John's Wort Plants Research Articles

Human Health Risk Assessment of Arsenic and Other Metals in Herbal Products Containing St. John's Wort in the Metropolitan Area of Mexico City.

Consumption of St. John's wort plant is high worldwide due to its various medicinal properties. However, herbal products containing St. John's wort may be contaminated with toxic metals. This is often related to contamination of both water and the atmosphere, lack of proper cultivation methods, and inadequate plant storage conditions, as well as a lack of stricter sanitary supervision. A safety assessment of copper (Cu), lead (Pb), cadmium (Cd) and arsenic (As) content in 23 products containing St. John's wort (pharmaceutical herbal products, food supplements and traditional herbal remedies) sold in the metropolitan area of Mexico City was conducted. The analysis of metals was determined using a graphite-furnace atomic absorption spectrometer. All herbal products were contaminated with Cu, Pb, Cd and As. The pharmaceutical herbal items showed less contamination by metals. The daily human intake (DHI) values for Pb exceeded the permissible limits in the group of traditional herbal remedies. The DHI calculation for As exceeded the permitted intake values for all items in the group of traditional herbal remedies, five food supplements and one pharmaceutical herbal product. The hazard indicator calculation of the non-carcinogenic cumulative risk values for traditional herbal remedies was greater than 1, suggesting a risk to human health.

Geleneksel tıp uygulamalarında kullanılan sarı kantaron (Hypericum perforatum l.) yağının standardizasyonunun belirlenmesine yönelik yürütülen bazı kalite analizlerinin incelenmesi

St. John's Wort (Hypericum perforatum L.) plant is among the medicinal plants used as pharmaceutical raw material with traditional methods for more than 2000 years. St. John's Wort plant and its medicinal oil (maserate) obtained from it, usage area is increasing day by day in the food, pharmaceutical and cosmetic industries thanks to the important bioactive components. The pharmacologically important component of the plant is known as hypericin. This study was carried out in Selcuk University, Faculty of Agriculture, Medical and Endemic Plants Training and Research Farm, and examined the effect of different holding environments (sun, shade), harvest periods (25% flowering period, 50% flowering period and full flowering period) and drying methods (wet herb, faded herb and dried herb) on the amount of hypericin in St. John's Wort and its medicinal oil. According to the results of the analysis, the highest amount of hypericin in St. John's Wort herb was determined as 0.32% in full flowering period. The highest amount of hypericin in St. John's Wort oils was determined as 271.92 mg/L in fresh herb during the full flowering period. According to the results of the research, the harvesting periods are effective on the amount of hypericin, and it can be suggested that the wet herb, which is harvested in full bloom and hold, should be macerated with olive oil in the sun to obtain St. John's Wort oil with high hypericin content.

Apoptotic and Anti-inflammatory Effects of Hypericum Perforatum Extract in Human Basal Cell Carcinoma TE 354.T Cell Line

Objectives: Basal cell carcinoma is the most common malignancy in in the Caucasian race and is a serious health problem with its ever-increasing incidence and high cost. Although the treatment is surgical, some elderly patients do not accept surgical intervention. In this case, non-surgical treatments come into prominence. The Hypericum perforatum (HP) / St. John's Wort plant has been used in the treatment of many diseases for centuries among local people. Here, we aimed to aimed to elucidate the effect and molecular mechanism of the HP plant on BCC cells.
 Methods: Human BCC cell lines TE 354.T were acquired from ATCC®, then were cultured in Dulbecco's Modified Eagle's Medium. BCC cells were seeded at a concentration of 2x106cells in each flask (n=12). After incubation, while six of the flasks were applied with a 0.8% HP extract and 99.2% medium for 48 hours, no application was made to the control group. The effects of HP on mitochondrial mediated intrinsic and extrinsic apoptotic pathway agents, cell cycle G2 / M checkpoint kinases and inflammatory mediators were investigated in BCC cancer cells. The expression and activities of these mediators in both groups were evaluated by ELISA test. 
 Results: It was determined that HP extract treatment increased the expression of apoptotic proteins (AIF, GADD153, GRP78, caspase-3, Bax) and cell cycle G2 / M checkpoint kinase (Wee1), though it reduced antiapoptotic protein (Bcl-2) and inflammatory mediators (iNOS, COX-2, cPLA2, NFkB) in BCC cell lines.
 Conclusion: HP extract can support routine chemotherapy on BCC cells with its apoptotic, anti-inflammatory and anti-cancer effect, and may be a beacon of hope in reducing resistance to chemotherapeutic drugs in the treatment of BCC.

