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The series of naturally occurring proanthocyanidins with 7,8-dihydroxylated A-rings is extended by identification of the proteracacinidins... more
The series of naturally occurring proanthocyanidins with 7,8-dihydroxylated A-rings is extended by identification of the proteracacinidins epioritin-(4beta-->6)-oritin-4alpha-ol, epioritin-(4beta-->6)-ent-oritin-4alpha-ol, ent-oritin-(4beta-->6)-epioritin-4alpha-ol, ent-oritin-(4beta-->6)-oritin-4alpha-ol, ent-oritin-(4alpha-->6)-epioritin-4alpha-ol, ent-oritin-(4alpha-->6)-oritin-4alpha-ol, ent-oritin-(4alpha-->6)-epioritin-4beta-ol, the 'mixed' pro-teracacinidins/-melacacinidins epioritin-(4beta-->6)-epimesquitol-4alpha-ol, epioritin-(4beta-->6)-epimesquitol-4beta-ol and epimesquitol-(4beta-->6)- epioritin-4alpha-ol, and the promelacacinidin epimesquitol-(4beta-->6)-epimesquitol-4beta-ol.
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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full... more
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
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The biflavanone (2S,2"S)-7,7"-di-O-methyltetrahydroamentoflavone and five known flavonoids, 7-O-methylnaringenin, 7,3'-O-dimethylquercetin, 7-O-methylapigenin,... more
The biflavanone (2S,2"S)-7,7"-di-O-methyltetrahydroamentoflavone and five known flavonoids, 7-O-methylnaringenin, 7,3'-O-dimethylquercetin, 7-O-methylapigenin, 7-O-methylluteolin, and eriodictyol were isolated from the leaves of Rhus retinorrhoea Steud, Ex Olive. The biflavanone exhibited moderate antimalarial activity with IC50 0.98 microg/ml against Plasmodium falciparum (W2 Clone) and weak activity against P. falciparum (D6 Clone) with IC50 2.8 microg/ml. Nevertheless, it did not display any cytotoxicity. 7-O-Methylnaringenin showed weak antimicrobial activity against Candida albicans, C. krusei, Staphylococcus aureus, Mycobacterium smegmatis, M. intracellulare, and M. xenopi with MIC approximately 100 microg/ml. Characterization of each compound was based on spectral analysis and comparison with reported data.
Research Interests: Microbiology, Phytochemistry, Biology, Flavonoids, Medicine, and 15 moreBiological Sciences, Mycobacterium, Spectral analysis, Animals, Candida, Antimicrobial activity, Candida albicans, Antimicrobial, CHEMICAL SCIENCES, Spectrum analysis, Plasmodium falciparum, Antimalarials, Microbial Sensitivity Tests, Molecular Structure, and Medical and Health Sciences
Procyanidin B‐3 (I) is subjected to readily occurring C‐ring isomerizations in alkaline buffer solution to form the novel tetrahydropyranochromene (II) and a series of flavanylbenzopyrans (III) and (IV), in which the C‐2 pyrocatechol and... more
Procyanidin B‐3 (I) is subjected to readily occurring C‐ring isomerizations in alkaline buffer solution to form the novel tetrahydropyranochromene (II) and a series of flavanylbenzopyrans (III) and (IV), in which the C‐2 pyrocatechol and C‐4 (+)‐catechin moieties are interchanged relative to their positions in the biflavanoid (I) (most yields in g; isolation of the compounds as their methyl or acetyl derivatives).
