Kotaro Murakami
Sojo University
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Publication
Featured researches published by Kotaro Murakami.
Antimicrobial Agents and Chemotherapy | 2005
Hirofumi Shibata; Kyoko Kondo; Ryo Katsuyama; Kazuyoshi Kawazoe; Yoichi Sato; Kotaro Murakami; Yoshihisa Takaishi; Naokatu Arakaki; Tomihiko Higuti
ABSTRACT We found that ethyl gallate purified from a dried pod of tara (Caesalpinia spinosa) intensified β-lactam susceptibility in methicillin-resistant and methicillin-sensitive strains of Staphylococcus aureus (MRSA and MSSA strains, respectively). This compound and several known alkyl gallates were tested with MRSA and MSSA strains to gain new insights into their structural functions in relation to antimicrobial and β-lactam susceptibility-intensifying activities. The maximum activity of alkyl gallates against MRSA and MSSA strains occurred at 1-nonyl and 1-decyl gallate, with an MIC at which 90% of the isolates tested were inhibited of 15.6 μg/ml. At concentrations lower than the MIC, alkyl gallates synergistically elevated the susceptibility of MRSA and MSSA strains to β-lactam antibiotics. Such a synergistic activity of the alkyl gallates appears to be specific for β-lactam antibiotics, because no significant changes were observed in the MICs of other classes of antibiotics examined in this study. The length of the alkyl chain was also associated with the modifying activity of the alkyl gallates, and the optimum length was C5 to C6. The present work clearly demonstrates that the length of the alkyl chain has a key role in the elevation of susceptibility to β-lactam antibiotics.
Phytochemistry | 1988
Kimiko Nakano; Emi Matsuda; Kaori Tsurumi; Tokushi Yamasaki; Kotaro Murakami; Yoshihisa Takaishi; Toshiaki Tomimatsu
Abstract Four steroidal compounds were isolated from the fresh flowers of Yucca gloriosa and their structures were elucidated as tigogenin 3-O-β- d -xylopyranosyl-β-lycotetraoside, gitogenin 3-O-β- d -xylopyranosyl-β-lycotetraoside, gitogenin 3-O-α- l -rhamnopyranosyl-β-lycotetraoside and proto-type of gitogenin 3-O-β- d -xylopyranosyl-β-lycotetraoside, on the basis of physical and chemical investigations.
Journal of Natural Medicines | 2006
Nozomi Komakine; Mamoru Okasaka; Yoshihisa Takaishi; Kazuyoshi Kawazoe; Kotaro Murakami; Yoshihide Yamada
A new ginsenoside and 22 known compounds were isolated from the roots of Panax notoginseng (Araliaceae). The structure of the new compound was elucidated from 2D-NMR and other spectral evidence.
Phytochemistry | 1989
Kimiko Nakano; Koji Nishizawa; Ikumi Takemoto; Kotaro Murakami; Yoshihisa Takaishi; Toshiaki Tomimatsu
Abstract Four flavonol glycosides and four phenyl-propanoid glucosides were isolated from a methanolic petal extract of Lilium cordatum . These structures were established as isorhamnetin 3-glucoside, 3-glucoside-7-rhamnoside, 3-rutinoside and 3-rutinoside-7-rhamnoside and isoeugenol, p -propenylphenol, coniferyl alcohol and p -coumaryl alcohol glucosides, respectively.
Chemical & Pharmaceutical Bulletin | 2014
Toshihiro Nohara; Yukio Fujiwara; Tsuyoshi Ikeda; Koki Yamaguchi; Hideyuki Manabe; Kotaro Murakami; Masateru Ono; Daisuke Nakano; Junei Kinjo
Six novel acyclic sulfides, named garlicnins L-1-L-4 (1-4), E (5), and F (6), were isolated from the acetone extracts, with the ability to suppress M2 macrophage activation, of the bulbs of garlic (Allium sativum L.), and their chemical structures were characterized.