In Vivo Investigation of Genotoxic and Antigenotoxic Potential of Hypericum Perforatum Extract in Rats

This study was planned to reveal in vivo genotoxic, antigenotoxic and cytotoxic properties of methanolic extracts of St. John's Wort plant (Hypericum perforatum). The methanol extract of H. perforatum was administrated to rats alone or in combination with N-nitrosodimethylamine and Triclosan (positive control). The concentrations of H. Perforatum were 20, 100, 500 mg/kg and the period of administration was 30 days. At the end of this period, chromosome aberration test used to determine genotoxic and antigenotoxic effects of H. perforatum. In addition, total oxidant and antioxidant levels of peripheral blood serum of rats were determined by spectrophotometric method. According to our result, H. perforatum extract did not demonstrate genotoxic effect at concentrations administrated. When compared to the negative control, the percentage of abnormal cells was increased in groups treated with test substance, N-nitrosodiethylamine and triclosan together. However, these increases were not as higher as groups treated with N-nitrosodiethylamine plus triclosan (positive control). Even, in groups treated with the test substance additional N-nitrosodiethylamine plus triclosan, the ratio of abnormal cells was inversely proportional to the increase in the concentration. The lowest ratio of abnormal cells was in the group in which the highest concentration of the H. perforatum (500 mg/kg) was applied. The highest two concentrations of the H. perforatum (100 and 500 mg/kg) significantly increased the mitotic index. In the group treated with test substance and positive control together, the mitotic index was even greater. At the same time 100 mg/kg of H. perforatum extract significantly reduced the oxidative stress.

Endemic North American Plants as Potentially Suitable Agents for Wound Cleaning Under Resource Scarce Conditions

Skin and subcutaneous infections are dangerous sequelae of soft tissue injuries, especially in austere situations where medical technology is not available. Numerous plant species endemic to North America have been described as having antibacterial properties. Of these, St. John's wort (Hypericum perforatum), chamomile (Matricaria chamomilla), and white oak (Quercus alba) were selected for testing against Staphylococcus aureus. Our objective was to assess the suitability of all 3 plants as potential antiseptic agents using methods easily replicated in a resource-scarce environment. Water-soluble natural products were extracted from different concentrations of each plant part using either mechanical agitation at ambient temperature or boiling in unsterilized tap water. Antibacterial activity of each extract against S aureus was assessed using a conventional agar well diffusion bioassay. Zones of inhibition were measured using electronic calipers and were compared to tap water as the negative control. Aqueous extracts of St. John's wort and white oak bark displayed antibacterial effects against Saureus, with St. John's wort being more potent. Chamomile displayed no inhibitory properties at the concentrations examined. These data suggest that both St. John's wort and white oak are potential candidates for infection prophylaxis and therapy in austere wilderness scenarios, with St. John's wort being the more potent agent. White oak may be more logistically feasible because the larger surface area of a white oak tree allows for harvesting a larger quantity of bark compared to the smaller surface area of the St. John's wort plant.

Headspace gas chromatographic analysis of St John’s Wort (Hypericum perforatum L.) and its medical derivatives

Static headspace gas chromatographic analysis method using flame ionization and mass spectrometric detection was applied for the qualitative and quantitative detection of volatile components in the equilibrium vapor phase of the medicinal St. John's Wort ( Hypericum perforatum L.) plant. The optimal conditions for the gas extraction, producing repeatable and characterizing chromatographic headspace profiles of the St. John's Wort, were established. The retention indices (IiT) for the linear programming of the column temperature with a low-polar stationary phase and the relative areas of the peaks ( A rl,i ) of the St. John's Wort volatile components have been determined. The obtained results were presented in the form of specific headspace-spectra « A rl,i - I i T » of the plants. It has been demonstrated that the headspace spectra of the botanical sample (Samara) and of the three industrial specimens of St. John's Wort obtained from various regions of Russia were close to each other. Major volatile compounds of the Russian St. John's Wort were: ethanal, propanal, dimethylsulfide, 2-methylpropanal, 2-methyl-3-butene-2-ol (marker), 2-methylbuthanal, 2-methyloctane, α-pinene, 3-methylnonane. Current research was the first to suggest using alcohol 2-methyl-3-butene-2-ol ( I i T = 617) as the volatile marker of St. John's Wort. Its relative quantity in the vapor phase of St. John's Wort ( A rl,i ) was equal to 15.53 – 20.75%. It has also been discovered that most of the components of the equilibrium phase of St. John's Wort including the 2-methyl-3-butene-2-ol marker were present in the vapor phase of the St. John's Wort medicines, dry tablet extract of St. John's Wort (Deprim, Slovenia) and oil extract of St. John's Wort (Russia). Keywords : Hypericum perforatum L., medical plant raw material, phytomedicines, volatile organic compounds, gas-liquid chromatography, headspace analysis, chromatographic profile (Russian) DOI: http://dx.doi.org/10.15826/analitika.2018.22.2.002 N.V. Pariichuk 1 , L.A. Onuchak 1 , Iu.A. Arutiunov 1 , V.A. Kurkin 2 , O.E. Pravdivtseva 2 1 Samara National Research University,Moskovskoe sh., 34, Samara, 443086, Russian Federation 2 Samara State Medical University, Chapaevskaia ul., 89, Samara, 443099, Russian Federation

