entirely new idea on conversion of DOMA to protocatechu aldehyde (PA).