Essential Oil Composition ofHypericum perforatumL. var.angustifoliumDC Growing Wild in Sardinia (Italy)

Chitosan oligosaccharides affect xanthone and VOC biosynthesis in Hypericum perforatum root cultures and enhance the antifungal activity of root extracts

Water-soluble chitosan oligosaccharides (COS) affect xanthone and volatile organic compound content, as well as antifungal activity against human pathogenic fungi of extracts obtained from Hypericum perforatum root cultures. Several studies have demonstrated the elicitor power of chitosan on xanthone biosynthesis in root cultures of H. perforatum. One of the major limitations to the use of chitosan, both for basic and applied research, is the need to use acidified water for solubilization. To overcome this problem, the elicitor effect of water-soluble COS on the biosynthesis of both xanthones and volatile organic compounds (VOCs) was evaluated in the present study. The analysis of xanthones and VOCs was performed by HPLC and GC-MS headspace analysis. The obtained results showed that COS are very effective in enhancing xanthone biosynthesis. With 400 mg L^-1 COS, a xanthone content of about 30 mg g^-1 DW was obtained. The antifungal activity of extracts obtained with 400 mg L^-1 COS was the highest, with MIC₅₀ of 32 µg mL^-1 against Candida albicans and 32-64 µg mL^-1 against dermatophytes, depending on the microorganism. Histochemical investigations suggested the accumulation of isoprenoids in the secretory ducts of H. perforatum roots. The presence of monoterpenes and sesquiterpenes was confirmed by the headspace analysis. Other volatile hydrocarbons have been identified. The biosynthesis of most VOCs showed significant changes in response to COS, suggesting their involvement in plant-fungus interactions.

GC-MS analysis of the essential oil, aroma components and n-hexane extract of St. John Wort (Hypericum perforatum L., Hypericaceae)

St. John Wort (Hypercum perforatum L., Hypericaceae) has been used as a medicinal plant for a long period of time as this plant is characterized by a diversity of bioactive constituents which possess well documented pharmacological activities including antiviral, antimicrobial, anti-inflammatory, antioxidant, hepatoprotective and anti-tumoral activity. Nowadays, special interest is put on its essential oil as some experimental studies showed great biological and pharmacological potential. According this, the main goal of this study was GC/MS analysis of the essential oil, aroma components as well as n-hexane extracts of Hypericum perforatum that grows in Western region in R. Macedonia. GC/FID/MS analyses of the isolated essential oils from leaf, flower and herb resulted in the identification of 84 compounds. The fraction of sesquiterpenes was dominated in all examined oils and the main constituents were germacrene D (17.77-39.03%), E-caryophyllene (11.37-25.71%) and β-selinene (0.69-4.77%). GC/HS/MS analyses of the aroma components resulted in the identification of 23 compounds. Among them, isononane was identified as main aroma component (up to 75%). GC/FID/MS analyses of the n-hexane extracts resulted in the identification of 60 compounds which were characterized by the presence of terpenoid (mono- and sesquiterpene) components and non-terpenoid constituents mainly consisted of hydrocarbons and their oxygenate derivatives and related components. The non-terpenoid fraction represented the largest part of the analysed extracts. The most abundant were nonacosane (15.45-49.28%), octacosane (1.33-40.05%) and pentacosane (1.68-9.04%). The aerial parts of H. perforatum collected from Western part of R. Macedonia could be considered as a good source of essential oil with specific chemical profile as well as aroma components and high lipophilic compounds, but further investigation should be done in accordance to their possible commercial or medicinal use. Keywords: Hypericum perforatum, essential oil, aroma components, n-hexane extract, GC-MS

Morphogenetic changes in essential oil composition of Hypericum perforatum during the course of ontogenesis

CONTEXT

In the past few years, an increasing interest in the volatile secondary metabolites of Hypericum perforatum L. (Guttiferae) has been arising.

OBJECTIVE

The present study is a contribution to better understand the relationship between the morphological variations and volatile composition during the phenological cycle.

MATERIALS AND METHODS

Leaves at the stages of vegetative, floral budding, flowering and green capsule, buds, full opened flowers and green capsules were assayed for essential oil (EO) components by gas chromatography-flame ionization detector (GC-FID) and GC-mass spectrometry (MS).

RESULTS

Significant amounts of sesquiterpenes (oxygenated 26-50% and hydrocarbons 20-40%) and oxygenated hydrocarbons (13-38%) characterized the all analyzed samples showing peculiar fluctuations during the seven phenological stages. Although monoterpenes were present in much lower amounts (monoterpene hydrocarbons 0.4-6%; oxygenated monoterpenes 0.8-6%) they were considered also important discrimination for several stages. The green capsules and the full opened flowers collected at flowering stage were clearly distinguished in terms of EO compositions from the other samples.

DISCUSSION

For the first time, the EO composition of Turkish wild Hypericum perforatum was monitored by the hydrodistillation of different plant organs collected at different seven stages in order to point out the modification of target volatiles related to each phenological step.

CONCLUSIONS

Based on the EO composition monitored during these seven morphological stages by GC-MS, principal component analysis and cluster analysis, significant metabolite modifications were observed during the phenological cycle which involved the levels of specific volatile target compounds belonging to the chemical classes of hydrocarbons, monoterpenes and sesquiterpenes.

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.

Essential oil composition and variability of Hypericum perforatum from wild populations of northern Turkey

CONTEXT

Hypericum perforatum L. (Guttiferae) contains many bioactive secondary metabolites including hypericins, hyperforins, and essential oil.

OBJECTIVE

The present study was conducted to determine the variation in composition of essential oil in H. perforatum accessions from Turkey.

MATERIAL AND METHODS

At full flowering, aerial parts of 30 plants were collected from 10 sites of northern Turkey and assayed for essential oil components by GC-FID and GC-MS.

RESULTS

The chemical analysis revealed that the main constituents of the all analyzed samples were hydrocarbon and oxygenated sesquiterpenes such as beta-caryophyllene (4.08-5.93%), gamma-muurolene (5.00-9.56%), beta-selinene (5.08-19.63%), alpha-selinene (4.12-10.42%), d-cadinene (3.02-4.94%), spathulenol (2.34-5.14%), and caryophyllene oxide (6.01-12.18%). Monoterpenes, both hydrocarbon and oxygenated, were represented by scarce amounts of alpha- and beta-pinene, myrcene, linalool, cis- and trans-linalool oxide, and alpha-terpineol. Principal component analysis was also carried out and, according to the results, the first nine principal components were found to represent 100% of the observed variation.

DISCUSSION

The chemical variation among the populations is discussed as the possible result of different genetic and environmental factors.

CONCLUSIONS

The wild populations examined here are potentially important sources for breeding and improvement of the cultivated varieties.