Essential Oils from Piper lhotzkyanum Kunth Leaves from Brazilian Atlantic Forest: Chemical Composition and Stability in Different Storage Conditions.

This work aimed to evaluate the impact of different storage conditions and light and temperature exposures on the visual aspect and chemical composition of the essential oil (EO) of Piper lhotzkyanum Kunth, obtained from leaves by hydrodistillation from a region of high altitude. For this purpose, aliquots of the EO were stored for up to 90 days (a) under a refrigerator condition of 5 ± 3°C, (b) under a long-term (LT) condition of 30 ± 2°C and 75 ± 5% relative humidity (RH) and an accelerated condition (AS) of 40 ± 2°C and 75 ± 5% RH, and (c) in a photostability test achieved in amber and colorless glass vials. The changes were monitored on days 0 (control), 60, and 90 for the refrigerator, LT, and AS conditions. All EO chemical analyses were assessed by GC-FID and GC-MS for quantification and identification, respectively. It is reported, for the first time, that the EO of P. lhotzkyanum is rich in the sesquiterpenes ß-elemene and α-zingiberene. No significant changes in the EO was observed, revealing a minimal impact of temperature on the sample at the different storage conditions. However, there was a change in the content of α-zingiberene to bicyclogermacrene after exposure to light. The visual appearance of the samples was altered for all test conditions except the refrigerator condition. These results can potentially contribute to the product development of a bioactive EO from leaves of P. lhotzkyanum, a sesquiterpene rich natural material.

Effect of Enzymatic, Ultrasound, and Reflux Extraction Pretreatments on the Chemical Composition of Essential Oils.

The effect of different hydrodistillation pretreatments, namely, reflux extraction, reflux extraction with the addition of cell wall-degrading enzymes, and ultrasound, on the yield and chemical composition of essential oils of sage, bay laurel, and rosemary was examined. All pretreatments improved essential oil yield compared to no-pretreatment control (40-64% yield increase), while the oil quality remained mostly unchanged (as shown by statistical analysis of GC-MS results). However, enzyme-assisted reflux extraction pretreatment did not significantly outperform reflux extraction (no-enzyme control), suggesting that the observed yield increase was mostly a consequence of reflux extraction and enzymatic activity had only a minute effect. Thus, we show that ultrasound and reflux extraction pretreatments are beneficial in the production of essential oils of selected Mediterranean plants, but the application of enzymes has to be carefully re-evaluated.

Effects of light irradiation on essential oil biosynthesis in the medicinal plant Asarum heterotropoides Fr. Schmidt var. mandshuricum (Maxim) Kitag.

Asarum heterotropoides Fr. var. mandshuricum (Maxim) Kitag (Chinese wild ginger) is an important medicinal herb. Essential oil extracted from its roots is the key ingredient and is mainly composed of phenylpropanoid compounds. As a skiophyte plant, light is a crucial factor for A. heterotropoides var. mandshuricum growth and metabolism. To investigate the effects of light irradiation on the essential oil biosynthesis in A. heterotropoides var. mandshuricum, the plants were cultivated in four light irradiation treatments (100, 50, 24 and 12% full sunlight). The photosynthetic capacity, essential oil content and composition, activities of several enzymes and levels of some secondary metabolites involved in the shikimic acid and cinnamic acid pathways were analyzed. The leaf mass per area, average diurnal net photosynthetic rate, and the essential oil content increased significantly with increasing light intensity. Phenylalanine, cinnamic acid, and p-coumaric acid in the cinnamic acid pathway were at their highest levels in plants cultivated in 100% full sunlight. The highest content of shikimic acid in the shikimic acid pathway was obtained in plants grown in 50% sunlight transmittance. The activity of the enzymes 3-Deoxy-D-arabino-heptulosonate-7-phosphate synthase, phenylalanine ammonia lyase, cinnamate-4-hydroxylase and 4-coumarate:CoA ligase increased proportionally with light intensity. Overall, we conclude that high light irradiation promotes high net photosynthetic rate, high activity of enzymes and high amounts of phenylpropanoid precursor metabolites leading to significant biosynthesis of essential oil in A. heterotropoides var. mandshuricum.

