Chemical hybridization of sulfasalazine and dihydroartemisinin promotes brain tumor cell death.

Gliomas are primary brain tumors with still poor prognosis for the patients despite a combination of cytoreduction via surgery followed by a radio-chemotherapy. One strategy to find effective treatment is to combine two different compounds in one hybrid molecule via linker to add to or at best potentiate their impact on malignant cells. Here, we report on the effects of a newly synthesized hybrid of sulfasalazine (SAS) and dihydroartemisinin (DHA), called AC254. In previous studies, both SAS and DHA have already proved to have anti-tumor properties themselves and to have sensitizing respectively potentiating effects on other treatments against malignant tumors. We investigated the impact of individual drugs SAS and DHA, their 1:1 combination and a novel SAS-DHA hybrid compound (AC254) on rodent and human glioma cells. In our study SAS alone showed no or only a mild effect on glioma, whereas DHA led to a significant reduction of cell viability in a dose-dependent manner. Next we compared the efficacy of the hybrid AC254 to the combinational treatment of its parent compounds SAS and DHA. The hybrid was highly efficient in combating glioma cells compared to single treatment strategies regarding cell viability and cell death. Interestingly, AC254 showed a remarkable advantage over the combinational treatment with both parent compounds in most used concentrations. In addition to its reduction of tumor cell viability and induction of cell death, the hybrid AC254 displayed changes in cell cycle and reduction of cell migration. Taken together, these results demonstrate that clinically established compounds such as SAS and DHA can be potentiated in their anti-cancer effects by chemical hybridization. Thus, this concept provides the opportunity to devise new effective chemotherapeutic agents.

Assessing factors for choosing a primary care specialty in medical students; A longitudinal study.

A shortage of primary care physicians exists in the US, and medical schools are investigating factors that influence specialty choice. To better understand the factors associated with medical students choosing primary care specialties, a longitudinal annual survey from 2013 to 2019 was administered to students at the University of Iowa Carver College of Medicine, starting pre-matriculation. A logistic regression model examined factors of interest. Matching into a primary care specialty (family medicine, internal medicine, pediatrics) for residency was the primary outcome. Our study compared factors students reported in annual surveys: demographics, mentorship, debt, and lifestyle. Factors significantly associated with primary care specialty included pre-medical and medical school research, a family member in primary care, student age and gender. 28% of men chose primary care, and 47% of women. Although there was no gender difference in rates of medical education debt (N = 286,χ2(1) = 0.28, p = 0.60), men were more likely to report being influenced by debt (N = 278, χ2(1) = 10.88, p = 0.001), and students who reported debt-influenced specialty choice were one-third as likely to enter primary care (N = 189, 95% CI [0.11-1.06], p = 0.06). For men, potential salary was negatively associated with entering primary care (p = 0.03). Women were more likely to have a mentor in primary care (N = 374, χ2(1) = 13.87, p < 0.001), but this was not associated with an increased likelihood of entering primary care for men or women. Having a family member who practices primary care was associated with a 2.87 times likelihood of entering primary care (N = 303, 95% CI [1.14-7.19], p = 0.03). The decision to enter primary care is influenced by many factors; a key gender differentiator is that men's specialty choice is more negatively influenced by financial concerns.

System Xc- Antiporter Inhibitors: Azo-Linked Amino-Naphthyl-Sulfonate Analogues of Sulfasalazine.

The cystine/glutamate antiporter system Xc- (SXc-) mediates the exchange of intracellular L-glutamate (L-Glu) with extracellular L-cystine (L-Cys2). Both the import of L-Cys2 and the export of L-Glu take on added significance in CNS cells, especially astrocytes. When the relative activity of SXc- overwhelms the regulatory capacity of the EAATs, the efflux of L-Glu through the antiporter can be significant enough to trigger excitotoxic pathology, as is thought to occur in glioblastoma. This has prompted considerable interest in the pharmacological specificity of SXc- and the development of inhibitors. The present study explores a series of analogues that are structurally related to sulfasalazine, a widely employed inhibitor of SXc-. We identify a number of novel aryl-substituted amino-naphthylsulfonate analogues that inhibit SXc- more potently than sulfasalazine. Interestingly, the inhibitors switch from a competitive to noncompetitive mechanism with increased length and lipophilic substitutions, a structure-activity relationship that was previously observed with aryl-substituted isoxazole. These results suggest that the two classes of inhibitors may interact with some of the same domains on the antiporter protein and that the substrate and inhibitor binding sites may be in close proximity to one another. Molecular modeling is used to explore this possibility.

