Understanding of lipid oxidation mechanisms (e.g., auto-oxidation and photo-oxidation) in foods and cosmetics is deemed essential to maintain the quality of such products. In this study, the oxidation mechanisms in foods and cosmetics were evaluated through analysis of linoleic acid hydroperoxide (LAOOH) and linoleic acid ethyl ester hydroperoxide (ELAOOH) isomers. Based on our previous method for analysis of LAOOH isomers, in this study, we developed a new HPLC-MS/MS method that enables analysis of ELAOOH isomers. The HPLC-MS/MS methods to analyze LAOOH and ELOOH isomers were applied to food (liquor) and cosmetic (skin cream) samples. As a result, LAOOH and ELAOOH isomers specific to photo-oxidation, and ELAOOH isomers characteristic to auto-oxidation were detected in some marketed liquor samples, suggesting that lipid oxidation of marketed liquor proceeds by both photo- and auto-oxidation during the manufacturing process and/or sales. In contrast, because only LAOOH and ELAOOH isomers specific to auto-oxidation were detected in skin cream stored under dark at different temperatures (−5 °C–40 °C) for different periods (2–15 months), auto-oxidation was considered to be the major oxidation mechanism in such samples. Therefore, our HPLC-MS/MS methods appear to be powerful tools to elucidate lipid oxidation mechanisms in food and cosmetic products.

1-Deoxynojirimycin (DNJ) is a potent α-glucosidase inhibitor and thus beneficial for prevention of diabetes. While we have succeeded in obtaining the culture supernatant extract (CSE) rich in DNJ from microorganism source, information regarding its anti-hyperglycemic effect and safety were still limited. Therefore, this study was aimed to evaluate the anti-hyperglycemic effect and safety of microorganism DNJ. Oral sucrose tolerance test was performed, and the result showed that CSE was able to significantly suppress the blood glucose elevation and suggested DNJ as the main active compound. To determine its safety, the absorption and excretion of microorganism DNJ were evaluated using 15N labeling method. Our findings investigated the recovery rate of 15N from DNJ reached 80% up to 48 hours after oral administration, suggesting its rapid excretion, suggesting the safety of DNJ. This study verified the functional properties and safety of DNJ from microorganisms, suggesting its potential use for functional purpose.

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Digalactosyldiacylglycerol- (DGDG-) monoestolide is a characteristic glycolipid in oats. DGDG-monoestolides possess a unique structure whereby a fatty acid of DGDG is replaced by a fatty acid ester of hydroxy fatty acid (FAHFA). While the physiological effects of DGDG and FAHFA have been reported previously, the effects of DGDG-monoestolides are unknown. Hence, we isolated a major DGDG-monoestolide molecular species from oats, analyzed its structure, and evaluated its anti-inflammatory effect. Based on GC-MS, MS/MS, and NMR analyses, the isolated compound was identified as a DGDG-monoestolide that contains the linoleic acid ester of 15-hydroxy linoleic acid (LAHLA) and linoleic acid (i.e., DGDG-LAHLA). The isolated DGDG-LAHLA was evaluated for its anti-inflammatory effect on LPS-stimulated RAW264 cells. The production of nitric oxide and cytokines (IL-6, TNF-α, and IL-10) were significantly decreased by DGDG-LAHLA, suggesting the anti-inflammatory effect of DGDG-LAHLA for the first time. In addition, our data showed a pronounced uptake of DGDG-LAHLA by cells. Some compounds corresponding to the predicted DGDG-LAHLA metabolites were also detected, suggesting that both intact DGDG-LAHLA and its metabolites may contribute to the above anti-inflammatory activities. These results are expected to expand the availability of oats as a functional food.

Supplementation of Bacillus amyloliquefaciens AS385 culture broth powder in high-fat diet restored adiposity, glucose tolerance and insulin sensitivity in mice.

We have studied the physiological effects and health functions of luteolin, especially focusing on its absorption and metabolism. Recent studies have reported the advantages of microemulsion to improve the bioavailability of poorly water-soluble compounds, including luteolin. In the present study, we aimed to evaluate the absorption and metabolic profile of luteolin delivered in microemulsion system via oral intake. First, we prepared water-dispersed luteolin (WD-L) using a microemulsion-based delivery system and confirmed that WD-L has superior water dispersibility compared to free luteolin (CO-L) based on their particle size distributions. Following administration of WD-L and CO-L to rats, we detected high level of luteolin-3'-O-β-glucuronide and lower levels of luteolin, luteolin-4'-O-β-glucuronide, and luteolin-7-O-β-glucuronide in plasma from both CO-L and WD-L groups, indicating that the metabolic profile of luteolin was similar for both groups. On top of that, we found a 2.2-fold increase in the plasma area under the curve (AUC) of luteolin-3'-O-β-glucuronide (main luteolin metabolite) in WD-L group (vs. CO-L). Altogether, our results suggested that delivering luteolin by microemulsion system improve its oral bioavailability without affecting its metabolite profile. This evidence thereby provides a solid basis for future application of microemulsion system for optimal delivery of luteolin.

1-Deoxynojirimycin (DNJ) has been known as a potent a-glucosidase inhibitor from mulberry leaves and considered beneficial in prevention of type 2 diabetes. Due to limited amount of DNJ in mulberry leaves, recent studies have focused in finding alternative source that can produce higher amount of DNJ. Previously, we produced a high DNJ-containing culture medium from Bacillus amyloliquefaciens AS385 and constructed a concentration method of bacterial culture medium using cation exchange column. However, less complicated concentration procedure is necessary to save time and cost during the large-scale production. Therefore, we developed a simpler concentration method using anion exchange resin to yield B. amyloliquefaciens AS385 culture broth powder (CBP; 1% DNJ) and evaluated the physiological effects of 5-wk dietary CBP intake in C57BL/6J mice. CBP intake tended to suppress the elevation of blood glucose level during oral glucose tolerance test. Moreover, CBP intake significantly lowered the fasting plasma glucose level and white adipose tissue mass. Next, we evaluated the absorption and distribution of DNJ in mice organs after daily CBP intake. We found detectable amount of DNJ in organs with intestine and kidney as the major targeted organs. We concluded that the DNJ content in CBP is absorbed from digestive tract, distributed and accumulated in organs, which most likely to contribute to the alteration of blood glucose regulation and adiposity in C57BL/6J mice. Our study was the first to report the physiological effects of CBP produced from B. amyloliquefaciens AS385 and the organ distribution of DNJ from CBP.

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