Supercritical CO2 Plant Extracts Show Antifungal Activities against Crop-Borne Fungi

Fungal infections of cultivated food crops result in extensive losses of crops at the global level, while resistance to antifungal agents continues to grow. Supercritical fluid extraction using CO₂ (SFE-CO₂) has gained attention as an environmentally well-accepted extraction method, as CO₂ is a non-toxic, inert and available solvent, and the extracts obtained are, chemically, of greater or different complexities compared to those of conventional extracts. The SFE-CO₂ extracts of Achillea millefolium, Calendula officinalis, Chamomilla recutita, Helichrysum arenarium, Humulus lupulus, Taraxacum officinale, Juniperus communis, Hypericum perforatum, Nepeta cataria, Crataegus sp. and Sambucus nigra were studied in terms of their compositions and antifungal activities against the wheat- and buckwheat-borne fungi Alternaria alternata, Epicoccum nigrum, Botrytis cinerea, Fusarium oxysporum and Fusarium poae. The C. recutita and H. arenarium extracts were the most efficacious, and these inhibited the growth of most of the fungi by 80% to 100%. Among the fungal species, B. cinerea was the most susceptible to the treatments with the SFE-CO₂ extracts, while Fusarium spp. were the least. This study shows that some of these SFE-CO₂ extracts have promising potential for use as antifungal agents for selected crop-borne fungi.

Essential Oil and Volatile Components of the Genus Hypericum (Hypericaceae)

The flowering plant genus Hypericum (Hypericaceae) contains the well-known medicinally valuable species Hypericum perforatum (common St. John's wort). Species of Hypericum contain many bioactive constituents, including proanthocyanins, flavonoids, biflavonoids, xanthones, phenylpropanes and naphthodianthrones that are characterized by their relative hydrophilicity, as well as acylphloroglucinols and essential oil components that are more hydrophobic in nature. A concise review of the scientific literature pertaining to constituents of Hypericum essential oils and volatile fractions is presented.

Positive correlations between hypericin and putative precursors detected in the quantitative secondary metabolite spectrum of Hypericum

A spectrum of eight pharmacologically important secondary compounds, all putatively belonging to the polyketide pathway (hypericin, pseudohypericin, emodin, hyperforin, hyperoside, rutin, quercetin, and quercitrin) were analyzed in several hypericin-producing species of Hypericum by LC-MS/MS. Different organs such as leaves, stems and roots of wild-grown plants of Hypericum hirsutum L., Hypericum maculatum Crantz s. l., Hypericum montanum L., Hypericum tetrapterum Fr. collected in Slovakia and of Hypericum perforatum L. collected in India were examined individually. Highest contents of hypericin, pseudohypericin, and emodin were found in H. montanum, suggesting that there are alternative species to H. perforatum with high pharmaceutical value. Amounts of hyperforin and quercetin were highest in H. perforatum, whereas highest contents of hyperoside and quercitrin were found in H. maculatum. A significant positive correlation between hypericin and pseudohypericin as well as between hypericin and emodin was observed by Kruskal's multidimensional scaling (MDS), indicating a parallel enhancement of emodin as a common precursor in the biosynthetic pathways of hypericin and pseudohypericin. Furthermore, MDS combined with principal component analysis (PCA) revealed strong correlations in the occurrence of pseudohypericin and emodin, pseudohypericin and quercitrin, hypericin and quercitrin, emodin and quercitrin, hyperoside and quercitrin, rutin and quercetin, and, hyperforin and quercetin. On the other hand, rutin showed a negative correlation with emodin as well as with quercitrin. Furthermore, hierarchical agglomerative cluster analysis (HACA) clustered hypericin and pseudohypericin, grouping emodin at equal distance from both. Considerable infraspecific variability in secondary compound spectrum and load of different populations of H. maculatum from Slovakia underscores the need for detailed studies of genotypic variation and environmental factors in relation to polyketide biosynthesis and accumulation.

