Changes in the charged metabolite and sugar profiles of pasteurized and unpasteurized Japanese sake with storage

Japanese sake (rice wine) is commonly heat treated (pasteurized) to maintain its quality. In this study, temporal changes in the metabolite profiles of pasteurized and unpasteurized sake were investigated during storage. Metabolomic analyses were conducted for eight sets of pasteurized and unpasteurized sake obtained from single process batches stored at 8 or 20 °C for 0, 1, 2, or 4 months. Capillary electrophoresis time-of-flight mass spectrometry and liquid chromatography tandem mass spectrometry were used to obtain charged metabolite and sugar profiles, respectively. The total amino acid concentration decreased with storage, and the decrease was faster in pasteurized sake than in unpasteurized. The organic acid concentrations were relatively constant in both types of sake. Peptide and glucose concentrations increased and polysaccharide concentrations decreased in unpasteurized sake, while they were relatively constant in pasteurized sake. Rather than stabilizing the sake metabolite profile during storage, pasteurization results in characteristic changes compared to unpasteurized sake.     

Intercropping with herbs minimizes cadmium availability through altering physicochemical dynamics and metabolite profiles in wheat rhizosphere

For the past few years, the production of safe crops in Cd-contaminated soil has attracted more and more attention, and the intercropping of wheat and herbaceous plants has gradually become an effective way. However, how the physicochemical and metabolic processes because of the intercropping change Cd availability are still unclear. In this study, we studied the influence of changes in soil physicochemical properties induced by intercropping of wheat with different herbs on soil Cd availability of Cd. Meanwhile, we innovatively studied the effect of intercropping on rhizosphere metabolites and evaluated the impact on Cd transfer. Results showed that the highest wheat biomass was presented in the intercropping system with the Cichorium intybus L. (W4) and Aus hypochondriacus L. (W5) increasing by 57.66% and 54.05% individually, compared with monocropping, while W1, W2, and W3 increasing slightly. Further, the Cd accumulation in wheat grains under W4 and W5 treatment decreased by 44.95% and 43.12%, respectively. Structural equation model confirmed that the increased pH, CEC contributed to the decreased Cd availability in soil, as well the changed metabolic profiles in wheat rhizosphere after intercropping. Specially, up-regulation of fatty acid metabolism allowed wheat plants to maintain a normal intracellular environment under stress conditions. Similarly, up-regulation of saccharide and amino acid metabolism induced the accumulation of sugars and proteins, which positively increased wheat biomass and Cd-binding proteins, thus inhibiting the migration of soil Cd into wheat tissue. Collectively, this study provided reasonable insights towards understanding the metabolic mechanisms how intercropping altered Cd availability.     

Isolation and identification of novel tocotrienols from rice bran with hypocholesterolemic, antioxidant, and antitumor properties

Two novel tocotrienols were isolated from stabilized and heated rice bran, apart from the known alpha-, beta-, gamma-, and delta-tocopherols and tocotrienols. These new tocotrienols were separated by HPLC, using a normal phase silica column. Their structures were determined by ultraviolet, infrared, nuclear magnetic resonance, circular dichroism, and high-resolution mass spectroscopies and established as desmethyl tocotrienol [3, 4-dihydro-2-methyl-2-(4,8,12-trimethyltrideca-3'(E),7'(E), 11'-trienyl)-2H-1-benzopyran-6-ol] and didesmethy tocotrienol [3, 4-dihydro-2-(4,8,12-trimethyltrideca-3'(E),7'(E), 11'-trienyl)-2H-1-benzopyran-6-ol]. These tocotrienols significantly lowered serum total and LDL cholesterol levels and inhibited HMG-CoA reductase activity in chickens. They had much greater in vitro antioxidant activities and greater suppression of B16 melanoma cell proliferation than alpha-tocopherol and known tocotrienols. Results indicated that the number and position of methyl substituents in tocotrienols affect their hypocholesterolemic, antioxidant, and antitumor properties.     

Identification of 4-methylspinaceamine, a pictet-spengler condensation reaction product of histamine with acetaldehyde, in fermented foods and its metabolite in human urine

Previous study demonstrated that 4-methylspinaceamine (4-methyl-4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine), a Pictet-Spengler condensation reaction product of histamine with acetaldehyde, is present in human urine. The current study sought to determine whether 4-methylspinaceamine is present in fermented foods; its presence might be expected since both histamine and acetaldehyde are often present in these foods. Soy sauce, fish sauce, cheese, and shao hsing wine (Chinese wine) were found to contain 4-methylspinaceamine. The concentration of 4-methylspinaceamine excreted in human urine was greatly elevated after ingestion of a meal containing soy sauce as a dietary source of 4-methylspinaceamine, demonstrating that the level of 4-methylspinaceamine in human urine was affected by dietary foods. In addition, a metabolite of 4-methylspinaceamine in human urine was investigated. An enhanced peak in the HPLC chromatogram of human urine samples after ingestion of 4-methylspinaceamine-containing foods was observed. A peak at the same retention time was also observed from a human urine sample after administration of 4-methylspinaceamine, suggesting that the peak was due to a metabolite. By comparison with the newly synthesized authentic compound, the metabolite was identified as 1,4-dimethylspinaceamine.