This diploma thesis is focused on study of antimutagenic properties in selected kinds of honey and propolis. In honey extracts compounds with antimutagenic and antioxidant effect were analysed by spectrophotometry, RP/HPLC/UV-VIS, HPLC/PDA and on-line LC/MS. Further, effect of long-term storage on active compound levels was studied. Antimutagenic activity was tested by simple eukaryotic system - yeast strain Saccharomyces cerevisiae D7. The highest antimutagenic effect and simultaneously the highest stability of antimutagenity values was found in several kinds of multi-floral honey, rape seed honey, honey from eucalypt and orange flowers and in honeydew honey. Samples obtained from trade network exhibited at general lower antimutagenity values when compared with samples from bee-keeper. The highest content of total phenolics was detected in honey with royal yelly, the lowest content was measured in acacia honey. The highest values of total flavonoids exhibited buckwheat and eucalypt flower honey. Total phenolic content was substantially changed during long-term storage (decrease about 50 -70 %), while total flavonoid content was stable and no significant changes during storage were observed. Honey with high antimutagenity values exhibited also higher phenolic and predominantly flavonoid content and high antioxidant activity. Because of relative stability and low changes in most of honey samples during storage it can be concluded that honey belong to foodstuffs which are able to conserve their positive nutritive properties for a long time.

Background: Although alcohol intake has been positively associated with breast cancer risk in epidemiologic studies, the mechanisms mediating this association are speculative. Objective: The Postmenopausal Women's Alcohol Study was designed to explore the effects of moderate alcohol consumption on potential risk factors for breast cancer. In the present analysis, we evaluated the relationship of alcohol consumption with antioxidant nutrients and a biomarker of oxidative stress. Design: Participants (n = 53) consumed a controlled diet plus each of three treatments (15 or 30 g alcohol/day or a no-alcohol placebo beverage), during three 8-week periods in random order. We measured the antioxidants, vitamin E (alpha (α)- and gamma (γ-tocopherols), selenium, and vitamin C in fasting blood samples which were collected at the end of diet periods, treated and frozen for assay at the end of the study. We also measured 15-F2t-IsoP isoprostane, produced by lipid peroxidation, which serves as an indicator of oxidative stress and may serve as a biomarker for conditions favorable to carcinogenesis. Results: After adjusting for BMI (all models) and total serum cholesterol (tocopherol and isoprostane models) we observed a significant 4.6% decrease (P=0.02) in α-tocopherol and a marginally significant 4.9% increase (P = 0.07) in isoprostane levels when women consumed 30 g alcohol/day (P = 0.06 and 0.05 for overall effect of alcohol on α-tocopherol and isoprostanes, respectively). The other antioxidants were not significantly modified by the alcohol treatment. Conclusions: These results suggest that moderate alcohol consumption increases some biomarkers of oxidative stress in postmenopausal women.

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Hydroxytyrosol is one of the most powerful known antioxidants. It is a naturally occurring polyphenol, most commonly produced in Olive tree, (Olea europaea). The remarkable antioxidant and pharmacological properties of hydroxytyrosol has made it an outstanding compound in the polyphenol family and of great interest to many researchers. Hydroxytyrosol has the ability to scavenge free radicals produced during cellular oxidative stress and helps to protect the integrity of cells in living systems. Despite its numerous biological and pharmacological uses, it is found in very low concentration in olive oil, this limits its biomedical applications. A novel method for synthesizing pure hydroxytyrosol from commercially less expensive precursor catechol was successfully developed in our lab. However, it is believed that the cellular uptake of hydroxytyrosol is slow because of its high hydrophilicity. Therefore, we plan in this ongoing research to synthesize less hydrophilic derivatives of hydroxytyrosol by introducing some hydrophobic groups (such as alkyl, acyl, …) to its molecular skeleton.

Blueberries (Vaccinium spp.) are valued for their high nutritional quality and flavor. There are five species in the Vaccinium genus native to the state of Florida, but only three are palatable to humans: V. myrsinites, V. darrowii, and V. corymbosum. While V. darrowii has been studied extensively due to its successful hybridization with northern highbush blueberry cultivars, V. myrsinites and wild V. corymbosum have been understudied. This study aims to 1) quantify the abundance of various phytochemicals in fruits of these wild blueberry species and compare fruit quality both among the wild taxa and two varieties of cultivated blueberries (V. corymbosum) and 2) compare the variation of fruit traits across sampling sites. Wild berries were collected from seven different sites across Central Florida, and cultivated berries were collected from a local blueberry farm. Chemical analyses scored for titratable acidity, sugar content, phenolic content, and anthocyanin content. Additionally, measurements were taken for fruit size and water content. Results indicated that V. myrsinites has the highest sugar content and a significantly higher sugar:acid ratio than all other sample types. V. corymbosum and V. myrsinites had similarly high total phenolic concentrations. V. corymbosum had the highest anthocyanin concentration. This exploratory analysis provides new insight into the phytochemical profiles of understudied native Florida blueberries with applications to blueberry breeding efforts.

Ferroptosis is a recently characterized iron-dependent form of regulated cell death associated with the accumulation of (phospho)lipid hydroperoxides. Since its characterization, there has been a spirited debate in the literature over the origin of the lipid hydroperoxides in ferroptotic cells. Many investigators have implicated lipoxygenases (LOXs), enzymes known to catalyze the oxidation of polyunsaturated fatty acids (especially linoleate and arachidonate) to yield lipid hydroperoxides. Previous work by our group, investigated the induction and suppression of ferroptosis in human embryonic kidney (HEK-293) cells transfected to overexpress the three most widespread isoforms of LOX (5-LOX, 15-LOX-1 and p12-LOX). The results suggested that LOX catalysis is not required for ferroptosis. Our previous work did not include investigations into cells transfected to overexpress 15-LOX-2. However, a series of recent publications has since implicated the 15-LOX-2/PEPB1 complex as a key player in ferroptotic cell death. Therefore, in this work, HEK-293 cells were transfected to overexpress the 15-LOX-2 isoform, as confirmed by immunodetection, and were subject to induction and suppression of ferroptosis pharmacologically. A library of small molecules was assembled consisting of LOX inhibitors, radical-traping antioxidants (RTAs) and LOX inhibitors that display off-target RTA activity. Consistent with our previous investigations, only LOX inhibitors with radical trapping activity or iron chelators were effective at suppressing ferroptosis. Furthermore, the poor performance of 15-LOX-2 inhibitors at rescuing cells transfected to overexpress 15-LOX-2 from ferroptosis does not support the role of the 15-LOX-2/PEBP1 complex as a central mediator of ferroptotic lipid peroxidation. We also report the details of corresponding investigations in cell lines that are reported to express high levels of LOXs and that have been used to establish characteristics of ferroptosis, including HT-22 mouse hippocampal cells (15-LOX-1 and/or 15-LOX-2) and HT-1080 human fibrosarcoma cells (all LOXs). The two cellular models were also subject to cell-rescue studies with our small molecule library. Again, only LOX inhibitors that possess radical-trapping antioxidant activity or which are good iron chelators could rescue cells from ferroptosis. These results underscore our previous conclusion that although lipoxygenase activity may contribute to the pool of cellular lipid hydroperoxides, autoxidation drives ferroptotic cell death.

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