Phenolic constituents from Grevillea robusta.

Seven phenolic compounds were isolated from a MeOH extract of the leaves of Grevillea robusta. Their structures were determined by various spectral methods including 2D NMR spectroscopy.

Anti-HIV-1 phorbol esters from the seeds of Croton tiglium.

Five phorbol diesters, together with three known ones, were isolated from a MeOH extract of the seeds of Croton tiglium, and their structures were determined by spectroscopic methods and selective hydrolysis of acyl groups. These compounds were assessed for their abilities to inhibit an HIV-induced cytopathic effect (CPE) on MT-4 cells and to activate protein kinase C (PKC) associated with tumor-promoting action. 12-O-Acetylphorbol-13-decanoate and 12-O-decanoylphorbol-13-(2-methylbutyrate) effectively inhibited the cytopathic effect of HIV-1 [complete inhibitory concentration (IC100) values of 7.6 ng/ml and 7.81 microg/ml, and minimum cytotoxic concentration (CC0) value of 62.5 and 31.3 microg/ml, respectively]; however, 12-O-acetylphorbol-13-decanoate showed no activation of PKC at concentrations of 10 and 100 ng/ml. 12-O-Tetradecanoylphorbol-13-acetate (TPA) was found to be not only the most potent inhibitor of HIV-1-induced CPE (IC100 value of 0.48 ng/ml), but also the most potent activator of PKC (100% activation at 10 ng/ml).

Anti-HIV-1 and anti-HIV-1-protease substances from Ganoderma lucidum.

A new highly oxygenated triterpene named ganoderic acid alpha has been isolated from a methanol extract of the fruiting bodies of Ganoderma lucidum together with twelve known compounds. The structures of the isolated compounds were determined by spectroscopic means including 2D-NMR. Ganoderiol F and ganodermanontriol were found to be active as anti-HIV-1 agents with an inhibitory concentration of 7.8 micrograms ml-1 for both, and ganoderic acid B, ganoderiol B, ganoderic acid C1, 3 beta-5 alpha-dihydroxy-6 beta-methoxyergosta-7,22-diene, ganoderic acid alpha, ganoderic acid H and ganoderiol A were moderately active inhibitors against HIV-1 PR with a 50% inhibitory concentration of 0.17-0.23 mM.

Iridoids from Phlomis aurea Decne growing in Egypt.

A new iridoid gentiobioside (4, assigned the name phlomiside) was isolated from the leaves of Phlomis aurea growing in Egypt, in addition to auroside (1), lamiide (2), 8-epi-loganin (3), forsythoside B (5), quercetin-3-O-beta-D-glucopyranoside (6) and kaempferol-3-O-beta-D-glucopyranosyl-(1-6)-beta-D-glucopyranoside (7). Structures of these compounds were elucidated by conventional methods of analysis as well as by different spectroscopic techniques.

Biotransformation of (-)-epicatechin 3-O-gallate by human intestinal bacteria.

The biotransformation of (-)-epicatechin 3-O-gallate (1) and related compounds was undertaken using a human fecal suspension. Of fifteen metabolites isolated, four compounds were new, namely, two epimers of 1-(3'-hydroxyphenyl)-3-(2",4".6"-trihydroxyphenyl)propan-2-ols (6, 19); 2",3"-dihydroxyphenoxyl 3-(3',4'-dihydroxyphenyl)propionate (14) and 1-(3',4'-dihydroxyphenyl)-3-(2",4",6"-trihydroxyphenyl)propan-2-ol (18). (-)-Epicatechin (2), (-)-epigallocatechin (16) and their 3-O-gallates (1, 17) were extensively metabolized by a human fecal suspension after incubation for 24 h, whereas the gallates (1, 17) resisted any degradation by a rat fecal suspension, even after a prolonged incubation time (48 h), suggesting a difference in metabolic ability between two intestinal bacterial mixtures from different species.

Metabolism and pharmacokinetics of orally administered saikosaponin b1 in conventional, germ-free and Eubacterium sp. A-44-infected gnotobiote rats.

