Munehiro Oda

AG(I)-N BOND-CONTAINING COMPOUND SHOWING WIDE SPECTRA IN EFFECTIVE ANTIMICROBIAL ACTIVITIES : POLYMERIC SILVER(I) IMIDAZOLATE

A neutral, Ag(I)-N bonding compound, polymeric silver(I)-imidazolate [Ag(imd)]n (1) consisting of Ag+: imd = 1:1 (Himd = imidazole, C3H4N2), showed wide spectra in effective antimicrobial activities against bacteria, yeast and mold. Of particular note are the activities against a wide range of mold. This polymeric solid does not crystallize and is sparingly soluble in all solvents. The monomeric, cationic, water-soluble Ag(I)-N bonding complex, [Ag(Himd)2](NO3) (2), has also shown wide spectra of effective antimicrobial activities. These activities observed here were significantly different from those of the recently prepared oligomeric Ag(I)-S bonding complexes; the latter have shown narrow spectra. It is proposed that the Ag(I)-N bonding is one of the key factors showing the wide spectra of antimicrobial activities and the potential targets for inhibition of bacteria and yeast by these Ag(I) complexes are proteins, but not nucleic acids. The physico-chemical properties of (1), in comparison with those of (2), with various measurements (FT-IR, Laser Raman scattering spectroscopy, ESCA and solid 13C CP-MAS NMR spectroscopies) are described.

Synthesis and crystal structure of coinage metal(I) complexes with tetrazole (Htetz) and triphenylphosphine ligands, and their antimicrobial activities. A helical polymer of silver(I) complex [Ag(tetz)(PPh3)2]n and a monomeric gold(I) complex [Au(tetz)(PPh3)]

Abstract Two novel coinage metal(I)-triphenylphosphine complexes with a heterocyclic ligand, [Ag(tetz)(PPh 3 ) 2 ] n ( 1 ) and [Au(tetz)(PPh 3 )] ( 2 ) (Htetz=tetrazole) were synthesized from a reaction in dichloromethane of the precursor complex [Ag(tetz)] n with PPh 3 and from a reaction in acetone of [AuCl(PPh 3 )] with Htetz in the presence of aqueous NaOH, respectively, and isolated as colorless needle crystals for both 1 and 2 . The crystal structures of 1 and 2 were determined by single-crystal X-ray diffraction. These d 10 complexes were also fully characterized by elemental analyses, TG/DTA and FT-IR in the solid-state, solution NMR ( 31 P, 1 H and 13 C, as well as 109 Ag for 1 ) spectroscopies and solution molecular weight measurements. Complex 1 , is composed of a helical polymer, a 2 1 helix with a pitch 9.471 A, formed by a bridged tetrazolate of an AgNP 2 core in the solid-state, but it was present as a monomer in solution. In contrast to 1 , complex 2 consisted of a monomeric two-coordinate AuNP core without gold(I)–gold(I) interaction both in the solid-state and in solution. The molecular structures of 1 and 2 were compared with those of the corresponding triazole complexes, i.e. silver(I) complexes [Ag(1,2,3-triz)(PPh 3 ) 2 ] n ( 3 ) and [Ag(1,2,4-triz)(PPh 3 ) 2 ] n ( 4 ) both as helical polymers, a monomeric gold(I) complex [Au(1,2,3-triz)(PPh 3 )] ( 5) and a dimeric gold(I) complex [Au(1,2,4-triz)(PPh 3 )] 2 ( 6) through an intramolecular gold(I)–gold(I) bond; the structures of complexes 3 – 6 being recently determined by X-ray crystallography. The antimicrobial activities of 1 , its precursor [Ag(tetz)] n and 2 were compared and key factors affecting them discussed.

Increased remineralization of tooth enamel by milk containing added casein phosphopeptide-amorphous calcium phosphate

Casein phosphopeptide amorphous calcium phosphate nano-complexes (CPP-ACP) in chewing gum, lozenges and mouthrinses have been shown to re-mineralize enamel subsurface lesions in human in situ experiments. The aim of this double-blind, randomized clinical study was to investigate the capacity of CPP-ACP added to bovine milk to re-mineralize enamel subsurface lesions in situ. Ten subjects drank milk containing either 2.0 or 5.0 g CPP-ACP/l or a control milk whilst wearing removable appliances with enamel slabs containing subsurface demineralized lesions. Each 200 ml milk sample was consumed once a day for each weekday over three consecutive weeks. After each treatment and one weeks rest the subjects crossed over to the other treatments. At the completion of the treatments the enamel slabs were removed and remineralization determined using microradiography and microdensitometry. The results demonstrated that all three milk samples re-mineralized enamel subsurface lesions. However, the milk samples containing CPP-ACP produced significantly greater remineralization than the control milk. The re-mineralizing effect of CPP-ACP in milk was dose-dependent with 2.0 and 5.0 g CPP-ACP/l producing an increase in mineral content of 70 and 148%, respectively, relative to the control milk. The differences in remineralization following exposure to the three milk samples were all statistically significant (P<0.001). In conclusion, this study shows that the addition of 2.0-5.0 g CPP-ACP/l to milk substantially increases its ability to re-mineralize enamel subsurface lesions.

