The effect of curcumin and PI3K/Akt inhibitor on monosodium glutamate-induced rat thymocytes toxicity.

Monosodium glutamate (MSG), the sodium salt of glutamic acid, is widely used in modern nutrition as flavor enhancer. However, it has been shown that curcumin has ability to induce apoptosis in the cells of the immune system. In the present study, we evaluate the potential protective effects of curcumin in MSG-induced apoptosis and signaling pathway which may be involved. Rat thymocytes were treated with increased (1, 10, 50 mM) MSG concentrations and/or curcumin (3 µM). Cell apoptosis rate, reactive oxygen species (ROS) production, mitochondrial membrane potential (MMP), Bcl-2, Bax protein expression and caspase-3 activity were determined after 24 hours of incubation. Treatment with MSG resulted with increased apoptosis, ROS production and caspase-3 activity, followed with decreased MMP and Bcl-2/Bax protein ratio. Inhibition of caspase-3 and caspase-9 activity reduced cell apoptosis, indicating the involvement of mitochondrial apoptotic pathway. Co-treatment with curcumin markedly reduced apoptosis and ROS production, together with increased MMP and Bcl2/Bax protein ratio. Inhibition of PI3K/Akt signaling pathway abolished protective effect of curcumin in MSG-induced toxicity in rat thymocytes. Obtained findings suggest that curcumin may attenuate the MSG-induced apoptosis through PI3K/Akt signaling pathway which could be useful in preventing the potential deficiencies in T cell-mediated immunity.

Cyclodidepsipeptides with a promising scaffold in medicinal chemistry.

Among the large family of cyclodepsipeptides, the simplest members are the cyclodidepsipeptides which have an ester group and an amide group in the same six-membered ring. To point out the pharmacological potential of this class of compounds, the present article reviews structure, isolation, synthesis and biological properties of the known cyclodidepsipeptides. Synthesis of cyclodidepsipeptides is achieved by two general approaches--by initial formation of the amide bond, or initial formation of the ester bond; and subsequent intermolecular cyclization to cyclodidepsipeptide structure. It is closely related to the condensation and ring-closure strategies applied in the preparation of the larger members of the cyclodepsipeptide family. However, due to synthesis of the smaller heretocycles it allows for the use of more versatile building blocks. There are data on antimicrobial, antioxidant and immunomodulatory activities of cyclodidepsipeptides as well as their inhibitory activities toward α-glucosidase, acyl-CoA:cholesterol acyltransferase, xanthine oxidase and platelet aggregation. Because we have recently found that two 6-(propan-2-yl)-4-methyl-morpholine-2,5-diones, as novel non-purine xanthine oxidase inhibitors, may give promise to be used in the treatment of gout, in this review we have included a study of molecular interactions of the selected cyclodidepsipeptides with xanthine oxidase using idTarget web server. Cyclodidepsipeptides showed promising pharmacological activities and meet all criteria for good solubility and permeability. However, further research of their medical application is necessary. In addition to this, the diversity of natural cyclodidepsipeptides, simplicity for synthesis and convenience for rational drug design indicate the cyclodidepsipeptide as promising scaffold in medicinal chemistry.

Serum levels of IL-17, IL-4, and INFγ in Serbian patients with early rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is a chronic, systemic, inflammatory disease with autoimmune etiology, characterized by synovial inflammation and destruction of joint cartilage and bone. There are controversial data about the profile of interleukin-17 (IL-17A), interleukin-4 (IL-4), and interferon-gamma (INFγ), indicating in some studies the key role of IL-17, while in others the Th1 cytokines. MATERIALS AND METHODS: Serum samples of 31 early RA patients were evaluated for erythrocytes sedimentation rate (ESR), rheumatoid factor (RF), C-reactive protein (CRP), anti-cyclic citrullinated peptide antibodies (anti-CCP), and for the tested cytokines (IL-17A, IL-4, and INFγ). Disease activity score (DAS28) calculation was done for all patients. Control serum samples were obtained from 29 healthy volunteers. RESULTS: The levels of tested cytokines were significantly higher (IL-17A, p < 0.001; INFγ, p < 0.001; IL-4, p < 0.01) in patients with early RA, compared to the healthy controls. In early RA patients, a strong correlation of serum IL-17A was found with DAS28, ESR, and CRP. Also, significant negative correlation was found between serum INFγ levels and the DAS28 score, indicating that INFγ may play a key role in maintaining immune homeostasis in patients with RA. CONCLUSION: The mean serum IL-17A levels in patients with early RA, corresponded with the disease activity and severity. This might highlight the usefulness of the serum IL-17A level in defining the activity and predictive patterns, for aggressive disease therapy, and it might express specific therapeutically targets.