The metabolic fate of saikosaponin b1 (1) was investigated using conventional, germ-free and Eubacterium sp. A-44-infected gnotobiote rats. After the oral administration of 1 to germ-free rats at a dose of 50 mg/kg, no metabolite was detected in the plasma, the cecal contents or the cumulative feces through the experiment. On the other hand, when 1 was orally given to the Eubacterium sp. A-44-infected gnotobiote rats, considerable amounts of its metabolites, prosaikogenin A (2) and saikogenin A (3), were detected in the rat plasma with the respective AUC0-10 h values of 17,424 and 22,260 pmol.min/ml, similar to the case of its oral administration to conventional rats (AUC0-10 h values of 9,936 and 12,414 pmol.min/ml for 2 and 3, respectively). Furthermore, significant amounts of both metabolites were detected in the cecal contents and the cumulative feces of the gnotobiote and conventional rats, but not in those of the germ-free rats, within 10 h after the administration. Fecal and cecal activities of hydrolyzing 1 and 2 were found in the gnotobiote and conventional rats, though there were no detectable activities in the germ-free rats. Accordingly, both hydrolyzing activities in the intestinal bacteria, such as Eubacterium sp. A-44, are essential for the appearance of 2 and 3 in the rat plasma and cumulative feces, since orally administered 1 was poorly absorbed from the gastrointestinal tract.

Enzymes responsible for the metabolism of saikosaponins from Eubacterium sp. A-44, a human intestinal anaerobe.

From a human intestinal bacterium, Eubacterium sp. A-44, which is capable of hydrolyzing saikosaponins to saikogenins, two glycosidases, beta-D-glucosidase and a novel type of beta-D-fucosidase, were isolated and characterized as saikosaponin-hydrolyzing beta-D-glucosidase and prosaikogenin-hydrolyzing beta-D-fucosidase. Relative to the hydrolyzing activities toward saikosaponins a, b1 and b2, the beta-D-glucosidase showed lower ability to hydrolyze saikosaponin d, but no ability to hydrolyze saikosaponin c or prosaikogenins. By Sephacryl S-300 column chromatography, the molecular weight of prosaikogenin-hydrolyzing beta-D-fucosidase was estimated to be about 130 kDa. The beta-D-fucosidase could hydrolyze prosaikogenins A and F, but not prosaikogenins D and G or saikosaponins. Relative to p-nitrophenyl beta-D-fucoside-hydrolyzing activity, this enzyme had 32.0% and 22.2% of its hydrolyzing ability toward p-nitrophenyl beta-D-glucoside and p-nitrophenyl beta-D-galactoside, respectively. p-Nitrophenyl beta-D-fucoside-hydrolyzing activity was inhibited by D-fucose, and was weakly inhibited by D-glucose, D-glucono delta-lactone, D-galactose and D-galactono delta-lactone. By combining these two glycosidases, saikosaponins a and b1 were converted to their saikogenins via the corresponding prosaikogenins.

Effect of tinctormine on contraction and Ca(2+) currents in single cardiac myocytes from dog.

Effect of tinctormine (TIN) on the contractile response and Ca(2+) currents (lea) were investigated in dispersed single canine ventricular myocytes. Contraction were measured by a video-edge detector and Ca(2+) currents were recorded using the whole-cell voltage clamp technique. TIN in low concentrations (10(-7)M) selectively reduced the contractile response in single ventricular cells by 50% of the control without affecting Ica. These inhibitory effects of the contractile response showed concentration-dependency and were reversible. However, TIN in high concentrations (10(-5)M) reduced the peak Ca(2+) currents by 42% of the controls and completely inhibited the contractile response in single myocytes. These inhibitory effects on lea were concentration-dependent. These results assumed that tinctormine exerts a negative inotropic effect which is mediated in part through reduction of the peak Ca(2+) currents and possibly also due to inhibition of the Na(+)-Ca(2+) exchange process and/or inhibition of the Ca(2+) release from the sarcoplasmic reticulum (SR).

Metabolism of strychnine N-oxide and brucine N-oxide by human intestinal bacteria.

Anaerobic incubation of strychnine N-oxide with human intestinal bacteria resulted in its transformation to strychnine and 16-hydroxystrychnine. Similarly, brucine N-oxide was transformed to brucine and 16-hydroxybrucine.

