Identification and genetic analysis of the APOSPORY locus in Hypericum perforatum L.

The introduction of apomixis – seed formation without fertilization – into crop plants is a long‐held goal of breeding research, since it would allow for the ready fixation of heterozygosity. The genetic basis of apomixis, whether of the aposporous or the diplosporous type, is still only poorly understood. Hypericum perforatum (St John’s wort), a plant with a small genome and a short generation time, can be aposporous and/or parthenogenetic, and so represents an interesting model dicot for apomixis research. Here we describe a genetic analysis which first defined and then isolated a locus (designated HAPPY for H ypericum AP OSP ORY ) associated with apospory. Amplified fragment length polymorphism (AFLP) profiling was used to generate a cleaved amplified polymorphic sequence (CAPS) marker for HAPPY which co‐segregated with apospory but not with parthenogenesis, showing that these two components of apomixis are independently controlled. Apospory was inherited as a dominant simplex gene at the tetraploid level. Part of the HAPPY sequence is homologous to the Arabidopsis thaliana gene ARI7 encoding the ring finger protein ARIADNE7. This protein is predicted to be involved in various regulatory processes, including ubiquitin‐mediated protein degradation. While the aposporous and sexual alleles of the HAPPY component HpARI were co‐expressed in many parts of the plant, the gene product of the apomict’s allele is truncated. Cloning HpARI represents the first step towards the full characterization of HAPPY and the elucidation of the molecular mechanisms underlying apomixis in H. perforatum.     

Somatic embryogenesis and shoot regeneration from leaf derived callus of Hypericum perforatum var. angustifolium (sin. Fröhlich) Borkh

Abstract

The development of in vitro regeneration systems for Hypericum perforatum var. angustifolium (sin. Fröhlich) Borkh, a medicinal plant used for treating neurological disorders, is described. For the first time in this variety, somatic embryogenesis and shoot regeneration were induced from leaf-derived callus. Well-formed plantlets were obtained through both shoot regeneration and somatic embryogenesis, with separate morphogenetic programmes. Proembryogenic masses were obtained in liquid MS and B5 media supplemented with 5.8 μM 2,4-D, 1.34 μM NAA, and 1.16 μM Kin; after being transferred onto hormone-free medium, they formed whitish and spherical structures that subsequently developed into the heart and torpedo stages.

On MS agarized medium containing thidiazuron (TDZ) at different concentrations (3, 6, 9, 12 μM) combined with 2 μM IBA, only shoot regeneration, and not somatic embryogenesis, was obtained. The mean number of shoots increased significantly when the concentration of TDZ was 3 μM.     

Hyperforin promotes mitochondrial function and development of oligodendrocytes

St. John's wort has been found to be an effective and safe herbal treatment for depression in several clinical trials. However, the underlying mechanism of its therapeutic effects is unclear. Recent studies show that the loss and malfunction of oligodendrocytes are closely related to the neuropathological changes in depression, which can be reversed by antidepressant treatment. In this study, we evaluated the effects of hyperforin, a major active component of St. John's wort, on the proliferation, development and mitochondrial function of oligodendrocytes. The study results revealed that hyperforin promotes maturation of oligodendrocytes and increases mitochondrial function without affecting proliferation of an oligodendrocyte progenitor cell line and neural stem/progenitor cells. Hyperforin also prevented mitochondrial toxin-induced cytotoxicity in an oligodendrocyte progenitor cell line. These findings suggest that hyperforin may stimulate the development and function of oligodendrocytes, which could be a mechanism of its effect in depression. Future in vitro and in vivo studies are required to further characterize the mechanisms of hyperforin.     

Hyperforin and its analogues inhibit CYP3A4 enzyme activity

Literature indicates that herb-drug interaction of St. John's wort is largely due to increased metabolism of the co-administered drugs that are the substrates of cytochrome P450 (CYP) 3A4 enzyme, alteration of the activity and/or expression of the enzyme. The major St. John's wort constituents, acylphloroglucinols, were evaluated for their effects on CYP3A4 enzyme activity to investigate their roles in herb-drug interaction. Hyperforin and four oxidized analogues were isolated from the plant and fully characterized by mass spectral and NMR analysis. These acylphloroglucinols inhibited activity of CYP3A4 enzyme potently in the fluorometric assay using the recombinant enzyme. Furoadhyperforin (IC(50) 0.072 microM) was found to be the most potent inhibitor of CYP3A4 enzyme activity, followed by furohyperforin isomer 1 (IC(50) 0.079 microM), furohyperforin isomer 2 (IC(50) 0.23 microM), hyperforin (IC(50) 0.63 microM) and furohyperforin (IC(50) 1.3 microM). As the acylphloroglucinols are potent inhibitors of the CYP3A4 enzyme, their modulation of the enzyme activity is unlikely to be involved in increased drug metabolism by St. John's wort.     