Novel analogs of sulfasalazine as system xc- antiporter inhibitors: Insights from the molecular modeling studies.

System xc- (Sxc- ), a cystine-glutamate antiporter, is established as an interesting target for the treatment of several pathologies including epileptic seizures, glioma, neurodegenerative diseases, and multiple sclerosis. Erastin, sorafenib, and sulfasalazine (SSZ) are a few of the established inhibitors of Sxc- . However, its pharmacological inhibition with novel and potent agents is still very much required due to potential issues, for example, potency, bioavailability, and blood-brain barrier (BBB) permeability, with the current lead molecules such as SSZ. Therefore, in this study, we report the synthesis and structure-activity relationships (SAR) of SSZ derivatives along with molecular docking and dynamics simulations using the developed homology model of xCT chain of Sxc- antiporter. The generated homology model attempted to address the limitations of previously reported comparative protein models, thereby increasing the confidence in the computational modeling studies. The main objective of the present study was to derive a suitable lead structure from SSZ eliminating its potential issues for the treatment of glioblastoma multiforme (GBM), a deadly and malignant grade IV astrocytoma. The designed compounds with favorable Sxc- inhibitory activity following in vitro Sxc- inhibition studies, showed moderately potent cytotoxicity in patient-derived human glioblastoma cells, thereby generating potential interest in these compounds. The xCT-ligand model can be further optimized in search of potent lead molecules for novel drug discovery and development studies.

Retrospective study of salazosulfapyridine in eight patients with rheumatoid arthritis on hemodialysis.

OBJECTIVE: We examined the pharmacokinetics (PK) of salazosulfapyridine (SASP) and its metabolite, sulfapyridine (SP), as well as the influence of hemodialysis (HD), and investigated the utility of consecutive administration of SASP in rheumatoid arthritis patients undergoing HD. METHODS: The PK of salazosulfapyridine and SP in serum samples from 8 patients was determined using high-performance liquid chromatography. RESULTS: When SASP 500 mg was administered, the area under curve for serum concentration of SASP was similar to that seen with normal subjects in the Phase I study. The maximum serum concentration of SP was significantly higher than that in normal subjects, but was far from the danger level. SASP was not dialyzed, whereas on average 62% of SP was dialyzed. Following 5 consecutive days of administration of SASP, serum levels of SASP and SP on day 5 were rather higher than those on day 1, although both remained within the safe range. SASP administration from four months to three years in seven subjects resulted in four American College of Rheumatology 20 improvement criteria (57.1%), with one developing a rash. CONCLUSIONS: If SASP is initiated at a low dosage (≤ 500 mg) and increased up to 1000 mg under careful monitoring, it is safe for HD patients.

The (13)C-butyrate breath test: a new non-invasive method for assessing colitis in a murine model.

The conventional method for the real-time assessment of murine colitis requires a large number of animals. The (13)C-butyrate breath test could be useful for evaluating disease activity and the amelioration of human ulcerative colitis non-invasively. The purpose of this study was to investigate whether this test can be used to assess the phase of inflammation in murine colitis. We investigated the excretion of (13)CO2 measured by the (13)C-butyrate breath test after rectal instillation of butyrate in the DSS colitis model. The colon length, MPO activity, and histological damage were analyzed as parameters. The efficacy of salicylazosulfa-pyridine (SASP) on (13)CO2 excretion was also studied. The (13)CO2 excretion curves in the 0.5% DSS- and 0.75% DSS-treated groups were significantly lower than those in the normal group (P < 0.01, P < 0.01). Good correlation between the results of the breath test and the inflammation parameters was observed. The (13)CO2 excretion curve in DSS murine colitis after the administration of SASP was significantly higher than in the normal group (P < 0.01). The (13)C-butyrate breath test can be used to evaluate the inflammatory phase of DSS murine colitis, and it may be a new non-invasive method for assessing murine colitis.

