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PubMed2001

Identification and functional characterization of arylamine N-acetyltransferases in eubacteria: evidence for highly selective acetylation of 5-aminosalicylic acid.

Arylamine N-acetyltransferase activity has been described in various bacterial species. Bacterial N-acetyltransferases, including those from bacteria of the gut flora, may be involved in the metabolism of xenobiotics, thereby exerting physiopathological effects. We characterized these enzymes further by steady-state kinetics, time-dependent inhibition, and DNA hybridization in 40 species, mostly from the human intestinal microflora. We report for the first time N-acetyltransferase activity in 11 species of Proteobacteriaceae from seven genera: Citrobacter amalonaticus, Citrobacter farmeri, Citrobacter freundii, Klebsiella ozaenae, Klebsiella oxytoca, Klebsiella rhinoscleromatis, Morganella morganii, Serratia marcescens, Shigella flexneri, Plesiomonas shigelloides, and Vibrio cholerae. We estimated apparent kinetic parameters and found that 5-aminosalicylic acid, a compound efficient in the treatment of inflammatory bowel diseases, was acetylated with a catalytic efficiency 27 to 645 times higher than that for its isomer, 4-aminosalicylic acid. In contrast, para-aminobenzoic acid, a folate precursor in bacteria, was poorly acetylated. Of the wild-type strains studied, Pseudomonas aeruginosa was the best acetylator in terms of both substrate spectrum and catalytic efficiency. DNA hybridization with a Salmonella enterica serovar Typhimurium-derived probe suggested the presence of this enzyme in eight proteobacterial and four gram-positive species. Molecular aspects together with the kinetic data suggest distinct functional features for this class of microbial enzymes.

Acetylation↗
PubMedDate not supplied

A prospective randomized double blind trial comparing prednisolone and 4-aminosalicylic acid enemas in acute distal ulcerative colitis.

A prospective double blind and randomized study was conducted to compare 4-aminosalicylic acid (4-ASA) and prednisolone-21-phosphate enemas in inducing remission in patients with acute distal ulcerative colitis. Patients with ulcerative colitis distal to the splenic flexure as assessed by flexible colonoscopy, barium enema and histology were included in the study. Of 40 consecutive patients, 20 were randomized to each of the two treatment groups. Clinical evaluation was done weekly; sigmoidoscopy and histology were performed at entry and at the end of 4 weeks. Therapy was discontinued in four patients treated with prednisolone enemas due to worsening of symptoms. The clinical improvement was significant in the remaining patients (P less than 0.001) and was similar in the two groups (P greater than 0.1). Sigmoidoscopic and histological improvement were better with 4-ASA than with prednisolone enemas. No adverse effects were observed in any of the patients treated. The present study suggests that 4-ASA is a safe and effective treatment for inducing remission in acute distal ulcerative colitis.

Acute Disease↗
PubMed1996

Systemic availability of 5-aminosalicylic acid: comparison of delayed release and an azo-bond preparation.

AIM: To determine the systemic uptake of 5-aminosalicylic acid (5-ASA) and acetyl-5-ASA (Ac-5-ASA) at steady state during treatment with either an azo-bond preparation, olsalazine, or a delayed-release mesalazine. METHODS: In an open cross-over trial with randomized sequence, 15 patients with ulcerative colitis in remission were given 7-day courses of olsalazine (Dipentum 1.0 g daily) and of mesalazine (Asacol 1.6 g daily). Plasma and urine were collected on days 6 and 7 of each course and concentrations of 5-ASA and Ac-5-ASA were determined by high-performance liquid chromatography (HPLC). RESULTS: Mean steady-state plasma concentrations of 5-ASA and Ac-5-ASA were significantly higher after treatment with mesalazine than with olsalazine (P < 0.0001). Total urinary excretion of 5-ASA and Ac-5-ASA as a percentage of the given dose was significantly higher on mesalazine than on olsalazine (P < 0.01). Only two patients experienced, during the first 3 days of treatment with olsalazine, transient watery diarrhoea which resolved spontaneously. No unexpected or major changes in haematology or biochemistry were detected during the study. CONCLUSION: As 5-ASA acts locally, the lower systemic load provided by olsalazine may increase efficacy and reduce the potential risk of nephrotoxicity during long-term maintenance treatment of ulcerative colitis.