Journal of Natural Medicines | 2014
Chika Hashida; Naonobu Tanaka; Kazuyoshi Kawazoe; Kotaro Murakami; Han-Dong Sun; Yoshihisa Takaishi; Yoshiki Kashiwada
Two new polyprenylated benzophenones, hypelodins A (1) and B (2), were isolated from the aerial parts of the Chinese medicinal plant Hyperium elodeoides (Choisy). Their structures were elucidated on the basis of spectroscopic evidence. Hypelodin A (1) is a polyprenylated benzophenone having a tetrahydropyrane ring with three prenyl groups and one 4-methyl-1,3-pentadiene moiety, while hypelodin B (2) has a cage-like structure with a 6/6/5/7/6/5 hexacyclic ring system.
Journal of Natural Medicines | 2016
Shuangxin Lu; Naonobu Tanaka; Kazuyoshi Kawazoe; Kotaro Murakami; Davaadagva Damdinjav; Enkhjargal Dorjbal; Yoshiki Kashiwada
Two tetrahydroxanthones, 1,3,5S,8S-tetrahydroxy-5,6,7,8-tetrahydroxanthone (1) and 1,3,5R,8S-tetrahydroxy-5,6,7,8-tetrahydroxanthone (2), and six new tetrahydroxanthone glycosides, amarellins A–F (3–8), were isolated from the aerial parts of a Mongolian medicinal plant Gentianella amarella ssp. acuta (Gentianaceae). The structures of 1–8 were elucidated on the basis of spectroscopic analysis, chemical conversion, and ECD calculation. Amarellins A–C (3–5) were assigned as 8-O-β-d-glucoside, 8-O-β-d-xyloside, and 1-O-β-d-glucoside of 1, respectively, while amarellins D–F (6–8) were elucidated to be 8-O-β-d-xyloside, 1-O-β-d-glucoside, and 3-O-β-d-glucoside of 2, respectively.
Journal of Natural Medicines | 2016
Toshihiro Nohara; Yukio Fujiwara; Tsuyoshi Ikeda; Kotaro Murakami; Masateru Ono; Mona El-Aasr; Daisuke Nakano; Junei Kinjo
Newly identified bicyclic sulfoxides, welsonins A1 (1) and A2 (2), were isolated from acetone extracts of the bulbs of the Welsh onion (Allium fistulosum). In this study, the structures of 1 and 2, which are tetrahydrothiophene-S-oxide derivatives, were characterized by spectroscopic analysis. These compounds appeared to be derived from the coupling of 1-propenyl sulfenic acid and uronic acid. Welsonin A1 (1) showed the potential to suppress tumor-cell proliferation by inhibiting the polarization of alternatively activated M2 macrophages.
Chemical & Pharmaceutical Bulletin | 2015
Toshihiro Nohara; Yukio Fujiwara; Jian Rong Zhou; Jun Urata; Tsuyoshi Ikeda; Kotaro Murakami; Mona El-Aasr; Masateru Ono
It has been shown that commercial tomato juice packaged in 900 g plastic bottles contains rare, naturally occurring steroidal solanocapsine-type tomato glycosides in which the saponins consist of esculeosides B-1 (2) and B-2 (3) in 0.041% as major components lacking esculeoside A. We suggest that these saponins are derived from esculeoside A (1) when the juice in plastic bottles is prepared by treatment with boiling water, similar to the process used in preparing canned tomatoes. Herein, the obtained tomato saponins (2) and (3) provided sapogenols esculeogenin B1 (4) and B2 (5), respectively, by acid hydrolysis. The former was identical to esculeogenin B previously reported, and the latter was a new sapogenol characterized to be (5α,22S,23S,25S)-22,26-epimino-16β,23-epoxy-3β,23,27-trihydroxycholestane.
Phytochemistry | 1988
Kimiko Nakano; Kōji Nishizawa; Ikumi Takemoto; Kotaro Murakami; Yoshihisa Takaishi; Toshiaki Tomimatsu
Abstract Two furostanol glycosides were isolated from the methanolic·extract of the petals of Lilium cordatum. Their structures were established as 26-O-β- d -glucopyranosyl-(25R)-22ξ-methoxy-furost-5-en- 3β, 26-diol 3-O-α- l -rhamnopyranosyl-(1→2)-β- d -glucopyranoside and its 6′-O-acetyl derivative.