Inhibition of xc⁻ transporter-mediated cystine uptake by sulfasalazine analogs.

A series of sulfasalazine analogs were synthesized and tested for their ability to block cystine-glutamate antiporter system xc⁻ using L-[(14)C]cystine as a substrate. Replacement of sulfasalazine's diazo group with an alkyne group led to an equally potent inhibitor, 2-hydroxy-5-((4-(N-pyridin-2-ylsulfamoyl)phenyl)ethynyl)benzoic acid 6. Our SAR studies also revealed that the carboxylate group of sulfasalazine is essential for its inhibitory activity while the phenolic hydroxyl group is dispensable. Truncated analogs lacking an N-pyridin-2-ylsulfamoyl moiety were less potent than sulfasalazine, but may serve as more tractable templates because of their low molecular weight by applying a variety of fragment growing approaches. Given that sulfasalazine is rapidly metabolized through cleavage of the diazo bond, these analogs may possess a more desirable pharmacological profile as system xc- blockers, in particular, for in vivo studies.

Spectroscopic, thermal and biological studies of the coordination compounds of sulfasalazine drug: Mn(II), Hg(II), Cr(III), ZrO(II), VO(II) and Y(III) transition metal complexes.

The complexations of sulfasalazine (H3Suz) with some of transition metals have been investigated. Three types of complexes, [Mn(HSuz)-2(H2O)4] x 2H2O, [M(HSuz)-2(H2O)2] x xH2O (M=Hg(II), ZrO(II) and VO(II), x=4, 8 and 6, respectively) and [M(HSuz)-2(Cl)(H2O)3] x xH2O (M=Cr(III) and Y(III), x=5 and 6, respectively) were obtained and characterized by physicochemical and spectroscopic methods. The IR spectra of the complexes suggest that the H3Suz behaves as a bidentate ligand. The thermal decomposition of the complexes as well as thermodynamic parameters (DeltaE*, DeltaH*, DeltaS* and DeltaG*) were estimated using Coats-Redfern and Horowitz-Metzger equations. In vitro antimicrobial activities of the H3Suz and the complexes were tested.

Novel sulfasalazine analogues with enhanced NF-kB inhibitory and apoptosis promoting activity.

The NF-kB transcription factor plays a key role in the regulation of apoptosis by modulating expression of a wide range of cell death control molecules. NF-kB also plays an important role in human diseases by promoting inappropriate cell survival. Small molecule inhibitors of NF-kB are therefore likely to provide novel therapeutic opportunities. Sulfasalazine (SFZ) is a synthetic anti-inflammatory comprising an aminosalicylate, 5-amino salicylic acid (5-ASA), linked to an antibiotic, sulfapyridine (SPY). SFZ, but not 5-ASA or SPY, inhibits activation of NF-kB. We synthesised a small number of SFZ analogues and determined their ability to inhibit NF-kB activity and promote apoptosis in chronic lymphocytic leukaemia and hepatic stellate cells, where NF-kB plays an important role in cell survival. Remarkably, 3 of the 6 analogues synthesised were significantly more effective (up to 8-fold) inhibitors of NF-kB dependent transcription and this increased activity was associated with enhanced apoptosis. Therefore, it is possible to readily improve the NF-kB inhibiting activity of SFZ and analogues of SFZ may be attractive therapeutic agents for malignancies and chronic liver disease where NF-kB is thought to play a significant role.

[Treatment of experimental chronic bacterial prostatitis with free-radical scavenger in rats].

OBJECTIVE: To evaluate the efficacy of free-radical scavenger in the treatment of chronic bacterial prostatitis (CBP). METHODS: Fifty-eight healthy male rats were randomly divided into a control group and four model groups (Groups A, B, C and D). The chronic prostatitis model was established in the latter groups through injecting E. coli into the ventral robe of the prostate according to document. Group A was untreated, Group B treated with free-radical scavenger vitamin C, Group C with salicylazosulfapyridine (SASP), Group D with SASP and vitamin C. Superoxide dismutase (SOD) and malondialdehyde (MDA) examinations were conducted in each group 2 months later. RESULTS: Vitamin C could significantly increase the level of SOD and decrease the level of MDA. There was significant difference between the model groups and the control one, as well as between the treated groups and the untreated one, but none among the treated groups. CONCLUSION: Free-radical scavenger may be useful for the treatment of chronic bacterial prostatitis.