Melatonin protects rat thymus against oxidative stress caused by exposure to microwaves and modulates proliferation/apoptosis of thymocytes.

The aim of the study was to evaluate the effect of melatonin on oxidative stress, DNA fragmentation, apoptsis and proliferation in thymus tissue of rats exposed to microwaves. Wistar rats were divided in four groups: I - treated with saline; II - treated with melatonin; III - microwaves exposed; IV - microwaves exposed and melatonin treated. Melatonin (2 mg/kg i.p.) was administered daily. Animals were sacrificed after 20, 40 and 60 days. A significant increase in malondialdehyde and carbonyl group content, as well as decrease in catalase and increase in xanthine oxidase activity were registered under microwave exposure. Melatonin prevented the increase in malondialdehyde and carbonyl group content, and reversed the effect on catalase and xanthine oxidase activity. Both, alkaline and acid DNase activity were increased due to microwave exposure. Furthermore, microwaves caused increase in apoptosis rate (detected using Annexin V-FITC/PI kit) and reduced proliferative capacity of thymocytes (induced by ConA). However, melatonin caused decrease in alkaline and acid DNase activity, decrease in apoptotic rate and increase in proliferation rate of thymocytes. Melatonin exerts protective effects on rat thymocytes by modulating processes of apoptosis and proliferation, and causes decrease in DNA fragmentation and oxidative stress intensity under exposure to microwaves.

Vitamin C and epigenetics: A short physiological overview.

In recent years, ascorbic acid (vitamin C) has acquired great interest due to its multiple functions, which results in homeostasis of normal tissues and organs. On the other hand, it has been shown that epigenetic modifications may have an important role in various diseases and therefore are a focus of the extraordinary investigation. Ascorbic acid serves as a cofactor for ten-eleven translocation dioxygenases, which are responsible for deoxyribonucleic acid methylation. Also, vitamin C is required for histone demethylation, since it acts as a cofactor of Jumonji C-domain-containing histone demethylases. It seems that vitamin C may be a mediator between the environment and the genome. The precise and multistep mechanism of ascorbic acid in epigenetic control is still not definitely determined. This article intends to provide the basic and newly discovered functions of vitamin C that are related to epigenetic control. Also, this article will help us to better understand the functions of ascorbic acid and will provide the possible implications of this vitamin in the regulation of epigenetic modifications.

Hypoplastic arteries of the cerebral arterial ring in the blind spot of computed tomography angiography.

BACKGROUND: Some variations of the cerebral arterial circle (CAC) are associated with an increased risk for the development of various pathological conditions. This paper aimed to determine the prevalence of hypoplastic arteries of CAC and to emphasize the limited possibility of their visualization by computed tomography angiography (CTA). MATERIALS AND METHODS: The research was performed on 400 adult cadavers by macro- and microdissection of the cerebral arteries. Each case was photographed and the diameter of the arteries was measured digitally, by analyzing photographs of the bases of the brain in the ImageJ program. RESULTS: The largest prevalence of artery diameter <1mm (<0.6mm) in CAC had the posterior communicating artery (PCoA). PCoA on the left side was hypoplastic in 44.9% (11.4%) of cases, while the same artery on the right side was hypoplastic in 44.3% (6.6%) of cases. The posterior cerebral artery was hypoplastic on the left side in 3% (0.6%) and on the right side in 4.2% (0.6%) of cases. The anterior cerebral artery had a hypoplastic caliber only on the right side in 2.4% (0.6%) of the cases, while the internal carotid arteries did not have a diameter <1mm in any case. The anterior communicating artery showed the greatest variability in morphology. Studies on CTA describe the occurrence of aplasia in a statistically significantly higher percentage, and the occurrence of hypoplastic arteries in a statistically significantly lower percentage compared to studies on cadavers. CONCLUSIONS: Due to significant differences between cadaveric and radiological studies, it is necessary to analyze their results regarding arterial hypoplasia and aplasia separately. A diameter of less than 1 mm has been suggested as a criterion for arterial hypoplasia.

