Iron phosphide nanocrystals as an air-stable heterogeneous catalyst for liquid-phase nitrile hydrogenation.

Iron-based heterogeneous catalysts are ideal metal catalysts owing to their abundance and low-toxicity. However, conventional iron nanoparticle catalysts exhibit extremely low activity in liquid-phase reactions and lack air stability. Previous attempts to encapsulate iron nanoparticles in shell materials toward air stability improvement were offset by the low activity of the iron nanoparticles. To overcome the trade-off between activity and stability in conventional iron nanoparticle catalysts, we developed air-stable iron phosphide nanocrystal catalysts. The iron phosphide nanocrystal exhibits high activity for liquid-phase nitrile hydrogenation, whereas the conventional iron nanoparticles demonstrate no activity. Furthermore, the air stability of the iron phosphide nanocrystal allows facile immobilization on appropriate supports, wherein TiO2 enhances the activity. The resulting TiO2-supported iron phosphide nanocrystal successfully converts various nitriles to primary amines and demonstrates high reusability. The development of air-stable and active iron phosphide nanocrystal catalysts significantly expands the application scope of iron catalysts.

Phosphorus-Alloying as a Powerful Method for Designing Highly Active and Durable Metal Nanoparticle Catalysts for the Deoxygenation of Sulfoxides: Ligand and Ensemble Effects of Phosphorus.

The modification of metal nanoparticles (NPs) by incorporating additional metals is a key technique for developing novel catalysts. However, the effects of incorporating nonmetals into metal NPs have not been widely explored, particularly in the field of organic synthesis. In this study, we demonstrate that phosphorus (P)-alloying significantly increases the activity of precious metal NPs for the deoxygenation of sulfoxides into sulfides. In particular, ruthenium phosphide NPs exhibit an excellent catalytic activity and high durability against sulfur-poisoning, outperforming conventional catalysts. Various sulfoxides, including drug intermediates, were deoxygenated to sulfides with excellent yields. Detailed investigations into the structure-activity relationship revealed that P-alloying plays a dual role: it establishes a ligand effect on the electron transfer from Ru to P, facilitating the production of active hydrogen species, and has an ensemble effect on the formation of the Ru-P bond, preventing strong coordination with sulfide products. These effects combine to increase the catalytic performance of ruthenium phosphide NPs. These results demonstrate that P-alloying is an efficient method to improve the metal NP catalysis for diverse organic synthesis.

Multiple Biological Effects of Olive Oil By-products such as Leaves, Stems, Flowers, Olive Milled Waste, Fruit Pulp, and Seeds of the Olive Plant on Skin.

As olive oil production increases, so does the amount of olive oil by-products, which can cause environmental problems. Thus, new ways to utilize the by-products are needed. In the present study, five bioactive characteristics of olive oil by-products were assessed, namely their antioxidant, anti-bacterial, anti-melanogenesis, anti-allergic, and collagen-production-promoting activities. First, the extracts of leaves (May and October), stems (May and October), flowers, olive milled waste, fruit pulp and seeds were prepared using two safe solvents, ethanol and water. According to HPLC and LC/MS analysis and Folin-Ciocalteu assay, the ethanol extracts of the leaves (May and October), stems (May and October) and flowers contained oleuropein, and the ethanol extract of the stems showed the highest total phenol content. Oleuropein may contribute to the antioxidant and anti-melanogenesis activities of the leaves, stems, and flowers. However, other active compounds or synergistic effects present in the ethanol extracts are also likely to contribute to the anti-bacterial activity of the leaves and flowers, the anti-melanogenesis activity of some parts, the anti-allergic activity of olive milled waste, and the collagen-production-promoting activity of the leaves, stems, olive milled waste and fruit pulp. This study provides evidence that the by-products of olive oil have the potential to be further developed and used in the skin care industry.

Applicability of the DPPH assay for evaluating the antioxidant capacity of food additives - inter-laboratory evaluation study -.

An inter-laboratory evaluation study was conducted in order to evaluate the antioxidant capacity of food additives by using a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Four antioxidants used as existing food additives (i.e., tea extract, grape seed extract, enju extract, and d-α-tocopherol) and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) were used as analytical samples, and 14 laboratories participated in this study. The repeatability relative standard deviation (RSD(r)) of the IC50 of Trolox, four antioxidants, and the Trolox equivalent antioxidant capacity (TEAC) were 1.8-2.2%, 2.2-2.9%, and 2.1-2.5%, respectively. Thus, the proposed DPPH assay showed good performance within the same laboratory. The reproducibility relative standard deviation (RSD(R)) of IC50 of Trolox, four antioxidants, and TEAC were 4.0-7.9%, 6.0-11%, and 3.7-9.3%, respectively. The RSD(R)/RSD(r) values of TEAC were lower than, or nearly equal to, those of IC50 of the four antioxidants, suggesting that the use of TEAC was effective for reducing the variance among the laboratories. These results showed that the proposed DPPH assay could be used as a standard method to evaluate the antioxidant capacity of food additives.

