Effects of UV‐B on Secondary Metabolites of St. John’s Wort (<i>Hypericum perforatum</i> L.) Grown in Controlled Environments

Brechner, Melissa L; Albright, L. D.; Weston, Leslie A.

doi:10.1111/j.1751-1097.2011.00904.x

Cited by 30 publications

(30 citation statements)

References 15 publications

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“…However, under normal growth conditions, the risk of photo-oxidative damage from chlorophyll and its intermediates is relatively low in grazing animals [15]. The production of light-absorbing SPPs in higher plants is generally maximized by exposure to increasing levels of UVA and UVB irradiation, resulting in an enhanced ability to cause photosensitization [32]. …”

Section: The Role Of Light Reactive Molecules In the Photosensitizatimentioning

confidence: 99%

“…Ingestion of St. John’s Wort by livestock readily causes primary photosensitization with incidences of affected stock being reported across Europe, America and Australasia, including Australia [41,64–66]. The bioactive compound identified to be the causal agent of photosensitivity in St. John’s Wort is the photocytotoxic and highly fluorescent pigment hypericin [32,64] (Figure 2). The leaves of this plant, which can reach two meters in height, are covered with small glands which contain this potent compound [31,64,67,68].…”

Section: Case Studies Documenting Photosensitization In Grazing Herbimentioning

confidence: 99%

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Secondary Plant Products Causing Photosensitization in Grazing Herbivores: Their Structure, Activity and Regulation

Quinn

Kessell

Weston

2014

IJMS

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Photosensitivity in animals is defined as a severe dermatitis that results from a heightened reactivity of skin cells and associated dermal tissues upon their exposure to sunlight, following ingestion or contact with UV reactive secondary plant products. Photosensitivity occurs in animal cells as a reaction that is mediated by a light absorbing molecule, specifically in this case a plant-produced metabolite that is heterocyclic or polyphenolic. In sensitive animals, this reaction is most severe in non-pigmented skin which has the least protection from UV or visible light exposure. Photosensitization in a biological system such as the epidermis is an oxidative or other chemical change in a molecule in response to light-induced excitation of endogenous or exogenously-delivered molecules within the tissue. Photo-oxidation can also occur in the plant itself, resulting in the generation of reactive oxygen species, free radical damage and eventual DNA degradation. Similar cellular changes occur in affected herbivores and are associated with an accumulation of photodynamic molecules in the affected dermal tissues or circulatory system of the herbivore. Recent advances in our ability to identify and detect secondary products at trace levels in the plant and surrounding environment, or in organisms that ingest plants, have provided additional evidence for the role of secondary metabolites in photosensitization of grazing herbivores. This review outlines the role of unique secondary products produced by higher plants in the animal photosensitization process, describes their chemistry and localization in the plant as well as impacts of the environment upon their production, discusses their direct and indirect effects on associated animal systems and presents several examples of well-characterized plant photosensitization in animal systems.

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Section: The Role Of Light Reactive Molecules In the Photosensitizatimentioning

confidence: 99%

Section: Case Studies Documenting Photosensitization In Grazing Herbimentioning

confidence: 99%

Secondary Plant Products Causing Photosensitization in Grazing Herbivores: Their Structure, Activity and Regulation

Quinn

Kessell

Weston

2014

IJMS

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“…Previous studies report an increase in the concentration of specific secondary metabolites in some medicinal species, such as methylxanthines in Ilex paraguariensis [19], alkaloid concentration in Delphinium barbeyi [20], and aloin (barbaloin) in Aloe mutabilis [22,23], under low light conditions. There were also numerous reports on an increase of secondary metabolites under high light condition and has been reported in tea [24], red kidney bean [25] and St. John’s wort [26]. These showed the importance of light in secondary metabolite regulation in medicinal plants.…”

Section: Introductionmentioning

confidence: 98%

Reduced Photoinhibition under Low Irradiance Enhanced Kacip Fatimah (Labisia pumila Benth) Secondary Metabolites, Phenyl Alanine Lyase and Antioxidant Activity

