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. This is the first report of the isolation and structure elucidation of such "big" glycosides.

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. chinense also had two polyhydroxytropanes bearing a methyl group on the nitrogen atom, unlike the previously reported nortropane alkaloids. They were established as N-methylcalystegines B2 and C1, and their N-methyl groups were found to be axially oriented from NOE experiments. 1Beta-amino-3beta,4beta,5alpha-trihydroxycyclohepta ne was also present in L. chinense and may be a biosynthetic precursor of the calystegines that occur in this plant. Two polyhydroxypiperidine alkaloids, fagomine and 6-deoxyfagomine, were isolated. Calystegine B2 is a potent competitive inhibitor of almond beta-glucosidase (Ki = 1.9 microM) and coffee bean alpha-galactosidase (Ki = 0.86 microM), while N-methylcalystegine B2 was a more potent competitive inhibitor of the latter enzyme (Ki = 0.47 microM) than the parent compound but showed a marked lack of inhibitory activities towards most other glycosidases. Since this compound is a very specific inhibitor of alpha-galactosidase and inhibits rat liver lysosomal alpha-galactosidase with a Ki of 1.8 microM, it may provide a useful experimental model for the lysosomal storage disorder, Fabry's disease. The addition of a hydroxyl group at C6exo, as in calystegines B1 and C1, enhances the inhibitory potential towards beta-glucosidase and beta-galactosidase but markedly lowers or abolishes inhibition towards alpha-galactosidase. Hence, the N-methylation of calystegine C1 did not enhance its inhibition of alpha-galactosidase. The chemical N-methylation of calystegines A3 and B4 markedly enhanced inhibition of coffee bean alpha-galactosidase, with Ki values of 5.2 microM and 36 microM, respectively, but almost eliminated their inhibitory potential towards beta-glucosidase and trehalase, respectively. Thus, methylation of the nitrogen atom significantly altered the specificity of the inhibitors.

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. The relationship between concentration (0.2-0.5%) and deposition ratio of HPC was studied. When 10 microliters of fluorescein isothiocyanate (FITC)-conjugated HPC solution was administered intranasally to BALB/c mice, deposition ratio of HPC at 6 h after inoculation in nasal cavity was dependent on its concentration. The deposition ratio of HPC in broncho-alveolar cavity, however, was reversely dependent on its concentration. Anti-influenza virus activity of F36 in nasal and broncho-alveolar cavities was dependent both on the concentration and deposition ratio of HPC. HPC was most effective at 0.5% in nasal cavity and at 0.3% in broncho-alveolar cavity. These results indicate that DDS with HPC enhances the anti-influenza virus activity of F36 in vivo.

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. The cell-associated virus determined by sialidase activity was also reduced by the treatment at 0 to 4 h. F36 (120 microM) inhibited the low pH-dependent membrane fusion of both the viruses with the liposome containing mixed gangliosides from bovine brain. However, the agent little affected the hemagglutination and RNA-dependent RNA polymerase activities of these viruses in vitro. These results suggest that F36 inhibits the replication of A/Guizhou and B/Ibaraki viruses at least partly by inhibiting the fusion of viral envelopes with the endosome/lysosome membrane which occurs at the early stage of the virus infection cycle. F36 (0.5 mg/kg) showed no antiviral activity against A/Guizhou and B/Ibaraki viruses in mice when administered intranasally 5 min prior to virus inoculation, whereas it significantly inhibited their proliferation in the mouse lung when administered intranasally 7 times (total 3.5 mg/kg) from 18 h before to 54 h after virus infection.

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. The cell-associated virus determined by sialidase activity was also reduced by F36 treatment at 0 or 2 h. F36 also inhibited the fusion of A/PR8 with liposomes containing bovine brain mixed gangliosides at pH 5.0. However, F36 little affected on the elongation activity of the viral RNA-dependent RNA polymerase in vitro. These results suggest that F36 reduces the replication of A/PR8 by inhibiting the fusion of the virus with endosome/lysosome membrane which occurs at early stage of virus infection cycle. Whereas, when F36 was added to the MDCK cells infected with A/PR8 at 3 or 4 h after incubation, release of the virus in the medium was reduced but the cell-associated virus was increased in comparison with control.(ABSTRACT TRUNCATED AT 250 WORDS)

[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. The structures of 10-14 were shown to be 5,7,2'-trihydroxy-6,8-dimethoxyflavone, O-5-hydroxy-6,8-dimethoxyflavone-7-yl beta-D-glucuronopyranoside, O-2-(3-hydroxy-4-methoxyphenyl)ethyl O-2,3-di-O-acethyl-alpha-L-rhamnopyranosyl- (1-->3)-(4-O-trans-feruloyl)-beta-D-glucopyranoside, O-2-(3-hydroxy-4-methoxyphenyl)ethyl O-alpha-L-rhamnopyranosyl-(1-->3)-(4-O-cis-feruloyl)-beta-D-glu cop yranoside and O-2-(3-hydroxy-4-methoxyphenyl)-ethyl O-2,3-di-O-acethyl-alpha-L-rhamnopyranosyl- (1-->3)-(4-O-cis-feruloyl)-beta-D- glucopyranoside, respectively, on the basis of the chemical and spectral data.

[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 = 0.05 nmol/mg prot) exhibited the most potent activity. In order to elucidate the relationships between substituents on the flavonoid skeleton and the biological activity, the quantitative structure-activity relationships (QSAR) were analyzed by the adaptive least-squares (ALS) method for 142 flavonoids. The analysis has shown that the presence of the 1,4- and 1,2-hydroquinone in A-ring and/or B-ring of flavonoids and hydrophobicity of the molecule are responsible for the in vitro inhibitory activity.

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. The flavone showed significant anti-influenza virus activity in vitro similar to isoscutellarein-8-methylether (F36) (Nagai, T., Miyaichi, Y., Tomimori, T., Suzuki, Y. and Yamada H., 1990, Chem. Pharm. Bull. 38, 1329-1332), and more potent virucidal activity in ovo than F36. However, F36 completely prevented proliferation of mouse-adapted influenza virus A/PR/8/34 in mouse lung by the intranasal (0.5 mg/kg) and intraperitoneal (4 mg/kg) administrations, and it was more potent than the known anti-influenza virus substance, amantadine. Intranasal administration of F36 (0.5 mg/kg) also protected mice against a lethal influenza virus A/PR/8/34 infection. Isoscutellarein significantly inhibited lung virus proliferation when administered intranasally or orally to mice. F36 and isoscutellarein showed negligible toxic effect against mice. These results suggested that flavones, which have potent influenza virus sialidase inhibitory activity, have anti-influenza virus activity in vivo.

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. This flavone also inhibited the infection by influenza virus A/PR/8/34 of Madin-Darby canine kidney cells, and replication of the virus in the allantoic sack of embryonated egg. These results suggest that flavone, which has potent influenza virus sialidase inhibitory activity, may have anti-influenza virus activity.

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. These results indicate that this flavone may be useful to elucidate the function of the lysosomal solubilized sialidase.

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.

Metabolism of homoorientin by human intestinal bacteria.

As a part of our studies on the metabolism of bioactive compounds from oriental medicines by intestinal flora, homoorientin, a C-glycosylflavonoid, was anaerobically incubated with a human intestinal bacterial mixture. Homoorientin was transformed to 6-C-glucosyleriodictyol, (+/-)-eriodictyol, luteolin, 3,4-dihydroxyphenylpropionic acid, and phloroglucinol. A novel cleavage of the C-glycosyl bond was discovered for the first time by using intestinal bacteria.