Double-prodrugs of L-cysteine: differential protection against acetaminophen-induced hepatotoxicity in mice

A series of double-prodrugs of L-cysteine, designed to release L-cysteine in vivo and stimulate the biosynthesis of glutathione (GSH), were synthesized. To evaluate the hepatoprotective effectiveness of these double-prodrugs, male Swiss-Webster mice were administered acetaminophen (ACP) (2.45 mmol/kg (360 mg/kg), intraperitoneally (i.p.)). Prodrug (2.50 mmol/kg, i.p. or 1.25 mmol/kg, i.p., depending on the protocol) was administered 1 h before ACP as a priming dose. A supplementary dose of prodrug (2.5 mmol/kg, i.p. or 1.25 mmol/kg, i.p. depending on the protocol) was administered 0.5 h after ACP. The plasma alanine amino transferase (ALT) values, 24 h after ACP administration were transformed to logs and the 95% and 99% confidence intervals of the log values were plotted and compared for each group. Hepatoprotection was assessed by the degree of attenuation of plasma ALT levels. With these multiple dose schedules, the use of 2% carboxymethylcellulose as vehicle for the prodrugs was found to be detrimental; therefore, the prodrugs were dissolved in dilute aqueous base and the pH adjusted for administration. When a priming dose was given 1 h before ACP followed by a supplementary dose 0.5 h after ACP, only N,S-bis-acetyl-L-cysteine, where both the sulfhydryl and amino groups of L-cysteine were functionalized with the acetyl group, was found to be effective in protecting mice against the hepatotoxic effects of ACP. This suggests that these acetyl groups were rapidly hydrolyzed in vivo to liberate L-cysteine. In contrast, N-acetylation of 2(R,S)-methylthiazolidine-4(R)-carboxylic acid (MTCA) and its 2-n-propyl analog (PTCA), or N-acetylation of 2-oxothiazolidine-4-carboxylic acid (OTCA), reduced the hepatoprotective effects relative to the parent MTCA, PTCA, and OTCA, indicating that the release of L-cysteine in vivo from these N-acetylated thiazolidine prodrugs was metabolically unfavorable. The carbethoxy group, whether functionalized on the sulfhydryl or on the amino group of L-cysteine, or on the secondary amino group of MTCA, appears to be a poor "pro-moiety," since these carbethoxylated double-prodrugs of L-cysteine did not protect mice from ACP-induced hepatotoxicity.     

Effect of a cysteine prodrug, L-2-oxothiazolidine-4-carboxylic acid, on the metabolism and toxicity of bromobenzene: an acute study

The effect of a cysteine prodrug, L-2-oxothiazolidine-4-carboxylic acid (OTCA), on certain aspects of the metabolism and toxicity of bromobenzene administered acutely to mice was investigated by (i) characterizing the influence of OTCA on the metabolic profile of low and high bromobenzene dose at 0-6, 6-12, and 12-24 h, (ii) determining the effective doses range and administration time for OTCA, as well as the optimum period for urine sampling; and (iii) measuring the efficacy of OTCA for protection against bromobenzene induced toxicity. Coadministration of OTCA and bromobenzene enhanced the urinary excretion of mercapturic acid and phenolic metabolites, during 6-12 h, by approximately 152 and 193%, respectively. Maximum efficacy was observed when OTCA (16.0 mmol/kg) was administered concomitantly with bromobenzene (4.0 mmol/kg). Finally, OTCA administration was found to afford substantial protection against elevation of plasma transaminases used as indices of bromobenzene-induced hepatotoxicity. N-acetylcysteine, another cysteine prodrug, had essentially similar effects on the metabolism and toxicity of bromobenzene. Thus, administration of cysteine prodrugs enhances the urinary excretion of several metabolites of bromobenzene and affords protection against bromobenzene-induced hepatotoxicity.     