Mechanisms of transport and structure-permeability relationship of sulfasalazine and its analogs in Caco-2 cell monolayers.

PURPOSE: To investigate the mechanisms involved in transport of sulfasalazine in Caco-2 cells. METHODS: Permeability coefficients of sulfasalazine and its analogs across Caco-2 cell monolayers were measured as a function of direction of transport, energy and concentration dependence, and in the presence of inhibitors of various cellular efflux pumps and transporters. RESULTS: Permeability coefficients of sulfasalazine across Caco-2 cell monolayers were approximately 342-, 261-, and 176-fold higher from basolateral to apical direction (BL-->AP) than from apical to basolateral direction (AP-->BL) at 100, 200, and 500 microM, respectively. Carrier permeability coefficient, non-saturable membrane permeability coefficient, and Michaelis constant were estimated to be 1.4x10(-5) cm/s, 1.9x10(-8) cm/s, and 369 microM, respectively. The efflux of sulfasalazine was completely blocked at 4 degrees C and in the presence of an uncoupler of oxidative phosphorylation. Using cellular efflux inhibitors, the permeability of sulfasalazine was shown to depend on multidrug resistance-associated protein and anion sensitive transport mechanisms. Structure-permeability studies showed that the affinity of sulfasalazine for the cellular efflux pumps and transporters in Caco-2 cells depended strongly on the carboxylic acid functional group. CONCLUSIONS: The permeability of sulfasalazine across Caco-2 cell monolayer is very low due to its strong interaction with multiple cellular efflux pumps and transporters. This may partially explain its low absorption in vivo.

Extensive biliary excretion of the sulfasalazine analogue, susalimod, but different concentrations in the bile duct in various animal species correlating to species-specific hepatobiliary toxicity.

Studies on biliary concentrations of susalimod were conducted in rat, dog and monkey to clarify the interspecies differences observed in toxicology studies with respect to hepatobiliary toxicity after long-term administration of the compound. Dose-related bile duct hyperplasia appeared only in dogs at doses > or =75 mg/kg/day, while in rats and monkeys it did not appear at doses up to 1500 and 2000 mg/kg/day respectively. Biliary excretion was investigated after intraduodenal administration of susalimod in anaesthetised animals. In addition excretion routes were determined by collecting urine and faeces following a radiolabelled intravenous dose. Susalimod was extensively excreted via the bile in all animal species, > or =90%, mainly as non-conjugated parent compound. However, the local concentrations in bile varied between the species. Highest concentrations were obtained in the dog. The bile/plasma concentration ratio was 3400 in the dog, 300 in the monkey and 50 in the rat. In the dog, bile duct concentrations of susalimod about 30,000 micromol/l was obtained at plasma concentrations approximately similar to those at which hepatobiliary toxicity occurred, while in rat and monkey the levels were < or =7000 micromol/l at plasma concentrations similar to those obtained at the highest doses in the toxicology studies. From these results supported by a previous biliary excretion study in conscious dogs with chronic bile fistula receiving repeated administration of susalimod (Påhlman et al. 1999), it is likely that the hepatotoxic findings in dog are induced by the high concentrations of susalimod in the bile duct.

Pharmacokinetic-pharmacodynamic modeling of the immunomodulating agent susalimod and experimentally induced tumor necrosis factor-alpha levels in the mouse.