Adult↗
PubMed1991

Pharmacokinetics of 5-aminosalicylic acid in man following administration of intravenous bolus and per os slow-release formulation.

The fate of 5-aminosalicylic acid (5-ASA), which is used in the treatment of chronic inflammatory bowel diseases, was studied in six healthy volunteers receiving doses of 100 mg and 250 mg intravenous bolus as well as 250 mg per os (slow release). Following intravenous administration, the drug was rapidly eliminated with a plasma half-life of about 40 min, mainly due to rapid metabolism. No parent drug was recovered in feces, and the total recovery following oral administration (30%) was significantly lower than following the intravenous doses (77% and 72%). Nonlinear pharmacokinetics were suggested as the 2.5-fold increase in intravenous dose was followed by a significant relative increase (greater than 2.5) in the renal elimination of 5-ASA, as well as a significant decrease (less than 2.5) in the elimination of the metabolite N-acetyl-5-ASA. There was also a trend towards a decreasing total body clearance and metabolic ratio. The present study confirms earlier findings on the pharmacokinetics of 5-ASA and suggests a possible saturation of the N-acetylating system in the dose range studied. This may be of interest in the design of controlled-release formulations and dosage regimes for the treatment of diseases of the small-bowel, where 5-ASA is easily absorbed. Further, for the first time, a marked difference in the intestinal fate compared to the systemic fate of the drug is demonstrated, suggesting alternative presystemic metabolism of 5-ASA, which may bear relevance to its mode of action. Further studies on the pharmacokinetics of 5-ASA, preferably in patients, are warranted.

Administration, Oral↗
PubMed1995

[5-Aminosalicylic acid in the prevention of recurrences of Crohn's disease].

AIM OF STUDY: To evaluate the efficacy of 5-aminosalicylic acid (5-ASA) in preventing recurrences of Crohn's disease. PATIENTS AND METHODS: Between January 1988 and December 1989 a total of 60 patients (37 men, 23 women, mean age 34.8 years) were selected in whom the diagnosis of Crohn's disease had been known for at least 2 years. A further criterion for inclusion was remission for at least one year in patients who had been operated or for one month in the nonoperated ones. Furthermore, the latter must have had at least one recurrence during the last year. They were in turn assigned to be treated with 5-ASA (2.4 g daily by mouth) or not treated (control). The activity and localization of Crohn's disease were defined according to the "Crohn's disease activity index" (CDAI) and the "laboratory index" (LI), as well as by endoscopy and (or) radiology. The patients were examined every 6 months for 4 years. A recurrence was diagnosed if the CDAI was more than 150 or had increased to at least 60 points above the initial value and the LI was above 100. RESULTS: 29 recurrences were noted, 72.4% within the first 2 years. 15 recurrences (46.9%) were in the treated patients and 14 (58.3%) among the untreated controls. The Kaplan-Meier curve (statistical comparison of the probability of recurrence) showed no significant difference between the two groups (P = 0.23): the recurrence rate was the same in the two groups, among the patients with or without previous operation and for different primary localizations. There were no notable side effects. CONCLUSION: Treatment with 5-ASA was not found to influence the likelihood of recurrence. Age, duration of the disease, primary localization and previous operation were not prognostic factors.

Adult↗
PubMed1990

Cytoprotection against neutrophil derived hypochlorous acid: a potential mechanism for the therapeutic action of 5-aminosalicylic acid in ulcerative colitis.

