A simple and reliable high-performance liquid chromatography (HPLC) method for the determination of quercetin (QR) was developed. The method requires no QR reference; instead, it uses relative molar sensitivity (RMS) to a single reference, methylparaben (MPB). The RMS of QR/MPB was determined using an offline combination of ¹H-quantitative NMR (¹H-qNMR) and HPLC/UV or HPLC/photodiode array (PDA). In this study, the RMS represents the sensitivity ratio of QR to MPB per mole under defined HPLC conditions. The QR in two natural food additives was quantified using three different techniques such as ¹H-qNMR, UV–Vis spectrophotometry, and our single-reference HPLC method. Based on certain amounts of QR in two food additive products, the similar results using ¹H-qNMR (mass fraction: 96.9% and 96.1%) and single-reference HPLC (95.8% and 95.0%) were exhibited. On the other hand, the results using UV–Vis spectrophotometry (98.5% and 99.2%) without separation of QR and others (kaempferol and isorhamnetin impurities) showed slightly higher amounts than other techniques. In these techniques, the single-reference HPLC is advanced for the simple and accurate quantification of QR in food additive products without native standard.

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In this study, the amount of ergothioneine (EGT) in hot water extracts of Coprinus comatus (Coprino extracts) was studied, and the anti-inflammatory activities of the extracts were evaluated using a cell system by simultaneously monitoring superoxide anion radical generation and intracellular Ca²⁺ levels in neutrophil-like HL-60 cells. The protective roles of the Coprino extracts and EGT against inflammatory oxidative damage of 3T3-L1 adipocytes induced by tumor necrosis factor alpha (TNF-α) were also examined. Based on these results, it is reasonably safe to conclude that Coprino extracts have a higher anti-inflammatory activity than EGT alone.

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Ginger (Zingiber officinale) rhizomes have been reported to exhibit multiple efficacies on human health. In this paper, we found that n-hexane extract from ginger rhizomes (ginger oil) exhibited the inhibiting abilities against monoamine oxidase A (MAO-A) and B (MAO-B), which catalyze the oxidative deamination of monoamine neurotransmitters, by using an in vitro luminescencebased method. To characterize the compounds responsible for the inhibiting abilities against MAO-A and MAO-B, all fractions from reversed-phase chromatographies were subjected to the luminescence assay. As a result, we isolated five compounds from ginger oil by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. The half-maximal inhibitory concentration (IC₅₀) measurement using purified compounds revealed that (ⅰ) 6-, 8-, and 10-gingerols had strong inhibiting ability against MAO-A, whereas they showed weak inhibiting ability against MAO-B. (ⅱ) IC₅₀ values of 6-, 8-, and 10-gingerols against MAO-A were calculated to be 175.7±11.0 μM, 54.6±2.0 μM, and 113.4±4.7 μM, respectively. (ⅲ) Furthermore, we revealed that 1-dehydro- [6]-gingerdione (compound 1) and diacetoxy-[6]-gingerdiol (compound 2) were contained in the ginger oil. (ⅳ) The compound 1 showed strong and selective inhibiting ability against MAO-B with IC₅₀ of 6.77±0.45 μM, which was 10 times stronger than that against MAO-A. (ⅴ) The compound 2 showed weak inhibiting ability against both MAO-A and MAO-B. These findings suggest that the compound 1 having strong inhibiting ability against MAO-B could lead to the development of functional food materials intended to improve brain function.

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Fag e 2 is a 16 kDa major buckwheat allergen that is highly resistant to pepsin digestion. We previously reported that phosphorylation reduced the IgE-binding activity of Fag e 2 and oral administration of phosphorylated Fag e 2 (P-Fag e 2) attenuated allergic reactions in mice. In this study, we investigated the effects of phosphorylation on the digestibility of Fag e 2 and assessed whether digested P-Fag e 2 (DP-Fag e 2) can attenuate allergic reactions in Fag e 2-sensitized mice. Recombinant Fag e 2, obtained using the Pichia expression system, was phosphorylated via dry-heating in the presence of pyrophosphate. The peptic digestibility of Fag e 2 was enhanced by phosphorylation. Mice orally administered DP-Fag e 2 for 6 weeks after Fag e 2 sensitization exhibited reduced allergic symptom scores compared to those of sham-treated mice. Furthermore, decreased total and specific IgE, decreased specific IgG₁, and increased total IgA were observed in the serum of the DP-Fag e 2-fed group. These results suggest that P-Fag e 2 is easily digested in the stomach and induces the attenuation of the IgE-mediated allergic reaction.

