• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.465-474
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• 1999

RNase activity of Saccharomyces cerevisiae ATCC 7754 was investigated to obtain strains with high ribonucleic acid (RNA) content. The yeast strain contained two RNase activities; an acidic RNase with a optima of pH $3{\sim}4$ and an alkaline RNase with a optima pH 9. The acidic RNase activity was inhibited by $0.08\;M\;HgCl_{2}$ most drastically. The alkaline RNase activity was inhibited by 2.0 M NaCl or KCl, while enhanced by addition of $0.05\;M\;CaCl_{2},\;0.02\;M\;ZnSO_{4},\;or\;0.008\;M\;HgCl_{2}$. Various mutants of Saccharomyces cerevisiae ATCC 7754 were isolated by ethylmethane sulfonate (EMS) treatment or $\gamma$-ray/ultra violet irradiation. Among the mutants that were sensitive to high concentration of KCl which inhibits alkaline RNase, B24 was selected for high RNA content per culture volume. Growth characteristics of the mutant were comparable to those of the mother strain with optimum growth at pH $4.5{\sim}5.5$. The mutant accumulated higher content of RNA than the mother strain when glucose was used as the carbon source. However, both growth rate and total RNA content of the mutant were higher in molasses medium than in glucose medium. RNA content of the mutant increased rapidly during the early stage of growth, and then decreased gradually until the culture reached stationary phase by a fed-batch culture in a 5 L jar fermenter. Maximal cell harvest and the final RNA content using the mutant B24 were 69.6 g/L culture broth and 19.8 g/100 g of the dry cell while those using the mother strain were 68 g/L culture broth and 16.1 g/100 g of dry cell, respectively.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.2
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• pp.929-935
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• 2014

Two types of nanosized titanium dioxide, anatase ($anTiO_2$) and rutile ($rnTiO_2$), are widely used in industry, commercial products and biosystems. $TiO_2$ has been evaluated as a Group 2B carcinogen. Previous reports indicated that $anTiO_2$ is less toxic than $rnTiO_2$, however, under ultraviolet irradiation $anTiO_2$ is more toxic than $rnTiO_2$ in vitro because of differences in their crystal structures. In the present study, we compared the in vivo and in vitro toxic effects induced by $anTiO_2$ and $rnTiO_2$. Female SD rats were treated with $500{\mu}g/ml$ of $anTiO_2$ or $rnTiO_2$ suspensions by intra-pulmonary spraying 8 times over a two week period. In the lung, treatment with $anTiO_2$ or $rnTiO_2$ increased alveolar macrophage numbers and levels of 8-hydroxydeoxyguanosine (8-OHdG); these increases tended to be lower in the $anTiO_2$ treated group compared to the $rnTiO_2$ treated group. Expression of $MIP1{\alpha}$ mRNA and protein in lung tissues treated with $anTiO_2$ and $rnTiO_2$ was also significantly up-regulated, with $MIP1{\alpha}$ mRNA and protein expression significantly lower in the $anTiO_2$ group than in the $rnTiO_2$ group. In cell culture of primary alveolar macrophages (PAM) treated with $anTiO_2$ and $rnTiO_2$, expression of $MIP1{\alpha}$ mRNA in the PAM and protein in the culture media was significantly higher than in control cultures. Similarly to the in vivo results, $MIP1{\alpha}$ mRNA and protein expression was significantly lower in the $anTiO_2$ treated cultures compared to the $rnTiO_2$ treated cultures. Furthermore, conditioned cell culture media from PAM cultures treated with $anTiO_2$ had less effect on A549 cell proliferation compared to conditioned media from cultures treated with $rnTiO_2$. However, no significant difference was found in the toxicological effects on cell viability of ultra violet irradiated $anTiO_2$ and $rnTiO_2$. In conclusion, our results indicate that $anTiO_2$ is less potent in induction of alveolar macrophage infiltration, 8-OHdG and $MIP1{\alpha}$ expression in the lung, and growth stimulation of A549 cells in vitro than $rnTiO_2$.

• Journal of Nutrition and Health
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• v.49 no.3
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• pp.135-143
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• 2016

Purpose: Ultraviolet (UV)-induced oxidative stress contributes to several adverse biological effects on skin. Many phenolic phytochemicals have been shown to have antioxidant properties and protect skin cells from UV-induced oxidative damage. In this study, we investigated whether or not Aralia elata (AE) has a protective effect against UVB-induced reactive oxygen species (ROS), ultimately leading to photoaging. Methods: Phenolic content of dried AE and antioxidant properties of AE extract in 70% ethanol weredetermined by measuring DPPH and ABTS radical scavenging activities and ferric reducing antioxidant power (FRAP). The effect of AE extract on cellular ROS generation and expression levels of oxidative stress-response proteins such as superoxide dismutase (SOD)-1, catalase, nuclear factor-erythroid 2-related factor (Nrf)-2, and heme oxygenase (HO)-1 in UVB-irradiated ($75mJ/cm^2$) human keratinocytes (HaCaT) were further determined by 2'-7'-dichlorofluoresceine diacetate assay and Western blotting, respectively. Results: The total phenolic and flavonoid contents of dried AE were 20.15 mg tannic acid/g and 18.75 mg rutin/g, respectively. The $IC_{50}$ of AE extract against DPPH radical was $98.5{\mu}g/mL$, and ABTS radical scavenging activity and FRAP upon treatment with $1,000{\mu}g/mL$ of AE extract were $41.8{\mu}g\;ascorbic\;acid\;(AA)\;eq./mL$ and $29.7{\mu}g\;AA\;eq./mL$,m respectively. Pretreatment with AE extract significantly reduced (p < 0.05) ROS generation compared to that in UVB-irradiated control HaCaT cells. Pretreatment with AE extract reversed reduction of Nrf-2 and SOD-1 protein expression and induction of HO-1 protein expression caused by UVB exposure in HaCaT cells, whereas it did not affect catalase expression. Conclusion: AE extract in 70% ethanol demonstrated a protective effect against UVB-induced oxidative stress and decreased expression of Nrf-2 and SOD-1 in human keratinocytes. These findings suggest that AE ethanol extract might have potential as a natural resource for a skin anti-photoaging product in the food and cosmetic industry.