Biological activities and phytochemical profiles of extracts from different parts of bamboo (Phyllostachys pubescens).

Besides being a useful building material, bamboo also is a potential source of bioactive substances. Although some studies have been performed to examine its use in terms of the biological activity, only certain parts of bamboo, especially the leaves or shoots, have been studied. Comprehensive and comparative studies among different parts of bamboo would contribute to a better understanding and application of this knowledge. In this study, the biological activities of ethanol and water extracts from the leaves, branches, outer culm, inner culm, knots, rhizomes and roots of Phyllostachys pubescens, the major species of bamboo in Japan, were comparatively evaluated. The phytochemical profiles of these extracts were tentatively determined by liquid chromatography-mass spectrometry (LC-MS) analysis. The results showed that extracts from different parts of bamboo had different chemical compositions and different antioxidative, antibacterial and antiallergic activities, as well as on on melanin biosynthesis. Outer culm and inner culm were found to be the most important sources of active compounds. 8-C-Glucosylapigenin, luteolin derivatives and chlorogenic acid were the most probable compounds responsible for the anti-allergy activity of these bamboo extracts. Our study suggests the potential use of bamboo as a functional ingredient in cosmetics or other health-related products.

Wild Mushrooms in Nepal: Some Potential Candidates as Antioxidant and ACE-Inhibition Sources.

Twenty-nine mushrooms collected in the mountainous areas of Nepal were analyzed for antioxidant activity by different methods, including Folin-Ciocalteu, ORAC, ABTS, and DPPH assays. Intracellular H2O2-scavenging activity was also performed on HaCaT cells. The results showed that phenolic compounds are the main antioxidant of the mushrooms. Among studied samples, Inonotus andersonii, and Phellinus gilvus exhibited very high antioxidant activity with the phenolic contents up to 310.8 and 258.7 mg GAE/g extracts, respectively. The H2O2-scavenging assay on cells also revealed the potential of these mushrooms in the prevention of oxidative stress. In term of ACE-inhibition, results showed that Phlebia tremellosa would be a novel and promising candidate for antihypertensive studies. This mushroom exhibited even higher in vitro ACE-inhibition activity than Ganoderma lingzhi, with the IC50 values of the two mushrooms being 32 µ g/mL and 2 µ g/mL, respectively. This is the first time biological activities of mushrooms collected in Nepal were reported. Information from this study should be a valuable reference for future studies on antioxidant and ACE-inhibitory activities of mushrooms.

The inhibitory effects of representative chalcones contained in Angelica keiskei on melanin biosynthesis in B16 melanoma cells.

In our effort to find new whitening agents, we evaluated the effects of representative chalcones [4-hydroxyderricin (1), xanthoangelol (2), xanthoangelol H (3), deoxyxanthoangelol H (4), and deoxydihydroxanthoangelol H (5)] contained in the stem of Angelica keiskei on tyrosinase and melanin formation in B16 melanoma cells. In addition, the antioxidant effects of these chalcones in ORAC and DPPH assays were also determined. Interestingly, all chalcones (1-5) inhibit melanin formation in B16 melanoma cells, with low cytotoxicity.

Generation of gaseous sulfur-containing compounds in tumour tissue and suppression of gas diffusion as an antitumour treatment.

BACKGROUND AND AIMS: The mechanisms of cancer cell growth and metastasis are still not entirely understood, especially from the viewpoint of chemical reactions in tumours. Glycolytic metabolism is markedly accelerated in cancer cells, causing the accumulation of glucose (a reducing sugar) and methionine (an amino acid), which can non-enzymatically react and form carcinogenic substances. There is speculation that this reaction produces gaseous sulfur-containing compounds in tumour tissue. The aims of this study were to clarify the products in tumour and to investigate their effect on tumour proliferation. METHODS: Products formed in the reaction between glucose and methionine or its metabolites were analysed in vitro using gas chromatography. Flatus samples from patients with colon cancer and exhaled air samples from patients with lung cancer were analysed using near-edge x-ray fine adsorption structure spectroscopy and compared with those from healthy individuals. The tumour proliferation rates of mice into which HT29 human colon cancer cells had been implanted were compared with those of mice in which the cancer cells were surrounded by sodium hyaluronate gel to prevent diffusion of gaseous material into the healthy cells. RESULTS: Gaseous sulfur-containing compounds such as methanethiol and hydrogen sulfide were produced when glucose was allowed to react with methionine or its metabolites homocysteine or cysteine. Near-edge x-ray fine adsorption structure spectroscopy showed that the concentrations of sulfur-containing compounds in the samples of flatus from patients with colon cancer and in the samples of exhaled air from patients with lung cancer were significantly higher than in those from healthy individuals. Animal experiments showed that preventing the diffusion of sulfur-containing compounds had a pronounced antitumour effect. CONCLUSIONS: Gaseous sulfur-containing compounds are the main products in tumours and preventing the diffusion of these compounds reduces the tumour proliferation rate, which suggests the possibility of a new approach to cancer treatment.