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A simple and rapid dialysis method was developed for the analysis of sweeteners such as aspartame, sucralose, dulcin, acesulfame potassium, sodium saccharin, and sodium cyclamate present in foods. In the conventional method, a suspension was prepared by mixing 20 g of food with the dialysate and added to the dialysis membrane; the final volume was made up to 200 mL with the addition of the dialysate. The dialysis continued for 24-48 hours, after which the sweeteners that permeated the dialysis membrane were analyzed by high performance liquid chromatography. In the development method, a suspension was prepared by mixing 5 g of food with the dialysate and a dialysis membrane containing 2 mL of the dialysate was added; the final volume made up 50 mL with the addition of the dialysate. The dialysate comprised of 30% methanol containing 0.5% ammonium formate. After 90 minutes, the inner solution of the dialysis membrane was taken and analyzed by the liquid chromatograph-photodiode array-mass spectrometry. Using the above protocol, a recovery rate from 88.8 to 109.4 % and a % RSD from 0.2 to 4.8 was obtained.

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In 2020, the government of Japan has designated Coleus forskohlii as “an ingredient calling for special attention”. To ensure the efficacy and safety of health food products containing C. forskohlii, it is essential to identify and quantify the active compounds present in that plant. In this study, we established a specific TLC identification method and a quantitative HPLC assay, and evaluated the quality and quantity of 14 health food products. For TLC identification and for a cleaner analysis method, we modified the USP method in which toluene is used as the TLC eluent. Forskolin and its isomer, isoforskolin, were clearly separated with n-hexane/ethyl acetate (1:1) and detected with 4-methoxybenzaldehyde/sulfuric acid/ethanol (1:1:18) spray on TLC plates. For HPLC quantification of forskolin in C. forskohlii-containing products, we developed a simpler and more sensitive method based on the USP monograph. Good linearity with a coefficient of determination (r² > 0.998) was achieved over a concentration range 2–4000 μg/mL. The limit of detection and the limit of quantification were estimated to be 0.42 and 1.28 μg/mL, respectively. The precision of the method was confirmed by 92.01% forskolin recovery. Surprisingly, the forskolin content in health food products varied greatly and ranged up to 300 fold (0.35–120.10 mg/day). Thus, it was considered that the differences in the forskolin content in the sample products were caused by the differences in their merchandise design. These developed methods would be useful for the qualitative and quantitative evaluations of health food products containing C. forskohlii.

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Half-dried vegetables and mushrooms in sunlight has recently been recommended by cookbooks and internet sites in order to improve umami taste, despite very little scientific evidence. To verify their saying we chose squash whose umami taste had been observed previously by sensory evaluation to become significantly more prominent than those of the undried samples; further, we investigated the effect of sunlight on the levels of umami components in dried squash. We analyzed glutamic acid (Glu) and aspartic acid (Asp) levels after drying in sunlight, shade, and warm air by high performance liquid chromatography (HPLC) or liquid chromatography-tandem mass spectrometry (LC-MS/MS). Simultaneously, irradiation using visible (VIS), ultraviolet (UV), and far-infrared (far-IR) wavelengths that constituted the sunlight was used to examine the effect of each wavelength field on the levels of Glu and Asp in the squash samples. In addition, to investigate the effect of half-dry processing on the umami taste of vegetables and mushrooms, we assayed 22 other samples after drying in sunlight, shade, and warm air. As a result, the Glu levels of squash in the warm-air-dried group decreased significantly compared to the control group and the shade-dried group. The Asp level in the sun-dried group decreased significantly as compared to the control group. VIS radiation (26.6 W, 24 h) decreased the Glu levels and increased the Asp levels in the squash samples. UV-A radiation (10 W, 24 h) to the squash samples showed no significant effects. When the squash samples were subjected to far-IR radiation with high energy (300 W, 0.5 h), the Asp levels decreased. These far-IR results for Asp were the same as those for the white mushroom and radish samples. From the results of assay tests with 22 samples, Glu levels increased significantly in spinach, zucchini, and shiitake mushroom samples dried in the sun, whereas the other samples exhibited a significant increase or decrease in Glu levels when dried in the sun or shade. These findings indicated that the half-dry processing of vegetables and mushrooms in sunlight does not always improve the umami taste; however, some species might show an increase in the umami components. A more detailed examination is needed to elucidate each condition for the augmentation of umami.

