Studies on macrolide antibiotics I. Synthesis and antibacterial activity of erythromycin A 9-O-substituted oxime ether derivatives against Mycobacterium avium complex

A series of erythromycin A 9-O-substituted oxime ether derivatives have been synthesized and evaluated for antibacterial activity against Mycobacterium avium complex (MAC) and Staphylococcus aureus. These compounds possessed stronger in vitro activity against MAC including macrolide-resistant strains than clarithromycin (2), although in vitro antibacterial activities of these compounds were less than that of 2 against Staphylococcus aureus. Our studies found that several factors contribute to the antibacterial activity against MAC. The length and spatial orientation of the substituent at 9-position were found to significantly influenced the anti-MAC activity, especially against macrolide-resistant strains. Of all the compounds prepared, erythromycin A 9-[O-(4-phenylbutyl)oxime] (12q) and erythromycin A 9-[O-(3-phenoxypropyl)oxime] (12t) possessed 16 times stronger antibacterial activity than 2 against clarithromycin-resistant strains. Surprisingly, the minimum inhibitory concentrations (MICs) of 12q and 12t against the resistant strains were almost same as those against the susceptible strains. These results suggest that the erythromycin A 9-O-substituted oxime ether derivatives would be promising macrolide antibiotics.     

Application of intramolecular 1,3-dipolar cyclic addition of azide and olefin; construction of (pyrrolidine-2-ylidene)glycinate and glycinamides

Oxopropyl E-(pyrrolidine-2-ylidene)glycinamide (5c) and allyl E-(pyrrolidine-2-ylidene)glycinate (5d) were effectively synthesized from 2,3,5-tri-O-benzyl-4-O-tert-butyldimethylsilyl(TBDMS)-D-arabinal (7) using intramolecular 1,3-dipolar cyclic reaction of azide and olefin as a key reaction. These results proved this cyclic reaction should be applicable for the synthesis of various (pyrrolidine-2-ylidene)glycinate and glycinamide. In addition, the development of a synthetic route for the precursor of an unsaturated cyclic dehydro amino acid involved in azinomycins (carzinophilin) using relating glycinate, methyl E-(pyrrolidine-2-ylidene)glycinate (5a) was described.     

Antioxidant effects of hydroxybenzalacetones on peroxynitrite-induced lipid peroxidation in red blood cell membrane ghost and SOS response in Salmonella typhimurium TA4107/pSK1002

Antioxidant activity of a series of hydroxybenzalacetones was determined against peroxynitrite-induced lipid peroxidation in red blood cell membrane and SOS response through DNA damage in bacterial cells. Hydroxybenzalacetone derivatives with hydroxy, methoxy, ethoxy or methyl substitution were analyzed and found to be more effective than the water-soluble vitamin E analogue Trolox. The inhibitory effect against lipid peroxidation correlated well to that against the SOS response, which is dependent on decomposition of peroxynitrite by hydroxybenzalacetones outside of the cell membrane. The antioxidant activity was shown to correlate well with the electric parameter sigma+. Electron-donating substituents with more negative sigma+ values increased the potencies. The result suggests that hydroxybenzalacetones with more electron-donating substituents will protect tissue more effectively against oxidative stress.     

Alkynylzirconation of alkynes and application to one-pot bisalkynylation of alkynes

Stereocontrolled alkynylzirconation of unactivated alkynes was achieved by the reaction of an alkyne with Cp2ZrEt2 and alkynyl halide in this order. After hydrolysis of the alkynylzirconation product, trisubstituted enyne derivatives were obtained in good yields. Functionalized enynes were also prepared by the reaction of the alkynylzirconation products with a variety of electrophiles. Subsequent addition of the second alkynyl halide to the alkynylzirconation products provided an in situ protocol for bisalkynylation of alkynes into (Z)-enediynes in good yields.     