The aim of the present study was to investigate the effects of 5-aminosalicyclic acid (5-ASA) on the cell injury mediated by activated neutrophils. We used a system constituted of neutrophils, triggered with phorbol myristate acetate, and 51Cr-labelled Daudi cells as targets. The results show that 5-ASA is capable of efficiently preventing neutrophil-mediated lysis. 5-ASA was up to 10-fold more effective than taurine, which acts as an hypochlorous acid scavenger. Moreover, 5-ASA was found to compete with taurine for the neutrophil derived hypochlorous acid. The results are consistent with the conclusion that 5-ASA is capable of limiting the neutrophil mediated cell damage by scavenging the generated hypochlorous acid. This may represent a potential mechanism for the therapeutic action of 5-ASA in ulcerative colitis.

Aminosalicylic Acids↗
PubMed2003

Effect of 5-aminosalicylic acid on radiation-induced micronuclei in mouse bone marrow.

5-Aminosalicylic acid (5ASA), a prescribed drug for ulcerative colitis, is a potent scavenger of oxygen-derived free radicals. The present study was undertaken to ascertain its ability to protect against radiation-induced damage. The drug dose-dependent effect, optimum time of drug administration and radiation dose-dependent effect (0-4 Gy) on in vivo radiation protection against micronuclei induction in polychromatic erythrocytes (PCE) and normochromatic erythrocytes (NCE) were studied in the bone marrow of mice. Intraperitoneal injection of 10-125 mg/kg of the drug 30 min before whole body irradiation with 3 Gy produced a significant reduction in the frequency of micronucleated erythrocytes at 24 h after exposure. The optimum dose for protection without drug toxicity was 25 mg/kg body weight. Injection of 25 mg/kg of the drug 60 or 30 min before or within 15 min after 3 Gy whole body gamma-irradiation resulted in a significant decrease in the radiation-induced PCE and NCE with micronuclei (MPCE and MNCE) and an increase in the ratio of PCE to NCE (P/N), at 24 h post-irradiation. Maximum effect was seen when the drug was administered 30 min before irradiation. Therefore, to study the radiation dose-response, mice were pre-treated with 25 mg/kg of 5ASA 30 min before 1-4 Gy of gamma-irradiation. Radiation increased the MN frequency linearly (r(2)=0.99) with dose. Pre-treatment with 5ASA significantly reduced the MN counts to 40-50% of the radiation (RT) alone values, giving a dose modification factor (DMF) of 2.02 (MPCE) and 2.53 (MNCE). Irradiation resulted in a dose-dependent decline in the P/N ratio at all the doses of radiation studied. 5ASA produced a significant increase in the P/N ratio from that of irradiated controls, at all doses of radiations tested. These results show that 5ASA protect mice against radiation-induced MN formation and mitotic arrest.

Animals↗
PubMed2006

Silencing of SH-PTP2 defines a crucial role in the inactivation of epidermal growth factor receptor by 5-aminosalicylic acid in colon cancer cells.

Recent studies have suggested that 5-aminosalicylic acid (5-ASA) inhibits colorectal cancer (CRC) development. However, the mechanism underlying the antineoplastic effect of 5-ASA remains unknown. We here examined the effect of 5-ASA on epidermal growth factor receptor (EGFR) activation, a pathway that triggers mitogenic signals in CRC cells. We show that 5-ASA inhibits EGFR activation, through a mechanism that does not rely on CRC cell death induction. 5-ASA enhances the activity, but not expression, of phosphorylated (p)-EGFR-targeting phosphatases (PTPs), and treatment of cells with PTP inhibitors abrogates the 5-ASA-mediated EGFR dephosphorylation. Both SH-PTP1 and SH-PTP2 interact with EGFR upon 5-ASA treatment. However, knockdown of SH-PTP2 but not SH-PTP1 by small interference RNAs prevents the 5-ASA-induced EGFR dephosphorylation. Finally, we show that 5-ASA attenuates p-EGFR in ex vivo organ cultures of CRC explants. Data indicate that 5-ASA disrupts EGFR signalling by enhancing SH-PTP2 activity, and suggest a mechanism by which 5-ASA interferes with CRC growth.

Adenocarcinoma↗
PubMed1999

Chronic interstitial nephritis due to 5-aminosalicylic acid.

