Interplay between the chalcone cardamonin and selenium in the biosynthesis of Nrf2-regulated antioxidant enzymes in intestinal Caco-2 cells.

Selenoenzymes and nuclear factor erythroid 2-related factor 2 (Nrf2)-regulated phase II enzymes comprise key components of the cellular redox and antioxidant systems, which show multiple interrelations. Deficiency of the micronutrient selenium (Se) and impaired biosynthesis of selenoproteins have been reported to result in induction of Nrf2 target genes. Conversely, transcription of the selenoenzymes glutathione peroxidase 2 (GPx2) and thioredoxin reductase 1 (TrxR1) is up-regulated upon Nrf2 activation. Here, we have studied the interplay between Se and the secondary plant metabolite cardamonin, an Nrf2-activating chalcone, in the regulation of Nrf2-controlled antioxidant enzymes. Se-deficient and Se-repleted (sodium selenite-supplemented) human intestinal Caco-2 cells were exposed to cardamonin. Uptake of cardamonin by the Caco-2 cells was independent of their Se status. Cardamonin strongly induced gene expression of GPx2 and TrxR1. However, cardamonin treatment did not result in elevated GPx or TrxR activity and protein levels, possibly relating to a concomitant down-regulation of O-phosphoseryl-tRNA(Sec) kinase (PSTK), an enzyme involved in translation of selenoprotein mRNAs. On the other hand, induction of the Nrf2-regulated enzyme heme oxygenase 1 (HO-1) by cardamonin was diminished in Se-replete compared to Se-deficient cells. Our findings suggest that cardamonin interferes with the biosynthesis of Nrf2-regulated selenoenzymes, in contrast to the Nrf2-activating isothiocyanate compound sulforaphane, which has been shown earlier to synergize with Se-mediated cytoprotection. Conversely, the cellular Se status apparently affects the cardamonin-mediated induction of non-selenoprotein antioxidant enzymes such as HO-1.

Supplementation with red palm oil increases ß-carotene and vitamin A blood levels in patients with cystic fibrosis.

Patients with cystic fibrosis (CF) show decreased plasma concentrations of antioxidants due to malabsorption of lipid soluble vitamins and consumption by chronic pulmonary inflammation. ß-Carotene is a major source of retinol and therefore is of particular significance in CF. The aim of this study was to investigate the effect of daily intake of red palm oil (RPO) containing high amounts of ß-carotene on the antioxidant levels in CF patients. Sixteen subjects were recruited and instructed to enrich their food with 2 to 3 tablespoons of RPO (~1.5 mg of ß-carotene) daily over 8 weeks. Carotenoids, retinol, and α-tocopherol were measured in plasma at baseline and after intervention. In addition ß-carotene, lycopene, α-tocopherol, and vitamin C were measured in buccal mucosa cells (BMC) to determine the influence of RPO on antioxidant tissue levels. Eleven subjects completed the study properly. Plasma ß-carotene, retinol, and α-carotene of these patients increased, but plasma concentrations of other carotenoids and α-tocopherol as well as concentrations of ß-carotene, lycopene, α-tocopherol, and vitamin C in BMC remained unchanged. Since RPO on a daily basis did not show negative side effects the data suggest that RPO may be used to elevate plasma ß-carotene in CF.

Chemical reactivity and biological activity of chalcones and other α,ß-unsaturated carbonyl compounds.

Abstract 1. Chalcones are structural analogues of benzalacetophenone (BAP). Several derivatives have been identified in plants and anticarcinogenic and anti-inflammatory properties were attributed to the compounds, probably related to their direct antioxidant activity or stimulatory effects on the expression of endogenous defence enzymes like hemeoxygenase-1 (HO-1). HO-1 expression is triggered by the Nrf2-Keap1 signalling pathway, initiated by the addition of chalcones to thiol groups of Keap1 via Michael-type reaction. 2. The present study used a model system estimating the reactivity of different synthetic chalcones and other α,ß-unsaturated carbonyl compounds with thiols and compared the chemical reactivity with the biological activity, measured by HO-1 expression in human dermal fibroblasts. 3. Chemical reactivity with the thiol group of N-acetylcysteine was determined with 5,5'-dithiobis-(2-nitrobenzoic acid) and followed chemical principles of structure-reactivity relationship. Most reactive were sulforaphane, dimethylfumarate, chalcone 3 ((2E)-1-phenyl-3-pyrimidin-2-ylprop-2-en-1-one) and chalcone 7 (1,3-diphenylprop-2-yn-1-one). This result demonstrates that α,ß-unsaturated carbonyl derivatives react with thiols differently. All compounds were also biologically active; however, expression of HO-1 was not only related to the chemical reactivity but also to the lipophilicity of the molecules which likely affected transmembrane uptake. Most efficient inducers of HO-1 expression were BAP, 4-hydroxynonenal and chalcone 1 (4-[(1E)-3-oxo-3-phenylprop-1-en-1-yl]benzonitrile), chalcone 5 ((2E)-1-phenyl-3-[4-(trifluoromethyl)-phenyl]prop-2-en-1-one) and chalcone 7.

