Leila Chekir Ghedira

Antioxidant and antigenotoxic activities in Acacia salicina extracts and its protective role against DNA strand scission induced by hydroxyl radical.

The antioxidant potency of Acacia salicina extracts was investigated. Total antioxidant capacity was determined using an ABTS(+) assay. Superoxide radical scavenging was measured using riboflavin-light-nitro blue tetrazolium (NBT) assay. In addition, the content of phenols, total flavonoids and sterols were measured in the tested extracts. The petroleum ether exhibited a potent scavenging activity toward ABTS radical cations. Whereas, chloroform extract showed the highest activity against superoxides radicals and was also able to protect pKS plasmid DNA against hydroxyl radicals induced DNA damages. The antimutagenicity of these extracts was assayed using the Ames assay against Salmonella typhimurium TA98 and S. typhimurium TA 1535 tester strains at different concentrations. These extracts decreased significantly the mutagenecity induced by sodium azide (SA) and 4-nitro-o-phenylenediamine (NOP). The antioxidant and antimutagenecity activities exhibited by A. salicina depended on the chemical composition of the tested extracts.

Evaluation of antioxidant and antigenotoxic activity of two flavonoids from Rhamnus alaternus L. (Rhamnaceae): Kaempferol 3-O-β-isorhamninoside and rhamnocitrin 3-O-β-isorhamninoside

The antioxidant activity of kaempferol 3-O-β-isorhamninoside (K3O-ir) and rhamnocitrin 3-O-β-isorhamninoside (R3O-ir), isolated from the leaves of Rhamnus alaternus L., was determined by the ability of each compound to inhibit NBT photoreduction and to scavenge the free radical ABTS(+)(.). Genotoxic and antigenotoxic activities were assessed using the SOS chromotest. At a concentration of 150 μg/assay the two compounds showed the most potent inhibitory activity against superoxide anion by respectively 80.4% and 85.6%. K3O-ir was a very potent radical scavenger with an IC(50) value of 18.75 μg/ml. Moreover, these two compounds exhibit an inhibitory activity against genotoxicity induced by nitrofurantoine and aflatoxine B1 using the SOS chromotest bacterial assay system in the presence of Escherichia coli PQ37 strain. In this study, we have also evaluated correlation between antigenotoxic and antioxidant effects of K3O-ir and R3O-ir. The highest correlation was showed with R3O-ir (r=0.999).

Investigation of the apoptotic way induced by digallic acid in human lymphoblastoid TK6 cells

BackgroundThe digallic acid (DGA) purified from Pistacia lentiscus. L fruits was investigated for its antiproliferative and apoptotic activities on human lymphoblastoid TK6 cells.MethodsWe attempt to characterize the apoptotic pathway activated by DGA. Apoptosis was detected by DNA fragmentation, PARP cleavage and by evaluating caspase activities.ResultsThe inhibition of lymphoblastoid cell proliferation was noted from 8.5 μg/ml of DGA. The induction of apoptosis was confirmed by DNA fragmentation and PARP cleavage. We have demonstrated that DGA induces apoptosis by activating the caspase-8 extrinsic pathway. Caspase-3 was also activated in a dose dependent manner.ConclusionIn summary, DGA exhibited an apoptosis inductor effect in TK6 cells revealing thus its potential as a cancer-preventive agent.

Degradation and detoxification of acid orange 52 by Pseudomonas putida mt-2: a laboratory study

IntroductionAcid orange 52 (AO52), extensively used in textile industries, was decolorized by Pseudomonas putida mt-2. AO52 azoreduction products such as N,N′-dimethyl-p-phenylenediamine (DMPD) and 4-aminobenzenesulfonic acid (4-ABS), were identified in the static degradation mixture. These amines were identified only in media of static incubation, which is consistent with their biotransformation under shaken incubation (aerobic conditions).Materials and methodsTests with azo products were carried out, and whole cells were found able to easily degrade DMPD contrary to 4-ABS. However, this last could be attacked by cell extract, and an oxygen uptake was observed during the reaction.ResultsDegradation of DMPD by entire cells led to the formation of catechol. These results show that P. putida was able to decolorize AO52 and metabolize its derivative amines. In addition, the ability of tested compounds was evaluated in vitro to reduce human plasma butyrylcholinesterase (BuChE) activity.ConclusionAzoreduction products seem to be responsible for BuChE inhibition activity observed in static biodegradation extract. However, toxicity of AO52 completely disappears after shaken incubation with P. putida, suggesting that bacterium has a catabolism which enables it to completely degrade AO52 and especially, to detoxify the dye mixture.