Comparative assessment of the therapeutic effects of the topical and systemic forms of Hypericum perforatum extract on induced oral mucositis in golden hamsters

Oral mucositis is a common and irritating complication of chemotherapy and radiotherapy for malignancies. Current treatments have failed to achieve complete remission of this complication. The St. John's wort plant (Hypericum perforatum) has long been known for its anti-inflammatory and antibacterial effects. The current study was designed to investigate the therapeutic efficacy of the topical and systemic administration of H. perforatum extract on oral mucositis. Oral mucositis was induced in 72 male golden hamsters by administration of 5-fluorouracil (60mg/kg), on days 0, 5, and 10 of the study. The cheek pouch was scratched with a sterile needle on days 1 and 2. On days 12–17, H. perforatum extract topical gel 10%, oral H. perforatum extract (300mg/kg), and gel base groups were treated and then compared with a control group. Weights and blood samples were evaluated, biopsies from buccal lesions were examined histopathologically, and tissue malondialdehyde (MDA) was measured. Both of the H. perforatum extract treatment groups saw a significant relief in oral mucositis compared to the control and base gel groups; the systemic form was superior to the topical form. H. perforatum extract, administered orally or topically, expedited the healing of chemotherapy-induced oral mucositis in hamsters.

Hyperforin modulates dendritic spine morphology in hippocampal pyramidal neurons by activating Ca(2+) -permeable TRPC6 channels.

The standardized extract of the St. John's wort plant (Hypericum perforatum) is commonly used to treat mild to moderate depression. Its active constituent is hyperforin, a phloroglucinol derivative that reduces the reuptake of serotonin and norepinephrine by increasing intracellular Na(+) concentration through the activation of nonselective cationic TRPC6 channels. TRPC6 channels are also Ca(2+) -permeable, resulting in intracellular Ca(2+) elevations. Indeed, hyperforin activates TRPC6-mediated currents and Ca(2+) transients in rat PC12 cells, which induce their differentiation, mimicking the neurotrophic effect of nerve growth factor. Here, we show that hyperforin modulates dendritic spine morphology in CA1 and CA3 pyramidal neurons of hippocampal slice cultures through the activation of TRPC6 channels. Hyperforin also evoked intracellular Ca(2+) transients and depolarizing inward currents sensitive to the TRPC channel blocker La(3+) , thus resembling the actions of the neurotrophin brain-derived neurotrophic factor (BDNF) in hippocampal pyramidal neurons. These results suggest that the antidepressant actions of St. John's wort are mediated by a mechanism similar to that engaged by BDNF.

PHOTOPERIOD EFFECTS ON FLOWERING AND SEED SETTING OFHYPERICUM PERFORATUM

SUMMARYThe effects of day length extension and night interruption on flowering responses of St John's Wort (Hypericum perforatum) plants were investigated. Field-grown plants were subjected to five different day lengths (11, 13, 15, 17 and 19 h d−1) or night interruption for 70 days. The results indicated that St John's Wort is a long-day plant requiring a critical day length of 15 hd−1for flowering induction. Both day length extension (duration longer than 15 h) and night interruption, with artificial light (fluorescent lamps that delivered 30 μmol m−2s−1photosynthetic photon flux density at plant height) were effective for flowering induction and seed setting. Day length extension or night interruption experienced by the maternal plant also affected the germination responses of the seeds produced. Plants that had received 19 h of day length treatment produced seeds with better germination responses. Night interruption with daylight type fluorescent lamps was also effective for producing relatively high quality seeds, although these seeds had slightly lower germination rates and longer mean germination time than seeds produced under 19 h of day length. Such a night interruption system could be considered for seed production of St John's Wort on a commercial scale.