Structure of an anti-plasmin inhibitor, eckol, isolated from the brown alga Ecklonia kurome Okamura and inhibitory activities of its derivatives on plasma plasmin inhibitors

Eckol (1), a novel phlorotannin with a dibenzo-1,4-dioxin skeleton, has been isolated from the brown alga Ecklonia kurome Okamura as a potent and specific anti-plasmin inhibitor. Its structure has been elucidated based on the spectral data, in particular, by means of negative nuclear Overhauser effect (NOE), and finally established as 1-(3,5-dihydroxyphenoxy)-2,4,7,9-tetrahydroxydibenzo-1,4-dio xin by X-ray analysis. Some partially methoxylated derivatives of eckol were prepared by methylation with diazomethane and also by selective dimethylation of eckol permethylate (1b) to establish the structural requirements for inhibitory activities on alpha 2-macroglobulin and alpha 2-plasmin inhibitor, the main plasmin inhibitors in plasma.     

1,4-cycloheptylene and the related allylic diradicals. Thermal nitrogen extrusion from 6,7-diazabicyclo[3.2.2]Non-6-enes

Thermal nitrogen extrusion of 2-methylene-6,7-diazabicyclo[3.2.2]non-6-enes and 6,7- diazabicyclo[3.2.2]nona-2,6-diene,6 proceeded easily to give closure and cleavage products $\text{via}$ the corresponding 5-methylene-1,4-cycloheptylenes and 4-cyclohepten-1,3-ylenes, respectively.     

Polymerization of vinylcyclopropanes. V. Radical copolymerization of 1, 1-dichloro-2-vinylcyclopropane with monosubstituted ethylenes

A peculiar copolymer composition equation applicable to the radical copolymerization of 1,1-dichloro-2-vinylcyclopropane with monosubstituted ethylenes was developed. The theory was applied to such ethylenes as methyl acrylate, methyl methacrylate, and styrene. The reactivity ratio parameters which give the best fit to the experimental data were determined.     

POLYETHYLENE GLYCOL-MODIFIED HEMATOPORPHYRIN AS PHOTOSENSITIZER

Abstract— Hematoporphyrin, having two carboxylic groups, was coupled with α-(3-aminopropyl)-ω-methoxypoly(oxyethylene), PEG-NH₂, through acid-amide bond formed with carbodtimide. PEG-modified hematoporphyrin was readily soluble not only in neutral aqueous solution but also in organic solvents. Its absorption spectrum showed a sharp band at 376 nm in neutral aqueous solution and at 403 nm in benzene. Modified hematoporphyrin acted as a photosensitizer; imidazole and indole were photooxidized in organic solvents such as benzene or chloroform, and uric acid was also photooxidized in neutral aqueous solution.     

Sulfur nitride in organic chemistry. 9. The reaction of tetrasulfur tetranitride with benzyl ketones. Preparation of 3,4-disubstituted-1,2,5-thiadiazoles

The reaction of tetrasulfur tetranitride ( 1 ) with various aryl and alkyl benzyl ketones ( 2a-o ), oxindole ( 11 ), benzyl α-pyridyl ketone ( 12 ) and α-phenacylpyridine ( 13 ) afforded the corresponding 1,2,5-thiadiazoles ( 3a-n, 11 and 14 ). The scope and limitations of the above reaction were investigated and the evidences suggesting the radical anion mechanism are presented.     

Change of concentrations of trace elements and protein contents in the liver of zinc deficient mice

The concentrations of essential trace elements and proteins in cytosolic fraction of hepatic cells of mice fed with Zn-deficient diet (Zn-def, mice) and control were determined by ICP-MS and BCA protein assay method, respectively, after division into forty fractions by gel filtration chromatography. The concentrations of zinc and proteins decreased in the 14–17th fractions of Zn-def, mice, whereas cobalt concentrations increased in the 14, 17, and 18th fractions. However, no significant differences were found on the gel after SDS-PAGE for the 12–21st fractions, although the BCA protein assay date showed the decrease of protein amounts in 13–15th fractions of Zn-def. mice.