Hyperforin is an important antidepressant constituent of Hypericum perforatum (St. John's wort). Cell cultures of the related species H. calycinum were found to contain the homologue adhyperforin and to a low extent hyperforin, when grown in BDS medium in the dark. Adhyperforin formation paralleled cell culture growth. Cell-free extracts from the cell cultures contained isobutyrophenone synthase activity catalyzing the condensation of isobutyryl-CoA with three molecules of malonyl-CoA to give phlorisobutyrophenone, i.e. the hyperforin skeleton. The formation of the hyperforins during cell culture growth was preceded by an increase in isobutyrophenone synthase activity. The cell cultures also contained benzophenone synthase and chalcone synthase activities which are involved in xanthone and flavonoid biosyntheses, respectively. The three type III polyketide synthases were separated by anion exchange chromatography.
"Hypericum perforatum has been intensively investigated throughout the world both chemically and pharmacologically (Farag and Wessjohann, 2012; Porzel et al., 2013). The genus Hypericum has been the source of diverse classes of bioactive phenolic and polyketide compounds (Klingauf et al., 2005). However, only a small proportion of the over 450 Hypericum species, other than the popular medicinal supplement "
[Show abstract][Hide abstract] ABSTRACT: Hypericum riparium A. Chev. is a Cameroonian medicinal plant belonging to the family Guttiferae. Chemical investigation of the methanol extract of the stem bark of H. riparium led to the isolation of four natural products, 7,7'-dihydroxy-6,6'-biscoumarin (1), 7,7'-dihydroxy-8,8'-biscoumarin (2), 7-methoxy-6,7'-dicoumarinyl ether (3), 2'-hydroxy-5'-(7 ''-methoxycoumarin-6 ''-yl)-4'-methoxyphenylpropanoic acid (4), together with one known 7,7'-dimethoxy-6,6'-biscoumarin (5), two flavones, 2'-methoxyflavone (6) and 3'-methoxy flavone (7), and two steroids, stigmast-4-en-3-one (8) and ergosta-4,6,8,22-tetraen-3-one (9). In addition, tetradecanoic acid (10), n-pentadecanoic acid (11), hexadecanoic acid (12), cis-10-heptadecenoic acid (13), octadecanoic acid (14) campesterol (15), stigmasterol (16), beta-sitosterol (17), stigmastanol (18), beta-eudesmol (19), 1-hexadecanol (20), and 1-octadecanol (21) were identified by GC-MS analysis. Compound 4 consists of a phenylpropanoic acid derivative fused with a coumarin unit, while compounds 2 and 3 are rare members of C8-C8' and C7-O-C6 linked biscoumarins. Their structures were elucidated by UV, IR, extensive 1D- and 2D-NMR experiments and electrospray (ESI) high resolution mass spectrometry (MS) including detailed MS/MS studies. This is the first report on the isolation of biscoumarins from the genus Hypericum, although simple coumarin derivatives have been reported from this genus in the literature. The cytotoxic activities of compounds 2-5 were evaluated against the human prostate cancer cell line PC-3 and the colon cancer cell line HT-29. They do not exhibit any significant cytotoxic activity.
"Specialized phytochemicals provide complex defense strategies to combat insects, fungi, animals or abiotic stressors, as well as attractants for pollination or dispersal. Such phytochemicals encompass tremendous structural diversity, from terpene alkaloids as in Digitalis purpurea (Chappell 2008), to polyketide alkylamides as in Echinacea (Wu et al. 2009), to waxes and scents (Fatland et al. 2002, Klingauf et al. 2005). Often, specialized metabolites are contained in discreet compartments. "
[Show abstract][Hide abstract] ABSTRACT: Species of the genus Hypericum contain a rich array of unusual polyketides, however, only a small proportion of the over 450 Hypericum species, other than the popular medicinal supplement St. John's Wort (H. perforatum), have even been chemically characterized. H. gentianoides, a small annual used medicinally by Cherokee Americans, contains bioactive acylphloroglucinols. Here, we identify acylphloroglucinol constituents of H. gentianoides and determine a potential pathway to their synthesis. Liquid chromatography/electrospray ionization-mass spectrometry (LC/ESI-MS) and HPLC-UV indicate that the level of accumulation and profile of acylphloroglucinols in H. gentianoides vary little seasonally when grown in a greenhouse, but do vary with development and are highly dependent on the accession, highlighting the importance of the selection of plant material for study. We identify the chemical structures of the nine prevalent polyketides, based on LC/ESI-MS and hybrid quadrupole orthogonal time-of-flight mass (Q-TOF) spectrometry; these metabolites include one monomeric phlorisobutyrophenone (PIB) derivative and eight dimeric acylphloroglucinols. Q-TOF spectrometry was used to identify eight additional PIB derivatives that were not detected by LC/ESI-MS. These data lead us to propose that diacylphloroglucinols are synthesized via modification of PIB to yield diverse phloroglucinol and filicinic acids moieties, followed by dimerization of a phloroglucinol and a filicinic acid monomer to yield the observed complement of diacylphloroglucinols. The metabolomics data from H. gentianoides are accessible in PMR (http://www.metnetdb.org/pmr), a public metabolomics database with analysis software for plants and microbial organisms.
Physiologia Plantarum 04/2013; 148(3). DOI:10.1111/ppl.12063 · 3.14 Impact Factor
"The biosynthesis of hyperforins can be divided into two phases of formation – carbon skeletons and prenyl side chains (Figure 4B) , , . This skeleton starts from one molecule of isobutyryl-CoA and three molecules of malonyl-CoA that undergo a condensation reaction catalyzed by type III PKS (known as isobutyrophenone synthase, or BUS). "
[Show abstract][Hide abstract] ABSTRACT: Hypericum perforatum L. (St. John's wort) is a medicinal plant with pharmacological properties that are antidepressant, anti-inflammatory, antiviral, anti-cancer, and antibacterial. Its major active metabolites are hypericins, hyperforins, and melatonin. However, little genetic information is available for this species, especially that concerning the biosynthetic pathways for active ingredients.
Using de novo transcriptome analysis, we obtained 59,184 unigenes covering the entire life cycle of these plants. In all, 40,813 unigenes (68.86%) were annotated and 2,359 were assigned to secondary metabolic pathways. Among them, 260 unigenes are involved in the production of hypericin, hyperforin, and melatonin. Another 2,291 unigenes are classified as potential Type III polyketide synthase. Our BlastX search against the AGRIS database reveals 1,772 unigenes that are homologous to 47 known Arabidopsis transcription factor families. Further analysis shows that 10.61% (6,277) of these unigenes contain 7,643 SSRs.
We have identified a set of putative genes involved in several secondary metabolism pathways, especially those related to the synthesis of its active ingredients. Our results will serve as an important platform for public information about gene expression, genomics, and functional genomics in H. perforatum.
PLoS ONE 07/2012; 7(7):e42081. DOI:10.1371/journal.pone.0042081 · 3.23 Impact Factor
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