The effect of camphor and borneol on rat thymocyte viability and oxidative stress.

Camphor and borneol are wildly distributed in the essential oils of medicinal plants from various parts of the World. Our study has been carried out to evaluate the effect of these two bicyclic monoterpenes on rat thymocytes. Camphor and borneol at concentrations of 0.5 and 5 µg/mL did not induce significant toxicity on the immune system cells, while a significant increase of thymocyte viability was detected when cells were incubated with 50 µg/mL of camphor. A significant increase of cell viability was similarly detected when thymocytes were cultivated with borneol at concentrations of 0.5 and 5 µg/mL. The role of camphor and borneol in reactive oxygen species (ROS) production and mitochondrial membrane potential (MMP) disturbances in rat thymocytes as well as their potential mechanism(s) of action were also discussed.

Platelet-rich fibrin: Basics of biological actions and protocol modifications.

Platelet-rich fibrin (PRF) represents second generation of platelet concentrates, which has gained increasing awareness in recent years for regenerative procedures. This biologic additive is completely autologous, easy to prepare, has minimal expense, and possesses prolonged growth factor release, together with several other advantages over traditionally prepared platelet concentrates. Since its introduction, various protocols for PRF preparation have been proposed with different amounts of growth factors and other biomolecules necessary for wound healing. However, reference data about potential effect of some PRF components on hard and soft tissue healing are still conflicting. The current article intends to clarify the relevant advances about physiological role of certain PRF components and to provide insight into the new developmental approach. Also, this review summarizes the evolution of platelet concentrates and biologic properties of different modifications of PRF procedure.

Effect of L-arginine on metabolism of polyamines in rat's brain with extrahepatic cholestasis.

Cholestatic encephalopathy results from accumulation of unconjugated bilirubin and hydrophobic bile acids in the brain. The aim of this study was to determine disturbances of polyamine metabolism in the brains of rats with experimental extrahepatic cholestasis and the effects of L-arginine administration. Wister rats were divided into groups: I: sham-operated, II: rats treated with L-arginine, III: animals with bile-duct ligation (BDL), and IV: cholestatic-BDL rats treated with L-arginine. Increased plasma gamma-glutamyltransferase and alkaline phosphatase activity and increased bile-acids and bilirubin levels in BDL rats were reduced by administration of L-arginine (P < 0.001). Cholestasis increased the brain's putrescine (P < 0.001) and decreased spermidine and spermine concentration (P < 0.05). The activity of polyamine oxidase was increased (P < 0.001) and diamine oxidase was decreased (P < 0.001) in the brains of BDL rats. Cholestasis increased the activity of arginase (P < 0.05) and decreased the level of citrulline (P < 0.001). Administration of L-arginine in BDL rats prevents metabolic disorders of polyamines and establishes a neuroprotective role in the brain during cholestasis.

Melatonin reduces oxidative stress induced by chronic exposure of microwave radiation from mobile phones in rat brain.

PURPOSE: The aim of the study was to evaluate the intensity of oxidative stress in the brain of animals chronically exposed to mobile phones and potential protective effects of melatonin in reducing oxidative stress and brain injury. MATERIALS AND METHODS: Experiments were performed on Wistar rats exposed to microwave radiation during 20, 40 and 60 days. Four groups were formed: I group (control)- animals treated by saline, intraperitoneally (i.p.) applied daily during follow up, II group (Mel)- rats treated daily with melatonin (2 mg kg(-1) body weight i.p.), III group (MWs)- microwave exposed rats, IV group (MWs + Mel)- MWs exposed rats treated with melatonin (2 mg kg(-1) body weight i.p.). The microwave radiation was produced by a mobile test phone (SAR = 0.043-0.135 W/kg). RESULTS: A significant increase in the brain tissue malondialdehyde (MDA) and carbonyl group concentration was registered during exposure. Decreased activity of catalase (CAT) and increased activity of xanthine oxidase (XO) remained after 40 and 60 days of exposure to mobile phones. Melatonin treatment significantly prevented the increase in the MDA content and XO activity in the brain tissue after 40 days of exposure while it was unable to prevent the decrease of CAT activity and increase of carbonyl group contents. CONCLUSION: We demonstrated two important findings; that mobile phones caused oxidative damage biochemically by increasing the levels of MDA, carbonyl groups, XO activity and decreasing CAT activity; and that treatment with the melatonin significantly prevented oxidative damage in the brain.

