Hidemasa Yamaguchi

In vitro digestibility and fermentability of levan and its hypocholesterolemic effects in rats

This study describes the in vitro digestibility and fermentability of high molecular weight (ca. 2,000,000) levan and its effect on the metabolism of lipids in growing rats fed cholesterol-free diets. Levan was synthesized from sucrose using bacterial levansucrase immobilized on a honeycomb-shaped ceramic support. Although body weight gain, weight of visceral organs, morphologic changes in the digestive tract, and the serum triacylglycerol and glucose concentrations were not affected by feeding levan diets for 4 weeks, a significant hypocholesterolemic effect was observed. Serum cholesterol level was decreased to 83% or 59% by feeding a 1% or 5% levan diet, respectively. The hypocholesterolemic effect was accompanied by a significant increase in fecal excretion of sterols and lipids. High molecular weight levan, though not hydrolyzed by the salivary amylases, was hydrolyzed by artificial gastric juice and was changed to a low molecular weight (ca. 4,000) levan with a small amount of fructose, but did not produce any fructooligosaccharides. Low molecular weight (ca. 6,000) levan was not hydrolyzed by either pancreatic juice or small intestinal enzymes. This suggests that, in vivo, low molecular weight levan derived from the high molecular weight material is not further digested and reaches the colon intact. The fermentation of low molecular weight levan (ca. 6,000) by several strains of bifidobacteria was not observed. These results showed that the hypocholesterolemic effect of levan may result from the prevention of intestinal sterol absorption, and not from the action of the fermentation products of levan.

Cyclocopolymerization of d-limonene with maleic anhydride

Abstract d -Limonene (Lim), a nonconjugated 1,5-diene, was copolymerized with maleic anhydride (MAn) in tetrahydrofuran with α,α′-azobisisobutyronitrile as initiator. The composition, spectral analyses, and other physical properties of the resulting copolymer and its hydrolysed product suggest that Lim readily undergoes an inter-intramolecular cyclocopolymerization with MAn, leading to a 1:2 alternating copolymer. The findings and the proposed cyclocopolymerization mechanism are consistent with participation of a charge-transfer complex of the comonomers in the propagation step. The copolymers are optically active and their CD spectra are characterized by dichroic bands attributable to electronic transitions of carbonyl or carboxylic chromophores.

Electrochemical investigation of thin films of cobalt phthalocyanine and cobalt-4,4′,4″,4′″-tetracarboxyphthalocyanine and the reduction of carbon monoxide, formic acid and formaldehyde mediated by the Co(I) complexes

Abstract Cyclic voltammetric investigations of thin films of cobalt(II) phthalocyanine( 1 ) and cobalt(II)-4,4′,4″,4′″-tetracarboxyphthalocyanine( 2 ) in N 2 -saturated 1 M sulfuric acid solution revealed that both compounds gave irreversibly semi-stable reduction products, R- 1 and R- 2 , at around −0.70 V vs sce . Reductions of CO, formaldehyde and formic acid by R- 1 or R- 2 were conducted with vibrating carbon fiber electrode ( cfe ) modified with 1 or 2 . Products of the reduction of CO were mainly formaldehyde and a small amount of methanol. In the reduction of CO, R- 2 / cfe was ca 17 times more efficient than R- 1 / cfe , which was however more efficient than the former in the reduction of formaldehyde. Reduction of formic acid by R- 2 and R- 1 seemed to be difficult under the conditions. Reduction of CO on the 2 / cfe polarized with rectangular potential pulse (−0.659 V for 5s and 0.20 V vs Ag/AgCl for 85s) produced nearly quantitative yield of formaldehyde and small amount of methanol.

A novel radical terminated compound produced in the antioxidation process of curcumin against oxidation of a fatty acid ester

Abstract Isolation and structure elucidation of a radical coupling product between curcumin and a lipid under atmospheric conditions was successful for the first time. The compound has a novel tricyclic structure including a peroxyl linkage.

Antioxidant Activity of Polymers Bearing Hindered Phenolic Groups

Abstract Polyallylamine and polystyrene beads were allowed to react with 3,5-dibutyl-4-hydroxybenzaldehyde (BHB) and t-butylhydroquinone (BHQ), respectively. The polymeric products, poly-Aa(BHB) and polySt(BHQ) beads worked functionally as antioxidants. The antioxidant effect of the polymer beads in the oxidation of linoleic acid suspensions was investigated by both the ferric thiocyanate and thiobarbituric acid methods. The antioxidant activity of poly-St(BHQ) beads was higher than that of poly-Aa(BHB) ones. It was found that the antioxidant activity for 2 mg of 3, 5-dibutyl-4-hydroxytoluene (BHT) corresponded to that for 11.7 g of poly-Aa(BHB) and that of 0.6 g of poly-St(BHQ). The polymer beads are potential antioxidants for foods since their separation from a food oil after their use is easy because of their insolubility.

Stereoelective radical copolymerization of (RS)-α-methylbenzyl vinyl ether with (S)-(−)- or (R)-(+)-N-(α-methylbenzyl) maleimide

Abstract Racemic α-methylbenzyl vinyl ether was copolymerized with optically active (S)-(-)- or (R)-(+)-N-(α-methylbenzyl)maleimide using 2,2′-azobisisobutyronitrile in order to examine the possibility of stereoelective radical polymerization of vinyl-type racemic monomers. The resulting copolymers were found to have almost alternating sequences of the two kinds of monomeric units. The non-polymerized α-methylbenzyl vinyl ether, recovered from the copolymerization system, showed an optical activity of opposite sign to the optically active comonomer used, indicating clearly that the co-polymerization process is stereoelective. It was confirmed that α-methylbenzyl vinyl ether preferentially incorporated in the copolymer has the same absolute configuration as the optically active N-substituted maleimide.

Cholesterol-lowering activity of linear- and gel-type sodium polyacrylate as dietary fiber models

Effects of linear- and gel-type (cross-linked) sodium polyacrylate and partially desalted sodium polyacrylates on serum cholesterol levels were investigated in rats fed cholesterol-free diets. Gel-type sodium polyacrylate had the lowest serum cholesterol concentration among the experimental groups. In the case of partially desalted gel-type sodium polyacrylate, the serum cholesterol-lowering effect was not found. It was thought that the water-holding capacity caused the cholesterol-lowering activity. The linear-type sodium polyacrylate and partially desalted ones reduced the serum cholesterol levels significantly (P < 0.05). The effects of the degree of polymerization of linear-type sodium polyacrylates on serum cholesterol levels were observed, but the differences among them were not significant (P < 0.05). In the case of linear-type sodium polyacrylate, their viscosity was more effective on cholesterol lowering than water-holding capacity was. Diets of 1% sodium polyacrylates did not approximately affect the body weight gain and visceral organ weight.