From a green chemical point of view, techniques for extracting organic substances employing conventional solvents must be replaced with novel environment-friendly techniques. Dimethyl ether (DME) may be one of such alternative solvents to be used. Rice bran is a co-product of rice milling, which is rich in oil content.Theoretically, around 20-25% of the total weight of rice bran must be oily components known as rice bran oil (RBO). In the present study, liquefied DME was used as a low temperature solvent for extracting RBO.From 10 g of fully dried rice bran used in a single batch extraction with DME, ca. 0.90 g of RBO were recovered (efficiency, 9.0%). Although the efficiency of total RBO extraction by batch extraction with DME was lower than the conventional solvent extraction system using acetone, lipid-pigment complexes potentially beneficial for human health such as ferulic acid-conjugated lipids were efficiently extracted.Fatty acid compositions found in RBO prepared by DME extraction and conventional solvent extraction did not differ. Lastly, improvement of the extraction efficiency was attempted by designing a column-based flow system allowing extraction of RBO with an optimized amount of liquefied DME. By this approach, the efficiency of RBO extraction attained ca. 24% (ca. 0.24 g of RBO extracted and recovered from 1 g of dried rice bran), using 10 to 20 g of liquefied DME applied to 1 g of rice bran packed in the column-type extraction chamber.

A variety of chemicals including foaming agents are used to aid in the protection of forest resources from the wild land fires. The fire-fighting foams (FFFs) are formulations composed principally of surfactants. As a part of Japanese national project, environmentally inert FFFs have been developed. There is an emerging need for testing the impacts of these FFFs on the living organisms composing the typical landscapes or eco-systems in Japan. In the present report, we aimed to describe our latest attempt for assessing both the short-tem and long-term impacts of FFFs in aquatic (fresh water) and semi-aquatic (wetland) eco-systems, by employing the laboratory-sized model assays (preliminary studies) and the biotope-based observation, respectively. In the biotope assays which was based on the observation in compact biotopes mimicking the fresh water environments and wetland, both the acute and long-term eco-toxic impacts of two FFFs (soap-based and synthetic detergent-based) were assessed. Spraying of synthetic detergent-based foam formula was shown to be more toxic compared to soap-based formula and mock water treatment.

Ferulic acid (FA) is one of phenolics found in most higher plants. It is important to quantify the internal FA level in vegetables and fruits, since it was epidemiologically demonstrated and a number of study supported that consumption of fruits and vegetables rich in phenolic acids including FA is associated with the prevention of chronic diseases such as cancer and cardiovascular disease. In order to allow handling of the intact fresh produces, non-invasive methods are desired. Previously, 355 nm ultraviolet (UV) laser-induced fluorescence spectrum revealed that living plants contain fluorophore corresponding to blue-green fluorescence (shown to be FA). However, quantification of FA based on fluorescence in UVexcited leaves can be hardly achieved since FA fluorescence measured at fixed excitation and emission can be applied only to the limited range of FA concentration. Here, we report a model experiment for fluorometric quantification of FA in solution in vitro which may provide a series of useful information required for estimation of FA concentrations in vivo fluid inside the vegetables. Based on deconvolution of intrinsic fluorescence spectra, we observed that FA fluorescence signals can be deciphered to determine the concentration of FA. By viewing that the recorded FA fluorescence (h) is reflecting the primitive function (f) corresponding to FA concentrations and kernel function (g) determining the spike position in the spectra. Thus, f should be obtained as f h g 1. In practice, cumulative curves of fluorescence signals at fixed emission wavelength (460 nm) along with the changes in excitation wavelength (200 400 nm) were plotted and the midpoints (along the scale of excitation wavelength) in the resultant curves corresponding to different FA concentration were graphically determined. FA's concentration-specific changes in fluorescence profiles must be due to the fact that FA possesses multiple fluorophores within the molecule despite its simple structure. Lastly, simplified protocol for determination of FA concentration using dual UV excitation wavelengths was proposed. In this assay, ratio of 460 nm fluorescence intensities induced by two distinct excitation wavelengths (short, 260 nm; long, 330 380 nm) were shown to be highly correlated with FA concentration ranged from M to mM orders.

Controlled generation of reactive oxygen species (ROS) is widely beneficial to various medical, environmental, and agricultural studies. As inspired by the functional motifs in natural proteins, our group has been engaged in development of catalytically active oligo-peptides as minimum-sized metalloenzymes for generation of superoxide anion, an active member of ROS. In such candidate molecules, catalytically active metal-binding minimal motif was determined to be X-X-H, where X can be most amino acids followed by His. Based on above knowledge, we have designed a series of minimal copper-binding peptides designated as GnH series peptides, which are composed of oligo-glycyl chains ended with C-terminal His residue such as GGGGGH sequence (G5H). In order to further study the role of copper binding to the peptidic catalysts sharing the X-X-H motif such as G5H-conjugated peptides, we should be able to score the occupancy of the peptide population by copper ion in the reaction mixture. Here, model peptides with Cu-binding affinity which show intrinsic fluorescence due to tyrosyl residue (Y) in the UV region (excitation at ca. 230 and 280 nm, and emission at ca. 320 nm) were synthesized to score the effect of copper occupancy. Synthesized peptides include GFP-derived fluorophore sequence, TFSYGVQ (designated as Gfp), and Gfp sequence fused to C-terminal G5H (Gfp-G5H). In addition, two Y-containing tri-peptides derived from natural GFP fluorophores, namely, TYG and SYG were fused to the G5H (TYG-G5H and SYG-G5H). Conjugation of metal-binding G5H sequence to GFP-fluorophore peptide enhanced the action of Cu2+ on quenching of intrinsic fluorescence due to Y residue. Two other Y-containing peptides, TYG-G5H and SYG-G5H, also showed intrinsic fluorescence which is sensitive to addition of Cu2+. There was linear relationship between the loading of Cu2+ and the quenching of fluorescence in these peptide, suggesting that Cu2+-dependent quenching of Y-reside-derived fluorescence could be a measure of copper occupancy in the peptides. Lastly, the fate of Y residue in the Cu-loaded peptides under oxidative condition in the presence of H2O2 was discussed based on the Cu/H2O2-dependent changes in fluorescence spectra.

Generation of reactive oxygen species is useful for various medical, engineering and agricultural purposes. These include clinical modulation of immunological mechanism, enhanced degradation of organic compounds released to the environments, removal of microorganisms for the hygienic purpose, and agricultural pest control; both directly acting against pathogenic microorganisms and indirectly via stimulation of plant defense mechanism represented by systemic acquired resistance and hypersensitive response. By aiming to develop a novel classes of artificial redox-active biocatalysts involved in production and/or removal of superoxide anion radicals, recent attempts for understanding and modification of natural catalytic proteins and functional DNA sequences of mammalian and plant origins are covered in this review article.