Cholesterol hydroperoxides (ChOOHs) are included as lipid peroxidation products in the skin exposed to ultraviolet (UV) light irradiation. They may exert physicochemical actions affecting biomembrane rigidity because cholesterol is one of the major components of cell membranes. We investigated the distribution of isomeric ChOOHs in heterogeneous cell membranes with different lipid profiles using mouse fibroblast NIH-3T3 cells as a model of the dermis. Before and after UVA irradiation in the presence of hematoporphyrin, cell membranes were partitioned to microdomains (lipid rafts and caveolae) containing a higher amount of cholesterol and non-microdomains (containing a lower amount of cholesterol) by ultracentrifugation. By a combination of diphenylpyrenylphosphine-thin-layer chromatography blotting analyses and gas chromatography-electron ionization-mass spectrometry/selected ion monitoring analyses, ChOOH isomers were determined as their trimethylsilyloxyl derivatives. Cholesterol 5?-, 7?- and 7?-hydroperoxide were found as isomeric ChOOHs before irradiation. The amounts of the three ChOOH isomers increased significantly after photoirradiation for 2h. No difference was observed between microdomains and non-microdomains with regard to the ratio of the amounts of isomeric ChOOHs to that of cholesterol, suggesting that these ChOOH isomers were distributed equally in both parts depending on cholesterol content. When cells were treated with a purified mixture of ChOOH isomers, cell membranes incorporated ChOOHs into microdomains as well as non-microdomains evenly. Cellular matrix metalloproteinase-9 (MMP-9) activity was elevated by treatment with the purified mixture of ChOOH isomers. These results strongly suggest that ChOOHs accumulate in cell membranes irrespective of the heterogeneous microstructure and promote MMP activity if dermal cells are exposed to photodynamic actions.
The effect of food combination on metabolic profile in postprandial plasma has hardly been reported. We investigated the absorption and metabolism of quercetin and soy isoflavones in humans after combination meal consumption.
Carotenoids are known to be potent quenchers of singlet molecular oxygen [O(2) ((1)?(g))]. Solar light-induced photooxidative stress causes skin photoaging by accelerating the generation of reactive oxygen species via photodynamic actions in which O(2) ((1)?(g)) can be generated by energy transfer from excited sensitizers. Thus, dietary carotenoids seem to participate in the prevention of photooxidative stress by accumulating as antioxidants in the skin. An in vivo study using hairless mice clarified that a O(2) ((1)?(g)) oxygenation-specific peroxidation product of cholesterol, cholesterol 5?-hydroperoxide, accumulates in skin lipids due to ultraviolet-A exposure. Matrix metalloproteinase-9, a metalloproteinase family enzyme responsible for the formation of wrinkles and sagging, was enhanced in the skin of ultraviolet-A -irradiated hairless mice. The activation of metalloproteinase-9 and the accumulation of 5?-hydroperoxide, as well as formation of wrinkles and sagging, were lowered in mice fed a ?-carotene diet. These results strongly suggest that dietary ?-carotene prevents the expression of metalloproteinase-9 (at least in part), by inhibiting the photodynamic action involving the formation of 5?-hydroperoxide in the skin. Intake of ?-Carotene therefore appears to be helpful in slowing down ultraviolet-A -induced photoaging in human skin by acting as a O(2) ((1)?(g)) quencher.
The present study assessed whether serum carotenoids and tocopherols are associated with atopic diseases (eczema and asthma) in 10- and 13-yr-olds in a Japanese community. Of 2796 students attending schools in Shunan, Japan, in 2006, 396 students were randomly selected for this study using nested case-control design. Atopic diseases and dietary food intake were assessed using self-administered questionnaires, and serum antioxidants were analyzed using high-performance liquid chromatography. We found no associations between serum carotenoids and atopic diseases. However, odds ratios (OR)s for the third and fourth quartiles of serum alpha-tocopherol with atopic eczema were 0.33 (95% confidence interval: 0.15-0.73) and 0.36 (0.14-0.89), respectively, and the trend was negatively significant (P(trend) = 0.048). We did not find a significant association for asthma. In conclusion, serum alpha-tocopherol was negatively associated with the prevalence of eczema. Serum carotenoids did not show definitive protective effects in Japanese youth.