The main objective of this study was to explore the concentration-effect relationship between the immunomodulating agent susalimod and lipopolycaccharide (LPS)-induced elevated serum levels of the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha). Bacterial LPS (1 mg/kg) was given i.p. along with different doses of susalimod (0, 25, 50, 100, and 200 mg/kg) to female CD-1 mice. Blood samples were drawn at different time points (15-300 min), and serum was analyzed with respect to susalimod and TNF-alpha. The concentration-effect relationship was explored by modeling the data from all dose levels simultaneously using specially written program models, i.e., a three-compartment pharmacokinetic model, including biliary excretion, and an indirect mechanistically based pharmacodynamic model. The models, which were successfully fitted to the experimental data, showed that LPS induced the TNF-alpha synthesis during approximately 70 min and that during this time course, the synthesis rate was governed by the serum phamacokinetics of susalimod. Because the results supported the assumption that the maximum inhibitory effect was equal to full inhibition of the synthesis, the in vivo potency (IC(50)) of susalimod could be estimated to 293 microM. In conclusion, susalimod decreased the LPS-induced TNF-alpha mouse serum levels in a concentration-related manner. The compound is suggested to inhibit the synthesis of TNF-alpha. The integrated pharmacokinetic-pharmacodynamic model estimated the in vivo potency of susalimod in the mouse to be 293 microM.

Efficient biliary excretion of susalimod, probably via the bromosulphthalein carrier, studied in a chronic bile fistula model in dogs.

Susalimod is a structural analogue of sulphasalazine, known to be extensively excreted in the bile in various animal species and for inducing bile duct hyperplasia after long-term treatment of the dog with doses exceeding 25 mg kg(-1). In this study local concentrations of susalimod in the bile duct were determined after oral administration in dogs. A chronic bile fistula experimental model was designed to affect the bile duct as little as possible. The dogs received repeated oral doses of 25-150 mg kg(-1) day(-1) for 5 days; these doses had been used in previous toxicology studies. Extremely high biliary concentrations of unchanged susalimod (20,000-43,000 microM) were measured. Biliary excretion approached saturation at the higher doses, resulting in super-proportional increases in peripheral plasma concentrations as the dose was increased. The maximal bile/plasma concentration ratio was 4300. The high biliary clearance was indicative of almost complete first-pass elimination at doses below saturation of the elimination process. Interaction studies with the biliary excretion marker bromosulphthalein (BSP) demonstrated that susalimod and BSP probably share the same carrier transport system in biliary excretion. The elimination of BSP from plasma was prolonged 20 times and the biliary excretion rate was markedly reduced when susalimod was co-administered with BSP. These results show that susalimod is highly enriched in the bile, in a saturable manner, after oral administration. The compound interacts with the biliary excretion of BSP, suggesting that it shares the same carrier-mediated transport system.

[The effect of basic therapy on the morphological picture of the rectal mucosa in patients with rheumatoid arthritis]. / Vliianie bazisnoi terapii na morfologicheskuiu kartinu slizistoi obolochki priamoi kishki u bol'nykh revmatoidnym artritom.

140 rectal mucosa biopsies were obtained from 86 patients with rheumatoid arthritis (RA), from 54 RA patients prior to or after a year basic therapy with either methotrexate or sulfa drug (sulfasalazine or salazopyridazine). 80% of the examinees exhibited large macrophages, lymphoid follicules, IgM- and IgG-containing cells. The knowledge of the initial morphologic changes in the rectal mucosa from RA patients helps predict efficacy of methotrexate or sulfonic drug treatment. Rectoromanoscopy with biopsy proved important diagnostic tool in RA capable of differentiating the disease variants, prompting valid therapeutic approach with control of the treatment results.

[The status of various indicators of the protease inhibitor system in blood and synovial fluid in rheumatoid arthritis]. / Sostoianie nekotorykh pokazatelei proteazno-ingibitornoi sistemy krovi i sinovial'noi zhidkosti pri revmatoidnom artrite.

Elastase-like activity, alpha 1-inhibitor of proteinases and acid stable antitryptic activity were studied in blood of 26 patients and in synovial fluid of 11 patients with rheumatoid arthritis during acute stage of the disease and after treatment with salase pyridasine and orthophene. The higher values of the elastase-like activity were detected in synovial fluid as compared with that of blood. In blood of these patients, hyperproduction of alpha 1-inhibitor of proteinases and acid stable inhibitors was observed, while deficiency of these substances occurred in synovial fluid. Distinct decrease in the patterns of the blood protease-inhibitory system studied simultaneously with clear positive clinical effect were observed after treatment with salase pyridasine together with orthophene; estimation of these patterns may be used in the evaluation of the therapy.