Nephrotoxicity has recently been reported with the use of 5-aminosalicylic acid (5-ASA) which has structural similarities to phenacetin and aspirin. The present paper describes 2 cases of interstitial nephritis and 1 case of end-stage failure associated with 5-ASA treatment. The first patient presented with severe renal failure which was partially reversed with 5-ASA discontinuation and steroid therapy. The second had severe renal failure (serum creatinine 469 mmol/l) but renal function stabilized with 5-ASA withdrawal. The third patient had end-stage renal failure and underwent hemodialysis and a successful kidney transplant.

Adult↗
PubMed1990

Pancreatitis after rectal administration of 5-aminosalicylic acid.

A patient treated with sulfasalazine for new-onset ulcerative colitis developed self-limited pancreatitis. Rechallenge with 5-aminosalicylic acid (5-ASA) in enema form (Rowasa) again induced pancreatitis. Recent case reports suggest that the salicylate component of sulfasalazine can lead to the development of pancreatitis with oral 5-ASA administration. This patient's course demonstrates further that rechallenge with 5-ASA in a rectal form may also lead to pancreatitis.

Administration, Rectal↗
PubMed1987

5-Aminosalicylic acid enemas in treatment of distal ulcerative colitis and proctitis in Canada.

The efficacy and safety of 4 g 5-aminosalicylic acid (5-ASA) enemas were assessed in 59 patients with ulcerative colitis involving up to 50 cm of their distal colon. Twenty-nine patients received 5-ASA and 30 received a placebo. There were 12 dropouts (five in the active and seven in the placebo group) during the study because of insufficient efficacy. After six weeks of therapy, 63% of the patients receiving the 5-ASA were considered to be "much improved" by the study physician compared to 20% patients on placebo (P less than 0.0001). A disease activity index (DAI), based upon patient symptoms and sigmoidoscopic appearance, was used to assess efficacy. Mean DAI declined 75% for patients on 5-ASA enemas and 32% for patients on placebo (P less than 0.05). The 5-ASA enemas are well tolerated and are of benefit in the treatment of ulcerative colitis confined to the distal colon.

Adult↗
PubMed1993

Effect of ascorbate and 5-aminosalicylic acid on light-induced 8-hydroxydeoxyguanosine formation in V79 Chinese hamster cells.

Recently we showed that ascorbate and 5-aminosalicylic acid (5-ASA) prevented 8-hydroxydeoxyguanosine (8-OHdG) formation in calf thymus DNA exposed to UV-visible light. However, the ultimate defense against oxidative DNA damage depends on an intracellular/intranuclear effect of the compounds. In the present study we investigated the effect of ascorbate and 5-ASA on 8-OHdG formation in V79 Chinese hamster cells exposed to light from a sun-lamp. Exposure for 1 min (4560 mJ/cm2) increased 8-OHdG formation in cellular DNA to 30-40 times background level. Preincubation of the cells with ascorbate or 5-ASA at concentrations of 0.1, 1 and 10 mM diminished the 8-OHdG formation to 0.67, 0.74 and 0.49 times controls (P < 0.05) for ascorbate respectively, and to 0.82, 0.66 and 0.33 times controls (P < 0.05), for 5-ASA. These findings demonstrate that both ascorbate and 5-ASA prevent oxidative DNA damage in cells by acting as intracellular/intranuclear antioxidants.

Aminosalicylic Acids↗
PubMed1992

Clinical tolerance to three 5-aminosalicylic acid releasing preparations in patients with inflammatory bowel disease intolerant or allergic to sulphasalazine.