Use of compressed fluids for sample preparation: Food applications

This review attempts to provide an updated overview (including works published till June 2006) on the latest applications of compressed fluids as sample preparation techniques for food analysis. After a general review of the principles of supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE; also called accelerated solvent extraction, ASE or subcritical water extraction, SWE, when water is employed as extraction solvent), the principal applications of such techniques in the mentioned fields of food and natural products are described, discussing their main advantages and drawbacks.

Comparison of methods for the exhaustive extraction of hypericins, flavonoids, and hyperforin from Hypericum perforatum L

Renewed interest in plant-derived drugs has led to an increased need for efficient extraction methods. Hypericum perforatum L. contains several groups of bioactive compounds with noteworthy pharmacological activities. Direct sonication of H. perforatum was investigated and compared with conventional maceration, indirect sonication, Soxhlet extraction, and accelerated solvent extraction (ASE). Highly selective liquid chromatography/tandem mass spectrometry analysis showed that the content of six investigated active compounds (hypericin, pseudohypericin, hyperoside, rutin, quercitrin, and hyperforin) in extracts obtained by direct sonication was significantly higher than in extracts obtained by the other methods. The active compound contents increased on increasing the ultrasonic power from 40 to 60 W when using direct sonication. Conventional maceration gave the lowest amount of analyzed active compounds. Soxhlet extraction gave better results than ASE or indirect sonication.

Supercritical CO2 extraction and purification of compounds with antioxidant activity

Supercritical fluid extraction (SCFE), based on the utilization of a fluid under supercritical conditions, is a technology suitable for extraction and purification of a variety of compounds, particularly those that have low volatility and/or are susceptible to thermal degradation. The interest in SCFE is promoted by legal limitations of conventional solvents for food and pharmaceutical uses. The physicochemical properties of supercritical CO2 (higher diffusivity, lower viscosity, and lower surface tension than conventional solvents) facilitate mass transfer and allow an environmentally friendly operation. This article presents a comprehensive compilation of data on the supercritical CO2 extraction of antioxidant compounds from vegetal materials, with particular attention to those of a phenolic nature. Aspects concerning the supercritical operation for extraction and fractionation of antioxidants compounds are considered, including equilibrium solubility of pure compounds and effects of the operational conditions on the antioxidant activity of isolated fractions. The data are compared to those reported for synthetic antioxidants and natural extracts obtained by conventional solvent extraction from vegetal matrices.

Development and evaluation of methods for determination of naphthodianthrones and flavonoids in St. John's wort

Several major constituents in St. John's wort were determined for a homogenized plant sample. Three extraction techniques were evaluated: Soxhlet extraction, pressurized-fluid extraction (PFE), and sonication extraction. Levels of nine constituents (chlorogenic acid, rutin, hyperoside, isoquercitrin, quercitrin, quercetin, amentoflavone, pseudohypericin, and hypericin) were measured using liquid chromatography with ultraviolet/visible absorbance, mass spectrometric, and fluorescence detection. Levels of total naphthodianthrones determined by liquid chromatography (LC) with absorbance detection at 590 nm were compared with levels determined by direct spectrophotometry at the same wavelength. Additionally, the methods described in this paper were applied to several brands of St. John's wort finished products.

St. John's Wort Hypericum perforatum L.: Supercritical extraction, antimicrobial and antidepressant activity of extract and some component

St. John's Wort, the Hypericum perforatum L. is one of the most analyzed plant species today. Plant was characterized with a wide ecological spectrum and is a plant with beautiful yellow flowers. St. John's Wort was used and still is in used in traditional medicine all over the World. Many bioactive components from St. John's Wort like hypericine, hyperforine, qercetrine and essential oil, were isolated and have been used in medicine. The most popular use of Hipericum extract is as an antidepressant for the medicinal treatment of mild and high depression. The medical use of hyperforine in photodynamic therapy for cancer treatment has now been intensively analyzed. The extract of St. John's Wort showed high antimicrobial, even on pathogenic microorganisms as well as antiviral activity. The use of bioactive components from St. John's Wort depends on the possibility to isolate them in the pure state. It seems that supercritical extraction with carbon dioxide might to be the best solution for obtaining pure extract as well as some of the components present in the essential oil and extract of St. John's Wort. Such a conclusion is supported by the many results of recently performed and published in scientific journals.