Medical therapy in Crohn's disease.

Traditionally, sulfasalazine and corticosteroids have been used to treat Crohn's disease. However, therapy has been expanded to include other drugs, and several newer agents show clinical promise. The authors discuss the therapeutic options now available and describe results of several drug trials. Despite the apparent benefits of newer therapies, caution must be used in choosing appropriate treatment.

[The comparative efficacy of slow-acting (basic) preparations in psoriatic arthritis]. / Sravnitel'naia éffektivnost' medlenno deistvuiushchikh preparatov pri psoriaticheskom artrite.

Overall 126 patients with verified and clinically active psoriatic arthritis (PA) were subjected to a randomized study of the efficacy of chrisanolum (Chr), sulfasalicylic drugs (SSD) (sulfasalazine and salazopyridazine) and methotrexate (MT) as compared to nonsteroidal anti-inflammatory drugs (NSAID). The treatment that lasted for a year was completed by 77 patients: in the group on NSAID, by 31, on Chr by 15, on SSD by 15, and on MT by 16. In the remainder, the treatment was discontinued because of side effects. The best clinical effect was recorded in patients on Chr. The improvement was observed in 73% of the patients, with a significant effect being attained in 60%. In the groups on SSD and MT, the improvement was observed in 80 and 69%, respectively. However, noticeable improvement was only recorded in 20 and 19%. SSD turned out more effective than MT. in the group on NAID, the improvement was ascertained but in 35% of the patients, with noticeable one being attained in 6%. According to Pearson's criterion chi 2, the results of the treatment with NAID alone were less potent than in the group given Chr (p < 0.001) and SSD (p < 0.05). The differences between the effect of the treatment with NAID and MT appeared nonsignificant (p > 0.1). Therefore, according to the diminution of the clinical efficacy in PA, the basic drugs may be distributed in the following way: Chr, SSD, MT. The side-effects in the group on NAID were. recorded in 37% of cases, in the group on Chr in 53%, on SSD in 33%, and on MT in 55%. This means that SSD were tolerated best of all.

The effects of sulfasalazine metabolites on hemoglobin-catalyzed lipid peroxidation.

Ulcerative colitis (UC) is a recurrent inflammation of the colon and rectum that is characterized by subepithelial hemorrhage, epithelial cell necrosis, infiltration of large numbers of phagocytic leukocytes (neutrophils, eosinophils, macrophages), and mucosal ulcerations. Recent evidence suggests that mucosal lipid peroxidation may play an important role in that pathogenesis of the inflammation-induced intestinal injury. Using hemoglobin (Hb)-catalyzed, H2O2-dependent peroxidation of phospholipid as a model of oxidative injury to membrane lipids, we assessed the ability of the anti-inflammatory drugs sulfasalazine (SAZ), olsalazine, and their metabolites, 5-aminosalicylic acid (5-ASA), N-acetyl-5-ASA, and sulfapyridine (SP) to inhibit this reaction. We found that Hb interacted with H2O2 to yield the radical and nonradical forms of ferryl Hb (Hb(V)) which were capable of initiating the peroxidation of a phospholipid. This interaction did not result in the peroxide-dependent release of iron from the hemoprotein. In addition, we demonstrated that the pharmacologically active moiety of SAZ (or olsalazine), 5-ASA, was significantly better at inhibiting the Hb-catalyzed peroxidative reaction. The concentration of 5-ASA required to inhibit lipid peroxidation by 50% (IC50) was determined to be 50 microM. Neither parent compound (SAZ, olsalazine) nor the pharmacologically inactive metabolite (SP) were effective in attenuating the lipid peroxidation at concentrations up to 100 microM. The N-acetylated derivative of 5-ASA was less effective as an inhibitor in this system possessing an IC50 of 100 microM. The mechanism by which 5-ASA inhibited lipid peroxidation appeared to be due to its ability to donate electrons to and thus scavenge the radical and nonradical forms of HB(IV).(ABSTRACT TRUNCATED AT 250 WORDS)