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Yamauchi S.,Ehime University | Yamauchi S.,South Ehime Fisheries Research Center | Isozaki Y.,Ehime University | Nishimura H.,Ehime University | And 3 more authors.
Bioscience, Biotechnology and Biochemistry | Year: 2012

Optically pure (+)- and (-)-boronolides were stereoselectively synthesized from yeast reductive products which had been obtained by yeast reduction of one common racemic substrate. The lactone structure of boronolide was constructed by Baeyer-Villiger oxidation. The stereochemistry of the yeast reduction products was studied to obtain the stereocenters at 5 positions of the dodecanolides of (+)- and (-)-boronolides. The stereochemistry of the 6 and 7 positions was obtained by AD-mix-α or β oxidation. The chiral center at the 8 position was constructed by employing (R)-(+)- or (S)-(-)-2-methyl-CBS- oxazaborolidine reduction or the Mitsunobu reaction. The plant growth-inhibitory activity against Echinochloa crusgalli L. of naturally occurring (+)-boronolide was higher than that of the (-)-boronolide. Source


Yamauchi S.,Ehime University | Yamauchi S.,South Ehime Fisheries Research Center | Nakayama K.,Ehime University | Nishiwaki H.,Ehime University | Shuto Y.,Ehime University
Bioorganic and Medicinal Chemistry Letters | Year: 2014

The synthesized 7-aryl derivatives of (7R,7′S,8S,8′S)-(+)-verrucosin were applied to growth inhibitory activity test against ryegrass at 1 mM. 7-(3-Ethoxy-4-hydroxyphenyl) derivative 12 and 7-(2-hydroxyphenyl) derivative 4 showed comparable activity to those of (+)-verrucosin against the root (-95%) and the shoot (-60%), respectively. The growth inhibitory activity test against lettuce using synthesized 7-aryl derivatives of (7S,7′R,8R,8′R)-(-)-verrucosin at 1 mM showed that the activities of 7-(3-hydroxyphenyl) derivative 20 and 7-(3-ethoxy-4-hydroxyphenyl) derivative 28 are similar to that of (-)-verrucosin against the root (-95%). Against the shoot, 7-(3-hydroxyphenyl) derivative 20 showed higher activity (-80%) than that of (-)-verrucosin (-60%). As the next step, (7S,7′R,8R,8′R)-7-(3-hydroxyphenyl)-7′-aryl-(-)-verrucosin derivatives, in which the most effective 3-hydroxyphenyl group is employed as 7-aromatic ring, were synthesized for the assay against lettuce. In this experiment, 7′-(2-hydroxyphenyl) derivative 37 and 7′-(3-hydroxyphenyl) derivative 38 showed similar activity to that of derivative 20. The effect of 7- and 7′-aryl structures of 7,7′-epoxylignanes on the plant growth inhibitory activity was clarified. The 7- and 7′-aryl structures were simplified to show comparable activity to or higher activity than that of (-)-verrucosin. The plant growth inhibitory activity of a nutmeg component, (+)-fragransin C3b, was estimated as -80% inhibition at 1 mM against ryegrass roots. © 2014 Elsevier Ltd. All rights reserved. Source


Yamauchi S.,Ehime University | Yamauchi S.,South Ehime Fisheries Research Center | Tomiyama C.,Ehime University | Wukirsari T.,Ehime University | Nishiwaki H.,Ehime University
Bioscience, Biotechnology and Biochemistry | Year: 2014

All the stereoisomers of butanol type 1,7-seco-2,7′-cyclolignane were stereoselectively synthesized by employing (S)- and (R)-Evans' auxiliaries to construct the stereochemistry. (+)- and (-)-Kadangustin J and their diastereomers were also prepared. The optical purity of the synthesized butanol type 1,7-seco-2,7′-cyclolignane was more than 99%ee. © 2014 Japan Society for Bioscience, Biotechnology, and Agrochemistry. Source


Yamauchi S.,Ehime University | Yamauchi S.,South Ehime Fisheries Research Center | Ichikawa H.,Ehime University | Nishiwaki H.,Ehime University | Shuto Y.,Ehime University
Journal of Agricultural and Food Chemistry | Year: 2015

The plant growth regulatory activity of furofuran lignan (7,9′:7′,9-diepoxylignan) was evaluated by employing optically pure synthesized (+)- and (-)-enantiomers. (+)-Sesamin possessing a 3,4-methylenedioxy group on the aromatic rings and 7-aryl structure showed growth promotion activity against lettuce roots (EC50 = 0.50 mM); on the other hand, growth inhibitory activity was observed against lettuce shoots (EC50 = 0.38 mM). Against ryegrass shoots, (-)-sesamolin, which has 3,4-methylenedioxy groups on the aromatic rings and a 7-acetal structure, was effective in showing growth inhibitory activity (EC50 = 0.23 mM). Different activity levels were observed between (+)- and (-)-enantiomers. It was assumed that the 3,4-methylenedioxy group on the aromatic ring was more potent for the plant growth regulatory activity. © 2015 American Chemical Society. Source


Yamauchi S.,Ehime University | Yamauchi S.,South Ehime Fisheries Research Center | Nishimura H.,Ehime University | Nishiwaki H.,Ehime University
Bioscience, Biotechnology and Biochemistry | Year: 2015

Cryptocarya diacetate and each of its stereoisomers were stereoselectively synthesized in 8-16 steps. One of the three chiral carbons was converted from the chiral center of a yeast-reduction product. The other two chiral carbons were constructed by employing stereoselective allylation and syn-and anti-1,3-reductions. The enantiomeric excesses of the synthesized cryptocarya diacetate and its stereoisomers were determined to be more than 99%ee using a chiral column. © 2014 Japan Society for Bioscience Biotechnology and Agrochemistry. Source

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