Levamisole inhibition of microsomal lipid peroxidation as related to its sulfhydryl metabolite dl-2-oxo-3-(2-mercaptoethyl)-5-phenylimadazolidine

Biochemical, immunomodulatory and antioxidant properties of levamisole at different storage conditions and administration routes

Levamisole is a broad-spectrum nicotinic anthelmintic drug; widely used in veterinary medicine. Levamisole actions are variable depending on storage temperature and administration route. The present study was conducted to test levamisole effects on immune responses and antioxidant status of rats at different storage temperature and administration routs. The experimental rats were allocated into four experimental groups and two controls. Group 1 was given levamisole orally. Group 2 was injected levamisole intramuscularly. In group 1 and 2 levamisole was stored at 4 degrees C for 72 h and given every two days for three weeks at a dose of 2.5 mg kg(-1) body weight. Group 3 and 4 were treated same as group 1 and 2 but levamisole was stored at 37 degrees C. Serum levels of total IgG and IgA and plasma levels of glutathione reductase (GSSG-R), TAC concentrations in addition to GST and GSH-Px activities were measured. The results indicated that the storage of levamisole at 4 degrees C significantly increased serum IgG and IgA levels in rats and improved rat's antioxidant status through significant increase in glutathione related enzymes (GSSG-R, GST and GSH-Px) and the TAC. Levamisole stored at 37 degrees C increased measured antioxidant biomarkers but decreased the rats' non-specific humoral immunity. Moreover, the intramuscular administration induced better antioxidant properties than oral administration of levamisole. In conclusion, levamisole actions could be specifically directed towards certain types of immune responses due to changes in storage temperature with better response to injectable routes than oral routs with more antioxidant activities.

[Polycyclic azines with heteroatoms in the 1- and 3-position. 40. Synthesis of heterocyclic immunomodulators. 2. 3-Mercaptoalkylthieno(2,3-d)pyrimidine-2,4(1H,3H)-diones: synthesis and testing of immunostimulant activity]

A series of 3-mercaptoalkylthieno[2,3-d]pyrimidine-2,4(1H,3H)-diones 3 was prepared and their immuno-stimulating activity was examined. The title compounds were obtained conveniently by hydrolytic ring cleavage of fused thiazolo- or 1,3-thiazino-thienopyrimidines 1 under alkaline or acidic reaction conditions. The ms fragmentation of the thieno[2,3-d]pyrimidine-2,4-diones 3 is discussed. In the delayed type hypersensitivity (DTH) test some compounds 3 showed immuno-stimulating activities in the range of isoprinosine.

Absence of significant effects by levamisole on circulating neutrophil levels in normal mice treated with 5-FU

When B6C3F1 mice were given a single intravenous (i.v.) injection of 150 mg/kg 5-fluorouracil (5-FU) their levels of circulating neutrophils plummeted, reaching a nadir at 6 to 7 days postdosing and then gradually increasing to normal and above-normal levels. Neutropenia (actual neutrophil count (ANC) below 100 ANC/microliters) extended until 8.7 +/- 0.2 days after 5-FU injection. When these mice were also given levamisole (2.5 mg/kg, po) on days 0-2 the mean time to ANC recovery greater than 100/microliters was 7.7 +/- 0.3 days, (p < 0.05 vs. controls), while IL-1 (2 micrograms/day, ip) positive controls yielded a mean time to > 100 ANC of 6.5 +/- 0.2 days. Although levamisole-treated mice attained normal neutrophil levels one day faster than controls did and this more rapid recovery led to their neutrophil levels being between 2- and 3-fold greater, these differences were not statistically significant. Effects were only manifested on neutrophil recoveries. There were no differences between levamisole-treated mice and controls when recovery rates for platelets, monocytes or lymphocytes were examined. These results demonstrate that levamisole has, at best, only weak myelopoietic properties against 5-FU-induced myelotoxicity in mice.

Regulation of glycogen synthase activity in isolated rat adipocytes by levamisole

The effect of levamisole on glycogen synthase activity in isolated adipocytes was studied. The addition of levamisole to these cells resulted in an acute concentration-dependent increase in glycogen synthase activity. In contrast, epinephrine, dibutyryl cyclic AMP (DcAMP) and cysteamine decreased glycogen synthase activity. The stimulatory effect of levamisole on the activity of the enzyme was not affected by the presence of epinephrine but was diminished when either DcAMP or cysteamine was present. The results of this study suggest that levamisole increases adipocyte glycogen synthase activity by a mechanism that can be reversed by the elevation of cAMP.