UVA photoprotective properties of an artificial carotenylflavonoid hybrid molecule.

Carotenoids and flavonoids represent two classes of natural antioxidants, a biological activity, which is determined by their chemical structure. To combine their antioxidant properties, a dual functional carotenylflavonoid hybrid molecule was synthesized. The antioxidant activity of this compound was tested in human dermal fibroblasts exposed to UVA irradiation. Test parameters were hemeoxygenase-1 (HO-1) expression, malondialdehyde (MDA), and reactive oxygen species (ROS) formation and cell viability. For comparison, the substructure components of the carotenylflavonoid, 4-hydroxyflavone and 11'-apo-ß-carotenylbenzene, were also tested. Incubation of cells with the carotenylflavonoid and 11'-apo-ß-carotenylbenzene attenuated UVA-induced HO-1 expression. In the MDA assay, the carotenylflavonoid and 11'-apo-ß-carotenylbenzene were moderately effective at low concentrations. At higher concentrations, the compound provoked an increase of MDA, which was confirmed by the H(2)DCF-DA assay measuring ROS formation. 4-Hydroxyflavone moderately inhibited the formation of MDA at all levels that were tested. The study showed that the carotenylflavonoid counteracts UVA-induced HO-1 expression. However, a photoprotection against lipid oxidation, ROS formation, and cell toxicity could not be proven in the experimental setting.

3,3'-Dihydroxyisorenieratene and isorenieratene prevent UV-induced DNA damage in human skin fibroblasts.

Skin cancer is among the most frequent neoplastic malignancies and exposure to UV irradiation is a major risk factor. In addition to topical sunscreens, photoprotection by dietary antioxidants such as carotenoids or polyphenols has been suggested as a means of prevention. Isorenieratene (IR) and dihydroxyisorenieratene (DHIR) are aromatic carotenoids with particular antioxidant properties produced by Brevibacterium linens. The aim of this study was to investigate the photoprotective and antioxidant activities of DHIR and IR in comparison to the nonaromatic carotenoid lutein in human dermal fibroblasts. Incubation of the cells with DHIR and IR significantly decreased the UV-induced formation of cyclobutane pyrimidine dimers and formation of DNA strand breaks. Lipid oxidation was lowered as determined by the formation of malondialdehyde as a biomarker. Both aromatic carotenoids also prevented oxidatively generated damage to DNA as demonstrated by a decrease in DNA strand breaks associated with the formation of oxidized DNA bases. These data highlight the multifunctional photoprotective properties of aromatic carotenoids, which may be suitable natural compounds for the prevention of skin cancer.

Conflict of evidence: carotenoids and other micronutrients in the prevention and treatment of cognitive impairment.

Cognitive impairment is a common age-related disorder which affects in the stadium and type Alzheimer's Disease (AD) a steadily growing number of patients. AD is not curable and is not being easily diagnosed in its preclinical phase. This work aims at highlighting the complex though promising rationale for the use of selected micronutrients against age-related cognitive impairment and its progression. The advances made in the last decades in both defining the etiopathogenesis of cognitive impairment and in revealing mechanisms of action underlying possible preventive effects of several vitamins and micronutrients--likely related to antioxidant activity and modulation of cellular signaling--is being accompanied by conflicting results of most clinical trials. Therefore, available data do not currently support the use of substances such as carotenoids, polyphenols, vitamin D, curcumin, vitamin E, vitamin C, or lipoic acid in AD prevention and/or treatment. This might be partly due to the fact that cognitive impairment and especially AD are extremely complex disorders. The main obstacle to the inclusion of micronutrients among anticognitive impairment drug strategies, however, is that studies conducted so far are poorly comparable and probably underestimate of the role of vascular damage in age-related cognitive impairment. A possible clinical benefit of these substances in AD is not disproved to date, thus further better designed studies are needed.

Adjunctive daily supplementation with encapsulated fruit, vegetable and berry juice powder concentrates and clinical periodontal outcomes: a double-blind RCT.

