Structures of bulgecins,bacterial metabolites with bulge-inducing activity

The structure of bulgecin A, a bacterial metabolite with bulge-inducing activity, was determined chemically and spectrometrically to be 4-o-(2'-acetylamino-2'-deoxy-4'-o-hydroxysulfonyl-β-D-glucopyranosyl)-(2S, 4S, 5R -4-hydroxy-5-hydroxymethylprolyltaurine monosodium salt. Bulgecns B and C, the minor components, were found to be analogs of bulgecin A in which the taurine moiety was replaced as shown in Fig, 1.     

Proton and Li-7 NMR study on the effect of the OH− anion upon the Li+-ion conduction in the solid solution Li5NI2LiOH

From ¹H and ⁷LiNMR relaxation times T₁, T₂ and T_1ρ in Li₅NI₂ and the solid solution Li₅NI₂?0.77LiOH, the diffusive motion of the Li⁺ ion was studied to make clear the role of the OH^? ion in improving the Li⁺ ionic conduction. At temperatures as low as 140 K, each Li⁺ ion jumps among four available positions. Its activation energies are 9.26 and 11.8 kJ mol^?1 for Li₅NI₂ and Li₅NI₂?0.77LiOH, respectively. Diffusive motion was observed in T₂ and T_1ρ above 240 K. The mode of the cation distribution and the diffusion mechanism are not affected by the presence of the OH^? anion. The most noticeable fact is that the OH^? ion is substituted selectively for the N^3? ion that is the nearest neighbour of the Li⁺ ion. This selective substitution increases the concentration of the Li⁺ vacancy most effectively up to 4.2% of the total Li positions. At the same time it diminishes the strong attractive force of the N^3? anion binding the Li⁺ ion to the position, and thus the activation energy. For the diffusion, an anomalously low attempt frequency of 3̃ × 10⁹Hz was obtained from T_1ρ, while the normal value of 4.8 × 10¹²Hz was obtained from the ionic conductivity. The large discrepancy was attributed to the collective nature of the Li⁺ diffusive motion.     

The Source of “Fairy Rings”: 2‐Azahypoxanthine and its Metabolite Found in a Novel Purine Metabolic Pathway in Plants

Rings or arcs of fungus‐stimulated plant growth occur worldwide; these are commonly referred to as “fairy rings”. In 2010, we discovered 2‐azahypoxanthine (AHX), a compound responsible for the fairy‐ring phenomenon caused by fungus; AHX stimulated the growth of all the plants tested. Herein, we reveal the isolation and structure determination of a common metabolite of AHX in plants, 2‐aza‐8‐oxohypoxanthine (AOH). AHX is chemically synthesized from 5‐aminoimidazole‐4‐carboxamide (AICA), and AHX can be converted into AOH by xanthine oxidase. AICA is one of the members of the purine metabolic pathway in animals, plants, and microorganisms. However, further metabolism of AICA remains elusive. Based on these results and facts, we hypothesized that plants themselves produce AHX and AOH through a pathway similar to the chemical synthesis. Herein, we demonstrate the existence of endogenous AHX and AOH and a novel purine pathway to produce them in plants.     

Preparation and Characterization of Phospha Sugar Analogues, 2,3-Dibromo-3-methyl-1- phenylphospholane 1-Oxide Derivatives,as Novel Anticancer Agents

The synthesis of new phospha sugar analogues or phosphorus heterocycles and their biological activities as novel anticancer agents are reported in this article. A 1,2-dibromo-1,2-dideoxy phospha sugar derivative, 2,3-dibromo-3-methyl-1-phenylphospholane 1-oxide (2), was prepared from 1-phenyl-3-methyl-2-phospholene 1-oxide (1), and the yield and ratio of diastereomers 2a to 2d were changed by a catalyst such as manganese(IV) oxide and manganese(II) bromide. The antitumor activities of the mixture of dibromides 2 and the separated diastereomeric components 2a to 2d of the dibromides were evaluated by MTT in vitro method against the human leukemia cell lines of K562 and U937. The results showed that all of the diastereomers 2a to 2d as well as the diastereomer mixture exert excellent anticancer activity, and moreover, among them, diastereomer 2d showed the highest antitumor activity.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Synthesis of poly(ethynylplatinumporphyrin) and its application as an oxygen pressure-sensitive paint

5-(4-Trimethylsilyethynylphenyl)-10,15,20-triphenylplatinumporphyrin was synthesized and copolymerized with trimethylsilylpropyne to give a new high-molecular-weight porphyrin polymer. The polymer formed a smooth and tough coating on many types of surfaces. The coating showed a strong blue luminescence from the platinumporphyrin residue which was quenched in the presence of oxygen. The relationship of the luminescence intensity vs oxygen pressure displayed a remarkably high pressure sensitivity in the low oxygen pressure area, which was ascribed to the high oxygen permeability of the polymer.