Influence of a cysteine prodrug, L-2-oxothiazolidine-4-carboxylic acid, on the urinary elimination of mercapturic acids of ethylene oxide, dibromoethane, and acrylonitrile: a dose-effect study

Metabolic disposition of ethylene oxide, dibromoethane, and acrylonitrile in rats after acute exposure was studied by examining the relationship between dose and urinary metabolites, and by establishing the influence of a glutathione precursor, L-2-oxothiazolidine-4-carboxylic acid (OTCA), on the above relationship. Respective urinary metabolites, hydroxyethylmercapturic acid, cyanoethylmercapturic acid, thiocyanate, and ethylene glycol, were quantified to estimate the extent to which each compound was metabolized. The animals were given either ethylene oxide (0.34, 0.68, or 1.36 mmol/kg), dibromoethane (0.2, 0.4, or 0.6 mmol/kg), or acrylonitrile (0.10, 0.38, or 0.76 mmol/kg). Urine samples were collected at 24 h. The metabolic biotransformation of all three chemicals to their respective mercapturic acids was strongly indicative of saturable metabolism. Administration of OCTA (4-5 mmol/kg) enhanced gluthathione availability and increased excretion of urinary mercapturic acids at the higher doses of the chemicals. This study indicates that OTCA increases the capacity for detoxification via the glutathione pathway thereby partially correcting the nonlinearity between the administered dose of ethylene oxide, dibromoethane, and acrylonitrile and the amount of certain urinary metabolites.     

Assessment of the protective and therapeutic effect of melatonin against thioacetamide‐induced acute liver damage

Acute or chronic damage to the liver may occur through alcohol, drugs, viruses, genetic disorders, and toxicity. In this study, we planned to investigate the protective and therapeutic effects of melatonin (Mel) by causing damage to the liver with thioacetamide (TAA). Thirty‐five rats were used. Group I: control group (seven pieces), group II: Mel group (seven pieces) the single dose on the first day of the experiment was 10 mg/kg, group III: TAA (seven pieces) 300 mg/kg with 24‐hour intervals, two doses, group IV: Mel + TAA group (seven pieces) 10 mg/kg single dose Mel was applied 24 hours before TAA application, group V: TAA + Mel group (seven pieces) single dose (24th hour) of 10 mg/kg Mel was administered after TAA (300 mg/kg) two doses. The liver histology was evaluated. Apoptosis, autophagy, and necrosis markers in tissue were determined by immunohistochemistry. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) levels in blood serum samples and transforming growth factor‐β (TGF‐β) and tumor necrosis factor‐α (TNF‐α) levels were determined in liver tissue. TAA affected histologically the classical lobule structure both in cell cords and sinusoids. Caspase‐3, RIP3, and LC3 levels were increased in group III compared with the control group. TAA did not cause a statistically significant change in TNF‐α level but decreased the TGF‐β level significantly. AST and ALT levels were statistically significant in group II and V compared with group I, the ALP level was significant in group IV compared with group II. The results of this study showed that TAA caused significant damage to tissues and increased cell death, Mel was found to have more therapeutic than the protective effect on tissues.     

Mutagenicities of nitrosated carboline derivatives

Food-borne amines have been considered as the potential precursors of endogenous carcinogenic N-nitroso compounds in humans. A compound which yields a direct mutagen after nitrite treatment was isolated from soy sauce and was identified as 1-methyl-1,2,3,4-tetrahydro-2-carboline-3-carboxylic acid (MTCA) (Wakabayashi, et al., 1983). The mutagenicities of other carboline derivatives such as harman, norharman, harmaline, harmalol, harmine, and harmol were studied. Like MTCA, the nitrosated carboline derivatives showed higher mutagenic activity as compared to their corresponding parent compounds. The demethylated analogue of MTCA, 1,2,3,4-tetrahydro-2-carboline-3-carboxylic acid was synthesized and its nitrosated products were shown to be mutagenic to Salmonella typhimurium TA 100 and TA 98. The potent mutagen Trp-P-2 is a typical 3-carboline derivative. The mutagenicity of Trp-P-2 was suppressed remarkably after nitrosation. Several 3-carboline derivatives also showed the similar property. Nitrosation of MTCA gave several derivatives which were isolated and showed direct mutagenicity to Salmonella typhimurium TA 98. Further characterization of these new carboline derivatives is in progress.     

