Dataset Information

Biogeographic variation in genetic variability, apomixis expression and ploidy of St. John's wort (Hypericum perforatum) across its native and introduced range.

ABSTRACT:

Background and aims

St. John's wort (Hypericum perforatum) is becoming an important model plant system for investigations into ecology, reproductive biology and pharmacology. This study investigates biogeographic variation for population genetic structure and reproduction in its ancestral (European) and introduced (North America) ranges.

Methods

Over 2000 individuals from 43 localities were analysed for ploidy, microsatellite variation (19 loci) and reproduction (flow cytometric seed screen). Most individuals were tetraploid (93%), while lower frequencies of hexaploid (6%), diploid (<1%) and triploid (<1%) individuals were also identified.

Key results

A flow cytometric analysis of 24 single seeds per individual, and five individuals per population demonstrated opposite patterns between ploidy types, with tetraploids producing more apomictic (73%) than sexual (24%) seed, while hexaploids produced more sexual (73%) than apomictic (23%) seed. As hexaploids are derived from tetraploids, these data imply that gene dosage, in addition to the effects of hybridization, influences the switch from apomictic to sexual reproduction. No significant differences in seed production were found between Europe and North America. An analysis of population structure based upon microsatellite profiling demonstrated three major genetic clusters in Europe, whose distribution was reflective of Pleistocene glaciation (e.g. refugia) and post-glacial recolonization of Europe.

Conclusions

The presence of pure and mixed populations representing all three genetic clusters in North America demonstrates that H. perforatum was introduced multiple times onto the continent, followed by gene flow between the different gene pools. Taken together, the data presented here suggest that plasticity in reproduction has no influence on the invasive potential of H. perforatum.

SUBMITTER: Molins MP

PROVIDER: S-EPMC3906961 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Background: Saint John's wort (Hypericum perforatum L., HP) is commonly registered in Europe under the THR scheme (Traditional Herbal Registration) or licensed as a medicine. Nonetheless unregulated medical products and food supplements are accessible through the internet which are often of poor quality. The species' natural distribution stretches through large regions of Europe to China and four subspecies have been distinguished. When compared to the European Pharmacopoeia reference, the presence of additional compounds was linked to so-called Chinese HP. Aim: In order to obtain an integrated picture of the entire chemoprofile, the chemical composition of HP materia prima was studied using a combination of techniques well-established in the relevant industries. The impact of phytogeographic factors on the materia prima can shed light on whether the variability of the final products is strongly influenced by these factors of whether they relate to poor processing, adulteration, or other factors linked to the processing of the material. Methods: Eighty-six Hypericum samples (77 H. perforatum) were collected from 14 countries. Most were authenticated and harvested in the wild; others came as roughly ground material from commercial cultivations, markets and pharmacies. The samples were analyzed using HPTLC and 1H-NMR-based principal component analysis (PCA). Results and Discussion: Limited chemical variability was found. Nonetheless, the typical fingerprint of Chinese HP was observed in each specimen from China. Additional compounds were also detected in some samples collected in Spain. Rutin is not necessarily present in the crude material. The variability previously found in the marketed products can be ascribed only partially to the geographical origin of harvested material, but mainly to the plant part harvested, closely related to harvesting techniques, processing and probably time of harvest. Conclusion: HP can be sourced in a consistent composition (and thus quality) from different geographical sources. However, chemical variability needs to be accounted for when evaluating what is considered authentic good material. Therefore, the processing and good practice are all stages of primary importance, calling for a better (self-)regulation and quality assurance along the value chain of an herbal medical product or botanical.

Project description:Hypericin, an extract from St John's Wort (Hypericum perforatum L.), is a promising photosensitizer in the context of clinical photodynamic therapy due to its excellent photosensitizing properties and tumoritropic characteristics. Hypericin-PDT induced cytotoxicity elicits tumor cell death by various mechanisms including apoptosis, necrosis and autophagy-related cell death. However, limited reports on the efficacy of this photomedicine for the treatment of melanoma have been published. Melanoma is a highly aggressive tumor due to its metastasizing potential and resistance to conventional cancer therapies. The aim of this study was to investigate the response mechanisms of melanoma cells to hypericin-PDT in an in vitro tissue culture model. Hypericin was taken up by all melanoma cells and partially co-localized to the endoplasmic reticulum, mitochondria, lysosomes and melanosomes, but not the nucleus. Light activation of hypericin induced a rapid, extensive modification of the tubular mitochondrial network into a beaded appearance, loss of structural details of the endoplasmic reticulum and concomitant loss of hypericin co-localization. Surprisingly the opposite was found for lysosomal-related organelles, suggesting that the melanoma cells may be using these intracellular organelles for hypericin-PDT resistance. In line with this speculation we found an increase in cellular granularity, suggesting an increase in pigmentation levels in response to hypericin-PDT. Pigmentation in melanoma is related to a melanocyte-specific organelle, the melanosome, which has recently been implicated in drug trapping, chemotherapy and hypericin-PDT resistance. However, hypericin-PDT was effective in killing both unpigmented (A375 and 501mel) and pigmented (UCT Mel-1) melanoma cells by specific mechanisms involving the externalization of phosphatidylserines, cell shrinkage and loss of cell membrane integrity. In addition, this treatment resulted in extrinsic (A375) and intrinsic (UCT Mel-1) caspase-dependent apoptotic modes of cell death, as well as a caspase-independent apoptotic mode that did not involve apoptosis-inducing factor (501 mel). Further research is needed to shed more light on these mechanisms.

