Experimental study platform for electrocatalysis of atomic-level controlled high-entropy alloy surfaces.

High-entropy alloys (HEAs) have attracted considerable attention to improve performance of various electrocatalyst materials. A comprehensive understanding of the relationship between surface atomic-level structures and catalytic properties is essential to boost the development of novel catalysts. In this study, we propose an experimental study platform that enables the vacuum synthesis of atomic-level-controlled single-crystal high-entropy alloy surfaces and evaluates their catalytic properties.

Enhanced electrochemical hydrogen oxidation reaction and suppressed hydrogen peroxide generation properties on Pt/Ir(111) bimetallic surfaces.

Simultaneous accomplishment of high hydrogen oxidation reaction (HOR) activity and suppressed hydrogen peroxide (HO) generation is desired for anode catalysts of polymer electrolyte fuel cells. 0.3 monolayer-thick-Pt-deposited Ir(111) showed three-fold higher HOR activity than Pt(111) and suppressed HO generation under the detection limit, providing insights for effective catalyst development.

Hydrogen peroxide generation and hydrogen oxidation reactions of vacuum-prepared Ru/Ir(111) bimetallic surfaces.

From the viewpoint of the application of Ir-Ru alloys for the anode of proton exchange membrane fuel cells (PEMFCs), hydrogen peroxide (HO) generation and the hydrogen oxidation reaction (HOR) properties of well-defined Ir-Ru bimetallic surfaces (Ru/Ir(111)) have been investigated using scanning electrochemical microscopy (SECM). Using thermal inter-diffusion of vacuum-deposited Ru and substrate Ir atoms, the topmost surface atomic ratios of Ru/Ir(111) were controlled changing the substrate temperature () during the deposition of 1 monolayer (ML)-thick Ru. Low-energy ion scattering spectroscopy (LE-ISS) estimated the Ru/Ir ratio to be 1 : 1 ( = 673 K), 1 : 2 ( = 773 K), and 1 : 4 ( = 873 K).

Studies on Nepalese crude drugs. XXIX. Chemical constituents of Dronapuspi, the whole herb of Leucas cephalotes SPRENG.

From the whole herb of Leucas cephalotes SPRENG., new labdane-, norlabdane- and abietane-type diterpenes named leucasdins A (1), B (2) and C (3), respectively, and two protostane-type triterpenes named leucastrins A (4) and B (5) were isolated, together with a known triterpene, oleanolic acid, five sterols, 7-oxositosterol, 7-oxostigmasterol, 7alpha-hydroxysitosterol, 7alpha-hydroxystigmasterol and stigmasterol, and eight flavones, 5-hydroxy-7,4'-dimethoxyflavone, pillion, gonzalitosin I, tricin, cosmosin, apigenin 7-O-beta-D-(6-O-p-coumaroyl)glucopyranoside, anisofolin A and luteolin 4'-O-beta-D-glucuronopyranoside. The structures of 1--5 were determined as (3S,6R,8R,9R,13S,16S)-9,13,15,16-bisepoxy-3,16-diacetoxy-6-formyloxylabdane, (3S,6R)-3-acetoxy-6-formyloxy-iso-ambreinolide, (4R,9S,12R,13R)-12,13-dihydroxyabiet-7-en-18-oic acid, (3S,17S,20S,24S)-3,20-dihydroxy-24-methylprotost-25-en, and (3S,17S,20S,24S)-3,20,24-trihydroxyprotost-25-en respectively, based on spectral and chemical data.

Studies on the constituents of Scutellaria species (XXII). Constituents of the roots of Scutellaria amabilis HARA.