The content of heavy metals in the leaves of Hypericum perforatum L. on serpentinite soils in Serbia

St John's wort is one of the best known and used medicinal plants. The demands for St John's wort in Serbia is still supplied by the collection of native plants. Therefore it was necessary to examine the concentration of heavy metals in the soil and in plant material on serpentinites and to assess the potential safe harvesting and further utilisation of this plant species. The research was performed on three serpentinite sites in Serbia: Zlatibor, Divcibare and Goc. The main soil types were determined and the contents of 7 chemical elements were analyzed in the soil and in the plant material. It was determined that the soils of all three localities had increased concentrations of nickel, chromium and manganese. The St John's wort plant material (leaves) showed the increased concentrations of iron, nickel and chromium. It was concluded that St John's wort was a tolerant species regarding the heavy metal content, and it was recommended to avoid its harvesting on the investigated localities.

Effect of Light Quality of Blue and Red Fluorescent Lamps on Growth of St. John's Wort (Hypericum perforatum L.)

St. John's wort (Hypericum perforatum L.) is a medicinal plant widely used for treatments of neurological disorders, depression, etc. Recently, studies have reported the production of St. John's wort plants under controlled environments with artificial light a promising technique to standardize and enhance the growth and medicinal contents. The present study investigated the effect of the light quality of fluorescent lamps on the growth of St. John's wort plants. The seedlings with 6-8 unfolded leaves were grown for 28 days under blue and red lamps in growth chambers under controlled environments. Dry weight of plants grown under the red lamps was greater compared with that of plants grown under the blue lamps.The CO2 absorption rate of plants grown under the red lamps was similar to that under the blue lamps. Absorption of red light (600-700 nm) by leaves was lower than that of blue light (400-500 nm). Leaf area, number of unfolded leaves, number of branches from the main stem, and number of nodes of plants grown under the red lamps were greater than those of plants grown under the blue lamps. These findings demonstrated that the difference in dry weight of plants grown under these conditions was not due to the spectral characteristic or photosynthetic ability of leaves but due to the amount of light actually absorbed by the leaves. In conclusion, controlling the light quality can be an important technique for enhancing production of St. John's wort plants.

Phytochemical and physiological changes in the leaves of St. John's wort plants under a water stress condition

Water stress is known to increase the secondary metabolites concentration in plant tissues and severe water stress conditions may cause oxidative stress due to the formation of reactive oxygen species and photoinhibitory damage. Current study was undertaken to evaluate the changes in the physiological status especially the photosynthetic efficiency and the biochemical profile of the leaf tissues of St. John's wort ( Hypericum perforatum) plants exposed to water stress. The net photosynthetic rates of the leaves of plants grown under a water stress condition were significantly low compared with those of the control. The maximal quantum efficiency of PSII photochemistry ( ϕ p max ) of the dark adopted leaves was similar for both wilted and recovered plants although these values were significantly low compared with those of the control. The leaf tissues of the plants under a water stress condition had a significantly higher capacity to detoxify oxygen radicals with an about 2.5-fold increase over the antioxidant potential of the leaves of non-treated (control) or recovered plants. In the leaf tissues of plants grown under a water stress condition, both hypericin and pseudohypericin concentrations reduced with time and on Day 12 of the treatment, the concentration was significantly lower than that of the control; in contrast, the hyperforin concentration increased significantly and the value was nearly double after 12 days of the treatment. Under a water stress condition, the hyperforin concentration was about 70-fold higher than the total hypericins concentration in the leaf tissues; in case of control it was only 10–12 times higher. The results also indicate that the major secondary metabolite, hyperforin concentration of 62-day-old plants was three- to four-fold higher than the previously reported values for 1–2-year-old field-grown plants.