冬虫夏草菌丝提取物对化学性肝损伤的辅助保护作用

为明确冬虫夏草菌丝提取物对急性肝损伤小鼠谷丙转氨酶（ALT）、谷草转氨酶（AST）、肝细胞变性及坏死程度的影响,采用四氯化碳（CCl4）诱导小鼠急性化学性肝损伤模型,将动物随机分成5组,分别是空白对照组、模型组、冬虫夏草菌丝提取物低剂量组（1.11g/kg BW）、中剂量组（3.33g/kg BW）、高剂量组（10.00g/kg BW）,检测血清ALT、AST值,并取肝脏作病理切片,观察肝脏的病理损伤情况。冬虫夏草菌丝提取物高剂量组能明显降低CCl4急性肝损伤小鼠血清ALT值,减轻肝细胞坏死程度,表明冬虫夏草菌丝提取物对化学性肝损伤有辅助保护功能。     

Cysteamine in combination with N-acetylcysteine prevents acetaminophen-induced hepatotoxicity.

N-Acetylcysteine (NAC) is protective against acetaminophen-induced hepatotoxicity primarily by providing precursor for the glutathione synthetase pathway, while cysteamine has been demonstrated to alter the cytochrome P-450 dependent formation of toxic acetaminophen metabolite. Mice administered acetaminophen (500 mg/kg) had elevations of serum alanine aminotransferase (ALT) to 273.0 +/- 37.5 and 555.8 +/- 193.4 U/mL at 12 and 24 h, respectively, after injection. Administration of cysteamine (100 mg/kg) or NAC (500 mg/kg) significantly reduced serum ALT activity (p less than 0.001). Reducing the dose of NAC or cysteamine by 50% greatly reduced their hepatoprotective effect while the co-administration of the reduced doses of NAC (250 mg/kg) and cysteamine (50 mg/kg) following acetaminophen overdose prevented elevation of serum ALT activity (39.2 +/- 1.17 and 32.5 +/- 5.63 U/mL at 12 and 24 h post-injection, p less than 0.001) and preserved normal mouse hepatic histology. Neither NAC (500 mg/kg), cysteamine (100 mg/kg), or the lower doses in combination of both agents were found to alter the half-life or peak levels of acetaminophen. Liver microsomal aryl hydrocarbon hydroxylase activity measured 24 h after drug administration was not significantly different between treatment groups and controls receiving only saline. These results indicate a possible role for the concomitant use of NAC and cysteamine in the prevention of hepatic necrosis following toxic doses of acetaminophen. Neither decrease in plasma acetaminophen levels nor depression of cytochrome P-450 enzyme activity appears to be the mechanism of protection when these doses of NAC, cysteamine, or both drugs together are administered with a toxic dose of acetaminophen in mice.     

酮康唑对小鼠肝脏和睾丸生理功能的影响*

目的: 观察不同剂量的酮康唑(KCZ)对昆明小鼠的肝脏和睾丸生理功能的影响。方法: 将 40 只雄性昆明小鼠随机分为 4 组(n=10):正常组、酮康唑低剂量组(30 mg/kg)、酮康唑中剂量组(50 mg/kg)、酮康唑高剂量组(70 mg/kg)。药物组小鼠按0.1 ml/10 g给药体积每日单次皮下注射酮康唑,酮康唑低、中、高剂量组药物浓度各为3 mg/ml、5 mg/ml、7 mg/ml,正常组注射等量生理盐水,连续 3 周。测定血清谷草转氨酶(AST)、谷丙转氨酶(ALT),以及睾丸组织 γ-谷氨酰胺转肽酶(γ-GT)、乳酸脱氢酶(LDH)和酸性磷酸酶(ACP)活性;HE 染色观察肝脏、睾丸病理组织改变。结果: 与正常组比较,酮康唑组AST、ALT活性显著升高(P＜0.01);γ-GT、ACP、LDH活性显著下降(P＜0.01),且以上指标的改变均随剂量增加而损伤加重。HE 染色显示小鼠肝细胞变性,排列松散,胞质色浅;睾丸曲细精管管腔增大,各级生精细胞、精子数量减少。结论: 酮康唑能导致小鼠肝脏、睾丸组织生理功能损伤与病理组织学改变,升高肝转氨酶水平,降低睾丸特异性酶活性,且损伤程度随剂量的升高而增大。     