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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full... more
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
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Additional members of the class of natural phlobatannins, resulting from stereoselective C-ring isomerization of the 2,3-trans-3,4-cis-flavan-3-ol moieties in the (4β,6:4β,8)-bis-fisetinidol-catechin triflavanoid have been identified from... more
Additional members of the class of natural phlobatannins, resulting from stereoselective C-ring isomerization of the 2,3-trans-3,4-cis-flavan-3-ol moieties in the (4β,6:4β,8)-bis-fisetinidol-catechin triflavanoid have been identified from natural sources. These comprise three functionalized hexahydrodipyrano[2,3-f:2′,3′-h]-chromenes and a fisetinidol-(4β,10)-tetrahydropyrano[2,3-f]chromene. The complex structures of these novel natural condensed tannins were confirmed by synthesis via base-catalysed pyran rearrangement of the 4-O(E)-methyl ether of their postulated biogenetic
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Research Interests: Chemistry, Biology, Macrophages, Polymers, Flavonoids, and 15 moreMedicine, Polyphenols, Mice, Nitric oxide, Animals, Phenols, Nitric Oxide Synthase, Recombinant Proteins, Extracellular, Bone Marrow Cells, Interferon gamma, Macrophage activation, Pharmacology and pharmaceutical sciences, Nitric oxide synthase type II, and Leishmania donovani
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Recent years have witnessed considerable development toward an understanding of the intricate principles governing the chemistry of oligomeric proanthocyanidins. These developments were initiated by the growing realization of the... more
Recent years have witnessed considerable development toward an understanding of the intricate principles governing the chemistry of oligomeric proanthocyanidins. These developments were initiated by the growing realization of the industrial importance of the proanthocyanidins, which is based upon their interactions with key molecules in the biological domain. Despite the surprisingly limited array of carbon-carbon and carbon-oxygen bonds in the heterocycles of proanthocyanidin oligomers, a rich variety of ingenious protocols aimed at manuevering these bonds in a controlled mode has emerged over the past 10–15 years. These studies blend with the heavy focus on the formation and rupture of the interflavanyl bond(s), which played such a decisive role in the structural elucidation of proanthocyanidin oligomers during the seventies and early eighties. Methodologies to chemically exploit the heterocyclic bonds are highly relevant to progress in the chemistry of these important and intriguing biomolecules and constitute the subject of this review.
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Procyanidin B‐3 (I) is subjected to readily occurring C‐ring isomerizations in alkaline buffer solution to form the novel tetrahydropyranochromene (II) and a series of flavanylbenzopyrans (III) and (IV), in which the C‐2 pyrocatechol and... more
Procyanidin B‐3 (I) is subjected to readily occurring C‐ring isomerizations in alkaline buffer solution to form the novel tetrahydropyranochromene (II) and a series of flavanylbenzopyrans (III) and (IV), in which the C‐2 pyrocatechol and C‐4 (+)‐catechin moieties are interchanged relative to their positions in the biflavanoid (I) (most yields in g; isolation of the compounds as their methyl or acetyl derivatives).
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Enantiopure (scalemic) flavonoid monomers such as permethoxylated chalcone epoxides and dihydroflavonols are available via HPLC resolution of the racemates using a Chiralpack OT(+) column. Depending on the oxygenation pattern, epoxy... more
Enantiopure (scalemic) flavonoid monomers such as permethoxylated chalcone epoxides and dihydroflavonols are available via HPLC resolution of the racemates using a Chiralpack OT(+) column. Depending on the oxygenation pattern, epoxy chalcones can also be prepared in enantiomeric purity up to 96 percent by the utilization of synthetic poly(peptide) or cinchona alkaloid catalyzed epoxidation with hydrogen peroxide, aqueous sodium hypochlorite, or tert-butyl hydroperoxide. Transformation of these oxiranes into dihydroflavonols and ultimately flavan-3,4-diols without ‘loss’ in optical purity is possible by treatment with hydrogen chloride in absolute methanol, followed by sodium borohydride reduction. Direct catalytic hydrogenation of the epoxides leads to α-hydroxydihydrochalcones of comparable enantiomeric purity that can be used for determination of the absolute configuration of naturally occurring analogues by comparison of CD data.
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Mirabilis multiflora is an acclaimed hallucinogen consumed traditionally by the Hopi Indians to induce diagnostic visions. Its root extract afforded a new (3) and four known (2, 5, 6, and 7) 12a-hydroxyrotenoids, a known rotenoid (4), and... more
Mirabilis multiflora is an acclaimed hallucinogen consumed traditionally by the Hopi Indians to induce diagnostic visions. Its root extract afforded a new (3) and four known (2, 5, 6, and 7) 12a-hydroxyrotenoids, a known rotenoid (4), and two known secondary metabolites (1 and 8). The structures of the compounds were elucidated based on spectroscopic and spectrometric data analysis. Electronic circular dichroism data were used to define the (6aS,12aR) absolute configuration of the 12a-hydroxyrotenoids. Compounds 2-7 were screened for their radioligand binding affinities toward the opioid (δ, κ, and μ) and cannabinoid (CB1 and CB2) receptor subtypes. The 6-methoxy-substituted rotenoids 3, 4, and 7 showed the highest receptor binding affinity with moderate selectivity toward the δ-opioid receptor subtype, with negligible binding affinities for CB1 and CB2. Their binding affinities toward the δ-opioid receptor were 64.5% (4), 58.7% (7), and 55.3% (3) at 10 μM, respectively.
