Protective effects of olive oil phenolics oleuropein and hydroxytyrosol against hydrogen peroxide-induced DNA damage in human peripheral lymphocytes.

This study investigates antioxidant capacity and protective effects of phenolic compounds oleuropein (OLP) and hydroxytyrosol (HT), present in olive oil and olive leaves, against H2O2-induced DNA damage in human peripheral lymphocytes. Antioxidant potency was determined using the measurement of radical-scavenging activity (ABTS∙+ assay), ferric reducing power (FRAP assay) and cupric reducing antioxidant capacity (CUPRAC assay). Both substances were found to be potent antioxidant agents due to their free radical-scavenging activities. Antigenotoxic effects of oleuropein and hydroxytyrosol against H2O2-induced damage in human lymphocytes were evaluated in vitro by alkaline comet assay. At tested concentrations (1, 5, 10 µmol L-1), oleuropein and hydroxytyrosol did not induce a significant increase of primary DNA damage in comparison with the negative control. Pretreatment of human lymphocytes with each of the substances for 120 min produced a dose-dependent reduction of primary DNA damage in the tested cell type. Hydroxytyrosol showed a better protective effect against H2O2-induced DNA breaks than oleuropein which could be associated with their free radical-scavenging efficacy.

Membrane of Candida albicans as a target of berberine.

BACKGROUND: We investigated the mechanisms of anti-Candida action of isoquinoline alkaloid berberine, active constituent of medically important plants of Barberry species. METHODS: The effects on membrane, morphological transition, synthesis of ergosterol and the consequent changes in membrane permeability have been studied. Polarization and lipid peroxidation level of the membrane following berberine treatment have been addressed. RESULTS: Minimal inhibitory concentration (MIC) of berberine against C. albicans was 17.75 µg/mL. Cytotoxic effect of berberine was concentration dependent, and in sub-MIC concentrations inhibit morphological transition of C. albicans cells to its filamentous form. Results showed that berberine affects synthesis of membrane ergosterol dose-dependently and induces increased membrane permeability causing loss of intracellular material to the outer space (DNA/protein leakage). Berberine also caused membrane depolarization and lipid peroxidation of membrane constituents indicating its direct effect on the membrane. Moreover, ROS levels were also increased following berberine treatment indicating further the possibility of membrane damage. CONCLUSION: Based on the obtained results it seems that berberine achieves its anti-Candida activity by affecting the cell membrane.

Antifungal Activity of Oleuropein against Candida albicans-The In Vitro Study.

In the present study we investigated activity of oleuropein, a complex phenol present in large quantities in olive tree products, against opportunistic fungal pathogen Candida albicans. Oleuropein was found to have in vitro antifungal activity with a minimal inhibitory concentration (MIC) value of 12.5 mg·mL-1. Morphological changes in the nuclei after staining with fluorescent DNA-binding dyes revealed that apoptosis was a primary mode of cell death in the analyzed samples treated with subinhibitory concentrations of oleuropein. Our results suggest that this antifungal agent targets virulence factors essential for establishment of the fungal infection. We noticed that oleuropein modulates morphogenetic conversion and inhibits filamentation of C. albicans. The hydrophobicity assay showed that oleuropein in sub-MIC values has significantly decreased, in both aerobic and anaerobic conditions, the cellular surface hydrophobicity (CSH) of C. albicans, a factor associated with adhesion to epithelial cells. It was also demonstrated that the tested compound inhibits the activity of SAPs, cellular enzymes secreted by C. albicans, which are reported to be related to the pathogenicity of the fungi. Additionally, we detected that oleuropein causes a reduction in total sterol content in the membrane of C. albicans cells, which might be involved in the mechanism of its antifungal activity.

Olive leaf extract activity against Candida albicans and C. dubliniensis - the in vitro viability study.

Olive leaf extract is characterized by a high content of polyphenols (oleuropein, hydroxytyrosol and their derivatives), which is associated with its therapeutic properties. The objective of the present research was to evaluate the antifungal activity of olive leaf extract against Candida albicans ATCC 10231 and C. dubliniensis CBS 7987 strains. Minimum inhibitory concentrations (MIC) of the extract were determined by several in vitro assays. The extract showed a concentration depended effect on the viability of C. albicans with MIC value of 46.875 mg mL-1 and C. dubliniensis with MIC value 62.5 mg mL-1. Most sensitive methods for testing the antifungal effect of the extracts were the trypan blue exclusion method and fluorescent dye exclusion method while MIC could not be determined by the method according to the EUCAST recommendation suggesting that herbal preparations contain compounds that may interfere with this susceptibility testing. The fluorescent dye exclusion method was also used for the assessment of morphological changes in the nuclei of treated cells. According to the obtained results, olive leaf extract is less effective against the tested strains than hydroxytyrosol, an olive plant constituent tested in our previous study.

Generic Medicines in Croatia--Regulatory Aspects and Statistics.

A generic medicine is an equivalent of an originator pharmaceutical product. It contains the same active substance as, is "essentially similar" to, and is therefore interchangeable with, the originator product. The objective of this study was to determine the share of generic medicines of the total received marketing authorization applications in Croatia, and the specificities in the approval of generic medicines with regard to assessments of their quality documentation. We collected the information from the Agency's medicinal products databases. Absolute numbers are shown for the applications for the authorizations of medicines in total and generics in particular in the period from 2005-2009. Data were analyzed using descriptive statistics. The annual number of marketing authorization applications for generic medicines received in Croatia increased from 148 applications in 2005 to 276 applications in 2009. In the period from 2005-2009, the number of applications for the approval of generic medicines accounted for 55% of all submitted applications. More than five generic medicines were approved for the following active compounds: amlodipine, lisinopril, atorvastatin, tamsulosin and omeprazole. In the following years, the number of applications from international manufacturers stagnated, while the number of applications by local manufacturers is on a steady climb, with the exception of 2008. From 2005-2009, an almost continual increase in the number of applications for the approval of generic medicines is evident. The largest number of generic medicines was approved for generic medicines intended for the treatment of cardiovascular disease (amlodipine, lisinopril, atorvastatin). A continual increase of applications from local manufacturers has been recorded. In the approval of these medicines, it is very important to develop a uniform approach to assessing the quality of each medicine, in order to guarantee a high quality product for the patient.

Hydroxytyrosol expresses antifungal activity in vitro.

Hydroxytyrosol (HT) is a potent antioxidant found in olive oil and leaves. Using several in vitro approaches, we tested antifungal activity of HT. HT showed broad spectrum of antifungal activity against medically important yeasts and dermatophyte strains with MIC values ranging between 97.6 µgml⁻¹ and 6.25 mgml⁻¹. The antimicrobial activity of HT was also tested using the time-kill methodology. Below the MIC value, HT showed potent damage of cell wall of Candida albicans ATCC 10231 using fluorescent dye-exclusion method. At the subinhibitory concentration, HT also influenced dimorphic transition of Candida indicating that HT is inhibitor of germ-tube formation as one of the most important virulence factor of C. albicans. Furthermore, HT showed disturbances in cell surface hydrophobicity (CSH) of C. albicans. The in vitro results indicate that HT caused a significant cell wall damage and changes in CSH as well as inhibition of germ-tube formation as virulence factor of C. albicans. The study indicates that HT has a considerable in vitro antifungal activity against medically important yeasts.