BenzophenoneO-glycosides fromHypericum elegans

Phytochemical profiling of several Hypericum species identified using genetic markers

In the present study, we performed phytochemical profiling of several under-exploited Hypericum representatives taxonomically belonging to the sections Ascyreia, Androsaemum, Inodora, Hypericum, Coridium, Myriandra, and Adenosepalum. The authenticity of the starting plant material was confirmed using the nuclear ribosomal internal transcribed spacer as a molecular marker, DNA content and chromosome number. Phenolic constituents were analyzed using high-performance liquid chromatography to complement species-specific metabolic profiles. In several Hypericum representatives, the pharmacologically important compounds, including naphthodianthrones; phloroglucinol derivatives; chlorogenic acid; and some classes of flavonoids, particularly the flavonols rutin and hyperoside, flavanol catechin, and flavanones naringenin and naringin, were reported for the first time. Comparative multivariate analysis of chemometric data for seedlings cultured in vitro and acclimated to the outdoor conditions revealed a strong genetically predetermined interspecific variability in phenolic compound content. In addition to hypericins, which are the most abundant chemomarkers for the genus Hypericum, rarely employed phenolic metabolites, including phloroglucinol derivatives, chlorogenic acid, catechin, naringenin, naringin, and kaempferol-3-O-glucoside, were shown to be useful for discriminating between closely related species. Given the increasing interest in natural products of the genus Hypericum, knowledge of the spectrum of phenolic compounds in shoot cultures is a prerequisite for future biotechnological applications. In addition, phytochemical profiling should be considered as an additional part of the integrated plant authentication system, which predominantly relies upon genetic markers.

Phenolic constituents with neuroprotective activities from Hypericum wightianum

Five undescribed phenolic compounds, inclusing a depsidone derivative, hyperwightin A, a flavone derivative, hyperwightin B, and three benzophenone glycosides, hyperwightins C-E, along with four known ones were isolated from the 95% EtOH extract of the whole plants of Hypericum wightianum. Structures of the obtained compounds were elucidated by spectroscopic analyses. The protective effects of the isolates against corticosterone-induced PC12 cell injury were assessed. Hyperwightin E, petiolin G and hyperxanthone exhibited noticeable neuroprotection at 10 μM.

A new benzophenone glycoside from the leaves of Mitracarpus villosus

A new benzophenone glycoside, mitraphenone A (1), together with three known compounds (2-4) were isolated from the leaves of the traditionally used medicinal plant Mitracarpus villosus (Rubiaceae) collected in Nigeria. A combination of one- and two-dimensional NMR spectroscopic and mass spectrometric measurements were carried out to identify the structure of 1. All isolated compounds (1-4) were screened for their antibacterial activity against several Gram-positive and Gram-negative bacteria. Compound 1 exhibited moderate activity against Enterococcus faecium (strains ATCC 35667 and ATCC 700221) and Staphylococcus aureus ATCC 25923 with MIC values ranging from 25 to 50 μM.

Benzophenones from Hypericum elegans with antioxidant and acetylcholinesterase inhibitory potential

BACKGROUND

Hypericum elegans is used in Bulgarian folk medicine for treatment of wounds, depression, gastrointestinal and bacterial diseases.

OBJECTIVE

RECENTLY, NEW NATURAL BENZOPHENONES: Elegaphenone and O-glycosides: Hypericophenonoside, Neoannulatophenonoside and Elegaphenonoside as well as already known 7-Epiclusianone were isolated from the titled species. The aim of the present study was to evaluate the antioxidant and acetyl cholinesterase inhibitory potential of the isolated compounds.

MATERIALS AND METHODS

1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) di-ammonium salt (ABTS) free radicals, ferric reducing antioxidant power (FRAP) assay as well as inhibition of lipid peroxidation in linoleic acid system were used for determination of antioxidant activity. Modified Ellman's colorimetric method was carried out to assess the acetyl cholinesterase inhibition potential. Hyperoside and Galantamine hydrobromide were used as positive controls.