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... dimeric profisetinidins5'6 and appropriate 4-arylflavan-3-ol model compounds7, and is summarized in Scheme I for the fisetinidol-(413,8)- catechin mono-O-methyl ... SL Bonnet, JP Steynberg, BCB Bezuidenhoudt, CM Saunders and D.... more
... dimeric profisetinidins5'6 and appropriate 4-arylflavan-3-ol model compounds7, and is summarized in Scheme I for the fisetinidol-(413,8)- catechin mono-O-methyl ... SL Bonnet, JP Steynberg, BCB Bezuidenhoudt, CM Saunders and D. Ferreira, Phylochemistry, 1995, in the ...
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ABSTRACT Asymmetric dihydroxylation of a series of poly-O-methoxymethyl-1,3-diarylpropenes with AD-mix-α or AD-mix-β and subsequent acid-catalyzed cyclization of the intermediate syn-diols permits the first synthetic access to all four... more
ABSTRACT Asymmetric dihydroxylation of a series of poly-O-methoxymethyl-1,3-diarylpropenes with AD-mix-α or AD-mix-β and subsequent acid-catalyzed cyclization of the intermediate syn-diols permits the first synthetic access to all four diastereoisomers of free phenolic flavan-3-ols in high enantiomeric excess and yield.
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Nine new glucosyloxybenzyl 2-hydroxy-2-isobutylsuccinates, pleionosides M-U (1-9), and 12 known compounds (10-21) were isolated from the pseudobulbs of Pleione yunnanensis. Their structures and absolute configurations were established... more
Nine new glucosyloxybenzyl 2-hydroxy-2-isobutylsuccinates, pleionosides M-U (1-9), and 12 known compounds (10-21) were isolated from the pseudobulbs of Pleione yunnanensis. Their structures and absolute configurations were established through a combination of HRESIMS and NMR data and supported by physical and chemical methods. Compounds 5, 6, 10, and 15 showed significant in vitro hepatoprotective activity against d-galactosamine (d-GalN)-induced toxicity in HL-7702 cells with increasing cell viability by 27%, 22%, 19%, and 31% compared to the model group (cf. bicyclol, 14%) at 10 μM, respectively. Compounds 4, 9, and 11 exhibited moderate hepatoprotective activity against N-acetyl-p-aminophenol (APAP)-induced toxicity in HepG2 cells with increasing cell viability by 9%, 16%, and 12% compared to the model group (cf. bicyclol, 9%) at 10 μM, respectively.
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Research Interests: Biophysics, Chemistry, Inorganic Chemistry, Developmental Biology, Natural Products, and 15 moreCancer, Medicine, Biological Sciences, Circular Dichroism, Data, Ms, Analogue, CHEMICAL SCIENCES, Configuration, Hepatoprotective, Dichroism, Combination, Lignan, Compound, and Medical and Health Sciences
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Two new ether-linked proanthocyanidins, epioritin-(4beta-->3)-epioritin-4beta-ol and epimesquitol-(4beta-->4)-epioritin-4beta-ol, were isolated from the heartwood of Acacia caffra. Their structures and absolute... more
Two new ether-linked proanthocyanidins, epioritin-(4beta-->3)-epioritin-4beta-ol and epimesquitol-(4beta-->4)-epioritin-4beta-ol, were isolated from the heartwood of Acacia caffra. Their structures and absolute configurations were established by spectroscopic methods and syntheses.
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Twelve new dimeric sesquiterpenoids (1-12) were isolated from the dried whole plants of Artemisia rupestris. Their structures were determined using MS and NMR data, and the absolute configurations were elucidated on the basis of... more
Twelve new dimeric sesquiterpenoids (1-12) were isolated from the dried whole plants of Artemisia rupestris. Their structures were determined using MS and NMR data, and the absolute configurations were elucidated on the basis of experimental and calculated ECD spectra. Compounds 1-9 are presumably formed via biocatalyzed [2+2] or [4+2] cycloaddition reactions. Stereoselectivity of the [4+2] Diels-Alder reaction dictated the formation of endo-products. The dimeric sesquiterpenoids exhibited moderate inhibition on NO production stimulated by lipopolysaccharide in BV-2 microglial cells, with IC50 values in the range 17.0-71.8 μM.