Synthesis, crystal structure and antimicrobial activities of two isomeric gold(I) complexes with nitrogen-containing heterocycle and triphenylphosphine ligands, [Au(L)(PPh3)] (HL = pyrazole and imidazole).

Two isomeric gold(I)-triphenylphosphine complexes with nitrogen-containing heterocycles, [Au(L)(PPh3) (HL = pyrazole (1), imidazole (2)) were isolated as colorless cubic crystals for 1 and colorless plate crystals for 2, respectively. The crystal structures of 1 and 2 were determined by single-crystal X-ray diffraction. These complexes were also fully characterized by complete elemental analyses, thermogravimetric/differential thermal analyses (TG/DTA) and FT-IR in the solid state and by solution NMR (31P, 1H and 13C) spectroscopy and molecular weight measurements in acetone solution. These complexes consisted of a monomeric 2-coordinate AuNP core both in the solid state and in solution. The molecular structures of 1 and 2 were compared with those of related gold(I) complexes, [Au(1,2,3-triz)(PPh3)] (3, Htriz = triazole), [Au(1,2,4-triz)(PPh3)]2 (4) as a dimer through a gold(I)-gold(I) bond in the solid state, and [Au(tetz)(PPh3)] (5, Htetz = tetrazole). Selective and effective antimicrobial activities against two gram-positive bacteria (B. subtilis, S. aureus) and modest activities against one yeast (C. albicans) found in these gold(I) complexes 1-4 are noteworthy, in contrast to poor activities observed in the corresponding silver(I) complexes.

Complete Sequencing and Pan-Genomic Analysis of Lactobacillus delbrueckii subsp. bulgaricus Reveal Its Genetic Basis for Industrial Yogurt Production

Lactobacillus delbrueckii subsp. bulgaricus (Lb. bulgaricus) is an important species of Lactic Acid Bacteria (LAB) used for cheese and yogurt fermentation. The genome of Lb. bulgaricus 2038, an industrial strain mainly used for yogurt production, was completely sequenced and compared against the other two ATCC collection strains of the same subspecies. Specific physiological properties of strain 2038, such as lysine biosynthesis, formate production, aspartate-related carbon-skeleton intermediate metabolism, unique EPS synthesis and efficient DNA restriction/modification systems, are all different from those of the collection strains that might benefit the industrial production of yogurt. Other common features shared by Lb. bulgaricus strains, such as efficient protocooperation with Streptococcus thermophilus and lactate production as well as well-equipped stress tolerance mechanisms may account for it being selected originally for yogurt fermentation industry. Multiple lines of evidence suggested that Lb. bulgaricus 2038 was genetically closer to the common ancestor of the subspecies than the other two sequenced collection strains, probably due to a strict industrial maintenance process for strain 2038 that might have halted its genome decay and sustained a gene network suitable for large scale yogurt production.

Insulin mimetic effect of a tungstate cluster. Effect of oral administration of homo-polyoxotungstates and vanadium-substituted polyoxotungstates on blood glucose level of STZ mice.

Aqueous vanadate and aqueous tungstate have been known to mimic all or most of the actions of insulin in intact cell systems with respect to normalization of the blood glucose level. By carrying out oral administration in vivo experiments on the blood glucose level of streptozotocin (STZ)-induced diabetes (STZ mice), the insulin-mimetic (IM) effects of metal-oxide clusters of all-inorganic composition were examined using many types of polyoxometalates (POM) with and without vanadium substitution. Several homo-POM and vanadium-substituted POM showed hypoglycemic effects. The observed hypoglycemic effects indicated that POM with the Dawson structure [[alpha-P(2)W(18)O(62)](6-) (W-2), [alpha-P(2)W(17)V(V)O(62)](7-) (V-19) and [alpha-1,2,3-P(2)W(15)V(V)(3)O(62)](9-) (V-04)] are more effective than those with the Keggin structure [[alpha-PW(12)O(40)](3-) (W-1), [alpha-PW(11)V(V)O(40)](4-) (V-01), [alpha-1,2-PW(10)V(V)(2)O(40)](5-) (V-02), [alpha-1,2,3-PW(9)V(V)(3)O(40)](6-) (V-03) and [alpha-1,4,9-PW(9)V(V)(3)O(40)](6-) (V-13)]. The vanadate cluster [V(10)O(28)](6-) (V-15) also showed a hypoglycemic effect. (31)P and (51)V NMR measurements showed that the Dawson POM (W-2, V-04 and V-19) are stable in aqueous solution under the conditions used. The effect of all POM on the body weight of STZ mice was also examined. The decrease in body weight after administration of W-2 was much less than for V-19, V-04 and V-15. This suggests that not only monomeric tungstate and vanadate, but also the structure factors of tungstate and vanadate clusters, can play a significant role in their biological action.

