Lipid hydroperoxide

Lipids in the human body can undergo oxidation due to various factors, such as inflammation, light exposure, and drug metabolism. This oxidation produces lipid peroxides, which are known to contribute to the development of several diseases. To help prevent such conditions, it is essential to understand what types of oxidative reactions are occurring in the body. Our laboratory aims to identify the specific oxidative pathways by analyzing the structures of lipid peroxides in human blood and animal tissues using advanced mass spectrometry techniques. By determining the type of oxidative stress involved, we can propose appropriate antioxidant strategies tailored to each condition. To support this approach, we also conduct cell- and animal-based experiments. While a wide range of antioxidant foods are currently available for disease prevention, their mechanisms of action are often unclear. Through our research, we hope to contribute to the development of more effective food-derived antioxidants with well-defined biological functions.

Glycated Lipid/Maillard Reaction

The Maillard reaction plays a key role in creating the aroma and color that develop during the cooking process—for example, the delicious crust and savory flavor of toasted bread or roasted meat. Traditionally, the Maillard reaction has been studied as a chemical interaction between carbohydrates and hydrophilic molecules, such as proteins. However, our laboratory has discovered that this reaction can also occur between carbohydrates and lipids, specifically phosphatidylethanolamine (PE), forming glycated lipids known as Amadori-PE. We are using mass spectrometry to quantify Amadori-PE in various foods, and to investigate its effects on nutritional value and physical properties. Moreover, because the Maillard reaction can also take place in the human body, we are exploring the physiological significance of lipid Maillard reactions in vivo.

Powdered lipids

Fish oil is rich in docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), polyunsaturated fatty acids known for their health benefits, including cholesterol-lowering, antithrombotic, and anti-inflammatory effects. However, because DHA and EPA are highly unsaturated, they are prone to oxidation, leading to the formation of lipid peroxides. Preventing the oxidation of fish oil is therefore a critical challenge. In our laboratory, we have successfully developed a powdered form of fish oil that is more resistant to oxidation than conventional liquid fish oil. This is achieved by coating the oil with gelatin and an emulsifier to form a protective powder. We are also incorporating this powdered fish oil into processed foods such as bread and evaluating its oxidative stability, palatability, and bioavailability. Our research is expected to make it easier and more effective for people to consume DHA and EPA through familiar foods like bread.

Plasmalogen

Plasmalogen is a type of phospholipid that is abundant in the brain, nervous system, and blood. Although its levels are known to decrease with aging and in individuals with Alzheimer’s disease, the underlying causes and mechanisms remain unclear. In our laboratory, we have developed a highly sensitive and specific analytical method using mass spectrometry to investigate the biological functions of plasmalogen in vivo. Using this assay, we are currently exploring its roles in the nervous system, its digestion and absorption pathways, and the dietary sources of plasmalogen. In the future, we aim to further elucidate the physiological functions of plasmalogen and its potential links to disease.

Vitamin E

Vitamin E (tocopherol) is a fat-soluble vitamin well known for its antioxidant properties. In the body, it is located within biological membranes, where it helps prevent the oxidation of membrane lipids. It is also widely used in the food industry as an antioxidant additive. In our laboratory, we have discovered that vitamin E can protect cells from death induced by lipid peroxides. We are currently conducting cell and animal experiments to clarify the underlying mechanisms. Additionally, we are investigating the health benefits and production of tocotrienols—another form of vitamin E. These studies aim to contribute to the prevention of oxidative stress-related diseases and to the maintenance and improvement of food quality.

γ-Oryzanol

γ-Oryzanol is a collective term for ferulic acid esters of plant sterols and triterpene alcohols, and it is characteristically found in rice bran and germ. It is known for its antioxidant, lipid-lowering, and anti-inflammatory effects, and is gaining attention as a food-derived functional ingredient. However, the detailed mechanisms of its action, absorption, and metabolism remain unclear. In our laboratory, we are conducting long-term studies in which mice are administered rice bran oil rich in γ-oryzanol. Using highly sensitive mass spectrometry, we analyze the levels of γ-oryzanol in plasma and tissues to elucidate its pharmacokinetics and to explore the relationship between its presence and physiological effects.

Carotenoid

Carotenoids are a group of yellow and red pigments found in vegetables and fruits, and they are important components in the human body. Interestingly, our laboratory has discovered that carotenoid levels are decreased in the erythrocyte membranes of patients with Alzheimer's disease, while lipid peroxide levels are elevated. We have also found that carotenoid intake increases carotenoid levels in the blood and reduces lipid peroxides. These findings suggest that carotenoids play a significant role in the body's antioxidant defense. However, the exact mechanisms—such as where and how carotenoids exert their antioxidant effects—remain unclear. Since carotenoids are believed to be converted into various oxidized forms as part of their antioxidant function, we are working to elucidate their mechanism of action by analyzing the structures of these oxidation products using mass spectrometry and related techniques.

Curcuminoid

Curcuminoids are yellow fat-soluble polyphenols that are abundant in turmeric. Among them, curcumin has been subjected to various in vitro tests and has been reported to have beneficial effects such as improvement of lipid metabolism, antitumor, and antioxidant. However, the absorbability of curcumin in animals and humans was limited. Therefore, it is difficult to mention that curcumin's effects can be effective in animals and humans. Therefore, in our laboratory, we are trying to increase the bioavailability by encapsulating curcumin in “nanoparticles” or “liposomes”. For example, we prepare curcumin-encapsulated nanoparticles and give them to cells and animals. Then, investigate the absorption of curcumin, as well as clarify its pharmacokinetics. Through the promotion of such research, it is expected that curcumin will be able to exert its beneficial effects more effectively in vivo, leading to the development of new functional foods.

Polyphenol; Luteolin

Luteolin is a type of flavonoid contained in paprika, perilla, and perilla, and has been reported to have anti-inflammatory, antioxidant, and anticancer effects. However, luteolin exists in various forms (e.g., various glucosides and aglycones) in food, and the differences in absorption metabolism and physiological action are not well understood. Until now, we have found that luteolin glucoside and luteolin aglycone are converted into metabolites (luteolin glucuronide) in the body of rats, and that these metabolites retain anti-inflammatory activity in cultured cells. Currently, we are conducting research focusing on whether it is the same in humans. It is expected that the function of luteolin can be confirmed by the accumulation of such evidence.

Aza sugar

"Aza" has the meaning of "having a nitrogen atom instead of a carbon atom". This suggests that azasugar has a structure in which the oxygen atom of sugar, such as glucose, is replaced with a nitrogen atom. It is known that azasugar inhibits the decomposition of sugar and suppresses its absorption. Moderating the absorption of sugar is expected to lead to the prevention and improvement of diabetes. We focused on DNJ (1-deoxynojirimycin), which is particularly active among aza-sugars. We used a certain microorganism to produce DNJ at a high level and investigated its functionality (e.g., suppression of sugar absorption using animals and cells) is being evaluated.