Evaluation of platelet activation in leukocyte-depleted platelet concentrates during storage.

Structural and functional changes in platelets during storage can lead to the loss of platelet reactivity and response. Our aim was to evaluate leukocyte-depleted platelet concentrates on storage days 0, 3 and 5, obtained by in-line filtration. In non-filtered platelet concentrates (NF-PC) group, 180 whole blood units were collected with quadruple blood bags and then compared to another group of 180 whole blood units (leukocyte-depleted platelet concentrates [LD-PC]), collected in Imuflex Whole Blood Filter Saving Platelets (WB-SP) bags with an integrated leukoreduction filter, with regard to the platelet quality and characteristics. The efficacy of the two techniques for platelet concentrate preparation was evaluated by white blood cell (WBC) and platelet count on day 0. The partial pressure of oxygen (pO2), pH, platelets positive for P-selectin (CD62P), CD63, cluster of differentiation 42b (CD42b), phosphatidylserine (PS), and mitochondrial membrane potential (MMP) were analyzed during the storage in both groups. A significantly lower WBC count and higher platelet count was observed in LD-PC compared to NF-PC group, indicating the overall efficacy of the first technique. During the 5-day storage, pH and pO2 decreased in both groups. In LD-PC group, higher pH, increased pO2 and decreased platelet surface expression of CD62P, CD63 and PS were observed compared to NF-PC group. In both groups, the percentage of CD42b positive platelets and MMP did not change significantly during the 5-day period. The assessment of different markers of platelet activation may be an effective tool in evaluating the quality of platelets during storage. A better understanding of platelet activation may provide new insights for developing a novel therapeutic approach in the manipulation of platelet aggregation.

Therapeutic role of methotrexate in pediatric Crohn's disease.

The main role of therapy in Crohn's disease (CD) is to achieve long-term clinical remission, and to allow for normal growth and development of children. The immunomodulatory drugs used for the maintenance of remission in CD include thiopurines (azathioprine and 6-mercaptopurine) and methotrexate (MTX). Development of hepatosplenic T-cell lymphoma in some patients with inflammatory bowel disease, treated with thiopurines only or in combination with anti-tumor necrosis factor agents, resulted in a growing interest in the therapeutic application of MTX in children suffering from CD. This review summarizes the literature on the therapeutic role of MTX in children with CD. MTX is often administered as a second-line immunomodulator, and 1-year clinical remission was reported in 25-69% of children with CD after excluding for the use of thiopurines. Initial data on MTX effectiveness in mucosal healing, and as a first-line immunomodulator in pediatric patients with CD, are promising. A definite conclusion, however, may only be made on the basis of additional research with a larger number of subjects.

Modulatory effect of curcumin on ketamine-induced toxicity in rat thymocytes: Involvement of reactive oxygen species (ROS) and the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway.