From the roots of Scutellaria amabilis HARA, eleven new flavonoids, 5,7,2'-trihydroxy-8-methoxyflavone 7-O-beta-D-glucopyranoside, 5,7,2'-trihydroxy-8-methoxyflavone 2'-O-beta-D-glucopyranoside, 5,7-dihydroxy-8,2'-dimethoxyflavone 7-O-beta-D-glucopyranoside, 5,7,2'-trihydroxyflavone 2'-O-beta-D-glucopyranoside, 5,7,2',5'-tetrahydroxyflavone 7-O-beta-D-glucuronopyranoside, (2S)-5,7,2',5'-tetrahydroxyflavanone, (2S)-5,7,2',5'-tetrahydroxyflavanone 7-O-beta-D-glucopyranoside, (2S)-5,7,2',5'-tetrahydroxyflavanone 7-O-beta-D-glucuronopyranoside, (2S)-7,2'-dihydroxy-5-methoxyflavanone 7-O-beta-D-glucuronopyranoside, (I-2S)-I-5,II-5,I-7,II-7,I-2',II-2',II-5'-heptahydroxy-[I-6,II-6']-flavanonylflavone and (I-2S)-I-5,II-5,I-7,II-7,I-2',II-2',I-5',II-5'-octahydroxy-[I-6,II-6']-flavanonylflavone, were isolated, together with ten known flavonoids, wogonin (5,7-dihydroxy-8-methoxyflavone), 5,7-dihydroxy-8,2'-dimethoxyflavone, (2S)-5,7,2'-trihydroxyflavanone, scutevulin (5,7,2'-trihydroxy-8-methoxyflavone), 5,7,4'-trihydroxy-8-methoxyflavone, alpinetin ((2S)-7-hydroxy-5-methoxyflavanone), 5,7,2'-trihydroxyflavone, 5,7,2',5'-tetrahydroxyflavone, (2S)-7,2'-dihydroxy-5-methoxyflavanone and 5,7-dihydroxy-8,2'-dimethoxyflavone 7-O-beta-D-glucuronopyranoside. The structures were determined on the basis of chemical and spectral data.

Studies on nepalese crude drugs. XXVIII. Chemical constituents of Bhote Khair, the underground parts of Eskemukerjea megacarpum HARA.

From the underground parts of Eskemukerjea megacarpum HARA, two new stilbenes (14, 15) were isolated, together with a known coumarin, 5,7-dihydroxycoumarin (1), a tyramine derivative, trans-feruloyltyramine (2), two pyrogallol derivatives, gallic acid (3) and beta-glucogallin (4), four flavonoids, trifolin (5), hyperin (6), myricetin 3-O-beta-D-galactopyranoside (7), and myricitrin (8), five stilbenes, resveratorol (9), astringenin (10), piceid (11) astringin (12), and resveratorol 3-O-beta-D-(6-O-galloyl)glucopyranoside (13), a flavan-3-ol, (-)-epigallocatechin 3-O-gallate (16), two proanthocyanidins, catechin-(4alpha-->8)-epigallocatechin 3-O-gallate (17) and epicatechin 3-O-gallate-(4beta-->8)-epigallocatechin 3-O-gallate (18), and an anthocyanin, idaein (19). Compounds 14 and 15 were identified as (E)-3,5,3',4'-tetrahydroxystilbene 3-O-beta-D-(6-O-galloyl)glucopyranoside and (E)-3,5,4'-trihydroxystilbene 3-O-beta-D-(6-O-galloyl)glucopyranoside, respectively, based on spectral and chemical data.

Studies on the constituents of Clematis species. VIII. Triterpenoid saponins from the aerial part of Clematis tibetana KUNTZ.

From the aerial part of Clematis tibetana, two new hederagenin 3,28-O-bisdesmosides called clematibetosides A and C, and a new gypsogenin 3,28-O-bisdesmoside called clematibetoside B, have been isolated together with ten known saponins. The structures of the new saponins have been elucidated based on chemical and spectral evidence as follows: clematibetoside A, 3-O-(2-O-caffeoyl)-beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->4)-beta-D-ribopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl hederagenin 28-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyraside; clematibetoside B, 3-O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl gypsogenin 28-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside; clematibetoside C, 3-O-beta-D-ribopyranosyl hederagenin 28-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside.

[On the constituents and biological activities of some Nepalese medicinal plants].

The chemical constituents of medicinal plants which have been used in Ayurvedic and Tibetan system of medicines in Nepal were examined. From 21 species consisting of 13 genera of the plants, 121 new compounds, whose structures are shown in Charts (1 to 13), were isolated mainly in our laboratory. Some of the compounds and their related ones showed several biological activities.

Studies on the constituents of Clematis species. VII. Triterpenoid saponins from the roots of Clematis terniflora DC. var. robusta Tamura.