牛樟芝提取物调控Nrf2/HO-1通路对酒精性肝损伤的保护作用

研究不同剂量（100、200和400mg/kg）的牛樟芝水提物（WE）、醇提后水提取物（WEE）和醇提物（EE）对酒精诱导的ICR小鼠急性肝损伤的保护作用和对Nrf2/HO-1抗氧化信号通路的影响。研究结果表明：与模型组比较,400mg/kg的WE和WEE均能显著抑制血清ALT和AST水平的升高,200mg/kg的WE和WEE分别显著降低血清ALT和AST含量。各剂量的WE、WEE和EE均能显著降低肝脏MDA含量,200和400mg/kg的WE和不同剂量的WEE均可明显提高肝脏的SOD和CAT活力。H&E染色结果表明WE、WEE和EE对酒精诱导的肝损伤均有一定的改善作用,EE处理组的效果相对较差。免疫组化染色结果表明各剂量的WE、WEE和EE均能促进Nrf2的核转位,诱导HO-1的表达,提高肝脏的抗氧化能力,对酒精诱导的急性肝损伤具有明显的保护作用。提示牛樟芝能通过调节Nrf2/HO-1抗氧化信号通路发挥解酒保肝功效。     

Development of novel water-soluble photocleavable protective group and its application for design of photoresponsive paclitaxel prodrugs

A novel coumarin-based highly water-soluble photocleavable protective group was designed and synthesized, and then this photosensitive protecting group was used to design paclitaxel prodrugs. These novel paclitaxel conjugates demonstrated excellent water solubility, over 100mgmL(-1). Thus, the use of a detergent in the formulation can be omitted completely, even at high doses. Phototaxel 11 released the parent drug, paclitaxel, quickly and efficiently by minimal tissue-damaging 365nm UV light irradiation at low power, while laser activation at 355nm led to extensive decomposition of the prodrug. The carbamate-type prodrug, phototaxel 11, was stable in the dark prior to activation, whereas carbonate-type phototaxel 9 demonstrated poor stability under aqueous conditions. For such prodrugs, tumor-tissue targeting after administration could be achieved by selective light delivery, similar to that used in photodynamic therapy. In addition, newly designed coumarin derivative 8 can be applied in organic chemistry as a photosensitive protective group and for the design of caged compounds.     

Development of acute tolerance to the cardiorespiratory effects of alfentanil after subsequent bolus injection in conscious rats

The cardiovascular and respiratory effects of alfentanil in conscious freely moving rats, were evaluated after initial and subsequent injections. Doses of alfentanil (50, 130, 260, and 500 ug/kg) were given to naive rats (n = 4-5) and 1 hour later this dose was repeated. The resultant cardiovascular and respiratory effects were compared. At all doses there was a significant (p less than 0.05) depression of mean arterial pressure and heart rate after the initial dose of alfentanil. At doses of 50, 130, and 260 ug/kg, the second administration elicited significantly less depression of cardiovascular parameters than the initial dose. Maximum changes in respiratory parameters (PaCO2 and PaO2) were also significantly less after the second administration of alfentanil. This difference, in maximum respiratory depression, was not seen at the highest doses (500 ug/kg). These results indicate that tolerance, to the cardiorespiratory side effects seen after alfentanil, can occur in as little as 1 hour after subsequent bolus injections.     

