Bacterial Β-glucuronidase Activity Research Articles

Flaxseed and Lignans Increase Cecal β-Glucuronidase Activity in Rats

Flaxseed has been shown in previous studies to decrease some early markers of colon cancer risk in part because of its lignans. This study determined whether the intake of flaxseed and lignans is related to the activity of bacterial β-glucuronidase, an enzyme suggested to increase colon cancer risk. Seven groups of six female rats each were fed, for four weeks, a basal high-fat (20%) diet (BD), BD supplemented with 2.5%, 5.0%, or 10.0% flaxseed, or BD with daily gavage of 0.75, 1.5, or 3.0 mg of secoisolariciresinol diglycoside (SDG), the major mammalian lignan precursor. The specific and total activities of b-glucuronidase in the cecum were significantly related to the levels of flaxseed (r = 0.539, p < 0.008 and r = 0.599, p < 0.002, respectively) and SDG (r = 0.567, p < 0.007 and r = 0.435, p < 0.04, respectively). The urinary mammalian lignan excretion also increased with increasing flaxseed or SDG levels and thus was significantly related to the specific activity (r = 0.38, p < 0.017) and total activity (r = 0.429, p < 0.007) of β-glucuronidase. Because flaxseed and lignans are colon cancer protective, it is concluded that, in contrast to other studies, β-glucuronidase activity may play a beneficial role in their presence by increasing mammalian lignan absorption and enterohepatic circulation.

Biliary manometry, bacterial characteristics, bile composition, and histologic changes fifteen to seventeen years after endoscopic sphincterotomy

Aim: To evaluate the function of the biliary sphincter 15 to 17 years after endoscopic sphincterotomy and to investigate if loss of sphincter function is associated with bacterial colonization, changes in bile composition, or inflammation of the biliary system. Methods: Eight patients who had undergone endoscopic sphincterotomy for bile duct stones 15 to 17 years previously underwent ERCP with biliary manometry, bile sampling, and biopsy. Manometry was performed using a perfused triple-lumen manometry catheter and a station pull-through technique. Bile samples were cultured and analyzed for biliary lipids, bile salts, bacterial β-glucuronidase, and phospholipase A 2. Biopsy specimens were taken from the proximal common hepatic duct for histologic examination. Results: Manometry demonstrated absent basal sphincter pressure and no choledochoduodenal pressure gradient in all patients. Phasic contractions were observed in two patients. Cholangiography showed stones in one patient. Positive cultures were obtained in three patients, including the patient with stones. All bile samples showed a high content of biliary lipids and cholesterol. Some samples contained considerable amounts of hydrophobic bile salts. Five samples contained very high levels of phospholipase A 2 activity. Significant bacterial β-glucuronidase activity was found in one patient, the patient with stones. Biopsy specimens of the proximal common hepatic duct in three patients showed chronic inflammation with fibrosis and reactive epithelial changes. Conclusions: After endoscopic sphincterotomy for bile duct stones, the function of the biliary sphincter is permanently lost. This is associated with bacterial colonization, presence of cytotoxic components in the bile, and chronic inflammation of the biliary system. (Gastronintest Endosc 1997;45:400-5.)

β-Glucuronidase in common duct bile, methodological aspects, variation of pH optima and relation to gallstones

β-Glucuronidase of human or bacterial origin may deconjugate bilirubin diglucuronide, causing pigment gallstones. Intrinsic interference by biliary compounds must be minimized for accurate assay of β-glucuronidase.We report a modified ion-pair extraction of interfering substances by tetrahexylammonium chloride (THAC) in ethyl acetate in the presence of albumin, and a microtitre plate assay for biliary β-glucuronidase activity in bile with the substrate β-nitrophenol-glucuronide. Adding albumin improved the recovery of β-glucuronidase activity to 99.8% (CV 1.9%), and 92.2% of the bilirubin in bile samples was extracted in one step. Competitive inhibition was overcome by increasing the substrate concentration. In endoscopically obtained common duct bile from 44 patients, five different β-glucuronidase activity peaks were identified, at pH 3.9, 4.8, 5.3, 5.8 and 7.2. The pH profiles were classified into one bacterial pattern and five patterns for presumed human β-glucuronidase. Of the latter patterns, four displayed dual activity peaks. In a second sample, obtained at follow up in four patients, their original pH profile was maintained.In conclusion, using the modified purification and assay system, we found functionally diverse subcategories of human β-glucuronidase with respect to activity at variable pH. Our results indicate that several pH optima have to be taken into consideration in order to clarify the role of human biliary β-glucuronidase in the pathogenesis of pigment gallstones. Bacterial β-glucuronidase activity was associated with duodenal diverticula (p<0.05) and common duct stones (p<0.05).

Hydrolysis of iodothyronine glucuronides by obligately anaerobic bacteria isolated from human faecal flora

35 bacterial strains isolated from the human faecal flora were screened for hydrolysis of the glucuronides of 3,3′,5-triiodothyronine and 3,3′-diiodothyronine. Two Gram-positive obligately anaerobic strains possessed glucuronidase activity. These strains probably belong to the genus Eubacterium, but ethanol was produced in high concentrations during glucose fermentation, which makes final classification difficult. Considering the number of bacteria in the intestinal flora (> 108/ml) and the biliary excretion of iodothyronine conjugates, the strains must be able to hydrolyse a major part of the total daily intestinal supply of these iodothyronine metabolites. The study extends previous observations with faecal suspensions of human and rat origin [24]. The relevance of bacterial β-glucuronidase activity for a possible enterohepatic circulation of iodothyronines is discussed.

