Antioxidant prenylated flavonoids from propolis collected in Okinawa, Japan

Propolis is a resinous substance collected by honeybees from various plant sources. The composition of propolis depends upon the vegetation at the site of collection. We previously isolated four prenylated flavonoids from propolis collected in Okinawa, Japan. In this study, further fractionation of the extracts of Okinawan propolis resulted in the isolation of a new prenylated flavonoid, prokinawan, and four known compounds. The structure of prokinawan was determined by MS and NMR spectroscopic methods. Furthermore, the antioxidant activity using 1,1-diphenyl-2-picryl-hydrazyl radical scavenging and beta-carotene bleaching systems was investigated. The present study proved that the position of the geranyl or prenyl groups on the flavonoid skeleton plays an important role in exhibiting antioxidant activity.     

Furan-2,5-dimethylene-tethered bis-imidacloprid insecticide conferring high potency

Bis-imidacloprid (bis-IMI) analogues with suitable alkylene spacers have plant-systemic insecticidal properties. The alkylene-tethered bis-IMI binds in a unique mode to the insect nicotinic acetylcholine receptor (nAChR) wherein the chloropyridine moieties are embraced by two distinct and distant domains. The heptamethylene spacer optimally bridges these two subsites, yet the linker itself binds in a relatively nonspecific manner. This investigation examines the hypothesis that a bis-IMI analogue with a heteroaromatic tether, which undergoes specific interaction(s) with the newly recognized receptor cavity, may enhance the potency relative to those of the alkylene-tethered derivatives. Remarkably, a novel bis-IMI with a furan-2,5-dimethylene fulcrum showed highest receptor potency and insecticidal activity among the analogues with various chemotype spacers. The nAChR structural model, simulating the binding site interactions of the furan-2,5-dimethylene-tethered bis-IMI, reveals that the furan ring is nestled in a hydrophobic pocket, consisting of three aromatic amino acids, and is stabilized via hydrogen bonding.     

Antioxidant activity of polyphenols in carob pods.

We extracted polyphenols from carob (Ceratonia siliqua L.) pods, and evaluated the in vitro antioxidant activity of the crude polyphenol fraction (CPP). The total polyphenol content in CPP determined by the Folin-Ciocalteu method was 19.2%. The condensed tannin content determined by the vanillin and proanthocyanidin assay systems was 4.37% and 1.36%, respectively. beta-Carotene bleaching, 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging, inhibition of lipid peroxidation by the erythrocyte ghost, and microsomal assay systems were used to evaluate the antioxidant activity. CPP showed a stronger inhibitory effect against the discoloration of beta-carotene than other polyphenol compounds such as catechins and procyanidins. CPP had weaker antioxidant activity in the DPPH free radical scavenging, the erythrocyte ghost, and microsomal systems than authentic polyphenol compounds at the same concentrations. The activity adjusted by the polyphenol concentration was, however, comparable to that of authentic polyphenol compounds. Considering most carob pods are discarded and not effectively utilized at present, these results suggested that carob pods could be utilized as a functional food or food ingredient.     

Asparagine test in relation with the nitrogen nutritional status of crop plants I

Extraordinary features of submerged rice soils and its relation to manuring practices has long been the problem of study to increase the average and maximum yield of rice per unit area. Out of these studies many remarkable results have so far been achieved, the mention of which in dentail is not possible in this paper. But in a summarized way it can be easily concluded that during the growth cycle of rice plant nitrogen is most important limiting fertilizer element and its need for the plant is multi-sided. The practical experience of the farmers of Shizuoka prefecture is quite in agreement with this, as they say that in rice-culture fertilizer should be applied at the transplanting time and a little before actual heading. Regarding the late dressing which is called (Hogoe) they have strong belief that it is effective in most of the cases. Taking this into account, in 1933 YAMAMOTO and SUZUKI(18) started to study as to when top dressing be applied with the help of pot experiments, and Were able to conclude that a top dressing of 0.5 g per pot was quite effective. This report is the first to be published on the top-dressing aspect of rice, but it does not seem to be a complete one. A field experiment for such a study was conducted by GOTO(1) in the year 1942. In his experiment, he used ammonium sulphate for top dressing with 3 dates viz. a) Maximum tillering b) Late tillering and c) Panicle formation. He concluded that amm. sulphate as top-dressing is mostly absorbed in the panicle formation stage and is utilized for grain formation. He also stressed the importance of top-dressing at the panicle formation stage.     

