Kotaro Murakami

Alkyl gallates, intensifiers of beta-lactam susceptibility in methicillin-resistant Staphylococcus aureus.

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.

The steroidal glycosides of the flowers of Yucca gloriosa

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.

New dammarane-type saponin from roots of Panax notoginseng

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.

Flavonol and phenylpropanoid glycosides from Lilium cordatum

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.

Acyclic sulfides, garlicnins L-1-L-4, E, and F, from Allium sativum.

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.

Hypelodins A and B, polyprenylated benzophenones from Hypericum elodeoides

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.

Tetrahydroxanthones from Mongolian medicinal plant Gentianella amarella ssp. acuta

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.

Two new bicyclic sulfoxides from Welsh onion

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.

Saponins, Esculeosides B-1 and B-2, in Tomato Juice and Sapogenol, Esculeogenin B1.

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.

Furostanol glycosides from Lilium cordatum

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.