Research Interests: Chemistry, Natural Products, Medicine, Cycloaddition reactions, Biological Sciences, and 13 moreMice, Nitric oxide, Animals, Microglia, Stereochemistry, Artemisia, Sesquiterpenes, CHEMICAL SCIENCES, Lipopolysaccharides, Absolute Configuration, Minimum inhibitory concentration, Molecular Structure, and Medical and Health Sciences
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Research Interests: Chemistry, Natural Products, Macrophages, Medicine, Biological Sciences, and 15 moreMice, Nitric oxide, Animals, Stereochemistry, Vitex negundo, CHEMICAL SCIENCES, Lipopolysaccharides, Molecular Conformation, Vitex, Oleanolic acid, Molecular Structure, Plant Leaves, Terpenoid, Triterpenoid, and Medical and Health Sciences
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The cytochrome P450 enzyme, CYP1B1, is an established target in prostate cancer chemoprevention. Compounds inhibiting CYP1B1 activity are contemplated to exert beneficial effects at three stages of prostate cancer development, that is,... more
The cytochrome P450 enzyme, CYP1B1, is an established target in prostate cancer chemoprevention. Compounds inhibiting CYP1B1 activity are contemplated to exert beneficial effects at three stages of prostate cancer development, that is, initiation, progression, and development of drug resistance. Pomegranate ellagitannins/microbial metabolites were examined for their CYP1B1 inhibitory activity in a recombinant CYP1B1-mediated ethoxyresorufin-O-deethylase (EROD) assay. Urolithin A, a microbial metabolite, was the most potent uncompetitive inhibitor of CYP1B1-mediated EROD activity, exhibiting 2-fold selectivity over CYP1A1, while urolithin B was a noncompetitive inhibitor with 3-fold selectivity. The punicalins and punicalagins exhibited potent CYP1A1 inhibition with 5-10-fold selectivity over CYP1B1. Urolithins, punicalins, and punicalagins were tested for their 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced CYP1 inhibitory activity in the 22Rv1 prostate cancer cell line. Urolithins A and B showed a decrease in their CYP1-mediated EROD inhibitory IC50 values upon increasing their treatment times from 30 min to 24 h. Urolithin C, 8-O-methylurolithin A, and 8,9-di-O-methylurolithin C caused a potent CYP1-mediated EROD inhibition in 22Rv1 cells upon 24 h of incubation. Neutral red uptake assay results indicated that urolithin C, 8-O-methylurolithin A, and 8,9-di-O-methylurolithin C induced profound cytotoxicity in the proximity of their CYP1 inhibitory IC50 values. Urolithins A and B were studied for their cellular uptake and inhibition of TCDD-induced CYP1B1 expression. Cellular uptake experiments demonstrated a 5-fold increase in urolithin uptake by 22Rv1 cells. Western blots of the CYP1B1 protein indicated that the urolithins interfered with the expression of CYP1B1 protein. Thus, urolithins were found to display a dual mode mechanism by decreasing CYP1B1 activity and expression.
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The consumption of pomegranate products leads to a significant accumulation of ellagitannins in the large intestines, where they interact with complex gut microflora. This study investigated the effect of pomegranate tannin constituents... more
The consumption of pomegranate products leads to a significant accumulation of ellagitannins in the large intestines, where they interact with complex gut microflora. This study investigated the effect of pomegranate tannin constituents on the growth of various species of human gut bacteria. Our results showed that pomegranate byproducts and punicalagins inhibited the growth of pathogenic clostridia and Staphyloccocus aureus. Probiotic lactobacilli and bifidobacteria were generally not affected by ellagitannins, while relatively small growth inhibition by ellagic acid likely resulted from decreasing media quality due to the formation of tannin-protein complexes. The effect of pomegranate ellagitannins on bifidobacteria was species- and tannin-dependent. The growth of Bifidobacterium animalis ssp. lactis was slightly inhibited by punicalagins, punicalins, and ellagic acid. POMx supplementation significantly enhanced the growth of Bifidobacterium breve and Bifidobacterium infantis.