From the roots of Clematis terniflora, nine new oleanolic acid 3,28-O-bisdesmosides called clematernosides A, B, E, F, G, H, I, J and K, and two new hederagenin 3,28-O-bisdesmosides called clematernosides C and D, have been isolated together with two known saponins, huzhangoside B and clematichinenoside C. The structures of the new saponins have been elucidated based on chemical and spectral evidence. Among the new spaonins, clematernosides I and J have a nonasaccharide moiety and a total of twelve monosaccharide moieties in the molecule.

Enhancement of in vivo anti-influenza virus activity of 5,7,4'-trihydroxy-8-methoxyflavone by drug delivery system using hydroxypropyl cellulose.

Enhancement of in vivo antiviral activity of 5,7,4'-trihydroxy-8-methoxyflavone (F36) against H3N2 subtype of influenza A virus by drug delivery system (DDS) with hydroxypropyl cellulose (HPC) was studied. Although in the absence of HPC F36 (0.5 mg/kg) showed no antiviral activity against mouse-adapted influenza virus A/Guizhou/54/89 (H3N2) in mice, when F36 solution containing HPC was administered intranasally 5 min after the virus inoculation, proliferation of the virus in both nasal and broncho-alveolar cavities was inhibited significantly.

Specific alpha-galactosidase inhibitors, N-methylcalystegines--structure/activity relationships of calystegines from Lycium chinense.

An examination of the roots of Lycium chinense (Solanaceae) has resulted in the discovery of 14 calystegines, a cycloheptane bearing an amino group and three hydroxyl groups, and two polyhydroxylated piperidine alkaloids. Calystegines A7 and B5, in addition to the previously known calystegines A3, A5, A6, B1, B2, B3, B4, C1, C2 and N1, were isolated and determined as 1alpha,2beta,4alpha-trihydroxy-nortropane and 1alpha,2alpha,4alpha,7alpha-tetrahydroxy-nort ropane, respectively. L.

Studies on the constituents of Clematis species. VI. The constituents of Clematis stans Sieb. et Zucc.

From the roots of Clematis stans three new oleanane-type triterpenoid saponins named clemastanoside A, B and C, and two new lignan glycosides named clemastanin A and B, have been isolated together with three known triterpenoid saponins, huzhangoside B, C and D, and three known lignan glycosides, (+)-lariciresinol 4-O-beta-D-glucopyranoside, (+)-lariciresinol 4'-O-beta-D-glucopyranoside and (+)-pinoresinol 4,4'-O-bis-beta-D-glucopyranoside. In addition, from the leaves, four new oleanane-type triterpenoid saponins, named clemastanoside D, E, F and G, have been isolated together with five known triterpenoid saponins, hederasaponin B, kizutasaponin K12, huzhangoside B, sieboldianoside B and huzhangoside D, and three known flavonoids, isoquercitrin, rutin and quercetin 3-O-beta-D-glucuronopyranoside. The structures of the new compounds were elucidated based on chemical and physicochemical evidence as follows: clemastanoside A, 3-O-beta-D-ribopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl-(1-->2)-a lpha-L- arabinopyranosyl oleanolic acid 28-O-(4-O-acetyl)-alpha-L-rhamnopyranosyl-(1-->4)-beta-D- glucopyranosyl-(1-->6)-beta-D-glucopyranosyl ester (terminal rhamnosyl 4-O-acetate of huzhangoside B); clemastanoside B and C, 3-O-beta-D-xylopyranosyl- and 3-O-beta-D-ribopyranosyl-(1-->3)-alpha-L- rhamnopyranosyl-(1-->2)-beta-D-galactopyranosyl oleanolic acid 28-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl- (1-->6)-beta-D-glucopyranosyl ester, respectively; clemastanoside D, 3-O-beta-D-ribopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl- (1-->2)-alpha-L-arabinopyranosyl hederagenin 28-O-beta-D-glucopyranosyl ester; clemastanoside E, F and G, terminal rhamnosyl 4-O-, 3-O- and 2-O-acetate of 3-O-beta-D-ribopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl-(1-->2)-a lpha-L- arabinopyranosyl hederagenin 28-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta- D- glucopyranosyl ester, respectively; clemastanin A, (7S,8R)-3-methoxy-3',4,9,9'-tetrahydroxy-4',7-epoxy-5',8-lignan 3'-O-beta-D-glucopyranoside; clemastanin B, (+)-lariciresinol 4,4'-O-bis-beta-D-glucopyranoside.