AIM: A double-blind randomized controlled trial to determine whether dietary supplementation with fruit/vegetable/berry juice powder concentrates, simultaneously with non-surgical periodontal therapy, improved 2-month treatment outcomes. METHODS: Volunteers with chronic periodontitis were randomly assigned to one of three groups: fruit/vegetable (FV), fruit/vegetable/berry (FVB) or placebo. Supplements were taken daily during non-surgical debridement and maintenance and outcomes assessed at 2, 5 and 8 months after completion. Primary outcomes were mean probing pocket depth (PPD), clinical attachment gain, % sites bleeding on probing (% BOP) at 2 months. Adherence and plasma ß-carotene were determined. RESULTS: Sixty-one nutritionally replete (by serum biochemistry) volunteers enrolled and 60 (n = 20 per arm) completed the 2-month review. Clinical outcomes improved in all groups at 2 months, with additional improvement in PPD versus placebo for FV (p < 0.03). Gingival crevicular fluid volumes diminished more in supplement groups than placebo (FVB; p < 0.05) at 2 months, but not at later times. The % BOP (5 months) and cumulative plaque scores (8 months) were lowered more in the FV group (p < 0.05). CONCLUSIONS: Adjunctive juice powder concentrates appear to improve initial pocket depth reductions in nutritionally replete patients, where plasma micronutrient bioavailability is attainable. Definitive multicentre studies in untreated and treated patients are required to ascertain the clinical significance of such changes.

Green tea polyphenols provide photoprotection, increase microcirculation, and modulate skin properties of women.

Dietary constituents including polyphenols and carotenoids contribute to endogenous photoprotection and modulate skin characteristics related to structure and function of the tissue. Animal and in-vitro studies indicate that green tea polyphenols affect skin properties. In a 12-wk, double-blind, placebo-controlled study, 60 female volunteers were randomized to an intervention or control group. Participants consumed either a beverage with green tea polyphenols providing 1402 mg total catechins/d or a control beverage. Skin photoprotection, structure, and function were measured at baseline (wk 0), wk 6, and wk 12. Following exposure of the skin areas to 1.25 minimal erythemal dose of radiation from a solar simulator, UV-induced erythema decreased significantly in the intervention group by 16 and 25% after 6 and 12 wk, respectively. Skin structural characteristics that were positively affected included elasticity, roughness, scaling, density, and water homeostasis. Intake of the green tea polyphenol beverage for 12 wk increased blood flow and oxygen delivery to the skin. Likewise, in a separate, randomized, double-blind, single-dose (0.5, 1.0, and 2.0 g) study of green tea polyphenols, blood flow was maximized at 30 min after ingestion. In summary, green tea polyphenols delivered in a beverage were shown to protect skin against harmful UV radiation and helped to improve overall skin quality of women.

3,3'-Dihydroxyisorenieratene prevents UV-induced formation of reactive oxygen species and the release of protein-bound zinc ions in human skin fibroblasts.

3,3'-Dihydroxyisorenieratene (DHIR) is a structurally unusual carotenoid exhibiting bifunctional antioxidant properties. It is synthesized by Brevibacterium linens, used in dairy industry for the production of red smear cheeses. The compound protects cellular structures against photo-oxidative damage and inhibits the UV-dependent formation of thymidine dimers. Here we show that DHIR prevents a UV-induced intracellular release of zinc ions from proteins in human dermal fibroblasts. The effect is correlated with a decreased formation of intracellular reactive oxygen species. In contrast, zinc release from cellular proteins induced by hyperthermia is not affected by pretreatment of cells with the antioxidant DHIR. It is suggested that the intracellular zinc release upon UV irradiation is due to oxidative modifications of the zinc ligands in proteins (e.g. cysteine) and that protection by DHIR is due to intracellular scavenging of reactive oxygen species generated in photo-oxidation.

Intervention with flaxseed and borage oil supplements modulates skin condition in women.

Ingestion of selected nutrients modulates dermal properties. In the present study, two groups of women ingested flaxseed or borage oil for 12 weeks. The control group received a placebo containing medium-chain fatty acids. Dose was 2.2 g total fatty acids/d with alpha-linolenic acid and linoleic acid as major constituents in the flaxseed oil group; in the borage oil group linoleic and gamma-linolenic acid were predominant. In the flaxseed oil group, the contribution of alpha-linolenic acid to total fatty acids in plasma was significantly increased on weeks 6 and 12, whereas there was an increase in gamma-linolenic acid in the borage oil group (P < 0.05). Skin irritation was performed by nicotinate treatment, and changes in skin reddening and blood flow were monitored. Compared to week 0, skin reddening was diminished in both groups; blood flow was also lowered. Skin hydration was significantly increased after 12 weeks of treatment compared to week 0, with flaxseed or borage oil (P < 0.05). Transepidermal water loss was decreased in both oil groups by about 10 % after 6 weeks of supplementation. A further decrease was determined after 12 weeks in the flaxseed oil group. Surface evaluation of living skin revealed that roughness and scaling of the skin were significantly decreased with flaxseed and borage oil comparing week 0 and week 12 (P < 0.05). Except for hydration, none of the parameters was affected in the placebo group. The present data provide evidence that skin properties can be modulated by an intervention with dietary lipids.