Ketamine is a widely used anesthetic in pediatric clinical practice. Previous studies have demonstrated that ketamine induces neurotoxicity and has a modulatory effect on the cells of the immune system. Here, we evaluated the potential protective effect and underlying mechanisms of natural phenolic compound curcumin against ketamine-induced toxicity in rat thymocytes. Rat thymocytes were exposed to 100 µM ketamine alone or combined with increasing concentrations of curcumin (0.3, 1, and 3 µM) for 24 hours. Cell viability was analyzed with CCK-8 assay kit. Apoptosis was analyzed using flow cytometry and propidium iodide as well as Z-VAD-FMK and Z-LEHD-FMK inhibitors. Reactive oxygen species (ROS) production and mitochondrial membrane potential [MMP] were measured by flow cytometry. Colorimetric assay with DEVD-pNA substrate was used for assessing caspase-3 activity. Involvement of phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway was tested with Wortmannin inhibitor. Ketamine induced toxicity in cells, increased the number of hypodiploid cells, caspase-3 activity and ROS production, and inhibited the MMP. Co-incubation of higher concentrations of curcumin (1 and 3 µM) with ketamine markedly decreased cytotoxicity, apoptosis rate, caspase-3 activity, and ROS production in rat thymocytes, and increased the MMP. Application of Z-VAD-FMK (a pan caspase inhibitor) or Z-LEHD-FMK (caspase-9 inhibitor) with ketamine effectively attenuated the ketamine-induced apoptosis in rat thymocytes. Administration of Wortmannin (a PI3K inhibitor) with curcumin and ketamine significantly decreased the protective effect of curcumin on rat thymocytes. Our results indicate that ketamine-induced toxicity in rat thymocytes mainly occurs through the mitochondria-mediated apoptotic pathway and that the PI3K/Akt signaling pathway is involved in the anti-apoptotic effect of curcumin.

Protective effect of interferon-alpha on the DNA- and RNA-degrading pathway in anti-Fas-antibody induced apoptosis.

AIM: Fas membrane-associated polypeptide antigen is a receptor molecule responsible for apoptosis-mediated signals. In animal models of acute viral hepatitis, apoptosis of hepatocytes is mediated by Fas-death receptors; therefore, the aim of this study was to evaluate the effect of interferon (IFN)-alpha on apoptotic markers and nuclease activity against different coding and non-coding single and double stranded RNAs during Fas-induced liver apoptosis. METHODS: An in vivo experiment was performed with simultaneous administration of anti-Fas (CD95) antibodies and IFN-alpha, and an in vitro experiment was performed in hepatocyte cultures treated with anti-Fas antibodies and IFN-alpha. RESULTS: Detection of apoptosis using Annexin V-FITC/propidium iodide, Bcl-2 and Bax expression in hepatocyte cultures confirmed the appearance of early apoptotic events and progression toward late apoptosis after anti-Fas antibody treatment. IFN-alpha had a tendency to retard the apoptosis process in Fas-induced apoptosis by increasing the number of viable cells and decreasing the number of cells in late apoptosis, by increasing the percentage of Bcl-2 positive cells, by decreasing the percentage of Bax positive cells, and by decreasing the nuclease activity compared to the anti-Fas antibody treated group. Total DNA and RNA concentration was much reduced in the Fas group and DNA fragmentation assay provided evidence for increased DNA degradation. Enhanced nuclease activity against DNA, rRNA, poly(A), poly(C), poly(U), poly(I:C), and poly(A:U) was manifested in the anti-Fas antibody treated group, except for the inhibitory-bound alkaline RNase. CONCLUSIONS: The results demonstrate that the RNA-degrading pathway in Fas-induced apoptosis can accelerate the liberation of the latent enzyme from the inhibitor complex. IFN-alpha prevented enormous, Fas-ligand induced degradation of all the substrates used in this experimental study, most probably due to similarities in the signal transduction pathways. Investigations of death receptor-induced apoptosis may lead to novel treatment combinations for patients with acute or chronic liver diseases.

Platelet Rich Plasma: a short overview of certain bioactive components.

Platelet rich plasma (PRP) represents a relatively new approach in regenerative medicine. It is obtained from patient's own blood and contains different growth factors and other biomolecules necessary for wound healing. Since there are various protocols for PRP preparing, it usually results with PRP generation with different amounts of bioactive substances, which finally may modulate the intensity of wound healing. The reference data about potential effect of some PRP compounds on wound healing, in different tissues, are still controversial. This review summarizes recently known facts about physiological role of certain PRP components and guidance for further research. Also, this review discusses different procedure for PRP generation and potential effect of leukocytes on wound healing.

Curcumin attenuates Mancozeb-induced toxicity in rat thymocytes through mitochondrial survival pathway.