Acute administration of the organochalcogen 3-methyl-1-phenyl-2-(phenylseleno)oct-2-en-1-one induces biochemical and hematological disorders in male rats

Organochalcogens are extensively produced and employed by industry and agriculture, and the risk of occupational and environmental toxicity to them has been poorly understood. Here, we investigated the acute effect of a new organochalcogen 3-methyl-1-phenyl-2-(phenylseleno)oct-2-en-1-one on biochemical and hematological parameters in male Wistar rats. The animals were treated with a single intraperitoneal injection of the organochalcogen at doses of 125, 250 or 500 μg·kg(-1). After 60 min, the animals were sacrificed by decapitation, and the trunk blood was collected for determination of glucose, triglycerides, cholesterol, alanine aminotransferase (ALT), aspartate aminotransferase, lactate dehydrogenase, urea, creatinine, C-reactive protein, red blood cells, hematocrit, hemoglobin and white blood cells (WBC). Our results showed a reduction in cholesterol levels in all treated groups, an increase in ALT activity at doses of 250 and 500 μg·kg(-1), a decrease of hemoglobin and an increase in WBC in animals that received 250 and 500 μg·kg(-1) of the organoselenium. In addition, we observed an increase in neutrophil counts at 125 μg·kg(-1) dose and a decrease at 500 μg·kg(-1) dose. We also verified an increase in lymphocyte counts at the dose of 500 μg·kg(-1). Thus, the present study shows that the acute treatment with this new organochalcogen causes biochemical changes and hematological disorders in male rats.     

THE CONVULSANT ACTION OF METHYLDITHIOCARBAZINATE: A COMPARISON WITH OTHER SULPHUR-CONTAINING HYDRAZIDES

—The convulsant action of methyldithiocarbazinate (MDTC), thiocarbohydrazide (TCH) and thiosemicarbazide (TSC) has been studied in mice. The relationship between dose and time to convulsions indicated that MDTC has a dual action and is more potent than TSC. Pretreatment of mice with pyridoxal phosphate (0.25 mmol/kg) protected against convulsions and death produced by low doses of MDTC or TCH, and low or high doses of TSC. Pretreatment with pyridoxine hydrochloride (0.25 mmol/kg) protected mice against TSC but not against TCH. It protected against low doses of MDTC (0.12 mmol/kg), but shortened the latency to convulsions after intermediate doses of MDTC (0.37 mmol/kg). Glutamate decarboxylase activity (GAD, EC 4.1.1.15) in whole brain homogenates from mice killed at the onset of seizures, was significantly reduced by all 3 drugs at all doses. This inhibition did not exceed 30% after any dose of TSC or TCH, but was 64% in mice killed 4 min after the injection of MDTC (0.98 mmol/kg). The addition of pyridoxal phosphate to brain homogenates abolished GAD inhibition after MDTC but not after TCH. In vitro brain GAD was 50% inhibited by 10⁻⁴m -MDTC, 18% by 10⁻⁴m -TSC and 8% by 10 ⁻⁴m -TCH. Kinetic studies suggested that at low concentrations MDTC inhibits by competing with pyridoxal phosphate. At the onset of convulsions the cerebral content of pyridoxal phosphate was reduced after low or high doses of TSC (0.27 and 2.2 mmol/kg) and after high doses of MDTC (0.98 mmol/kg). All three drugs (at 10⁻⁵−10⁻⁴m ) inhibited pyridoxal phosphokinase (EC 2.7.1.35) in vitro. Short latency convulsions after MDTC (0.37–0.98 mmol/kg) very probably arise from inhibition of cerebral GAD, due to competition for coenzymic sites and/or unavailability of coenzyme. Long-latency convulsions after MDTC (0.12–0.37 mmol/kg) are comparable to those seen after TSC (0.27–2.2 mmol/kg) and may depend on a mechanism additional to inhibition of GAD.     

The effect of the enantiomers of ibuprofen and flurbiprofen on the beta-oxidation of palmitate in the rat.

The effects of the enantiomers of ibuprofen (0.25 and 0.50 mmol/kg b.w.) and flurbiprofen (0.01, 0.03, and 0.06 mmol/kg b.w.) on the beta-oxidation of palmitate were investigated in the rat. The mean cumulative exhalation of 14CO2 after ip administration of [U-14C]palmitic acid was significantly reduced over 6 h by ibuprofen at the higher dose but not at the lower dose for either enantiomer. There was no difference between the enantiomers, the reduction over 6 h being 31.3 and 33.0% for (R)- and (S)-ibuprofen, respectively. There was also a significant inhibition of beta-oxidation by flurbiprofen at all 3 doses. Again, there was no stereoselectivity evident in this inhibition. Flurbiprofen was much more potent than ibuprofen in eliciting this effect, the 0.01mmol/kg dose giving a similar reduction in beta-oxidation as observed for the 0.50 mmol/kg dose of ibuprofen. The data support the hypothesis that inhibition of the in vivo beta-oxidation of palmitate by ibuprofen and flurbiprofen is primarily via a nonstereoselective noncoenzyme A-dependent mechanism.     

