Different Localization Patterns of Anthocyanin Species in the Pericarp of Black Rice Revealed by Imaging Mass Spectrometry

Black rice (Oryza sativa L. Japonica) contains high levels of anthocyanins in the pericarp and is considered an effective health-promoting food. Several studies have identified the molecular species of anthocyanins in black rice, but information about the localization of each anthocyanin species is limited because methodologies for investigating the localization such as determining specific antibodies to anthocyanin, have not yet been developed Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) is a suitable tool for investigating the localization of metabolites. In this study, we identified 7 species of anthocyanin monoglycosides and 2 species of anthocyanin diglycosides in crude extracts from black rice by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis. We also analyzed black rice sections by MALDI-IMS and found 2 additional species of anthocyanin pentosides and revealed different localization patterns of anthocyanin species composed of different sugar moieties. Anthocyanin species composed of a pentose moiety (cyanidin-3-O-pentoside and petunidin-3-O-pentoside) were localized in the entire pericarp, whereas anthocyanin species composed of a hexose moiety (cyanidin-3-O-hexoside and peonidin-3-O-hexoside) were focally localized in the dorsal pericarp. These results indicate that anthocyanin species composed of different sugar moieties exhibit different localization patterns in the pericarp of black rice. This is the first detailed investigation into the localization of molecular species of anthocyanins by MALDI-IMS

Visualization of acetylcholine distribution in central nervous system tissue sections by tandem imaging mass spectrometry

Metabolite distribution imaging via imaging mass spectrometry (IMS) is an increasingly utilized tool in the field of neurochemistry. As most previous IMS studies analyzed the relative abundances of larger metabolite species, it is important to expand its application to smaller molecules, such as neurotransmitters. This study aimed to develop an IMS application to visualize neurotransmitter distribution in central nervous system tissue sections. Here, we raise two technical problems that must be resolved to achieve neurotransmitter imaging: (1) the lower concentrations of bioactive molecules, compared with those of membrane lipids, require higher sensitivity and/or signal-to-noise (S/N) ratios in signal detection, and (2) the molecular turnover of the neurotransmitters is rapid; thus, tissue preparation procedures should be performed carefully to minimize postmortem changes. We first evaluated intrinsic sensitivity and matrix interference using Matrix Assisted Laser Desorption/Ionization (MALDI) mass spectrometry (MS) to detect six neurotransmitters and chose acetylcholine (ACh) as a model for study. Next, we examined both single MS imaging and MS/MS imaging for ACh and found that via an ion transition from m/z 146 to m/z 87 in MS/MS imaging, ACh could be visualized with a high S/N ratio. Furthermore, we found that in situ freezing method of brain samples improved IMS data quality in terms of the number of effective pixels and the image contrast (i.e., the sensitivity and dynamic range). Therefore, by addressing the aforementioned problems, we demonstrated the tissue distribution of ACh, the most suitable molecular specimen for positive ion detection by IMS, to reveal its localization in central nervous system tissues

Legumes as food ingredient: characterization, processing, and applications

Editores: Jiménez-López, José Carlos (CSIC); Clemente, Alfonso (CSIC

Effective species for ignition of premixed burner flame in effluent of dielectric barrier discharge

The ignition probability of a premixed burner flame was improved in the effluent of a dielectric barrier discharge. In addition, the propagation speed of the flame kernel was increased by the dielectric barrier discharge. The increase in the propagation speed of the flame kernel was more significant in the region close to the nozzle of the effluent gas. We measured the spatial distributions of the densities of OH and atomic oxygen in the effluent. We found that the axial decay of the density of atomic oxygen was steeper than that of the OH density under the experimental conditions. By comparing the spatial distributions of the radical densities with that of the propagation speed of the flame kernel, we concluded that atomic oxygen works more effectively than OH in improving the ignition probability of the premixed burner flame

Antibacterial activity of mango kernel extracts

This study is emphasized specifically on the potential of the mango Mangifera Indica seed kernel by discovering the prospective usage of mango seed kernels as a source of antibacterial compounds against Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial strains. For this study, three types of mango were used; Blackgold, Lemak and Waterlily from Malaysia and Thiland. The approach adopted for this purpose was by implementing agar well diffusion method. The results were expressed as the average diameter of bacterial inhibition zones surrounding the wells. The required solvents for the extraction were ethanol, methanol, acetone and phosphate buffer solutions were prepared in a different concentration; 0.10M, 0.05M and 0.01M. The results showed that Lemak gave relatively high antibacterial activity among other types of mango ranging between 1.40 and 2.23 cm. For the known antibiotic, which was Tetracycline, under the same conditions the diameter of inhibition zones were between 2.30 to 3.30. Then, the minimum inhibition concentration tests were conducted for Lemak for two solvents extract that gave the highest inhibition zones which were methanol and acetone. The results showed that the minimum inhibition concentration of extracts that inhibited the growth of Escherichia coli and Bacillus subtilis was after 10X dilution (1 mM). The results obtained confirmed the antibacterial potential of mango kernels extracts and this would probably become an alternative source of new and natural antibacterial agents