The clinical tolerance to three 5-aminosalicylic acid (5-ASA) releasing preparations (mesalazine, olsalazine and balsalazide) was assessed in a consecutive series of 43 patients with inflammatory bowel disease who were intolerant to sulphasalazine. The relative contributions to the side-effects of sulphasalazine made by its two components, 5-ASA and sulphapyridine, were also assessed in these patients. Thirty-nine (91%) patients were able to tolerate at least one of the three 5-ASA preparations. Only four (9%) patients were intolerant to all preparations, having adverse reactions previously experienced with sulphasalazine and presumably related to 5-ASA rather than sulphapyridine. The clinical tolerance to mesalazine (63%), olsalazine (70%) and balsalazide (70%) was similar, and tolerance to one drug only was found in nine (18%) patients. The commonest adverse reactions associated with 5-ASA preparations were gastrointestinal. Diarrhoea was a problem in five patients during treatment with olsalazine and three each while on mesalazine and balsalazide. Allergic reactions from 5-ASA preparations were uncommon; of ten patients with rash following sulphasalazine only one developed a rash with mesalazine. The results of this study indicate that the vast majority of patients with inflammatory bowel disease can be managed with at least one of these four 5-ASA containing preparations and that the side-effects of sulphasalazine are multifactorial in aetiology, some being due to the parent molecule, and some to one of its two metabolites, 5-ASA and sulphapyridine.

Aminosalicylic Acids↗
PubMed1996

Systemic absorption of 5-aminosalicylic acid in patients with inactive ulcerative colitis treated with olsalazine and mesalazine.

OBJECTIVE: To compare the systemic load of 5-aminosalicylic acid (5-ASA) as a basis for potential long-term toxicity during treatment in usual dosage with olsalazine (Dipentum) and one controlled-release mesalazine preparation (Salofalk) in patients with inactive ulcerative colitis. DESIGN: Open, randomized, crossover study. TREATMENT SCHEDULE: Olsalazine 500 mg twice daily for 7 days and mesalazine 500 mg thrice daily for 7 days consecutively. PATIENTS: Fifteen patients (12 males/3 females) aged between 18-70 years with ulcerative colitis in endoscopically confirmed remission for at least one month. METHODS: A morning predose plasma sample and a 24-h urine collection on days 6 and 7 of each course were obtained from all patients for quantitative determination of 5-ASA and acetyl-5-ASA (Ac-5-ASA) concentrations. High performance liquid chromatography was used and all analyses were performed blindly on coded samples. RESULTS: Treatment with mesalazine compared with olsalazine gave significantly higher levels of 5-ASA and Ac-5-ASA in plasma and urine. Maximum values and ranges of all variables were higher in the mesalazine group than in the olsalazine group. It is noteworthy that there was clear discriminance in the range of urine 5-ASA and Ac-5-ASA concentrations after mesalazine and olsalazine treatment. CONCLUSION: 1. The mesalazine preparation used, in comparison with olsalazine given in usual dosages, causes significantly higher levels of 5-ASA and Ac-5-ASA in plasma and urine in patients with inactive ulcerative colitis. 2. The lower systemic load of 5-ASA may reduce the potential risk of adverse events and in particular of nephrotoxicity.

Administration, Oral↗
PubMed1986

Effect of 5-aminosalicylic acid (5-ASA) and other salicylates on short-chain fat metabolism in the colonic mucosa. Pharmacological implications for ulcerative colitis.

5-Aminosalicylic acid (5-ASA) suppressed nitrite-stimulated oxidation of the fatty acid n-butyrate in a dose-dependent manner in isolated human and rat colonic epithelial cells. 4-ASA had one-sixth of the capacity of 5-ASA and sulphapyridine (SP) little of the capacity of 5-ASA to suppress fatty acid oxidation in human colonic epithelial cells. Sulphasalazine (SASP), azodisalicylic acid (ADS), acetyl-5-ASA and acetyl salicylic acid (ASA) did not suppress fatty acid oxidation in rat colonocytes. The suppression index of fatty acid oxidation (SIFO) of respective salicylic acids correlated with the reported clinical effectiveness of each drug against ulcerative colitis (UC). The capacity of 5-ASA to affect nitrite-stimulated oxidation of fat in the colonic mucosa suggests that nitrite ions and control of fatty acid oxidation play a central role in the development and therapy of active UC.

Aminosalicylic Acids↗