Evaluation of an eventual ecotoxicity induced by textile effluents using a battery of biotests

Textile industry is considered as one of the important factors of the economic growth in Tunisia. However, this prominent role has certainly some drawbacks mainly represented by the huge amounts of textile wastewaters generated that become a real menace to nature. Many previous studies showed the purifying potential of some activated sludge and bacteria (Pseudomonas putida) to decolourize textile effluents. However, in many cases, decolourization of wastewaters is not necessary associated with detoxification, generating a real risk for the ecosystem in general. We evaluated in this work the induced toxicity of a textile effluent before and after its treatment with activated sludge followed by P. putida, using a battery of biotests. This study proved the detoxifying power of the activated sludge according to most of ecotoxicity tests. The treatment with P. putida did not improve the quality of the effluent; on the contrary, it could increase its toxicity. Daphnia magna and Raphidocelis subcapitata appear to be the most sensitive organisms in assessing eventual toxicity caused by this kind of wastewaters.

A comparative evaluation of mutagenic, antimutagenic, radical scavenging and antibacterial activities of essential oils of Pituranthos chloranthus (Coss. et Dur.).

The Salmonella typhimurium/microsome assay is a widely used bacterial genotoxicity assay to test potential carcinogens. The aim of this work was to evaluate the mutagenic and antimutagenic activities with and without the addition of an extrinsic metabolic activation system of essential oils obtained from an aerial part of Pituranthos chloranthus harvested from different stations in Tunisia. The oils showed no mutagenicity when tested with S. typhimurium strains TA98, TA100, and TA1535. On the other hand, we showed that these essential oils reduced significantly Benzo [a] pyrene (B[a] P) and sodium-azide–induced mutagenicity. The scavenging capacity of these essential oils was also estimated by evaluating the inhibition of DPPH radical. Essential oils harvested at Medenine and Gabes in November were more effective in scavenging activity. The essential oils were tested for their antimicrobial properties against five different bacteria, and were found to be weakly active, with MIC and MBC values in the range 0.6–4 and 2.2–5 mg/mL, respectively.

Mumps Infection Associated with Intravascular Hemolysis, Acute Renal Failure and Pancreatitis

To the Editor:Mumps is an acute, self-limiting, systemic viral illness caused by a specific RNAvirus, known asRubulavirus. The specific incidence of hemolysis caused by mumps is still unknown. An eight-year-old girl presented with fever, increasing epigastric pain, fatigability and progressive darkening of urine. One week previously she had had parotid swelling. Physical examination showed deep pallor with jaundice, right parotitis, hepatomegaly, general abdominal tenderness and tachycardia. The initial laboratory values were as follows: hemoglobin 5.8 g/dL, platelet count 139,000/mm, reticulocytes 2.2 %, and white blood cell count 10,600/mm. Urine dipstick test for hemoglobin was positive. Serum amylase was 3,210 IU/L, lipase 68 U/L, haptoglobin 54 mg/L, creatinine 175 μmol/L and urea 21.5 mmol/L. Patient had oliguria at about 0.8 mL/kg/h. The Coombs’ test was negative. The hemoglobin electrophoresis test was normal. The cold agglutinin titer, resistance test, acid hemolysis (Ham-Dacie test), flow cytometry analysis of CD55 and CD59, were negative, and glucosesix-phosphate dehydrogenase level was normal. The syphilis serology was negative. The bone marrow aspiration was normal. The patient’s hospital course was marked by restoration of normal renal function by simple hydration and alkalinization with normal diuresis and progressive clarification of urine within 3 d from admission and an enhancement in hemolysis markers and pancreatic enzymes. To the best of our knowledge, only two cases of intravascular hemolysis associated to mumps infection have been reported in the literature [1, 2]. It is possible that in the present case, hemolysis, caused by a direct effect of the virus on red cells, resulted in the activation of F proteins in paramyxovirus [3]. The main differential diagnosis is paroxysmal cold hemoglobinuria. In fact, mumps infection is reported to be an etiologic factor for this disease, with a positive DonathLandsteiner test generally after a free period of clinical mumps; but no evidence of this type of antibody was found in the present case [4]. In conclusion, this new observation confirms the possible involvement of mumps and its strong relationship with intravascular hemolysis.