12-O-acetylphorbol-13-decanoate potently inhibits cytopathic effects of human immunodeficiency virus type 1 (HIV-1), without activation of protein kinase C.

Through bioactivity-guided fractionation, eight phorbol diesters, including five new ones (1-5), were isolated from the seeds of Croton tiglium collected in Egypt. 12-O-Acetylphorbol-13-decanoate (6) and 12-O-decanoylphorbol-13-(2-methylbutyrate) (4) potently inhibited the HIV-1-induced cytopathic effect on MT-4 cells (IC100 values of 7.6 ng/ml and 7.81 micrograms/ml, and CC0 values of 62.5 micrograms/ml and 31.3 micrograms/ml, respectively) without activating protein kinase C.

Human intestinal bacteria capable of transforming secoisolariciresinol diglucoside to mammalian lignans, enterodiol and enterolactone.

Seven metabolites were isolated after anaerobic incubation of secoisolariciresinol diglucoside (1) with a human fecal suspension. They were identified as (-)-secoisolariciresinol (2), 3-demethyl-(-)-secoisolariciresinol (3), 2-(3-hydroxybenzyl)-3-(4-hydroxy-3-methoxybenzyl)butane-1,4-diol (4), didemethylsecoisolariciresinol (5), 2(3-hydroxybenzyl)-3-(3,4-dihydroxybenzyl)butane-1,4-diol (6), enterodiol (7) and enterolactone (8). Furthermore, two bacterial strains, Peptostreptococcus sp. SDG-1 and Eubacterium sp. SDG-2, responsible for the transformation of 1 to a mammalian lignan 7, were isolated from a human fecal suspension. The former transformed 2 to 3 and 5, as well as 4 to 6, and the latter transformed 5 to 6 and 7.

Biotransformation of a C-glycosylflavone, abrusin 2''-O-beta-D-apioside, by human intestinal bacteria.

After anaerobic incubation of abrusin 2''-O-beta-D-apioside (1) with a human fecal suspension, five metabolites were isolated and identified as abrusin (2), 1-(2',6'-dihydroxy-3',4'-dimethoxyphenyl)-3-(4''-hydroxyphenyl)propan-1- one (5), 5,6-dimethoxybenzene-1,3-diol (6), 3-(4'-hydroxyphenyl)propionic acid (7) and 3-phenylpropionic acid (8). However, methyl ether derivatives of abrusin (4'-O-methylabrusin and 4'-O-, 5-O-dimethylabrusin) resisted degradation under the same conditions.

Two new quinochalcone yellow pigments from Carthamus tinctorius and Ca2+ antagonistic activity of tinctormine.

Two new quinochalcone C-glycosides, hydroxysafflor yellow A (1a) and tinctormine (2a), were isolated from Carthamus tinctorius L. (Compositae) together with carthamin, safflor yellow B and safflomin C. The structures of 1a and 2a have been determined by spectroscopic methods including heteronuclear multiple-bond multiple-quantum coherence and linked scan FAB-MS. The latter compound (2a) was demonstrated to have potent Ca2+ antagonistic action.

Inhibitory effects of Egyptian folk medicines on human immunodeficiency virus (HIV) reverse transcriptase.

Extracts of 41 medicinal plants used in Egyptian folk medicine were screened for their inhibitory effects on human immunodeficiency virus-1 reverse transcriptase. The extracts of fruits of Phyllanthus emblica, Quercus pedunculata, Rumex cyprius, Terminalia bellerica, Terminalia chebula and Terminalia horrida showed significant inhibitory activity with IC50 < or = 50 micrograms/ml. Through a bioassay guided-fractionation of the methanol extract of the fruit of P. emblica, putranjivain A (1) was isolated as a potent inhibitory substance with IC50 = 3.9 microM, together with 1,6-di-O-galloyl-beta-D-glucose (2), 1-O-galloyl-beta-D-glucose (3), kaempferol-3-O-beta-D-glucoside (4), quercetin-3-O-beta-D-glucoside (5) and digallic acid (6). The inhibitory mode of action by 1, 2 and 6 was non-competitive with respect to the substrate but competitive with respect to a template-primer. Furthermore, the stereochemistry of 1 was established in this paper by nuclear magnetic resonance spectroscopy.

