Unexpected effect of dry olive leaf extract on the level of DNA damage in lymphocytes of lead intoxicated workers, before and after CaNa2EDTA chelation therapy.

The CaNa2EDTA chelation therapy is often practiced with antioxidant supplementation. Dry olive leaf extract (DOLE) is natural product with antioxidant and DNA protective properties. The effects of DOLE on the levels of DNA damage were investigated ex vivo in peripheral blood lymphocytes (PBLs) of 19 workers occupationally exposed to lead (Pb), before and after CaNa2EDTA chelation therapy. DOLE demonstrated pronounced radical scavenging activity in concentrations ≥1 mg/mL, and showed no genotoxicity per se, in concentrations 0.125-1 mg/mL. The level of DNA damage in PBLs of workers before chelation therapy was elevated (24.21 ± 14.26) compared to controls (6.0 ± 3.37). The incubation of PBLs before chelation therapy with selected concentration of DOLE lead to a severe increase of DNA damage (64.03 ± 20.96), exhibiting prooxidant rather than antioxidant effect. After the five-day CaNa2EDTA chelation regimen, DNA damage in PBLs of workers decreased (8.26 ± 4.62) significantly compared to baseline. Treatment of PBLs with DOLE after chelation, again produced high level of damage (41.82 ± 23.17) and the acute prooxidant effects of DOLE remained, but, DNA damage was less severe than before chelation. The DOLE exhibits prooxidant effect in presence of Pb in lymphocytes of exposed workers, and its effect is less pronounced following the removal of Pb after standard chelation therapy.

Cordyceps sinensis: Genotoxic Potential in Human Peripheral Blood Cells and Antigenotoxic Properties Against Hydrogen Peroxide by Comet Assay.

Context • Cordyceps sinensis (C sinensis) is a well-known, traditional, Chinese medicinal mushroom, valued for its beneficial properties for human health. C sinensis has been reported to have immunomodulatory, anticancer, antiaging, antioxidant and anti-inflammatory activity. Despite potential medicinal benefits, no previously published reports are available about the genotoxicity or antigenotoxicity of C sinensis, as detected by comet assay. Objective • The objective of the study was to evaluate both the genotoxic and antigenotoxic potential of an extract of C sinensis (CS extract) in human peripheral blood cells. Design • The research team designed a pilot study. Setting •The study was conducted at the Center for Biological Research, University of Belgrade, in Belgrade, Serbia. Participants • Participants were 6 healthy individuals (2 males and 4 females), between the ages of 20 and 45 y, recruited on a voluntary basis, who provided heparinized, peripheral blood samples. Intervention • Four concentrations of the CS extract-125 µg/mL, 250 µg/mL, 500 µg/mL, and 1000 µg/mL-were used in the treatment of tested blood cells from the blood samples. Three independent procedures were performed: (1) a genotoxicity assessment, (2) an antigenotoxicity assessment for pretreatment of human cells with the CS extract prior to their exposure to hydrogen peroxide (H2O2) (ie, an evaluation of the benefits of the CS extract as a preventive agent); and (3) posttreatment of human cells with the CS extract after their exposure to H2O2 (ie, an evaluation of the benefits of the CS extract as an interventional agent). Outcome Measures • Cells were graded by eye inspection into 5 classes, depending on the extent of DNA damage, representing: (1) class A-undamaged cells with no tail (<5% damaged DNA); (2) class B-low-level damage (5%-20%); (3) class C-medium-level damage (20%-40%); (4) class D-high-level damage (40%-95%), and (5) class E-total destruction (>95%).Results • The CS extract proved to be nongenotoxic because no induced DNA damage was detected at all tested concentrations. For the antigenotoxicity assessment of the pretreatment with the CS extract, only the 1000-µg/mL concentration showed a significant decrease in the number of cells exhibiting H2O2-induced DNA damage. For the posttreatment, the CS extract exhibited antigenotoxic potential by attenuating H2O2-induced DNA damage at all concentrations tested. The evaluation of repair kinetics showed a decrease in DNA-damaged cells 15 min after the application of the CS extract, reaching a maximum potency after 45 min. Conclusions • The results indicated that C sinensis can be used as a postapplicative agent that counteracts the effect of oxidative stress. The resulting reduction in DNA damage might be related to its scavenging properties and stimulation of DNA repair.