Temperature stress can alter the photosynthetic efficiency and secondary metabolite concentrations in St. John's wort

Temperature stress is known to cause many physiological, biochemical and molecular changes in plant metabolism and possibly alter the secondary metabolite production in plants. The hypothesis of the current study was that temperature stress can increase the secondary metabolite concentrations in St. John's wort. Plants were grown under controlled environments with artificial light using cool white fluorescent lamps and CO 2 enrichment and 70-day-old plants were subjected for 15 days to different temperature treatments of 15, 20, 25, 30 and 35 °C before harvested. Major aim of the study was to increase the major secondary metabolites in St. John's wort by applying temperature stress and to evaluate the physiological status of the plant especially the photosynthetic efficiency and peroxidase activity of the leaf tissues exposed to different temperatures under precisely controlled environmental factors. Results revealed that relatively high (35 °C) or low (15 °C) temperatures reduced the photosynthetic efficiency of the leaves of St. John's wort plants and resulted in low CO 2 assimilation. Net photosynthetic rates and the maximal quantum efficiency of PSII photochemistry of the dark adopted leaves (ϕ p max) decreased significantly in the leaves of plants grown under 35 or 15 °C temperature treatments. High temperature (35 °C) treatment increased the leaf total peroxidase activity and also increased the hypericin, pseudohypericin and hyperforin concentrations in the shoot tissues. These results provide the first indication that temperature is an important environmental factor to optimize the secondary metabolite production in St. John's wort and controlled environment technology can allow the precise application of such specific stresses.

Variation in concentrations of major bioactive compounds of St. John's wort: Effects of harvesting time, temperature and germplasm

St. John's wort ( Hypericum perforatum L.) plants grown in a field or a greenhouse have been used for the preparation of phytopharmaceutical products. However, fields and greenhouse have such changeable environments, which can lead to high variations in the concentrations of bioactive compounds. In addition, due to the changeable environment, studies aiming to determine the effect of a unique environmental factor, the harvesting time or the germplasm on concentrations of bioactive compounds cannot be conclusive. In the current study, plants were grown in a growth chamber under controlled environments, and the effect of two different temperatures, 25 and 30 °C, was determined on concentrations of the major bioactive compounds. Moreover, the variation in the concentrations of the major bioactive compounds with harvesting time, and germplasm lines were investigated. The concentrations of major bioactive compounds in the shoots reached a peak on day 52, regardless of the temperature. Throughout the experiment, pseudohypericin and hypericin concentrations were higher at 30 °C than at 25 °C, whereas hyperforin concentrations remained higher at 25 °C than at 30 °C. Moreover, high variations in the concentrations of the major bioactive compounds were found among the different germplasm lines.

Relationships between net photosynthetic rate and secondary metabolite contents in St. John's wort

Hypericum perforatum L. (St. John's wort), a traditional herb with antidepressive and wound healing properties, was grown under 100, 300 and 600 μmol m −2 s −1 photosynthetic photon flux (PPF) each with 500, 1000 and 1500 μmol mol −1 CO 2, with the objective of maximizing the biomass and secondary metabolite production. Plants grown in the field (1770 μmol m −2 s −1 PPF and 380 μmol mol −1 CO 2) were used as a control. On day 45, total fresh and dry mass, and the number of stem nodes were greatest in plants grown under 600 μmol m −2 s −1 PPF with 1500 μmol mol −1 CO 2 concentration (HH-treatment) and were 29, 30 and 4 times greater, respectively, than those of the control. Leaf net photosynthetic rate (Pn) increased with increasing PPF and/or CO 2 concentration, with the highest value occurring in the plants grown under the HH-treatment. Secondary metabolite contents (mg/plant) in the leaf tissues were generally higher in the plants grown under the controlled environments than those in the field (control). Hypericin and pseudohypericin contents were highest in the HH-treatment, being 30 and 41 times greater, respectively, than those of the control. Hypericin and pseudohypericin contents in the leaf tissues increased with increasing Pn. The second order polynomial correlations between Pn and hypericin, and between Pn and pseudohypericin contents with R 2 of 0.82 and 0.79, respectively, were obtained. Moreover, total hypericin (hypericin + pseudohypericin) concentration (mg g −1 leaf DM) in leaf tissues was related to both PPF and CO 2 concentration as expressed by second order polynomial correlations ( R 2 = 1). Therefore, growing St. John's wort plants under a controlled environment can enhance biomass and secondary metabolite production by increasing net photosynthetic rate.

Production of St. John's wort plants under controlled environment for maximizing biomass and secondary metabolites

Abstract St. John's wort (Hypericum perforatum L.) is a medicinal plant used in the treatment of neurological disorders and has been recently shown to have anticancer potential. The principle medicinal components of St. John's wort are hypericin, pseudohypericin, and hyperforin. One of the problems associated with medicinal plant preparations including St. John's wort is the extreme variability in the phytochemical content, mostly due to environmental variability, and biotic and abiotic contamination during cropping. The current study was undertaken to transplant St. John's wort plants from in vitro bioreactors in a closed controlled environment system (CCES) with CO2 enrichment for the optimized production of biomass and phytochemicals. The growth and levels of hypericin, pseudohypericin, and hyperforin in plants grown in CCES were compared with those of the greenhouse and in vitro-grown plants. The environmental parameters in the greenhouse were found to be variable whereas in the CCES these parameters ...