Ibrahim

Jaafar

2012

IJMS

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A randomized complete block design experiment was designed to characterize the relationship between production of total flavonoids and phenolics, anthocyanin, photosynthesis, maximum efficiency of photosystem II (Fv/Fm), electron transfer rate (Fm/Fo), phenyl alanine lyase activity (PAL) and antioxidant (DPPH) in Labisia pumila var. alata, under four levels of irradiance (225, 500, 625 and 900 μmol/m2/s) for 16 weeks. As irradiance levels increased from 225 to 900 μmol/m2/s, the production of plant secondary metabolites (total flavonoids, phenolics and antocyanin) was found to decrease steadily. Production of total flavonoids and phenolics reached their peaks under 225 followed by 500, 625 and 900 μmol/m2/s irradiances. Significant positive correlation of production of total phenolics, flavonoids and antocyanin content with Fv/Fm, Fm/Fo and photosynthesis indicated up-regulation of carbon-based secondary metabolites (CBSM) under reduced photoinhibition on the under low light levels condition. At the lowest irradiance levels, Labisia pumila extracts also exhibited a significantly higher antioxidant activity (DPPH) than under high irradiance. The improved antioxidative activity under low light levels might be due to high availability of total flavonoids, phenolics and anthocyanin content in the plant extract. It was also found that an increase in the production of CBSM was due to high PAL activity under low light, probably signifying more availability of phenylalanine (Phe) under this condition.

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“…Supplemental exposure to UV-B light has been shown to increase the concentration of secondary metabolites in maize, basil, peanut, and lettuce [Li & Kubota, 2009]. UV-B has also been associated with antifeedant properties in many higher plants, leading to enhanced secondary metabolites production in some plants [Brechner et al, 2011].…”

Section: Biotic and Abiotic Stressesmentioning

confidence: 99%

Current Approaches for Enhanced Expression of Secondary Metabolites as Bioactive Compounds in Plants for Agronomic and Human Health Purposes

Jiménez-García¹,

Vazquez-Cruz²,

Guevara-González³

et al. 2013

Pol. J. Food Nutr. Sci.

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The study of secondary metabolism in plants is an important source for the discovery of bioactive compounds with a wide range of applications. Today these bioactive compounds derived from plants are important drugs such as antibiotics, and agrochemicals substitutes, they also have been economically important as fl avors and fragrances, dyes and pigments, and food preservatives. Many of the drugs sold today are synthetic modifi cations of naturally obtained substances. There is no rigid scheme for classifying secondary metabolites, but they can be divided into different groups based on their chemical components, function and biosynthesis: terpenoids and steroids, fatty acid-derived substances and polyketides, alkaloids, phenolic compounds, non-ribosomal polypeptides and enzyme cofactors. The increasing commercial importance of these chemical compounds has resulted in a great interest in secondary metabolism, particularly the possibility of altering the production of bioactive plant metabolites by means of tissue culture technology and metabolomics. In today's world the use of bioactive compounds derived from plants plays an important role in pharmaceutical applications. This review presents information about these metabolites and their applications as well as their importance in agronomy and bioactive effects on human health as nutraceuticals. This review includes also the new tendencies to produce these bioactive compounds under different stresses conditions such as biotic and abiotic stress that could be included in production systems.

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Effects of UV‐B on Secondary Metabolites of St. John’s Wort (Hypericum perforatum L.) Grown in Controlled Environments

Cited by 30 publications

References 15 publications

Secondary Plant Products Causing Photosensitization in Grazing Herbivores: Their Structure, Activity and Regulation

Secondary Plant Products Causing Photosensitization in Grazing Herbivores: Their Structure, Activity and Regulation

Reduced Photoinhibition under Low Irradiance Enhanced Kacip Fatimah (Labisia pumila Benth) Secondary Metabolites, Phenyl Alanine Lyase and Antioxidant Activity

Current Approaches for Enhanced Expression of Secondary Metabolites as Bioactive Compounds in Plants for Agronomic and Human Health Purposes

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