Lead detoxification activities and ADMET hepatotoxicities of a class of novel 5-(1-carbonyl-L-amino-acid)-2,2-dimethyl-[1,3]dithiolane-4-carboxylic acids

By linking the mercapto groups with isopropyl and introducing l-amino acid into the 5-carboxyl of DMSA a class of novel 5-(1-carbonyl-l-amino-acid)-2,2- dimethyl-[1,3]dithiolane-4-carboxylic acids were prepared. Their in vivo activities were evaluated on lead loaded mice at the dose of 0.4 mmol/kg. The results showed that the lead levels of the livers, kidneys, femurs and brains in particular could be efficiently decreased by 0.4 mmol/kg of 5-(1-carbonyl-l-amino-acid)-2,2-dimethyl-[1,3]dithiolane-4-carboxylic acids. The benefit of 5-(1-carbonyl-l-amino-acid)-2,2-dimethyl-[1,3]dithiolane-4-carboxylic acids to the detoxification of the brain lead was attributed to their transmembrane ability. Compared with the lead detoxification efficacy, they did not affect the essential metals such as Fe, Cu, Zn, and Ca of the treated mice. Silico molecular modeling predicted that 5-(1-carbonyl-l-amino-acid)-2,2-dimethyl-[1,3]dithiolane-4-carboxylic acids had no hepatotoxicity.     

Effect of a polyherbal formulation, Ambrex, on butylated hydroxy toluene (BHT) induced toxicity in rats

Effect of polyherbal formulation Ambrex was evaluated in butylated hydroxytoluene (BHT) induced toxicity of lungs and liver in rats. Toxicity was produced by administering BHT (500 mg/kg/day) for 3 days. Lung damage was evidenced by elevated levels of broncho alveolar lavage fluid (BAL) parameters such as protein, lactate, lactate dehydrogenase (LDH), alkaline phosphatase (ALP), acid phosphatase (ACP) and glucose-6-phosphate dehydrogenase (G6PDH). Liver damage was proved by elevated levels of serum protein and markers such as LDH, ALP, aspartate amino transferase (AST), alanine amino transferase (ALT), decreased level of lipid peroxides (LPO) in serum and glutathione (GSH) in liver. Administration of aqueous suspension of Ambrex (50 mg/kg orally) retained these elevated levels of BAL-protein, lactate, LDH, ALP, ACP, G6PDH and serum-protein, LDH, ALP, AST and ALT at near normal values. Decreased level of liver GSH was retained at near normalcy in Ambrex pretreated BHT-administered animals. There was no change in liver LPO in all the four groups.     

Stimulation of somatotropin secretion following peripheral administration of the tripeptide, syndyphalin 33 in sheep, pigs and rats

In the present study, a simple tripeptide alkylamine, syndyphalin 33 (SD33, Tyr-DMet (O)-Gly-methylphenethylamide) was shown to stimulate somatotropin (GH) secretion in sheep, hogs and rats following peripheral administration. Intravenous (i.v.) administration of SD33 at doses of 0.05, 0.1 and 0.2 mumol/kg stimulated a significant increase in circulating GH levels in sheep within 5 minutes post-injection. This response was not attenuated following repeated i.v. injections of SD33 (0.05 /mmol/kg) administered at 2 hour intervals. In addition, plasma GH levels were significantly stimulated following either subcutaneous (s.c.) or oral administration of SD33 in hogs and rats. Subcutaneous administration of SD33 at doses of 0.5, 1.0 and 2.0 mumol/kg stimulated a significant increase in plasma GH concentrations within 30 minutes of injection in both species. Oral administration of SD33 at 1.0, 10 or 100 mumol/kg in rats resulted in a significant elevation in plasma GH levels which peaked at 30 minutes post-gavage. In the pig, circulating GH levels were significantly increased within 30 minutes post-ingestion and remained elevated for at least 2 hours at the 2.0 mumol/kg dose level. The ability of naloxone to block SD33-stimulated GH secretion suggests that this peptide acts via mu opiate receptors.     