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We previously reported effects of diosgenin on cognitive function in normal mice and Alzheimer’s disease model mice and healthy humans. The low oral bioavailability of diosgenin has been well recognized. However, our previous study showed that diosgenin dissolved in olive oil was efficiently distributed in the brain and exerted a memory-enhancing effect in mice after oral administration. This study investigated potencies of olive oil, fish oil and medium-chain triglyceride to transfer diosgenin in the brain. Diosgenin detected in the cerebral cortex after oral administration was very high in case of dissolved in olive oil. Brain penetration of diosgenin dissolved in fish oil was lower than that in olive oil. Medium-chain triglyceride showed very low potential of brain penetration of diosgenin after p.o. administration. We found in this study potencies of transporting diosgenin to the brain were different by fats as solvents.

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We investigated the effect of long-term administration of kale (Brassica oleracea L. var. acephala) on hippocampal gene expression in senescence-accelerated mouse prone 8, SAMP8. The mice were fed the AIN-93M diet containing 0.05% (w/w) kale extract (KE) for 31 weeks. The long-term KE administration resulted in significant decreases in escape latency compared to control group in the Barnes maze test. According to the DNA microarray analysis, KE administration significantly up-regulated various genes of G protein-coupled receptors pathways in the hippocampus. In contrast, KE administration significantly down-regulated genes of complement and coagulation cascades and focal adhesion-PI3K-Akt-mTOR-signaling pathway. Up-regulated pathways included genes involved in the modulation of neurotransmission and synaptic plasticity. Down-regulated pathways included genes related to the thrombus formation. These results could provide partial information about one of the molecular mechanisms underlying the suppressive effect of KE intake against cognitive decline.

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We developed an analytical method for the simultaneous determination of six sweeteners such as saccharin sodium (Sa), acesulfame potassium (AK), aspartame (APM), dulcin (Du), sucralose (SCR) and cyclamic acid (CY) in foods using liquid chromatograph coupled with photo diode array and single mass spectrometric detectors (LC-PDA-MS). This method was based on our previous study concerning determination of Sa, AK, APM, Du in foods using rapid dialysis technique for 1 hour. In this study, the previous condition was also applied to SCR and CY. After the dialysis clean-up, the six sweeteners were separated on a phenyl type HPLC column, and were detected by PDA for Sa, AK and Du, and by MS for SCR, CY and APM. Owing to the effective clean-up and measurement system described above, SCR and CY were successfully determined without any additional treatment such as solid phase extraction for SCR and derivatization for CY those had been required in some conventional method. The analytical time of this method was about a half day for one sample. The recovery test of various foods after spiking six sweeteners at 0.02 g/kg (CY: 0.01 g/kg) were 92.5 to 108.8% and the relative standard deviation ranged from 0.1 to 4.7%.

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The concentration of di(2-ethylhexyl) phthalate (DEHP) in mineral water (MW) products were determined using the GC-MS method. After a performance evaluation of the method, the spiked samples, which were prepared with twenty products randomly selected from the 155 MW products, were concurrently analyzed. The analytical results of the spiked samples show that the recovery ranged from 93% to 99%, suggesting that the method is highly applicable to MW products. We surveyed the DEHP concentrations in 155 MW products purchased from Japanese markets in 2018 using the validated GC-MS method. No product was found to have the level that exceeded above the lower limit of quantification (0.007 mg/L), nor at concentrations exceeding the WHO guidelines for drinking water quality (0.008 mg / L).

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