Karyotype Analysis of Hypericum Perforatum L.

A karyotype study was made on Hypericum perforatum using plants differentiated in vitro with different ploidy level. The chromosomes of this species are small, morphologically similar, median and submedian. In the basic chromosome set the most distinguishable is chromosome number 1 which was subjected to detail analysis. It was found that there are two types of this chromosome which contribute differentially in diploid, triploid and tetraploid plants.     

Influence of Hypericum perforatum extract and its single compounds on amyloid-beta mediated toxicity in microglial cells

As immunocompetent cells of the brain, microglia are able to counteract the damaging effects of amyloid-beta in Alzheimer's disease by phagocytosis-mediated clearance of protein aggregates. The survival and health of microglia are therefore critical for attenuating and preventing neurodegenerative diseases. In a microglial cell line pretreated with St. John's wort (Hypericum perforatum L.) extract (HPE), the cell death evoked by treatment with amyloid-beta (25-35) and (1-40) was attenuated significantly in a dose-dependent manner. Investigation of the single compounds in the extract revealed that the flavanols (+)-catechin and (-)-epicatechin increase cell viability slightly, whereas the flavonol quercetin and its glycosides rutin, hyperosid and quercitrin showed no effect on cell viability. In contrast, at the same concentration, the flavonoids reduced the formation of amyloid-induced reactive oxygen species in microglia, indicating that improvement of cell viability by the catechins is not correlated to the antioxidant activity. No influence of HPE on the capacity of microglia to phagocytose sub-toxic concentrations of fibrillar amyloid-beta (1-40) was observed. Other experiments showed that HPE, (+)-catechin and (-)-epicatechin can alter cellular membrane fluidity and thereby may have a beneficial effect on cell health. Our findings provide in vitro evidence that treatment especially with the complex plant extract HPE may restore or improve microglial viability and thereby attenuate amyloid-beta mediated toxicity in Alzheimer's disease.     

Simultaneous determination of total hypericin and hyperforin in St. John's wort extracts by HPLC with electrochemical detection

An analytical procedure was developed for the simultaneous determination of total hypericin (protopseudohypericin, pseudohypericin, protohypericin and hypericin) and hyperforin in Hypericum perforatum (St. John's wort) extracts and its preparations. The determination of total hypericin and hyperforin in one step was achieved by exposing the samples to artificial daylight in amber glass vials. This procedure allows both the photoconversion of the protoforms into the appropriate hypericins and the protection of the photosensitive hyperforin. For quantification, an HPLC method with electrochemical detection was applied. As an example of the application of the principle, two preparations containing St. John's wort were assayed.     

The biodiversity of predominant lactic acid bacteria in dolo and pito wort for the production of sorghum beer

AIM: To quantify and identify the predominant lactic acid bacteria (LAB) in dolo and pito wort processing, and to examine their biodiversity at strain level. MATERIALS AND RESULTS: The processing of dolo and pito wort was studied at four production sites in Burkina Faso and Ghana. The succession of dominant micro-organisms, pH and titratable acidity were determined from sorghum malt through mashing and acidification to final wort. In the sorghum malt and during mashing, the LAB counts were 5.7-7.5 log CFU g(-1). Similar levels of yeasts and gram-negative, catalase-positive bacteria were observed. These levels decreased to 3.7-4.5 log CFU g(-1) and相似文献   

Preliminary Study of Fat Oxidation in Sorghum and Maize Brewing

Superoxide dismutase (SOD) activity in the white sorghum farafara and ICRISAT sorghum variety – ICSV 400 was at a high activity in the embryo at about 8 SOD units/tissue. This activity was almost completely destroyed at 80 °C. Totox index of the brewing grains were 366 for ICSV 400, 312 for farafara, 112 for maize grits and 90 for barley malt. Worts from sorghum/maize and sorghum/barley malt brews all had hydroperoxy linoleic acid (15–19 μM) which remained undetected after wort boiling. Sorghum/maize brews formed very little trub (wort proteinous sediments) in the whirlpool and trub increased in sorghum/barley brews with increased usage of barley malt. Sorghum/maize brews had free fatty acids (FFA) at 22 mg/l in pitching wort but in sorghum/barley brew (50/50) only 9 mg/l. This revised version was published online in July 2006 with corrections to the Cover Date.