The widely used fungicide Mancozeb (Man) has been shown to cause genotoxic effects in rodents and toxicological manifestations in different cells, mainly by altering the antioxidant defense in cells. On the other hand, curcumin (Cur), a natural phenolic compound, is thought to possess anti-inflammatory and antioxidant properties. Here, we investigated the possible protective role of Cur on Man-induced toxicity in rat thymocytes and potential mechanism involved. Rat thymocytes were treated with Man(0.01 µg/ml) and/or increasing Cur(0.3, 1, 3 µM) concentrations and levels of cell viability, apoptosis, mitochondrial membrane potential (MMP),Bcl-2, Bax protein expression, caspase-3 and -9 activity and p38 MAPK signaling involvement were examined. Cells treated with Man displayed increased cell toxicity, hypodiploid cells, caspase-3 and -9 activity, Bax protein expression, followed with decreased MMP and Bcl-2 protein expression. Inhibition of p38 MAPK signaling pathway markedly reduced apoptosis rate and caspase-3 activity in thymocytes exposed to Man. Application of increasing Cur (1, 3 µM) concentrations resulted with significantly reduced cytotoxicity, apoptosis, caspase-3, -9 activity, Bax protein expression, together with increased MMP and Bcl-2 protein expression in rat thymocytes. These result suggest that certain Cur concentrations may mediate Man-induced rat thymocytes toxicity through mitochondrial survival pathway, which may be useful in preventing possible secondary immunological consequences induced by Man.

Relation between bone mineral density and IL-17 serum levels in Serbian patients with early Rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by synovial inflammation and destruction of joint cartilage and bone. Different cytokines play important role in the processes that cause articular destruction and extra-articular manifestations in RA. The contribution of cytokines representing the Th1 (INF-γ), Th2 (IL-4) and IL-17A to the pathogenesis of early RA and bone mineral density (BMD) loss in still poorly understood. Serum samples of 38 early RA patients were evaluated for erythrocyte sedimentation rate (ESR), rheumatoid factor (RF), C-reactive protein (CRP), anti-cyclic citrullinated peptide antibodies (anti-CCP) and for the tested cytokines (IL-17A, IL-4 and INF-γ). BMD was evaluated by dualenergy X-ray absorptiometry (DXA). Disease activity score (DAS28) calculation was assessed for all patients. Control serum samples were obtained from 34 healthy volunteers. The levels of tested cytokines were significantly higher (IL-17A, p<0.001; INF-γ, P<0.001; IL-4, P<0.01) in patients with early RA, compared to the healthy controls. In early RA patients, strong correlation of serum IL-17A was found with DAS28, ESR and CRP. Also, a significant negative correlation was found between serum INF-γ levels and the DAS28 score. Significantly positive correlation of BMD values and CRP, DAS28 IL-17A were also demonstrated. DXA analysis revealed that the most common site for osteoporosis was the lumbar spine followed by the femoral neck. BMD values significantly correlated with CRP, DAS28 score and IL-17A serum levels. The mean serum IL-17A levels, in patients with early RA, corresponded with disease activity, severity and BMD loss, indicating the potential usefulness of serum IL-17A in defining the disease activity and bone remodeling.

Effect of four lichen acids isolated from Hypogymnia physodes on viability of rat thymocytes.

