Previous methods for the determination of homogentisic acid have been based upon its ability to reduce silver (I), phosphomolybdic acid (a), or iodine (3-5). The error introduced by other biological substances which have similar reducing properties is inconsequential in the determination of the relatively large amounts of homogentisic acid present in urine from a patient with alcaptonuria. Such...

A new method is described for qualitative and quantitative determination of urinary homogentisiC acid. The method involves extraction of urine with ethyl acetate, thin-layer chromatography of the extract on Silica Gel G, elution of the homogentisiC acid into water, and color development with Folin’s phenol reagent. Absorbance is maximum at 750 nm and linear to a concentration of at least 5 mg o...

Yarrowia lipolytica produces brown extracellular pigments that correlate with tyrosine catabolism. During tyrosine depletion, the yeast accumulated homogentisic acid, p-hydroxyphenylethanol, and p-hydroxyphenylacetic acid in the medium. Homogentisic acid accumulated under all aeration conditions tested, but its concentration decreased as aeration decreased. With moderate aeration, equimolar con...

The first clear recognition that novel phenotypes may reflect discrete biochemical differences was provided by the English physician Archibald E. Garrod at the turn of the 20th century. In 1902, barely after the rediscovery of Mendel’s work, Garrod described a disease, alkaptonuria, in which affected patients produced urine that turned black upon exposure to air—a rather disconcerting symptom. ...

A relatively simple method for the quantitative determination of homogentisic acid in urine is presented. Homogentisic acid (2,5-dihydroxyphenylacetic acid) is oxidized by atmospheric oxygen in mild alkali to form 1,4-benzoquinone-2-acetic acid. The latter compound is then conjugated with 2,4-dinitrophenylhydrazine. The resulting hydrazone, in the presence of alcoholic sodium hydroxide, produce...

Alkaptonuria ochronosis is a rare metabolic disease in which the body does not have enough enzyme called homogentisic acid oxidase. Due to the homogentisic acid oxidase deficiency, homogentisic acid accumulates in cartilage and connective tissues which leads to ochronotic arthritis. We reported a case of bilateral ochronotic arthritis verified by clinical presentation, imaging, arthroscopic and...

a 2-year-old boy was born at term of healthy, non-consanguineous iranian parents. his mother attended in the clinic with the history of sometimes discoloration of diapers after passing urine. she noticed that first at the age of one month with intensified in recent months. his physical examination and growth parameters were normal. his mother denied taking any medication (sorbitol, nitrofuranto...

In the course of a study of the properties of the homogentisic acid oxidase of rat liver the activity of other animal tissues has been briefly examined. The enzyme has been reported to occur in beef and hog (I), guinea pig (2), and rabbit (3) livers and in a strain of Pseudomonas (4). The experiments reported here show that the enzyme is also present in pigeon liver and in guinea pig, rabbit, p...

The literature on alcaptonuria has been well summarized (1--6). Paschkis et al. (7) reported that thiouracil and para-aminobenzoic acid inhibited the in vitro conversion of tyrosine to melanin by tryrosinase, and White (8) found that thiouracil inhibited melanuria. Lerner and associates (9) noted that the tyrosinase of mouse melanoma is a copper protein whose activity can be inhibited by the ad...