Characterization of the Aldehydes and Their Transformations Induced by UV Irradiation and Air Exposure of White Guanxi Honey Pummelo (Citrus Grandis (L.) Osbeck) Essential Oil.

Aldehydes are key aroma contributors of citrus essential oils. White Guanxi honey pummelo essential oil (WPEO) was investigated in its aldehyde constituents and their transformations induced by UV irradiation and air exposure by GC-MS, GC-O, and sensory evaluation. Nine aldehydes, i.e., octanal, nonanal, citronellal, decanal, trans-citral, cis-citral, perilla aldehyde, dodecanal, and dodecenal, were detected in WPEO. After treatment, the content of citronellal increased, but the concentrations of other aldehydes decreased. The aliphatic aldehydes were transformed to organic acids. Citral was transformed to neric acid, geranic acid, and cyclocitral. Aldehyde transformation caused a remarkable decrease in the minty, herbaceous, and lemon notes of WPEO. In fresh WPEO, ß-myrcene, d-limonene, octanal, decanal, cis-citral, trans-citral, and dodecenal had the highest odor dilution folds. After the treatment, the dilution folds of decanal, cis-citral, trans-citral, and dodecenal decreased dramatically. This result provides information for the production and storage of aldehyde-containing products.

The role of supplemental ultraviolet-B radiation in altering the metabolite profile, essential oil content and composition, and free radical scavenging activities of Coleus forskohlii, an indigenous medicinal plant.

The effects of supplemental ultraviolet-B (s-UV-B; 3.6 kJ m(-2) day(-1) above ambient) radiation were investigated on plant metabolite profile, essential oil content and composition, and free radical scavenging capacities of methanolic extracts of Coleus forskohlii (an indigenous medicinal plant) grown under field conditions. Essential oil was isolated using hydrodistillation technique while alterations in metabolite profile and oil composition were determined via gas chromatography-mass spectroscopy (GC-MS). Leaf and root methanolic extracts were investigated via various in vitro assays for their DPPH radical-, superoxide radical-, hydrogen peroxide-, hydroxyl radical-, and nitric oxide radical scavenging activities, ferrous ion chelating activity, and reducing power. Phytochemical analysis revealed the presence of alkaloids, anthocyanins, coumarins, flavonoids, glycosides, phenols, saponins, steroids, tannins, and terpenoids. Oil content was found to be reduced (by ∼7 %) in supplemental UV-B (s-UV-B) treated plants; the composition of the plant extracts as well as essential oil was also considerably altered. Methanolic extracts from treated plant organs showed more potency as free radical scavengers (their EC50 values being lower than their respective controls). Anomalies were observed in Fe(2+) chelating activity for both leaves and roots. The present study concludes that s-UV-B adversely affects oil content in C. forskohlii and also alters the composition and contents of metabolites in both plant extracts and oil. The results also denote that s-UV-B treated plant organs might be more effective in safeguarding against oxidative stress, though further studies are required to authenticate these findings.

Chemical composition and antioxidant properties of γ-irradiated Iranian Zataria multiflora extracts.

CONTEXT: Irradiation is the process of exposing food such as herbal plant to ionizing radiation to destroy microorganisms. Zataria multiflora Boiss (Lamiaceae), known as Avishan-e-Shirazi in Persian, is a thyme-like plant that grows naturally in central and southern parts of Iran and is used in traditional folk medicine. OBJECTIVE: In this study, the effects of γ-radiation on chemical composition and antioxidant properties of Z. multiflora were investigated. MATERIALS AND METHODS: The plants were first irradiated with Co60 source (0, 10, and 25 kGy) and then subjected to Clevenger extraction to obtain essential oils. The composition of the oil was analyzed by a gas chromatography and compared with samples pretreated under different conditions. In parallel, the hydroalcoholic extract was prepared and used for measuring flavonoid content. Thereafter, the free-radical scavenging and antioxidant properties of essential oils and hydroalcoholic extract were examined. RESULTS: Despite the minor change in the individual oil constituents, the total percentage of the main components remained unaffected before and after irradiation (~95%). In addition, the total flavonoid content of hydroalcoholic extract was also unchanged due to irradiation (~32 mg QE/g extract). The high radical scavenging activity of the oil (~67%) and hydroalcoholic extract (~71%), in addition, the antioxidant properties of the oil (~91%) and hydroalcoholic extract (~95%), were unaffected after irradiation. DISCUSSION AND CONCLUSIONS: These findings may suggest the sustainability of Z. multiflora extract properties pretreated with γ-radiation. With a view to its antioxidant applications, resistance of Z. multiflora and its properties against radiation effects are promising findings.