PIP: The fundamental role played by reverse transcriptase (RT) in the replication of retroviruses has made this enzyme a key target in the chemotherapy of HIV infection. Since the replicative cycle of HIV is interrupted by RT inhibitors, the inhibition of HIV RT is currently considered as a useful approach in the prophylaxis and intervention of AIDS. The MeOH and water extracts of 41 medicinal plants used in Egyptian folk medicine were evaluated for their HIV-1 RT inhibitory effects, and inhibitory substances were identified from the fruit of Phyllanthus emblica that showed a potent inhibitory activity to HIV-1-RT. The enzyme activity was determined by the amount of tritium labeled-substrate incorporation into a polymer fraction in the presence of a template-primer. Of the plant materials tested, the fruits of Phyllanthus emblica L. (MeOH extract), Quercus pedunculata (MeOH and water extracts), Rumex cyprius (MeOH and water extracts), Terminalia bellerica (MeOH and water extracts), Terminalia chebula (MeOH and water extracts), and Terminalia horrida (MeOH extract) showed significant inhibitory activity with IC50 of 2-49 mcg/ml. However, in the presence of bovine serum albumin (BSA), the inhibitory potency of most of the extracts, except for P. emblica (MeOH extract) and T. chebula (water extract), was appreciably reduced by nonspecific binding of their ingredients with BSA. Through a bioassay guided-fractionation of the methanol extract of the fruit of P. emblica, putranjivain A (1) was isolated as a potent inhibitory substance with IC50 = 3.9 mcM, together with 1,6-di-O-galloyl-beta-D-glucose (2), 1-O-galloyl-beta-D-glucose (3), kaempferol-3-O-beta-D-glucoside (4), quercetin-3-O-beta-D-glucoside (5), and digallic acid (6). The inhibitory mode of action by 1, 2, and 6 was noncompetitive with respect to the substrate but competitive with respect to a template-primer. Furthermore, the stereochemistry of 1 was established in this paper by nuclear magnetic resonance spectroscopy.

In vivo antiviral activity of Stephania cepharantha against herpes simplex virus type-1.

The antiviral activity of a MeOH extract of Stephania cepharantha (root tubers), its CHCl3-soluble fraction (alkaloid fraction) and the major alkaloid FK-3000 (1) were investigated in BALB/c mice cutaneously infected with HSV-1 strain 7401H. At doses of 125 and 250 mg/kg body weight, p.o., the MeOH extract significantly delayed skin lesion on score 2 (vesicles in the local region), limited the development of further lesions on score 6 (mild zosteriform lesion) and prolonged the mean survival time of HSV-1 infected mice. After p.o. administration of the CHCl3-soluble fraction at doses of 25 and 50 mg/kg or FK-3000 (1) at 10 and 25 mg/kg, similar results were obtained. Although the alkaloid improved the survival of infected mice, it had a narrow therapeutic index.

The heterocyclic ring fission and dehydroxylation of catechins and related compounds by Eubacterium sp. strain SDG-2, a human intestinal bacterium.

A human intestinal bacterium, Eubacterium (E.) sp. strain SDG-2, was tested for its ability to metabolize various (3R)- and (3S)-flavan-3-ols and their 3-O-gallates. This bacterium cleaved the C-ring of (3R)- and (3S)-flavan-3-ols to give 1,3-diphenylpropan-2-ol derivatives, but not their 3-O-gallates. Furthermore, E. sp. strain SDG-2 had the ability of p-dehydroxylation in the B-ring of (3R)-flavan-3-ols, such as (-)-catechin, (-)-epicatechin, (-)-gallocatechin and (-)-epigallocatechin, but not of (3S)-flavan-3-ols, such as (+)-catechin and (+)-epicatechin.

Four mono-tetrahydrofuran ring acetogenins, montanacins B-E, from Annona montana.

Four novel mono-tetrahydrofuran (THF) acetogenins, montanacins B-E (1-4), were isolated from the ethanolic extract of the leaves of Annona montana. The structures of 1-4 were established by spectroscopic methods and their absolute stereochemistries were determined by the advanced Mosher ester method. Montancins D (3) and E (4) bear a non-adjacent tetrahydropyran (THP) ring along with a THF ring and are the most unusual type of acetogenins discovered so far.