Four lichen acids, physodalic acid (F1), physodic acid (F2), 3-hydroxyphysodic acid (F3), and isophysodic acid (F4), were isolated from Hypogymnia physodes methanol extract using preparative reversed-phase high performance liquid chromatography and their structures were determined by UV, MS, (1)H NMR and (13)C NMR. This is the first report on the isolation of F4 from H. physodes. Isolated rat thymocytes were cultivated with increasing F1-F4 concentrations (0.1, 1, 10µg/well) and proliferative activity, viability, ROS (reactive oxygen species) production and MMP (mitochondrial membrane potential) disturbances were evaluated. Obtained results show significantly decreased thymocytes proliferation was observed when cells were treated with F1 (1µg, p<0.05; 10µg; p<0.001), F2 (10µg, p<0.05) and F3 compound (10µg, p<0.05). Significantly increased cytotoxicity was detected when cells were incubated with F1 (1µg, p<0.05; 10µg, p<0.01), F2 (10µg, p<0.05) and F3 compound (10µg, p<0.001). Increased H2DCF-DA fluorescence intensity, when cells were treated with F1 (1µg, p<0.001; 1µg, p<0.01; 10µg, p<0.001) and F2 (1µg, p<0.05; 10µg, p<0.01) compound, indicating the increase of intracellular ROS production. Simultaneously, increased ROS levels were followed with significantly decreased MMP when thymocytes were cultivated with F1 (0.1µg, p<0.001; 1µg, p<0.001; 10µg, p<0.001) and F2 compound (10µg, p<0.001). Thymocytes exposure to increased (0.1, 1, 10µg) concentrations of F3 and F4 compounds did not result with significant alterations in MMP and intracellular ROS production. We have shown that higher F1 and F2 concentrations induce thymocytes toxicity mainly through induction of oxidative stress, while cytotoxicity effect of F3 is followed with altered antioxidant/oxidant balance. The rigid 11H-dibenzo[b,e][1,4]dioxepin-11-one ring in the depsidone structure may play a important role for the examined biological activities.

Stimulatory effect on rat thymocytes proliferation and antimicrobial activity of two 6-(propan-2-yl)-4-methyl-morpholine-2,5-diones.

Recently we reported the identification and synthesis of cyclodidepsipeptides, 3,6-di(propan-2-yl)-4-methyl-morpholine-2,5-dione (PPM) and 3-(2-methylpropyl)-6-(propan-2-yl)-4-methyl-morpholine-2,5-dione (BPM), as potential precursors of enniatin B in Fusarium sporotrichioides. No data concerning biological activity of PPM and BPM have hitherto been published. The possible immunomodulatory effect and antimicrobial activity of PPM and BPM were investigated in this study, due to well known biological activities of enniatin B. The cytotoxicity effect of PPM and BPM on rat thymocytes demonstrated that increasing concentrations (0.1, 1, 10 µg/well) of PPM and BPM to cell culture, showed no significant effect on thymocytes toxicity. Simultaneously, incubation with studied cyclodidepsipeptides did not result with decreased mitochondrial membrane potential. Further, thymocytes exposure to increasing concentration of PPM and BPM was not able to induce significant reactive oxygen species (ROS) production in rat thymocytes. PPM and BPM administrations to cell culture in concentrations of 0.1 and 1 µg/well resulted with no significant increase of proliferative activity. However, significantly increased proliferative activity was detected with 10 µg of PPM (p<0.001) and BPM (p<0.05), as compared to their respective controls. The in vitro antimicrobial activity of PPM and BPM was tested against two Gram-positive and three Gram-negative bacteria. The results indicated that MIC values against tested strains ranged between 2.00 and 25.00 mg/ml. PPM showed much better activity against all tested bacteria in comparison with BPM. PPM was equally effective against both Gram-positive and Gram-negative bacteria, at the dose of 2.00 mg/ml.

6-(Propan-2-yl)-3-methyl-morpholine-2,5-dione, a novel cyclodidepsipeptide with modulatory effect on rat thymocytes.

A study has been carried out on the potential effect of a novel cyclodidepsipeptide, 6-(propan-2-yl)-3-methyl-morpholine-2,5-dione (PMMD), on rat thymocytes. Rat thymocytes were cultivated with increasing PMMD concentrations (0.1, 1, 10 µg/well), for 24h, and evaluated for proliferative activity, viability, reactive oxygen species and mitochondrial membrane potential. The higher PMMD concentrations inhibited thymocytes proliferative activity mainly through induction of oxidative stress and resulting cytotoxicity, without any mitochondrial membrane potential alterations in thymocytes. The obtained results are correlated with previously published data on effects of 6-(propan-2-yl)-4-methyl-morpholine-2,5-diones on rat thymocytes. The presence of methyl group in position 4 or/and the length of alkyl chain in position 3 of 6-(propan-2-yl)-morpholine-2,5-dione core plays a role for the obtained differences in the biological response between PMMD and two previously tested 6-(propan-2-yl)-4-methyl-morpholine-2,5-diones.