Antiviral activity of plant flavonoid, 5,7,4'-trihydroxy-8-methoxyflavone, from the roots of Scutellaria baicalensis against influenza A (H3N2) and B viruses.

We investigated effects of isoscutellarein-8-methylether (5,7,4'-trihydroxy-8-methoxyflavone, F36) from the roots of Scutellaria baicalensis on the single-cycle replication of mouse-adapted influenza viruses A/Guizhou/54/89 (H3N2 subtype) and B/Ibaraki/2/85 in Madin-Darby canine kidney (MDCK) cells. The agent suppressed replication of these viruses from 6 to 12 h after incubation in a dose-dependent manner by 50% at 20 microM and 90% at 40 microM, respectively. F36 (50 microM) reduced the release of B/Ibaraki virus in the medium by 90-93% when it was added to the MDCK cells at 0 to 4 h after incubation.

Mode of action of the anti-influenza virus activity of plant flavonoid, 5,7,4'-trihydroxy-8-methoxyflavone, from the roots of Scutellaria baicalensis.

When mouse-adapted influenza virus A/PR/8/34 (A/PR8) (10 PFU/cell) was adsorbed to Madin-Darby canine kidney (MDCK) cells at 4 degrees C for 1 h and incubated at 37 degrees C, release of the virus from the cells was detected in the medium from 4 h after incubation and reached to plateau at 8 h. However, 5,7,4'-trihydroxy-8-methoxyflavone (F36) from the roots of Scutellaria baicalensis significantly reduced this single-cycle replication of A/PR8 from 4 h to 12 h after incubation by dose-dependent manner and the dose which decrease the virus titer one tenth was 11 microM. F36 (50 microM) did not inhibit the adsorption of A/PR8 to MDCK cells, but reduced release of the virus in the medium, when it was added at 0 or 2 h after the incubation.

[Studies on the Nepalese crude drugs. XIX. On the flavonoid and phenylethanoid constituents of the root of Scutellaria repens Buch.-Ham. ex D. Don].

From the root of Scutellaria repens Buch.-Ham ex D. Don, two new flavonoids (10, 11) and three new phenylethanoids (12-14) were isolated, together with nine known compounds.

[Studies on the Nepalese crude drugs. XVII. On the naphthalene related compounds from the root bark of Oroxylum indicum VENT].

Nine new naphthalene related compounds (I, IV, V, VII-XII) together with four known compounds (II, III, VI, XIII) were isolated from the root bark of Oroxylum indicum Vent. (Bignoniaceae), one of the Nepalese crude drugs. Their structures were determined based on chemical and physiocochemical evidence.

[Studies on the constituents of Scutellaria species. XV. On the diterpenoid constituents of the leaves of Scutellaria alpina L].

From the leaves of Scutellaria alpina L., four new neo-clerodane diterpenes (1-4) were isolated. The structures of 1-4 were shown to be (4S)-19-acetoxy-8 beta-hydroxy-6 alpha-benzoyloxy-4,18-epoxy-neo-cleroda-11,13- dien-15,16-olide, (4S)-19-acetoxy-8 beta-hydroxy-6 alpha-tigloyloxy-4,18-epoxy-neo-cleroda-11,13- dien-15,16-olide, (4S, 11S)-11-acetoxy-8 beta,19-dihydroxy-6 alpha-tigloyloxy-4,18-epoxy-neo- clerod-13-en-15,16-olide, and (4S)-19-acetoxy-8 beta-hydroxy-6 alpha, 7 beta-dibenzoyloxy-4,18-epoxy-neo- cleroda-11,13-dien-15,16-olide, respectively, by the chemical and spectral data.

[Studies on the constituents of the leaves of Phellodendron japonicum Maxim].