Effects of paeoniflorin derivatives on scopolamine-induced amnesia using a passive avoidance task in mice; structure-activity relationship.

Paeoniflorin (1) and its derivatives having in common a cage-like pinane skeleton with hemiketal-acetal system, were evaluated for their effects on memory impairment induced by scopolamine in mice using a step-down type passive avoidance task. In the test session, 1 and its derivatives were intraperitoneally (i.p.) administered at doses of 0.002, 0.01, 0.02 and 0.2 mmol/kg, and 30 min later (15 min before the experiment), scopolamine (1 mg/kg, i.p.) was given. These compounds showed dose-dependent attenuation in a dose range of 0.002-0.02 mmol/kg and also enhancement of scopolamine-induced decrease in step-down latency. The effects of these compounds, except that of 2',3',4',5'-O-tetraacetyl-3-O-methylpaeoniflorin (8), followed a bell-shaped dose response profile. 8-Debenzoyl-6-deglucosyl-3-O-methylpaeoniflorin (6) showed no significant increase in the step-down latency at all tested doses. Maximum step-down latency was obtained by 3-O-methylpaeoniflorin (3) and 2',3,3',4',5'-penta-O-methylpaeoniflorin (7) (the minimal effective dose was 0.002 mmol/kg). Relative to 3, debenzoylation, as in 8-debenzoyl-3-O-methylpaeoniflorin (4), slightly increased the latency, while deglucosylation, as in 6-deglucosyl-3-O-methylpaeoniflorin (5), significantly reduced the prolongation of latency. Removal of both glucose and benzoyl moieties resulted in the loss of activity as seen in 6. These results revealed that, in addition to the cage-like pinane skeleton, the benzoyl and the glucosyl moieties are important structural elements of the paeoniflorin skeleton as its effects on scopolamine-induced amnesia.

Anticonvulsant activity of paeonimetabolin-I adducts obtained by incubation of paeoniflorin and thiol compounds with Lactobacillus brevis.

Seventeen thiopaeonimetabolin-I adducts were obtained as mixtures of diastereoisomers after incubation of paeoniflorin with Lactobacillus brevis in the presence of various thiols. The anticonvulsant activity of the adducts was investigated in mice using the maximal subcutaneous pentylenetetrazol seizure test and sodium valproate (1.5 mmol/kg) as a positive control. Thirteen adducts showed dose-dependent prolongation of latencies of clonic and tonic convulsions. Maximal protection against convulsions was effectively demonstrated by 8-(n-hexylthio)paeonimetabolin I (8) and 8-benzoylthiopaeonimetabolin I (18) at doses of 0.125 and 0.25 mmol/kg, respectively, while 100% protection was only achieved at 0.5 mmol/kg of 8-cyclopentylthiopaeonimetabolin I and 8-(p-tolylthio)paeonimetabolin I. The principal anticonvulsant activity of the diastereoisomers of 8 and 18 was attributed to their 7S-isomers [ED50 values of 0.09 and 0.12 mmol/kg, and protective indices of 5.0 and 4.0 for 8 (7S) and 18 (7S), respectively], while the 7R counterparts [8 (7R) and 18 (7R)] showed a muscle relaxation effect.

Potent anticonvulsant paeonimetabolin-I derivatives obtained by incubation of paeoniflorin and thiol compounds with Lactobacillus brevis.

Seventeen thiopaeonimetabolin-I adducts were obtained as mixtures of diastereoisomers after incubation of paeoniflorin with Lactobacillus brevis in the presence of various thiols. Four compounds, 8-(n-hexylthio)- (8), 8-cyclopentylthio-, 8-(p-tolyl)thio- and 8-benzoylthio- (18) paeonimetabolins, showed 100% protection against pentylenetetrazole-induced convulsions at doses of 0.125, 0.25, or 0.50 mmol/kg, relative to valproic acid (100% protection at 1.5 mmol/kg). For 8 and 18, the principle anticonvulsant activity resided in the (7S)-isomers while (7R)-isomers showed muscle relaxation effects.