Biotransformation and nitroglycerin-induced effects on antioxidative defense system in rat erythrocytes and reticulocytes.

The effects of nitroglycerin (glyceryl trinitrate - GTN) are mediated by liberated nitric oxide (NO) and formed reactive nitrogen species, which induces oxidative stress during biotransformation in red blood cells (RBCs). The aim of this study was to evaluate effects of GTN on antioxidative defense system (AOS) in rat erythrocytes (without) and reticulocytes (with functional mitochondria). Rat erythrocyte and reticulocyte-rich RBC suspensions were aerobically incubated (2 h, 37°C) without (control) or in the presence of different concentrations of GTN (0.1-1.5 mM). After incubation, concentrations of non-enzymatic components of AOS, activities of antioxidative enzymes and oxidative pentose phosphate (OPP) pathway activity were followed in RBC suspensions. In rat reticulocytes, GTN decreased the activity of mitochondrial MnSOD and increased the activity of CuZnSOD. In rat RBCs, GTN induced increase of Vit E concentration (at high doses), but decreased glutathione content and activities of all glutathione-dependent antioxidative enzymes; the OPP pathway activity significantly increased. GTN biotransformation and induction of oxidative stress were followed by general disbalance of antioxidative capacities in both kinds of RBCs. We suggest that oxidative stress, MnSOD inhibition and depletion of glutathione pool in response to GTN treatment lead to decreased bioavailability of NO after GTN biotransformation in rat reticulocytes.

Antioxidative and antiproliferative evaluation of 2-(phenylselenomethyl)tetrahydrofuran and 2-(phenylselenomethyl)tetrahydropyran.

PURPOSE: To determine the antioxidant and antiproliferative influence of 2-(phenylselenomethyl)tetrahydrofuran (1a) and 2-(phenylselenomethyl)tetrahydropyran (2a) on colon cancer cell line HCT-116 and breast cancer cell line MDA-MB-231. METHODS: Cell viability was monitored in a dose-dependent manner using MTT assay. The concentration of superoxide anion radical (O2 •(-)) was determined spectrophotometrically. Spectrophotometric determination of nitrites (NO2 -) was performed by using the Griess method. Determination of total glutathione (GSH) was also performed spectrophotometrically. RESULTS: HCT-116 cell line was more sensitive to the effects of the investigated substances than MDA-MB-231 cell line. Also, it was noticed that 1a produced greater effect compared to 2a. Moreover, both investigated compounds decreased to a certain degree the oxidative stress by decreasing the O2•(-) and thus the peroxynitrite concentration. At the same time, 1a and 2a acted more efficiently in promoting the endogenous antioxidative capacities (increased GSH concentration) providing better self-defence capabilities for cells. CONCLUSION: Our findings showed that the investigated selenium compounds play an important role in reducing the levels of reactive oxygen species (ROS); therefore, we believe that, as antioxidants, they could prevent the processes arising as a consequence of oxidative stress, including cancer.

Biological effects, total phenolic content and flavonoid concentrations of fragrant yellow onion (Allium flavum L.).

The antioxidant, antibacterial and antiproliferative activities, total phenolic content and concentrations of flavonoids of A. flavum extracts were determined. The total phenolic content was determined with Folin-Ciocalteu reagent and it ranged between 42.29 to 80.92 mg GA/g. The concentration of flavonoids in various extracts of A. flavum was determined using spectrophotometric method with aluminum chloride and obtained results varied from 64.07 to 95.71 mg RU/g. The antioxidant activity was monitored spectrophotometrically and expressed in terms of IC50 (µg/ml), and its values ranged from 64.34 to 243.34 µg/ml. The highest phenolic content and capacity to neutralize DPPH radicals were found in acetone extract. Antibacterial efficacy was defined by determining minimum inhibitory and minimum bactericidal concentrations using microdilution method. Significant antibacterial activity, especially for ethyl acetate extract, was observed. The best activity was showed against G+ bacteria, Staphylococcus aureus ATCC 25923 and Bacillus subtilis, while Escherichia coli was one of the least sensitive bacteria. Antiproliferative activity of the methanolic extract on HCT- 116 cell line was determined by MTT assay. Results showed that A. flavum has good antiproliferative activity with IC50 values of 28.29 for 24 h and 35.09 for 72 h. Based on these results, A. flavum is a potential source of phenols as natural antioxidant, antibacterial and anticancer substance of high value. Phenolic content of extracts depend on the solvents used for extraction.

Antiproliferative and proapoptotic activities of methanolic extracts from Ligustrum vulgare L. as an individual treatment and in combination with palladium complex.

The aim of this study is to examine the growth inhibitory effects of methanolic leaf and fruit extracts of L. vulgare on HCT-116 cells over different time periods and their synergistic effect with a Pd(apox) complex. The antiproliferative activity of plant extracts alone or in combination with the Pd(apox) complex was determined using MTT cell viability assay, where the IC(50) value was used as a parameter of cytotoxicity. Results show that antiproliferative effects of L. vulgare extracts increase with extension of exposure time, with decreasing IC(50) values, except for 72 h where the IC(50) values for methanolic leaf extract were lower than for the fruit extract. The Pd(apox) complex alone had a weak antiproliferative effect, but combination with L. vulgare extracts caused stronger effects with lower IC(50) values than with L. vulgare extracts alone. The type of cell death was explored by fluorescence microscopy using the acridin orange/ethidium bromide method. Treatments with plant extracts caused typical apoptotic morphological changes in HCT-116 cells and co-treatments with Pd(apox) complex caused higher levels of apoptotic cells than treatment with plant extracts alone. The results indicate that L. vulgare is a considerable source of natural bioactive substances with antiproliferative activity on HCT-116 cells and which have a substantial synergistic effect with the Pd(apox) complex.

Teucrium plant species as natural sources of novel anticancer compounds: antiproliferative, proapoptotic and antioxidant properties.

This study deals with total phenolic content, antiproliferative and proapoptotic activity of methanolic extracts from different Teucrium species and the effect on the prooxidant/antioxidant status in HCT-116 cells. The total phenolic content of the extracts was measured spectrophotometricaly and the obtained results ranged from 56.62 mg/g to 172.50 mg GA/g. The antiproliferative activity of methanolic extracts from different Teucrium species was determined using MTT cell viability assay, where IC(50) value was used as a parameter for cytotoxicity. The type of cell death was explored by fluorescence microscopy using the acridin orange/ethidium bromide method. MTT assay showed that all extracts significantly reduced cell viability in a dose-dependent manner, with very low IC(50) values. The highest content of phenolic compounds and the best cytotoxic activity on HCT-116 cells after 24 h of exposure was in T. chamaedrys extract, with IC(50) values of 5.48 × 10(-9) µg/mL. After 72 h, methanolic extract of T. arduini appeared to have the best cytotoxic activity on HCT-116, with IC(50) values of 0.37 µg/mL. Treatments caused typical apoptotic morphological changes in HCT-116 cells and showed a high percentage of apoptotic cells. The results of the presented research indicate that some Teucrium extracts are a very rich source of phenols, which may directly contribute to high antiproliferative and proapoptotic activity.