From the leaves of Phellodendron japonicum Maxim. (Rutaceae), six new flavonoid glycosides (I-VI) were isolated, together with eight known compounds. The structures of I-VI were shown to be 8-prenyl-3,4',5-trihydroxy-flavone 7-O-beta-D-(6-O-malonyl) glucopyranoside, (2R,3R)-8-prenyl-3,4',5-trihydroxyflavanone 7-O-beta-D-(6-O-malonyl) glucopyranoside, 8-[(S)-2,3-dihydroxy-3-methylbutyl]-3,4',5-trihydroxyflavone 7-O-beta-D-glucopyranoside, 8-[(R)-2,3-dihydroxy-3-methylbutyl]-3,4',5-trihydroxyflavone 7-O-beta-D-glucopyranoside (2R,3R)-8-[(S)-2,3-dihydroxy-3-methylbutyl]-3,4',5-trihydroxyflavanon e 7-O-beta-D-glucopyranoside and (2R,3R)-8-[(R)-2,3-dihydroxy-3-methylbutyl]-3,4',5-trihydroxyflavanon e 7-O-beta-D-glucopyranoside, respectively, on the basis of the chemical and spectral data.

[Structure-activity relationship of flavonoids in suppressing rat liver lipid peroxidation].

145 flavonoids were studied for their inhibitory effects on the iron-induced lipid peroxidation in mitochondria obtained from rat livers. Of these compounds tested, 30, 57, 59, 67, 70, 72, 77, 102 and 110 (ED50 < or = 0.5 nmol/mg prot) showed distinctly more potent inhibitory activity than baicalein (ED50 < or = 5 nmol/mg prot) and 59 and 72 (ED50 < or = 0.

In vivo anti-influenza virus activity of plant flavonoids possessing inhibitory activity for influenza virus sialidase.

Isoscutellarein (5,7,8,4'-tetrahydroxyflavone) from the leaf of Scutellaria baicalensis non-competitively inhibited (IC50, 20 microM) the hydrolysis of sodium p-nitrophenyl-N-acetyl-alpha-D-neuraminate by influenza virus sialidase with an apparent Ki value of 41 microM. Negligible inhibitory activity was observed for mouse liver sialidase at a concentration of 79 microM. Isoscutellarein also inhibited the replication of influenza virus A/WSN/33 in Madin-Darby bovine kidney cells with 50% virus inhibitory dose at 16 nmol/well and influenza virus A/PR/8/34 in the allantoic sac of embryonated egg with little toxic effects.

Inhibition of influenza virus sialidase and anti-influenza virus activity by plant flavonoids.

Flavonoids (103 species) were tested for inhibitory activity against influenza virus sialidase using sodium p-nitrophenyl-N-acetyl-alpha-D-neuraminate as substrate. 5,7,4'-Trihydroxy-8-methoxyflavone from the root of Scutellaria baicalensis showed the most potent activity (IC50, 55 microM), and this flavone appeared to be a non-competitive inhibitor of the enzyme. Whereas, negligible or weak inhibitory activities were observed for mouse liver sialidase, beta-galactosidase and alpha-mannosidase as tested.

Inhibition of mouse liver sialidase by plant flavonoids.

Flavonoids (103 species) were tested for inhibitory activity against mouse liver sialidase using sodium p-nitrophenyl-N-acetyl-alpha-D-neuraminate (PNP-NeuAc) as substrate. Isoscutellarein-8-O-glucuronide from the leaf of Scutellaria baicalensis showed most potent activity (IC50, 40 microM), and this flavone appeared to be a non-competitive inhibitor of the enzyme. This flavone inhibited the lysosomal solubilized sialidase against PNP-NeuAc and sialyllactose effectively, but not microsomal enzyme against gangliosides and colominic acid, whereas, negligible or weak inhibitory activities were observed for influenza virus sialidase, beta-galactosidase, alpha-mannosidase, and alpha-glucosidase tested.

Inhibition of adenosine 3',5'-cyclic monophosphate phosphodiesterase by flavonoids. III.

Sixty-one flavanones, twenty-six isoflavones and eight other flavonoids, obtained from Sophora tomentosa, S. flavescens, Scutellaria baicalensis and other medicinal plants or synthesized, were tested for their inhibitory activity against adenosine 3',5'-cyclic monophosphate (cAMP) phosphodiesterase from beef heart. The structure-activity relationships were investigated.