Dry Olive Leaf Extract in Combination with Methotrexate Reduces Cell Damage in Early Rheumatoid Arthritis Patients-A Pilot Study.

The effects of co-administration of dry olive leaf extract (DOLE) with standard methotrexate (MTX) therapy on the parameters of cell damage and inflammation in patients with early and long-term rheumatoid arthritis (RA) were evaluated at baseline, 3 and 6 weeks. Patients were assigned to groups: the early phase RA group on MTX monotherapy (E MTX), and the two RA groups that received co-treatment with DOLE and MTX: early (E MTX + DOLE) and long-term phase patients (L-t MTX+ DOLE). Baseline values indicated increased parameters of cell damage and disruption of redox balance in all groups. After three weeks the E MTX + DOLE group maintained high catalase activity, exhibited decrease of lipid peroxidation and protein damage indicators-thiols and nitrites, while levels of DNA damage and pro-inflammatory interleukin-6 were significantly reduced. In E MTX group catalase activity remained unaltered while significant lipid peroxidation and DNA damage reductions were seen only after six weeks. L-t MTX + DOLE group showed only modest alterations of cell damage parameters during six weeks. Combined administration of DOLE with MTX contributes to faster reduction of cell damage, restores oxidative balance and improves interleukin-6 suppression during high disease activity in early phase RA, but not in long term patients. Copyright © 2016 John Wiley & Sons, Ltd.

Dry olive leaf extract counteracts L-thyroxine-induced genotoxicity in human peripheral blood leukocytes in vitro.

The thyroid hormones change the rate of basal metabolism, modulating the consumption of oxygen and causing production of reactive oxygen species, which leads to the development of oxidative stress and DNA strand breaks. Olive (Olea europaea L.) leaf contains many potentially bioactive compounds, making it one of the most potent natural antioxidants. The objective of this study was to evaluate the genotoxicity of L-thyroxine and to investigate antioxidative and antigenotoxic potential of the standardized oleuropein-rich dry olive leaf extract (DOLE) against hydrogen peroxide and L-thyroxine-induced DNA damage in human peripheral blood leukocytes by using the comet assay. Various concentrations of the extract were tested with both DNA damage inducers, under two different experimental conditions, pretreatment and posttreatment. Results indicate that L-thyroxine exhibited genotoxic effect and that DOLE displayed protective effect against thyroxine-induced genotoxicity. The number of cells with DNA damage, was significantly reduced, in both pretreated and posttreated samples (P < 0.05). Comparing the beneficial effect of all tested concentrations of DOLE, in both experimental protocols, it appears that extract was more effective in reducing DNA damage in the pretreatment, exhibiting protective role against L-thyroxine effect. This feature of DOLE can be explained by its capacity to act as potent free radical scavenger.

Protective effect of dry olive leaf extract in adrenaline induced DNA damage evaluated using in vitro comet assay with human peripheral leukocytes.

Excessive release of stress hormone adrenaline is accompanied by generation of reactive oxygen species which may cause disruption of DNA integrity leading to cancer and age-related disorders. Phenolic-rich plant product dry olive leaf extract (DOLE) is known to modulate effects of various oxidants in human cells. The aim was to evaluate the effect of commercial DOLE against adrenaline induced DNA damage in human leukocytes by using comet assay. Peripheral blood leukocytes from 6 healthy subjects were treated in vitro with three final concentrations of DOLE (0.125, 0.5, and 1mg/mL) for 30 min at 37°C under two different protocols, pretreatment and post-treatment. Protective effect of DOLE was assessed from its ability to attenuate formation of DNA lesions induced by adrenaline. Compared to cells exposed only to adrenaline, DOLE displayed significant reduction (P<0.001) of DNA damage at all three concentrations and under both experimental protocols. Pearson correlation analysis revealed a significant positive association between DOLE concentration and leukocytes DNA damage (P<0.05). Antigenotoxic effect of the extract was more pronounced at smaller concentrations. Post-treatment with 0.125 mg/mL DOLE was the most effective against adrenaline genotoxicity. Results indicate genoprotective and antioxidant properties in dry olive leaf extract, strongly supporting further explorations of its underlying mechanisms of action.