Effect of synthesized constituents in the L-tryptophan product on the differentiation of eosinophils and the induction of IL-6: a possible cause of eosinophilia-myalgia syndrome.

While the pathogenesis of eosinophilia-myalgia syndrome (EMS) remains obscure, the ingestion of L-trypophan (LT) and possibly certain constituents in the LT product might be associated. We investigated the effect of chemically synthesized substances, 1,1'-ethylidene bis[tryptophan] (EBT) and its decomposition product, 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid (MTCA) recently identified in the implicated LT, on the eosinophil differentiation and the induction of IL-1 and IL-6. EBT and MTCA alone did not support colony formation. However, EBT or MTCA in conjunction with IL-2 induced colony-forming activity containing a small number of eosinophils. In addition, these LT constituents induced a significant level of IL-6 but not IL-1 beta in the mononuclear cells from normal volunteers and a patient with hypereosinophilic syndrome. These results suggest that certain constituents of LT product are associated with the pathogenesis of EMS through the induction of colony-stimulating factors and IL-6, hence giving rise to eosinophilia and inflammation.     

Acute liver damage induced by 2-nitropropane in rats: effect of diphenyl diselenide on antioxidant defenses

The effect of post-treatment with diphenyl diselenide on liver damage induced by 2-nitropropane (2-NP) was examined in male rats. Rats were pre-treated with a single dose of 2-NP (100 mg/kg body weight dissolved in canola oil). Afterward, the animals were post-treated with a dose of diphenyl diselenide (10, 50 or 100 micromol/kg). The parameters that indicate tissue damage such as liver histopathology, plasma aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), urea and creatinine were determined. Since the liver damage induced by 2-NP is related to oxidative damage, lipid peroxidation, superoxide dismutase (SOD), catalase (CAT) and ascorbic acid level were also evaluated. Diphenyl diselenide (50 and 100 micromol/kg) effectively restored the increase of ALT and AST activities and urea level when compared to the 2-NP group. At the higher dose, diphenyl diselenide decreased GGT activity. Treatment with diphenyl diselenide, at all doses, effectively ameliorated the increase of hepatic and renal lipid peroxidation when compared to 2-NP group. 2-NP reduced CAT activity and neither alter SOD activity nor ascorbic acid level. This study points out the involvement of CAT activity in 2-NP-induced acute liver damage and suggests that the post-treatment with diphenyl diselenide was effective in restoring the hepatic damage induced by 2-NP.     

Simultaneous determination of l-tryptophan impurities in meat products

L-tryptophan has been used as a feed additive for swine and poultry and as a nutrient supplement for humans. However, some impurities in l-tryptophan have been reported as causative components of eosinophilia-myalgia syndrome. Therefore, from a safety perspective, it is important to analyze meat samples for these impurities. This study aims to develop an analytical method for the simultaneous detection of l-tryptophan impurities in meat products using LC–MS/MS. Among the various impurities, detection methods for (S)-2-amino-3-(5-hydroxy-1H-indol-3-yl)propanoic acid (5-hydroxytryptophan) (HTP), 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (MTCA), 3a-hydroxy-1,2,3,3a,8,8a-hexahydropyrrolo-[2,3-b]-indole-2-carboxylic acid (PIC), and 1,1′-ethylidenebistryptophan (EBT) and 2-(3-indoylmethyl)-l-tryptophan (IMT) were developed. The developed method allowed simultaneous determination of these four impurities in 5 min. No interferences from the matrix were observed, and the method showed good sensitivity to each analyte. The method detection limit and limit of quantification in meat matrices were below 11.2 and 35.7 μg/kg, respectively.