In vitro photo-induced cytotoxic activity of Citrus bergamia and C. medica L. cv. Diamante peel essential oils and identified active coumarins.

CONTEXT: The search for innovative therapeutic approaches is gaining more interest in clinical oncology. OBJECTIVE: In the present investigation we reported the chemical profile and the photo-induced cytotoxic activity of two endemic Calabrian Citrus species (Rutaceae): Citrus bergamia Risso & Poit. and Citrus medica L. cv. Diamante. MATERIALS AND METHODS: Essential oils were obtained by hydrodistillation and analyzed by GC and GC/MS. In order to evaluate the cytotoxic activity two melanoma models, such as amelanotic melanoma C32 and malignant melanoma A375, were used. RESULTS: The essential oil of C. bergamia was characterized by limonene, linalyl acetate, gamma-terpinene, linalool and beta-pinene as major components. The most abundant compounds of C. medica cv. Diamante oil were limonene, gamma-terpinene, citral, geranial, beta-pinene and alpha-pinene. Two coumarins, bergapten and citropten, were also identified in C. bergamia and C. medica cv. Diamante, respectively and tested for biological activity. Both C. bergamia and C. medica cv. Diamante oils exhibited a selective interesting activity against the A375 cell line with IC(50) values of 79.3 and 89.1 microg/mL, respectively, after 100 min exposure to UV irradiation. The strong antiproliferative activity demonstrated with bergapten (IC(50) value of 71.3 microg/mL after 20 min of irradiation) was not found with citropten. DISCUSSION AND CONCLUSION: Our study suggested that UV irradiation is effective in activating essential oils and in particular bergapten. This phototoxicity may be considered as a treatment option in some cases of lentigo maligna or lentigo maligna melanoma.

Hepatoprotective effects of gamma-irradiated caraway essential oils in experimental sepsis.

Irradiation is an important method of processing herbal drugs, while our understanding of the effects of gamma-irradiation on pharmacological properties of seed products such as caraway essential oils is however still very limited. In this study, caraway seeds were irradiated at dose levels of 0, 10 and 25kGy. After extracting the essential oils, the effects of fresh and gamma-irradiated caraway oils (100mg/kg b.w) on preventing septic-related oxidative liver injury induced by cecal ligation and puncture (CLP) model were investigated by measuring oxidative stress parameters in the liver. CLP operation caused a marked increase in myeloperoxidase (MPO) activity which was readily reversed in rats treated with fresh and irradiated caraway oils. Likewise, thiobarbituric acid reactive substances (TBARS) level in the liver was compensated in rats treated with the fresh and irradiated caraway oils. Moreover, liver GSH which was initially depleted due to CLP was recovered by essential oil treatments. The protective role of oils was further confirmed by showing that liver function tests (ALT/AST) as well as histopathological changes following CLP operation were recovered in rats treated with oils from either fresh or irradiated caraway seeds. These data may suggest that gamma-irradiation to caraway seeds at 10 and 25kGy has no influence on the antioxidative properties of caraway essential oils.

Influence of gamma-irradiation and microwaves on the antioxidant property of some essential oils.

The antioxidant property of anise, caraway, cumin and fennel essential oils extracted from untreated, gamma-irradiated and microwaved fruits against sunflower oil oxidative rancidity was evaluated. The fruits were exposed to gamma-irradiation at 10 KGy and to microwaves at low oven power setting for 1 min. The essential oils were added individually (200 ppm) to sunflower oil and the rate of oil oxidation was followed by determining the peroxide value during storage at room temperature. The irradiated and microwaved essential oils exhibited an antioxidant activity and was superior to that of sunflower oil catalysed by a mixture of BHT + BHA (200 ppm) in most cases. The present data show that gamma-irradiation and microwave treatments did not affect the antioxidant property of the essential oils under study. In addition the essential oils extracted from the gamma-irradiated fruits were more effective as an antioxidant in sunflower oil than those produced from microwaved fruits.