Project description:Stimulant medication can effectively treat 60% to 70% of youth with attention-deficit/hyperactivity disorder (ADHD). Yet many parents seek alternative therapies, and Hypericum perforatum (St John's wort) is 1 of the top 3 botanicals used.To determine the efficacy and safety of H. perforatum for the treatment of ADHD in children.Randomized, double-blind, placebo-controlled trial conducted between March 2005 and August 2006 at Bastyr University, Kenmore, Washington, among a volunteer sample of 54 children aged 6 to 17 years who met Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) criteria for ADHD by structured interview.After a placebo run-in phase of 1 week, participants were randomly assigned to receive 300 mg of H. perforatum standardized to 0.3% hypericin (n = 27) or a matched placebo (n = 27) 3 times daily for 8 weeks. Other medications for ADHD were not allowed during the trial.Performance on the ADHD Rating Scale-IV (range, 0-54) and Clinical Global Impression Improvement Scale (range, 0-7), and adverse events.One patient in the placebo group withdrew because of an adverse event. No significant difference was found in the change in ADHD Rating Scale-IV scores from baseline to week 8 between the treatment and placebo groups: inattentiveness improved 2.6 points (95% confidence interval [CI], -4.6 to -0.6 points) with H. perforatum vs 3.2 points (95% CI, -5.7 to -0.8 points) with placebo (P = .68) and hyperactivity improved 1.8 points (95% CI, -3.7 to 0.1 points) with H. perforatum vs 2.0 points (95% CI, -4.1 to 0.1 points) with placebo (P = .89). There was also no significant difference between the 2 groups in the percentage of participants who met criteria for improvement (score < or = 2) on the Clinical Global Impression Improvement Scale (H. perforatum, 44.4%; 95% CI, 25.5%-64.7% vs placebo, 51.9%; 95% CI, 31.9%-71.3%; P = .59). No difference between groups was found in the number of participants who experienced adverse effects during the study period (H. perforatum, 40.7%; 95% CI, 22.4%-61.2% vs placebo, 44.4%; 95% CI, 25.5%-64.7%; P = .78).In this study, use of H. perforatum for treatment of ADHD over the course of 8 weeks did not improve symptoms.clinicaltrials.gov Identifier: NCT00100295.

Project description:BACKGROUND:In some countries extracts of the plant Hypericum perforatum L. (popularly called St. John's wort) are widely used for treating patients with depressive symptoms. OBJECTIVES:To investigate whether extracts of hypericum are more effective than placebo and as effective as standard antidepressants in the treatment of major depression; and whether they have fewer adverse effects than standard antidepressant drugs. SEARCH STRATEGY:Trials were searched in computerised databases, by checking bibliographies of relevant articles, and by contacting manufacturers and researchers. SELECTION CRITERIA:Trials were included if they: (1) were randomised and double-blind; (2) included patients with major depression; (3) compared extracts of St. John's wort with placebo or standard antidepressants; (4) included clinical outcomes assessing depressive symptoms. DATA COLLECTION AND ANALYSIS:At least two independent reviewers extracted information from study reports. The main outcome measure for assessing effectiveness was the responder rate ratio (the relative risk of having a response to treatment). The main outcome measure for adverse effects was the number of patients dropping out due to adverse effects. MAIN RESULTS:A total of 29 trials (5489 patients) including 18 comparisons with placebo and 17 comparisons with synthetic standard antidepressants met the inclusion criteria. Results of placebo-controlled trials showed marked heterogeneity. In nine larger trials the combined response rate ratio (RR) for hypericum extracts compared with placebo was 1.28 (95% confidence interval (CI), 1.10 to 1.49) and from nine smaller trials was 1.87 (95% CI, 1.22 to 2.87). Results of trials comparing hypericum extracts and standard antidepressants were statistically homogeneous. Compared with tri- or tetracyclic antidepressants and selective serotonin reuptake inhibitors (SSRIs), respectively, RRs were 1.02 (95% CI, 0.90 to 1.15; 5 trials) and 1.00 (95% CI, 0.90 to 1.11; 12 trials). Both in placebo-controlled trials and in comparisons with standard antidepressants, trials from German-speaking countries reported findings more favourable to hypericum. Patients given hypericum extracts dropped out of trials due to adverse effects less frequently than those given older antidepressants (odds ratio (OR) 0.24; 95% CI, 0.13 to 0.46) or SSRIs (OR 0.53, 95% CI, 0.34-0.83). AUTHORS' CONCLUSIONS:The available evidence suggests that the hypericum extracts tested in the included trials a) are superior to placebo in patients with major depression; b) are similarly effective as standard antidepressants; c) and have fewer side effects than standard antidepressants. The association of country of origin and precision with effects sizes complicates the interpretation.