Masayoshi Ohyama

A xanthanolide with potent antibacterial activity against methicillin-resistant Staphylococcus aureus.

Abstract— With the therapeutic concept of using the defensive ability of plants against microbial infections, phytoalexin, an antimicrobial phytochemical was studied for its ability to inhibit the growth of methicillin‐resistant Staphylococcus aureus (MRSA). Extracts from Sophora exigua (Leguminosae) were fractionated by serial chromatography and the anti‐MRSA activity of each fraction was determined by the agar‐plate method. Among the active isolates, 5,7,2′,6′‐tetrahydroxy‐6‐isoprenyl‐8‐lavandulyl‐4′‐methoxyflavanone (exiguaflavanone D) completely inhibited the growth of all the MRSA strains examined at the concentration of 1·56–6·25 μg mL−1, and 5, 2′,6′‐trihydroxy‐8‐lavandulyl‐7‐methoxy‐flavanone (exiguaflavanone B) inhibited at a concentration of 50 μg mL−1. This former compound is expected to be a phytotherapeutic agent for MRSA infections as an alternative to conventional antibiotics with unwanted side‐effects or the appearance of antibiotic‐resistant bacteria.

Antitumor agents 200. Cytotoxicity of naturally occurring resveratrol oligomers and their acetate derivatives.

Eleven resveratrol oligomers and six acetylated derivatives were evaluated for in vitro cytotoxicity against a panel of human tumor cell lines. The acetate of (-)-ampelopsin A (12) showed potent and selective cytotoxic activity with ED50 values of 0.6, 0.7 and 2.0 microg/mL against KB, 1A9 and MCF-7 cells, respectively. Hopeaphenol (10) and pallidol hexaacetate (13) also showed significant cytotoxicity against KB cells with ED50 values of 1.2 and 1.6 microg/mL, respectively.

Inhibition of the growth of cariogenic bacteria in vitro by plant falvanones

Phytoalexins, defensive compounds produced by plants against microbial infections, were purified fromSophora exigua (Leguminosae) and their growth inhibitory effects on oral cariogenic bacteria were determined in vitro. Among three isolated compounds, 5,7,2′,4′-tetrahydroxy-8-lavandulylflavanone completely inhibited the growth of oral bacteria including primary cariogenic mutans streptococci, other oral streptococci, actinomycetes, and lactobacilli, at concentrations of 1.56 to 6.25 μg/ml.

A Novel Bridged Stilbenoid Trimer and Four Highly Condensed Stilbenoid Oligomers in Vatica rassak.

Abstract Vaticanol G ( 1 ) and vaticaside D ( 2 ) isolated from stem bark of Vatica rassak (Dipterocarpaceae) were the first instance of stilbenoid trimers with an unusual tribenzobicyclo[3.3.2]decatriene system. Vaticanols D ( 3 ) and H ( 4 )–J ( 6 ) were elucidated to be a stilbenoid hexamer or heptamer containing a structurally identical trimeric unit. Their structures and the relative configurations were established on the basis of 2D NMR spectroscopy. The hexamers ( 3 , 4 and 5 ) and the heptemer ( 6 ) showed cytotoxicity against KB cells.

Stilbenoids in the stem bark of Hopea parviflora.

From the bark of Hopea parviflora, two stilbenoids, named (+)-parviflorol and (-)-ampelopsin A, were isolated in addition to three known compounds: (+)-balanocarpol, (-)-epsilon-viniferin and (-)-hopeaphenol. Their structures were determined by analysis of spectral data, including 2D NMR and NOE experiments, respectively.

A resveratrol dimer from Parthenocissus tricuspidata

From the stem wood of Parthenocissus tricuspidata, four stilbene derivatives were isolated. Three known structures were characterized as resveratrol, e-viniferin and pallidol, and a new resveratrol dimer was confirmed to be a stereochemical isomer of ampelopsin F, isoampelopsin F, by spectroscopic analysis including 2D NMR.

Five resveratrol oligomers from roots of Sophora leachiana

Abstract Five novel oligostilbenes, named leachianols C-G, were isolated from the roots of Sophora leachiana . Their structures were established by means of 2D NMR spectroscopic analysis, including HMBC, COLOC and PSNOESY, to be a resveratrol tetramer with a 2-cyclohexen-4-one ring (leachianol C), a resveratrol trimer with a dihydrobenzofuran ring (leachianol D), a regioisomer of leachianol D (leachianol E), a resveratrol dimer (leachianol F) and a stereoisomer of leachianol F (leachianol G), respectively. These oligostilbenes in S. leachiana derived from pallidol are different from those in S. moorcroftiana , which are derived from e-viniferin.

Five flavonoid compounds from Echinosophora koreensis

Abstract Further investigation of the phenolic compound in the roots and stems of Echinosophora koreensis led to the isolation of three new isoflavanones from the roots and 14 compounds, including two new flavanones, from the stems. Their structures were determined by means of spectral analysis to be 3,5,7,4′-tetrahydroxy-2′-methoxy-3′-γ,γ-dimethylallylisoflavanone (kenusanone F), 5,7,3′-trihydroxy-4′-methoxyisoflavanone (kenusanone G) and 8-geranyl-5, 7,2′,4′-tetrahydroxyisoflavanone (kenusanone H) as root constituents, and 5,2′,4′-trihydroxy-7-methoxy-8-γ,γ-dimethylallylflavanone (kenusanone I), 5,2′,4′-trihydroxy-6″,6″-dimethyldihydropyrano [2″,3″: 7,8] flavanone (kenusanone J), sophoraflavanones C and D, sophoronol, echinoisosophoranone, scopoletin, scoparone, liquilitigenin, genistein, licoisoflavone A, 2-(2′,4′-dihydroxyphenyl)-5, 6-methylenedioxybenzofuran, caffeic acid ester and sophoracarpan B as stem constituents.

Laxative Effect of Agarwood Leaves and Its Mechanism

We investigated the laxative activity of an extract of agarwood leaves from Aquilaria sinensis. The laxative activity was measured in mice by counting the stool frequency and stool weight, and the drugs were orally administered. An acetone extract of agarwood leaves and senna (a representative laxative drug) both increased the stool frequency and weight, but a methanol extract did not. The laxative effect of the acetone extract was milder than that of the anthraquinoid laxative, senna, and the former did not induce diarrhea as a severe side effect. We identified the main constituent contributing to the laxative effect of the acetone extract as genkwanin 5-O-β-primeveroside (compound 4). Compound 4 strengthened the spontaneous motility and induced contraction in the ileum. This ileal contraction induced by compound 4 was inhibited by atropine, but not by azasetron, suggesting that the effect of compound 4 was mediated by acetylcholine receptors, and not by serotonin. The laxative mechanism for compound 4 may in part involve stimulation of intestinal motility via acetylcholine receptors.

Flavonoids in roots of Sophora prostrata

Abstract Further investigation of the phenolic constituents in the roots of Sophora prostrata gave 14 phenolic compounds, including four new ones, prostratols D-G. Structures were characterized by means of spectral data involving 2D NMR techniques.