Melanin biosynthesis inhibitory and antioxidant activities of quercetin-3'-O-beta-D-glucoside isolated from Allium cepa.

In the course of searching for new whitening agents, we have found that the methanol extract of dried skin of Allium cepa shows potent melanin biosynthesis inhibitory activity in B16 melanoma cells. Bioassay-guided fractionation led to the isolation of quercetin-3'-O-beta-D-glucoside (1) from the methanol extract of dried skin of A. cepa, which inhibited melanin formation in B16 melanoma cells with an IC50 value of 38.8 microM and mushroom tyrosinase with an IC50 value of 6.5 microM using L-tyrosine and 48.5 microM using L-dihydroxyphenylalanine as substrates, respectively. In addition, the antioxidant activity of 1 was evaluated in the oxygen radical absorbance capacity assay; it showed 3.04 micromol Trolox equivalents/mmol. 1 was shown to be a promising ingredient that could be useful for treating hyperpigmentation and for protecting against oxidative stress.

pH of solution greatly affects sorption of ionizable compounds into low-density polyethylene film.

Sorption of ionizable compounds of pyridines and aromatic carboxylic acids into low-density polyethylene (LDPE) film was investigated as a function of pH ranging from 4 to 7. The sorptions for pyridines were increased with increasing pH. Within the range examined, pH 7 was observed to promote the highest degree of sorption. When the pH increased by one unit from 6 to 7, the sorptions for 2-propylpyridine and 2,4,6-trimethylpyridine were both increased approximately 3.8 and 10.5 times, respectively. At pH 4, the sorption for the pyridines entirely disappeared. In contrast, the sorptions for aromatic carboxylic acids increased with decreasing pH. Within the range examined, pH 4 was observed to promote the highest degree of sorption. The magnitude of sorption for pyridines and carboxylic acids apparently depended on the affinity (delta(c)) of these compounds for LDPE film. Another factor affecting the sorption at various pHs was the pK(a) of these compounds; the sorption greatly decreased with the ionization degree of these compounds. To elucidate the phenomena, the following thermodynamic sorption equation was applied: S = S(0)gamma exp[V(v){(delta(w) - delta(v))(2) - delta(c)(2))/RT}. The plots of ln S for pyridines vs the term of the equation gave an insufficient relationship (r = 0.519). In contrast, taking into account the ratio (chi(i)()) of concentration of un-ionized compound to total concentration, the improvement for the equation was made: S' = S/chi(i)() = S(0)gamma exp[V(v){(delta(w) - delta(v))(2) - delta(c)(2))/RT}. The plots of ln S' vs the term of the equation gave a better relationship (r = 0.884). Furthermore, the equation was also applicable for the sorption behavior of carboxylic acids into LDPE (r = 0.769).

Preparation and characterization of a polyclonal antibody from rabbit for detection of trinitrotoluene by a surface plasmon resonance biosensor.

A polyclonal antibody against trinitrophenyl (TNP) derivatives was raised in rabbit, and the antibody was applied to detection of trinitrotoluene (TNT) using a surface plasmon resonance (SPR) biosensor. TNP-keyhole limpet hemocyanine (TNP-KLH) conjugate was injected into a rabbit, and a polyclonal anti-TNP antibody was realized after purification of the sera using protein G. Aspects of the anti-TNP antibody against various nitroaromatic compounds, such as cross-reactivities and affinities, were characterized. The temperature dependence of the affinity between the anti-TNP antibody and TNT was also evaluated. The quantification of TNT was based on the principle of indirect competitive immunoassay, in which the immunoreaction between the TNP-beta-alanine-ovalbumin (TNP-beta-ala-OVA) and anti-TNP antibody was inhibited in the presence of free TNT in solution. TNP-beta-ala-OVA was immobilized to the dextran matrix on the Au surface by amine coupling. The addition of a mixture of free TNT to the anti-TNP antibody was found to decrease the incidence angle shift due to the inhibitory effect of TNT. The immunoassay exhibited excellent sensitivity for the detection of TNT in the concentration range of 3x10(-11) to 3x10(-7)g/ml. To increase the sensitivity of the sensor, anti-rabbit IgG antibody was used. After flowing the mixture of free TNT and anti-TNP antibody, anti-rabbit IgG antibody was injected, and the incidence angle shift was measured. Amplification of the signal was observed and the detection limit was improved to 1x10(-11)g/ml.