Effect of dietary fiber on intestinal bacterial beta-glucuronidase activity in chicks fed a cholesterol-containing diet.

The effect of dietary fiber isolated from blackgram (Phaseolus mungo) was studied on the metabolic activity of microflora in the large intestine and cecum in chicks fed a cholesterol diet. The results indicate that inclusion of cholesterol in the diet increased the bacterial as well as tissue (large intestine, small intestine, and cecum) beta-glucuronidase activity when compared to a cholesterol-free diet. Dietary fiber isolated from blackgram when given at 30% level to chicks fed a cholesterol diet significantly lowered bacterial as well as tissue beta-glucuronidase activity. Pure cellulose at the same level did not have this effect.

The epidemiology of cancer of the large bowel.

The geographic distribution of cancer of the colon, particularly its low incidence in Japan, its increase among Japanese immigrants to the United States, and the high rate of this disease among North Americans and most Western Europeans, indicate that environmental factors are of etiological significance in the development of this disease. Available evidence suggests an association of colon cancer to dietary factors, largely related to dietary fat intake. Studies in metabolic epidemiology have shown a correiation between dietary fat intake and the composition of intestinal micro-flora, and between the fecal bile acids and cholesterol metabolites. A significant association has also been established between the level of fecal anaerobic bacteria, bacterial β-glucuronidase activity, bile acid and cholesterol metabolites, and the risk of colon cancer among different populations. We also found that in the rat model, lithocholic acid and deoxycholic acid, which are present in high concentration in the stool of man, acted as tumor promotors to an established large-bowel carcinogen. It remains to be shown whether this established association is causative in nature.

EFFECT OF KNOWN CONSTITUENTS OF BILE ON THE ACTIVITY OF BACTERIAL BETA-GLUCURONIDASE.

As demonstrated in the preceding paper, normal bile has a significant in-hibitory effect on bacterial β-glucuronidase which is known to play an important role in the development of calcium bilirubinate stones. To elucidate the pheno-menon, a number of substances that are generally accepted as bile constituents were independently examined for the effect on the activity of bacterial β-glucuronidase. It was then revealed that fatty acids, lecithin, cholesterol and inorganic ions except Cu++ did not influence the enzyme activity. Bile acids inhibited the activity of a commercial preparation of this enzyme but rather activated bacterial β-glucuronidase of infected bile. Free bilirubin as well as glucuronic acid exhibited a considerable inhibitory power only at a concentration exceeding the actual concentration in normal bile. Cu++ inhibited the enzyme activity at a concentration near the normal Cu content of bile, but there was no significant correlation between the Cu content and the inhibitory power of normal bile specimens. The results thus seem to suggest that bile includes a strong inhibitor of this enzyme which has not yet been identified as a normal constituent of bile.

Quantitative determination of D-glucaric acid in bile in relation to inhibitory effect of bile on bacterial beta-glucuronidase.

Normal bile has a considerable effect to inhibit the activity of bacterial β-glucuronidase, and such a property of bile is of practical interest since this enzyme is concerned with formation of calcium bilirubinate gallstones. In relation to this fact, it was demonstrated qualitatively in the preceding paper that bile might contain D-glucaro-l, 4-lactone, a lactone of D-glucaric acid and strong inhibitor of this enzyme. To confirm the fact on a quantitative basis, the method of Ishidate et al. for quantitative estimation of D-glucaric acid in urine was modified so that it was made applicable to bile specimens. The D-glucaric acid content of human gallbladder bile as measured by this method ranged from 38 to 634μg/ml. Furthermore, a significant positive correlation was pointed out between the D-glucaric acid content and the inhibitory power of bile over bacterial β-glucuronidase.

IDENTIFICATION OF GLUCARO-1,4-LACTONE IN BILE AS A FACTOR RESPONSIBLE FOR INHIBITORY EFFECT OF BILE ON BACTERIAL BETA-GLUCURONIDASE.

It has been demonstrated in the author's previous experiments that normal bile has a remarkable inhibitory effect on bacterial β-glucuronidase but such an effect is not ascribable to any of known constituents of bile. Experiments were undertaken to identify glucaro-1, 4-lactone, a lactone of glucaric acid and strong inhibitor of β-glucuronidase, in bile. When bile was boiled with HCl to remove bile pigments as a deposit and then dialyzed against water, the inhibitory effect disappeared. A condensate of the dialyzate, on the other hand, exhibited a remarkable inhibitory power. This fraction gave a positive qualitative reaction for sugar acids and their relatives, and revealed on paper chromatography a spot with the same Rf as reference glucaro-1, 4-lactone. Oral administration of glucaro-l, 4-lactone calcium salt to patients with biliary infection was always followed by a more than 50 per cent decrease of the bacterial β-glucuronidase activity of bile. From these results, it has been concluded that bile contains glucaro-1, 4-lactono as a normal constituent and this compound is responsible for the inhibitory effect of bile on β-glucuronidase of bacterial origin.

INHIBITORY EFFECT OF BILE CONSTITUENTS UPON BACTERIAL BETA-GLUCURONIDASE ACTIVITY. I. EFFECT OF NORMAL BILE.

Using and assay system consisting of a bacterial β-glucuronidase preparation and phenolphthalein glucuronide, it was experimentally demonstrated that the bile, both the bladder bile and the choledochus bile, of patients without liver or biliary tract diseases had an inhibitory effect on the activity of bacterial β-glucuronidase.