The effect of immunostimulatory drugs on sulfhydryl compounds in plasma, liver and brain after ethanol-induced liver injury in rats

Sulfhydryl compounds in plasma, liver and brain of rats treated with two immunostimulant drugs, isoprinosine and levamisole, after alcoholic liver injury have been investigated. After use of both drugs for 6 days we found partially beneficial effect on the SH-groups in plasma and liver. No changes in nonprotein SH compounds were observed in rat brain after treatment with isoprinosine, levamisole or ethanol. Furthermore, levamisole shortens the time necessary for the return of AlAT activity to normal value.

Immunomodulatory action of levamisole--I. Structural analysis and immunomodulating activity of levamisole degradation products

In our laboratory we observed that solutions of levamisole (LMS) stored at 4 degrees C consistently enhanced the lymphocyte proliferation response to concanavalin A (Con A) more than freshly prepared solutions did. To determine if the increased immunopotentiation observed with the stored solutions of LMS was due to products formed from LMS, we assessed the stability of LMS when stored at 4 or 37 degrees C at pH 6, 7, 7.5 and 8. Analysis of the various solutions by high pressure liquid chromatography demonstrated that LMS decomposes during storage in neutral and alkaline conditions to form three products. The formation of the products was accelerated by increasing the temperature from 4 to 37 degrees C. The three degradation products were purified by preparative high pressure liquid chromatography and their structures determined by mass spectrometry, infrared spectrometry and homo- and heteronuclear two dimensional nuclear magnetic resonance spectroscopy. The degradation products, denoted as No. 1, No. 2 and No. 3, based on their high pressure liquid chromatography retention times, were identified as: No. 1, 3-(2-mercaptoethyl)-5-phenylimidazolidine-2-one; No. 2, 6-phenyl-2,3-dihydroimidazo (2,1-b) thiazole and No. 3, bis [3-(2-oxo-5-phenylimidazolidin-1-yl) ethyl] disulfide. Product 2 significantly enhanced murine lymphocyte proliferation responses to concanavalin A (Con A) at concentrations between 0.5 and 10.0 micrograms/ml (whereas the optimum concentration of LMS is 10-100 fold higher (50-100 micrograms/ml)). Products 1, 2 and 3 significantly inhibited the lymphocyte proliferative response at concentrations greater than 2.2, 10.0 and 10.0 micrograms/ml, respectively. These studies indicate that under relatively mild conditions, including physiological conditions, LMS may decompose to products which inhibit or enhance lymphocyte responses to Con A.

A novel interaction of diethyldithiocarbamate with the glutathione/glutathione peroxidase system

Diethyldithiocarbamate (DDC) exhibits a variety of pharmacologic activities, including both radioprotective and sensitizing properties. Since the glutathione/glutathione peroxidase system may be a significant factor in determining radiation sensitivity, the potential mechanisms of action of DDC in relation to this system were examined in vitro. The interaction of DDC with reduced glutathione (GSH) was tested using a simple system based on the reduction of cytochrome c. When DDC (0.005 mM) was incubated with GSH (0.5 mM), the reduction of cytochrome c was eightfold greater than that expected from an additive effect of DDC and GSH. GSH could be replaced by oxidized glutathione and glutathione reductase. Cytochrome c reduced by DDC was oxidized by mitochondria. The interaction of DDC with both the hexosemonophosphate shunt pathway and the mitochondrial respiratory chain suggests the possibility of linking these two pathways through DDC. Oxidation of DDC by peroxide and reversal by GSH indicated that the drug can engage in a cyclic reaction with peroxide and GSH. This was confirmed when DDC was used in the assay system for glutathione peroxidase (GSHPx) without GSHPx. DDC at a concentration of 0.25 mM was more active than 0.01 unit of pure GSHPx in eliminating peroxide, and much more active than the other sulfhydryl compounds tested. These studies indicate that DDC can supplement GSHPx activity or substitute for it in detoxifying peroxides, and suggests a unique role in the chemical modification of radiation sensitivity.