Simultaneous determination of residual antiparasitic lactones in bovine muscle and liver by liquid chromatography with fluorescence detection

Abamectin, doramectin, eprinomectin, ivermectin, milbemectin, and moxidectin in bovine muscle and liver were extracted with acetonitrile. The extracts were partitioned with n-hexane and then evaporated to dryness. The residue was cleaned up on Bond Elute NH2 cartridge, and the drugs were eluted from the cartridge with methanol-ethyl acetate (3 + 7). The eluate was evaporated to dryness, and residues were derivatized with N,N-dimethylformamide-acetic anhyride-1-methylimidazole. The derivatives were determined by liquid chromatography with fluorescence detection. Recoveries of the 6 drugs were 79.6-63.8% in muscle and 71.6-60.6% in liver at 0.01 ppm levels. The quantitation limits were 5 ppb for each drug.     

Semiempirical MO study on the abnormal bond orders of large networks of highly branched polyenes

The π-electronic structures of the ground state of linear and highly branched polyenes with up to 80 π-electrons are calculated with particular reference to the alternation of the bond orders. The MO methods adopted are HMO, PPP , variable-β, γ, and its improved version. The effect of the electron correlation through singly and doubly excited configurations is estimated with a second-order perturbation calculation. The calculated bond orders systematically vary with the degree of approximation used. Most of the bond order values can be grouped into either a single or double bond region. In certain series of highly branched polyenes the bond orders of double and single bonds at the root of branching, respectively, get smaller and larger as the size of the molecule increases and sometimes their difference gets diminishingly small. The origin of these abnormal bond orders is discussed in terms of the π-electron flow networks.     

INTERACTION OF RHODOPSIN, G-PROTEIN AND KINASE IN OCTOPUS PHOTORECEPTORS

Light induced phosphorylation of octopus rhodopsin was greatly enhanced by guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), suggesting that the kinases are involved in regulating interaction between rhodopsin and G-protein. We determined phosphorylated peptides of octopus rhodopsin in the presence or absence of GTP gamma S. Possible phosphorylation sites for octopus rhodopsin enhanced by GTP gamma S were Thr329, Thr330 and/or Thr336, which suggest that the G-protein associates with cytoplasmic loops including C-terminal peptide in the seventh helix of octopus rhodopsin.     

Inhibitors of nitric oxide production from the flowers of Angelica furcijuga: structures of hyuganosides IV and V

The methanolic extract from the flowers of Angelica furcijuga KITAGAWA was found to inhibit nitric oxide production in lipopolysaccharide-activated mouse peritoneal macrophages. From the methanolic extract, two new glycosides, hyuganosides IV and V, were isolated together with 28 known constituents. The structures of the new constituents were determined on the basis of chemical and physicochemical evidence. Furthermore, the inhibitory effects of 11 coumarin constituents on nitric oxide production were examined. Among them, 3'-angeloyl-cis-khellactone (IC(50)=82 microM), (S)-(-)-oxypeucedanin (57 microM), imperatorin (60 microM), isoepoxypteryxin (53 microM), and isopteryxin (8.8 microM) showed inhibitory activity.     

Medicinal flowers. VIII. Radical scavenging constituents from the flowers of Prunus mume: structure of prunose III

The methanolic extract and its fractions from the fresh flowers of Prunus mume SIEB. et ZUCC. were found to show scavenging effects on 1,1-diphenylpicryl-2-hydrazyl (DPPH) radical and superoxide. The fragrance constituents of P. mume were analyzed by GC-MS and a new polyacylated sucrose, prunose III, was isolated from the ethyl acetate-soluble fraction. The structure of prunose III was determined on the basis of chemical and physicochemical evidence as 4,3',4',6'-tetra-O-acetyl-6-O-p-coumaroylsucrose. In addition, the scavenging effects of the principal constituents on DPPH radical and superoxide were examined.     

MALDI TOF mass study on oligomerization of Pd(OAc)2(L)2 (L = pyridine derivatives): relevance to Pd black formation in Pd-catalyzed air oxidation of alcohols

[reaction: see text] Oligomerization of Pd(OAc)2(L)2 (L = pyridine derivatives), a catalyst for the air oxidation of alcohols, is studied with MALDI TOF mass, using dithranol as the matrix. The degree of the Pd oligomerization is influenced by the pyridine ligands, and this ligand effect is similar to one observed for Pd black formation in the catalysis.     

Nondestructive real-time radioisotope imaging system for visualizing 14C-labeled chemicals supplied as CO2 in plants using Arabidopsis thaliana

We have developed a real-time radioisotope imaging system (RRIS) that can nondestructively trace ¹⁴C-labeled chemicals in plants. In an experiment, after feeding ¹⁴CO₂ to a plant, the plant was fixed inside a box where lighting was regulated, and beta rays emitted from the ¹⁴C in the plant were intermittently imaged using the developed system. As a first step, using a series of standard sources of ¹⁴C, the data depth and detection limits of the ¹⁴C images captured by the RRIS were evaluated for various integral times. As a result, the linearity between the ¹⁴C activity and signal intensity was determined for the range 10³. Next, the linearity was validated using plant (Arabidopsis thaliana) organs, resulting that the linearity was shown in the case of young leaf, but was not maintained in the thick organs, such as a flower, mature leaf, siliques, and stem. Considering the good correlation between the intensity by RRIS and the PSL value by an imaging plate (IP) as well as the relative low energy of beta rays emitted from ¹⁴C, the thickness of the organs would easily affect the quantitativity of the RRIS as well as an IP. Our findings prove that sequential images of ¹⁴C in a living plant sample in a regulated light and air environment can be nondestructively analyzed using the developed system, whose quantitativity is similar to that of an IP.     

Synthesis of unimolecular reversed micelle consisting of a poly(L‐lactide) shell and hyperbranched D‐mannan core

A novel biodegradable unimolecular reversed micelle consisting of a poly(L ‐lactide) (PLA) shell and a hyperbranched D ‐mannan (HBM) core, that is, a chestnut‐shaped polymer (PLA–HBM), was synthesized by the polymerization of L ‐lactide on HBM with 4‐(dimethylamino)pyridine (DMAP) as the catalyst. The obtained polymers were soluble in dimethyl sulfoxide, tetrahydrofuran, and chloroform but insoluble in H₂O. The molecular weights of the PLA chain on PLA–HBM tended to increase with increasing polymerization time. The number of PLA chains on PLA–HBM could be controlled by the ratio of DMAP to the sugar unit in HBM. The obtained copolymer, PLA–HBM, acted as a unimolecular reversed micelle with an encapsulation ability toward the hydrophilic molecule. In addition, the entrapped hydrophilic molecules were slowly released from the core of PLA–HBM, and the release rate was accelerated by the breaking of the PLA chains of the shell when proteinase K as a hydrolase of PLA was used. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 406–413, 2006