Measurement of radioactivity in contaminated crops (Part 1)

It is a prerequisite to settle down how to subtract the counts based on natural radio-potassium in crops, finding out an accurate and efficient method. Considerable effort has been made so far with the investigations which have been conducted In various parts of Japan in accordance with this purpose. The writers wish to present a tentative method for measuring the radioactivity, reporting on the results obtained in comparison of this method with here-to-fore methods.     

Magnesium in barley plants on magnesium-deficient soils

Working with fused phosphate containing Mg, we have known some of the Mg-deficient areas in Shizuoka prefecture as a field problem. In these areas, crop plants develop visual hunger signs, resulting in restricted growth and reduced yield. The manurial effect of Mg-salt added or fused phosphate is remarkably excellent in these areas or soils.     

Unidentified compound specifically accumulated in soybean nodules formed with H2-uptake negative rhizobium japonicum strains

A large quantity of an unidentified compound was detected by a fluorogenic method in the soybean nodules formed with H₂-uptake negative Rhizobium japonicum strains. The unidentified compound (compound X) reacted with o-phthalaldehyde in the presence of 2-mercaptoethanol giving rise to a fluorescent compound, and was not hydrolyzed in strong acid and strong base. Therefore, the compound X was considered to be one of amines and amino acids. The content of the compound X in the nodules formed with H₂-uptake positive strains was remarkably lower than that in the nodules formed with H₂-uptake negative strains. It was suggested that the compound X may be involved in the process of hydrogen metabolism in soybean nodules. The compound X was not detected in leaves, stems, petioles, and roots of soybean plants, but detected in H₂-uptake negative strains of free-living R. japonicum. In nodules, a great portion of the compound X was distributed into cytosol fraction.     

人工降水条件下土壤脱盐动态规律的实验研究

本文通过室内模拟实验，并结合野外灌水脱盐实验，对比分析了土壤和淋溶液中的电导率、盐基离子以及pH的动态变化，探讨了滨海盐渍土灌水脱盐的动态规律与机理，为节约用水和盐渍土改良利用提供了理论依据。     

Stereochemical and chiral aspects in the synthesis of 3-(2,2- dihalovinyl)-2,2-dimethylcyclopropanecarboxylic acids

The synthesis of (1RS)-cis,trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid by dehydrohalogenation of 4,6,6,6-tetrahalohexanoates has been modified to produce stereo-selectively the cis-isomer. A new stereospecific synthesis of cis-3-(2,2-dihalovinyl)-2,2-dimethylcyclopropanecarboxylic acids using a bicyclic lactone and its extension to the preparation of the optically active (1R)-cis acid are described.     

Attachment of Vibrio parahaemolyticus strains to estuarine algae.

Attachment of Vibrio parahaemolyticus strains to estuarine microalgae was examined in artificial seawater by viable counts of the organism and direct counts of the bacterial cells after immunoperoxidase staining. Thermostable direct hemolysin (TDH)-producing and TDH-non-producing strains of V. parahaemolyticus were found to attach to five estuarine strains of Navicula (diatom alga) in similar levels. The level of the bacterial attachment depended on salinity and temperature of the water, in which the maximum attachment was observed in 15% artificial seawater at 25 degrees C, a typical condition of Hashizu estuary in Japan during summer months. The attachment was inhibited by pectinase digestion of the algal cells. These evidences confirmed the participation of the microalgae to the ecological cycle of V. parahaemolyticus at the estuary.