Roller Compaction and Tabletting of St. John's Wort Plant Dry Extract Using a Gap Width and Force Controlled Roller Compactor. I. Granulation and Tabletting of Eight Different Extract Batches

The purpose of this study was to investigate the influence of roller compaction parameters on granule and tablet quality of a dry herbal extract from St. John's wort (Hypericum perforatum L.), which is widely used in the treatment of mild to moderate depressive disorders. Eight different extract batches were blended with 0.5, 2, and 5% of magnesium stearate and were compacted at different compaction forces using a gap width and force controlled roller compactor. The ribbon formed was milled into granules having mean particle sizes up to 700 μm. The roller compaction of the extracts decreased significantly the angle of repose from about 45 to 32° and the Hausner ratio from about 1.2 to 1.1. Tabletting of granulated extract instead of extract powder effectively reduced not only dust and feeding problems during the tabletting process but also prevented capping. The incorporation of 2 and 5% of magnesium stearate into the roller compacted extract reduced significantly the sticking of the dry herbal extracts to the punch faces without affecting the crushing strength of the tablets. Tablets containing granulated extracts exhibited a 3-fold lower disintegration time of about 12 min compared to tablets containing extract powder. Dissolution studies revealed that hyperforin, hypericin, and rutin were more rapidly released from tablets containing granulated extract. Therefore, roller compaction leveled out the differences in technological properties between the eight dry herbal extracts and compression of granulated extract significantly improved tablet quality.

Roller Compaction and Tabletting of St. John's Wort Plant Dry Extract Using a Gap Width and Force Controlled Roller Compactor. II. Study of Roller Compaction Variables on Granule and Tablet Properties by a 33 Factorial Design

The purpose of this study was to investigate the influence of roller compaction parameters and the amount of magnesium stearate used in dry granulation on granule and tablet properties of a dry herbal extract from St. John's wort (Hypericum perforatum L.). Two different extract batches were blended with magnesium stearate and compacted using a gap width and force controlled roller compactor. A 33 factorial design was used to evaluate the influence of the three independent variables, the amount of magnesium stearate, the roller compaction force, and the granulating sieve size on the mean particle size of granulated extracts and on the disintegration time of tablets containing these granulated extracts. The evaluation was done by multilinear stepwise regression analysis. The mean particle size d50 (R2>0.9) of both compacted extracts increased with increasing compaction force and with granulating sieve size. The disintegration time of the tablets was mostly in the range 5–15 min and increased slightly with increasing magnesium stearate concentration in the compacted extract and with decreasing compaction force of the roller compaction. The incorporation of magnesium stearate into the granulated extract reduced its potential negative influence on the disintegration time, while maintaining its functionality as a lubricant.

Evidence and characterization of a virus of St John's Wort (Hypericum perfora tum L.)

Vein yellows, necrotic leaf spots and growth inhibition were observed on St John's wort plants (Hypericum perforatum L.) growing in a field in northern Thuringia. A virus was isolated from diseased plants and mechanically transmitted to several species of the genera Antirrhinum, Chenopodium, Cucurbita, Datura, Gomphrena, Lathyrus, Malva, Nicotiana, Ocimum, Petunia, Phaseolus and Spinacia. After retransmitting the virus to H. perforatum it developed symptoms similar to those observed in the field and was reisolated from experimentally infected H. perforatum plants. High concentrations of the virus were found in Nicotiana clevelandii Gray and N. occidentalis Wheeler. The thermal inactivation point was 52°C. The virus remained infectious in frozen and dried leaves of N. clevelandii for at least 3 months, but lost its infectivity in crude sap of N. clevelandii plants already after 3 days, in crude sap of H. perforatum plants even after 1 day. The virus has isometric particles with a diameter of 27 nm. It is highly immunogenic and an antiserum was produced with a titre of 1/2 048. The virus is serologically not identical or related with 10 other viruses investigated. It is not transmissible by the aphid species Myzus persicae (Sulz.), but it seems easily transmissible by leaf contact and by cutting of leaves or stalks. The contents of valuable active compounds in diseased plants differ partly from those in healthy plants. According to the first preliminary studies different varieties of St John's wort respond the virus infection in a distinct manner.