RESULTS

Hypericophenonoside was found to possess the strongest DPPH radical scavenging activity (IC50 = 181.85 ± 6.82 μM), while Neoannulatophenonoside showed the highest ABTS (IC50 = 0.25 ± 0.005 μM) and lipid peroxidation inhibitor activity. FRAP activity was demonstrated only by prenylated aglycones - Elegaphenone [942.16 ± 4.03 μM Trolox Equivalent (TE)] and 7-Epiclusianone (642.95 ± 3.95 μM TE) and was stronger compared to the control Hyperoside (421.75 ± 9.29 μM TE). Elegaphenone and 7-Epiclusianone were found to possess moderate acetyl cholinesterase inhibitory potential with IC50 values of 192.19 ± 3.54 μM and 142.97 ± 4.62 μM, respectively.

CONCLUSION

The results obtained revealed that H. elegans is a potential natural source of bioactive compounds and benzophenones could be useful in therapy of free radical pathologies and neurodegenerative disorders.

Benzophenone glycosides from Hypericum humifusum ssp. austral

Six new benzophenone glycosides, 2,3',4,5',6-pentahydroxybenzophenone 4-O-(6″-benzoyl)-β-d-glucopyranoside (1), 2,3',4,5',6-pentahydroxybenzophenone 4-O-β-d-glucopyranoside (2), 2,3',4,5',6-pentahydroxybenzophenone 2-O-(2″-benzoyl)-α-l-arabinopyranoside (3), 2,3',4,5',6-pentahydroxybenzophenone 2-O-α-l-arabinopyranoside (4), 2,3',4,5',6-pentahydroxybenzophenone 2-O-(4″-acetyl)-β-d-xylopyranoside (5), and 2,3',4,5',6-pentahydroxybenzophenone 3-C-(4″-benzoyl)-β-d-glucopyranoside (6), and five known compounds were isolated from the aerial parts of Hypericum humifusum ssp. austral. The structures of 1-6 were elucidated by mass spectrometry and extensive 1D and 2D NMR spectroscopy.

Studies on the synthesis and the antimicrobial and antioxidant activities of a novel class of fluorescein-based glycosides

Facile glycosylation of a fluorescein diol derivative with per-O-acetyl/benzoyl sugar derivatives using BF(3)·Et(2)O catalyst resulted in the formation of the expected glycosides in 54-66% yield. The biological screening of the glycosides against different microbes shows good inhibitory activity. The antioxidant activity of the fluorescein-based glycosides shows remarkable inhibition (IC(50) ∼80%).

Bioactive xanthones from the roots of Hypericum perforatum (common St John's wort)

BACKGROUND

Extracts of Hypericum perforatum L. (common St John's wort; Hypericaceae) are sold as phytopharmaceuticals and herbal supplements to treat mild to moderate depression and as food additives. Extensively cultivated in Europe, plants can be infected by anthracnose (Colletotrichum gloeosporioides), a virulent fungal pathogen that causes tissue necrosis and dramatically decreases crop value. Such infections triggered the production of new secondary metabolites, specifically xanthones, in cell culture experiments.

RESULTS

Bioassay-guided fractionation of H. perforatum root extracts, testing for growth inhibition of plant pathogenic fungi from the genera Colletotrichum, Botrytis, Fusarium and Phomopsis, was performed. In vitro anti-inflammatory activity through inhibition of COX-1, COX-2 and 5-LOX-catalyzed LTB(4) formation was also evaluated. Extracts were analyzed by various chromatographic means and structure elucidation was performed using data from nuclear magnetic resonance and mass spectrometry.

CONCLUSION

Researchers have previously described constituents from the aerial parts of this species, but few reports describe secondary metabolites found in underground parts, of particular interest because the lower stem and upper root are often sites of fungal infection. This work resulted in the isolation of three xanthones: 1,6-dihydroxy-5-methoxy-4',5'-dihydro-4',4',5'-trimethylfurano-(2',3':3,4)-xanthone; 4,6-dihydroxy-2,3-dimethoxyxanthone; and cis-kielcorin, one of which possessed novel bioactivity against species of Phomopsis and inhibited 5-LOX-mediated LTB(4) formation.