- 著者
- Keiko KOBAYASHI Yuki ISHIZAKI Shosuke KOJO Hiroe KIKUZAKI
- 出版者
- Center for Academic Publications Japan
- 雑誌
- Journal of Nutritional Science and Vitaminology (ISSN:03014800)
- 巻号頁・発行日
- vol.62, no.2, pp.123-129, 2016 (Released:2016-06-03)
- 参考文献数
- 30
- 被引用文献数
- 3 6
Sphingomyelinases (SMases) are key enzymes involved in many diseases which are caused by oxidative stress, such as atherosclerosis, diabetes mellitus, nonalcoholic fatty liver disease, and Alzheimer’s disease. SMases hydrolyze sphingomyelin to generate ceramide, a well-known pro-apoptotic lipid. SMases are classified into five types based on pH optimum, subcellular localization, and cation dependence. Previously, we demonstrated that elevation of secretory sphingomyelinase (sSMase) activity increased the plasma ceramide concentration under oxidative stress induced by diabetes and atherosclerosis in murine models. These results suggest that sSMase inhibitors can prevent the progress of these diseases. The present study demonstrated that sSMase activity was activated by oxidation and inhibited by reduction. Furthermore, we examined whether catechins inhibited the sSMase activity in a physiological plasma concentration. Among catechins, (−)-epicatechin 3-O-gallate (ECg) exhibited strong inhibitory effect on sSMase (IC50=25.7 μM). This effect was attenuated by methylation at the 3″- or 4″-position. On the other hand, (−)-epigallocatechin 3-O-gallate (EGCg) and (−)-catechin 3-O-gallate (Cg) exhibited weaker inhibitory activity than ECg, and (−)-epicatechin and (−)-epigallocatechin did not affect sSMase activity. Additionally, one synthetic catechin, (−)-3′-O-methylepigallocatechin 3-O-gallate (EGCg-3′-O-Me), showed the strongest inhibitory effect (IC50=1.7 μM) on sSMase. This phenomenon was not observed for (−)-4′-O-methylepigallocatechin 3-O-gallate. These results suggest that the reduction potential, the presence of the galloyl residue at the C-3 position, and the steric requirement to interact with sSMase protein are important for effective inhibition of sSMase.
- 著者
- Hinako ITO Hiroe KIKUZAKI Hiroshi UENO
- 出版者
- Center for Academic Publications Japan
- 雑誌
- Journal of Nutritional Science and Vitaminology (ISSN:03014800)
- 巻号頁・発行日
- vol.65, no.3, pp.264-271, 2019-06-30 (Released:2019-06-30)
- 参考文献数
- 11
- 被引用文献数
- 18
Vegetables are rich sources of nutrients such as fiber, minerals, vitamins, and antioxidants. Vegetables also contain various free-form amino acids, which improves their nutritional and palatable value. Cooking alters the content of free amino acids in vegetables, which affects their nutritional values. In this study, free amino acid levels were evaluated after cooking vegetables by different methods, boiling, roasting in an oven, and using a microwave. Results showed that many vegetables analyzed contain aspartate and glutamine abundantly. On the other hand, hydroxyproline, cysteine, ornithine and citrulline are the free amino acids existing at low or undetectable levels in all vegetables tested. The total free amino acid content in vegetables tended to decrease after boiling, and almost the same amount of free amino acids was obtained in the cooking liquid. Roasting of vegetables in an oven resulted in an increase in the content of specific amino acids, including γ-aminobutyric acid (GABA). Thus, it is important to choose the right cooking methods to prevent the loss of free amino acids. The results of the present study emphasize the changes in the contents of free amino acids during cooking with methods that are typically used on a daily basis. Our study on the dynamics of free amino acids caused by various cooking methods provides ample information for future nutritional studies.