Synthesis and characterization of polymeric, anionic thiosalicylato-Ag(I) complexes with antimicrobial activities

Abstract Thiosalicylic acid ligand (H 2 TSA = o-HS(C 6 H 4 )COOH) forms two types of anionic light- and thermally stable Ag(I) complexes with remarkable antimicrobial activities for bacteria, yeast, and mold; one is a yellow, water-soluble complex 1 and the other an orange, water-insoluble complex 2 , either of which can be converted to the other, and both of which do not crystallize. Both are complexes with composition of metal: TSA 2− ligand = 1:1. The complex 2 is probably polymeric, whereas the complex 1 is an oligomer with a formula of {Na[Ag(TSA 2− )·H 2 O]} n (n = 12 − 14; MW = 3600 − 4200). Both complexes have been characterized with complete elemental analyses, TG/DTA, FT-IR, and ESCA spectra in the solid state, and complex 1 as well as with molecular weight measurement in aqueous solution, and with 109 Ag and 2D NMR( 1 H- 1 H COSY, 1 H- 13 C COSY, and HMBC) measurements in aqueous solution.

Synthesis and characterization of oligomeric, anionic thiomalato-silver(I) complexes with biological activities

Abstract A water-soluble, thermally and light-stable, anionic AgI complex with a trianion of thiomalic acid, TMA3− (H3TMA = HOOCCH(SH)CH2COOH) as a ligand was prepared and isolated as a typically yellow-coloured powder of the sodium salt, which showed excellent antimicrobial activity against some bacteria, yeast and moulds. All attempts at crystallization were unsuccessful. This compound was characterized by complete elemental analyses, TG/DTA, FT-IR, various NMR (1H, 13C and 109Ag) spectroscopies, and molecular weight determination in aqueous solution by a combination of molmass measurement based on the cryoscopic method with degree of dissociation determination based on the [Na+] measurement in the equilibrium state using an Na+ ion-selective electrode. It was shown that this complex was not a monomeric species, but an oligomer with a formula of [NaH [Ag(TMA)]·0.5H2O]n(n = 15–19; MW = 4320–5470). Analogues of this anionic AgI complex were also obtained as potassium, barium, ammonium, lithium and caesium salts, as well as a free-acid form.

High levels of urinary midkine in various cancer patients.

Midkine (MK) is a heparin-binding growth factor, which promotes growth, migration, and survival of various cells, and MK expression is increased in many human carcinomas. We determined the urinary MK level by enzyme-linked immunoassay. Taking 311pg/mg creatinine as a cut-off level, 70% of patients with various carcinomas (n=142) gave positive values, while only 5.5% of healthy volunteers (n=330) did. In case of gastric carcinoma, 17 out of 21 patients with stage 1 tumor were positive. Urinary MK levels are expected to become a convenient marker as an aid in detection of tumors.

Antihypertensive effect of an angiotensin converting enzyme inhibitory peptide from enzyme modified cheese.

Two angiotensin converting enzyme (ACE)-inhibitory peptides were isolated from enzyme modified cheese (EMC) and their amino acid sequences were identified as Leu-Gln-Pro and Met-Ala-Pro. The EMC was prepared by a combination of Protease N, Umamizyme, and Flavourzyme 500L. Both peptides were derived from beta-casein, f 88-90 and f 102-104, respectively. Met-Ala-Pro showed strong ACE inhibitory activity (IC50=0.8 mum) and antihypertensive activity in spontaneously hypertensive rats (SHR) after single oral administration. The IC50 value of Met-Ala-Pro was not affected by pre-incubation with ACE, suggesting that this peptide was a true ACE-inhibitory peptide. We report here, for the first time antihypertensive peptides from EMC.