Thermal treatment of luteolin-7-O-β-glucoside improves its immunomodulatory and antioxidant potencies

Phytochemicals extracted from flowers, roots and bark, leaves, and other plant sources have been used extensively throughout human history with varying levels of efficacy in prevention and treatment of disease. Recently, advanced methods for characterization and clinical use of these materials have allowed modern understanding of their properties to be used as immunomodulatory agents that act by enhancement of endogenous cytoprotective mechanisms, avoiding interference with normal physiologic signaling and highly effective medical treatment with minimal adverse side effects. Simple methods have been identified for improving their biological effects, such as thermal conditioning by heating or freezing—prominent example being heat treatment of lycopene and tetrahydrocannabinol. The present investigation shows improvement of the ability of heat to augment splenocyte proliferation, natural killer (NK) cell activities, and antioxidant capacity of the flavonoid luteolin-7-O-β-glucoside (L7G) in comparison with the native (non heat-treated) molecule, while further demonstrating that both the native and the heat-treated variants exhibit comparable antioxidant properties, as evidenced by their effects in macrophages by inhibition of nitric oxide production and lysosomal enzyme activity in experiments that strengthen lysosomal membrane integrity. Outcomes of these studies suggest that heat-treated L7G shows promise for use in immunotherapy, including anti-cancer regimens, as shown by its improvement of NK cell cytotoxicity.

Cell protection induced by Acacia salicina extracts: Inhibition of genotoxic damage and determination of its antioxidant capacity

Antioxidant activity of Acacia salicina extracts was determined by the ability of each extract to inhibit lipid peroxidation, to protect against DNA strand scission induced by hydroxyl radicals, and to scavenge the free radical, 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+). The IC50 values of the inhibitory activity toward lipid peroxidation of total oligomer flavonoids (TOF), methanol, ethyl acetate, and aqueous extracts were respectively 28, 52, 472, and 480 μg/mL. All extracts have the ability to scavenge the ABTS•+ radical by a hydrogen-donating mechanism and to protect pKS plasmid DNA against hydroxyl radicals- induced DNA damage. An assay for the ability of A. salicina extracts to prevent mutations induced by various mutagens in Salmonella typhimurium TA102 and TA104 cells was conducted. TOF, methanol, ethyl acetate, and aqueous extracts from leaf parts of A. salicina showed no mutagenicity either with or without the metabolic enzymes preparation (S9). Protection against methylmethanesulfonate-induced mutagenicity was observed for TOF, methanol, and ethyl acetate extracts. Likewise, all extracts exhibited a high inhibition level of the Ames response induced by the indirect mutagen, 2-aminoanthracene. The antigenotoxic activity could be ascribed, at least in part, to their antioxidant properties, but we cannot exclude additionally mechanisms. Thus, A. salicina may serve as an ideal candidate for a cost- effective, readily exploitable natural phytochemical compound.

Digallic acid from Pistascia lentiscus fruits induces apoptosis and enhances antioxidant activities.

The antioxidant and apoptotic activities of digallic acid, isolated from the fruits of Pistascia lentiscus, were investigated. The study demonstrated that digallic acid possessed pro‐apoptotic effects, as shown by provoking DNA fragmentation of K562 cells. It also revealed a significant antioxidant potential and effective scavenging activity against 2,2‐diphenyl‐1‐picrylhdrazyl (DPPH·) and O2·− radicals, and reduced cupric ions. We conclude that this integrated approach to apoptotic and antioxidant assessment may be useful to maximize the beneficial effects associated with using P. lentiscus derivatives as medicinal and dietary compounds. Copyright