Beta-carotene is a carotenoid with a range of reported health benefits besides vitamin A activity. If the enzymatic conversion of beta-carotene to retinal is suppressed in the digestive tract, residual beta-carotene that reaches the tissues increases. We evaluated the function of quercetin and rutin (quercetin-3-rutinoside) to increase the accumulation of beta-carotene in vitro and in vivo in BALB/c mice. When the conversion of beta-carotene by a preparation of the murine small intestine was measured in vitro, the addition of quercetin or rutin considerably inhibited the conversion. When the levels of hepatic beta-carotene and retinoids were measured among three groups of mice fed a diet supplemented with beta-carotene plus quercetin or rutin or beta-carotene alone (four to six mice per group), quercetin increased the level of beta-carotene and decreased the level of retinol, whereas rutin did not. These results demonstrate that quercetin can suppress the conversion of beta-carotene which develops in the cytosol of small intestinal epithelial cells, and that rutin whose rutinose-moiety prevents being absorbed in the small intestine cannot suppress the conversion in vivo. This study offers a novel insight into the interaction between flavonoids and carotenoids with respect to the health benefits from the latter.
The mechanism of immunological benefits induced by carotenoids has not been fully elucidated. Here, we investigated some of the immunity-related properties of beta-carotene and two other carotenoids, beta-cryptoxanthin, and lutein, on the murine macrophages cell line RAW264. beta-Carotene added to the culture medium accumulated in the cells in a time- and dose-dependent manner. The accumulation was positively correlated with cellular lipid peroxidation, demonstrating the pro-oxidative activity of beta-carotene, and also with the synthesis of glutathione, an intracellular antioxidant. Conversely, accumulation of beta-carotene was negatively correlated with the transcription of immune-active molecules, such as IL-1beta, IL-6, and IL-12 p40, in cells stimulated by LPS and INF-gamma. The transcription of the pro-inflammatory cytokines IL-1beta and IL-6 was more sensitive to the accumulation of beta-carotene than was IL-12 p40. The accumulation of beta-cryptoxanthin in cells resulted in effects similar to those of beta-carotene. However, lutein accumulated minimally and did not significantly affect the cells. These results demonstrate that beta-carotene, and beta-cryptoxanthin as well, can accumulate in RAW264 cells and induce changes in intracellular redox status, which in turn regulate the immune function of macrophages.
We investigated the association between nutrient biomarkers and dietary intake estimated using a brief self-administered dietary history questionnaire (BDHQ) for Japanese children and adolescents. Blood samples were collected from 398 subjects (5th graders of elementary school aged 10-11 y, and 2nd graders of secondary schools aged 13-14 y) randomly selected from among students in Shunan City, Japan, who were then required to answer two questionnaires. Spearman correlations were calculated between dietary intake and the corresponding biomarkers (serum carotenoids, tocopherols, and erythrocyte fatty acids). Correlations with beta-carotene and beta-cryptoxanthin were significant in the 13- and 14-y age group (r=0.220-0.333, p<0.030) and the 10- and 11-y age subgroup who answered the questionnaire with assistance (r=0.295-0.299, respectively, p=0.006). Consumption of green-yellow vegetables and fruits was significantly correlated with beta-carotene and beta-cryptoxanthin levels (r=0.205-0.341, p<0.047). In the 13- and 14-y age group, correlations with eicosapentaenoic and docosahexaenoic acids were between 0.215 and 0.473 (p<0.040). Total seafood intake was significantly correlated with marine n-3 polyunsaturated fatty acids (PUFAs; r=0.239-0.420, p<0.023). In the 10- and 11-y age subgroup who completed the questionnaire with assistance, seafood intake was significantly correlated with marine n-3 PUFAs (r=0.239-0.243, p<0.032). In conclusion, dietary intake assessed using the BDHQ reflects the corresponding biomarkers for 13- and 14-y-olds; however, when used for elementary school children, caution is necessary in interpreting the results.
The activation of matrix metalloproteinase (MMP)-9 leading to the formation of wrinkle and sagging of skin is an essential step in the skin photoaging on exposure to ultraviolet A (UVA). This study attempted to elucidate the role of peroxidized cholesterol including cholesterol hydroperoxides (Chol-OOHs), primary products of lipid peroxidation in biomembranes, in MMP-9 activation and the effect of dietary beta-carotene in MMP-9 activation. Hairless mice were subjected to periodic UVA irradiation for 8 weeks. The amount of peroxidized cholesterol detected as total hydroxycholesterol in the skin was increased significantly by the exposure. The activity and protein level of MMP-9 were elevated with wrinkling and sagging formation. MMP-9 activity was also enhanced by the intracutaneous injection of Chol-OOHs into the mouse skin. Adding beta-carotene to the diet of the mice during the period of irradiation suppressed the activity and expression of MMP-9 as well as the wrinkling and sagging formation. The amount of cholesterol 5alpha-hydroperoxide, a singlet molecular oxygen oxygenation-specific peroxidized cholesterol, was significantly lowered by the addition of beta-carotene to the diet. These results strongly suggest that Chol-OOHs formed on exposure to UVA contribute to the expression of MMP-9, resulting in photoaging. Dietary beta-carotene prevents the expression of MMP-9, at least partly, by inhibiting photodynamic action involved in the formation of Chol-OOHs.
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