76 research outputs found

    Rapid extraction of volatile compounds from Citrus fruits using a microwave dry distillation

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    Three different extraction methods were used for a comparative study of essential oil (EO) from fresh Citrus peels: Traditional hydrodistillation (HD), cold pressing (CP) and innovative microwave ‘dry’ distillation or microwave-accelerated distillation (MAD). The microwave process offers significant advantages over conventional alternatives, viz. shorter distillation period (30 min vs. 3 h for hydrodistillation and 1 h for cold pressing); better yields (0.24% vs. 0.21% for HD and 0.054% for CP); environmental impact (energy charge is noticeably superior for performing HD and for mechanical motors (CP) than that necessary for quick MAD assay); cleaner features (as no remains creation and no solvent or water used); raises antibacterial properties ; and offers a more precious EO (with high amounts of oxygenated compounds).Keywords: Microwave extraction; Hydrodistillation; Cold pressing; Essential oil; Citru

    Bioactive properties of medicinal plants from the Algerian flora: selecting the species with the highest potential in view of application purposes

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    The Algerian flora contains a wide variety of plant species with potential to be used in medicinal applications. Herein, the bioactive properties of medicinal plants from Algeria were evaluated to select the species with highest suitability to be used under specific purposes, while scientifically validating their health claims. The antioxidant activity of the infusions was screened by using several tests and cytotoxic properties were evaluated against human tumor cell lines (as also against non-tumor cells). Different hydrophilic bioactive compounds were also quantified. The results were analyzed considering individual variations in each parameter (ANOVA), but also in an aggregated approach by applying principal component analysis to acquire a comprehensive knowledge regarding the overall bioactive potential of the studied species. Limoniastrum guyonianum and Thymus pallescens showed the highest antioxidant activity (EC50 values ranging from 29 to 229 μg/mL and 54 to 240 μg/mL, respectively), whilst Asteriscus graveolens and L. guyonianum gave the best cytotoxicity against human tumor cell lines (GI50 values ranging from 11 to 29 μg/mL and 22 to 70 μg/mL, respectively). T. pallescens stood out as the species with highest bioactive compounds contents (phenols: 463 mg GAE, flavonoids: 194 mg CE, esters; 186 mg CAE; flavonols: 85 mg QE, considering g of lyophilized infusion basis). From a global point of view, T. pallescens, Saccocalyx satureioides and Ptychotis verticillata proved to be the preferable choices as high potential sources of bioactive compounds, while Haloxylon scoparium, L. guyonianum and A. graveolens would be the most suitable matrices considering the bioactivity (especially cytotoxicity) criterion, as inferred from the PCA outputs.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support to CIMO (PEst-OE/AGR/UI0690/2014), R.C. Calhelha (SFRH/BPD/68344/2010), J.C.M. Barreira (SFRH/BPD/72802/2010) and L. Barros (“Compromisso para a Ciência 2008” contract)

    Antioxidant activity of twenty wild Spanish Thymus mastichina L. populations and its relation with their chemical composition

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    The antioxidant activity and chemical composition of essential oils and methanolic extracts of twenty Spanish Thymus mastichina L. populations were studied. Both essential oils and methanolic extracts possessed antioxidant properties. However, the total phenol contents of the methanolic extracts varied between 2.90 and 9.15mg GAE/g extract and the EC 25 values of DPPH free radical scavenging activity between 0.90 and 3.45mg/mL for the methanolic extracts and 78-241mg/mL for essential oils, these showing low antioxidant potential. Actually, in essential oils the main compound determined was the 1,8-cineole (56.8-69.6%), whereas thymol, γ-terpinene, terpinolene and geraniol (species with considerable DPPH scavenging activity) were observed in low amounts. Concerning methanolic extracts, rosmarinic acid was the most abundant polyphenol (1.70-9.85mg/g), followed by methoxysalicylic acid, apigenin, kaempferol and luteolin.The authors are grateful to the POCTEPePrograma Cooperação Transfronteiriça España-Portugal 2007 e 2013 for financial support through the project “Mejora de la competitividad del sector agrario de Castilla y León y Norte de Portugal a través de la innovación y el desarrollo de productos diferenciados de alto valor”.info:eu-repo/semantics/publishedVersio

    Rapid extraction of volatile compounds from Citrus fruits using a microwave dry distillation

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    Three different extraction methods were used for a comparative study of essential oil (EO) from fresh Citrus peels: Traditional hydrodistillation (HD), cold pressing (CP) and innovative microwave ‘dry’ distillation or microwave-accelerated distillation (MAD). The microwave process offers significant advantages over conventional alternatives, viz. shorter distillation period (30 min vs. 3 h for hydrodistillation and 1 h for cold pressing); better yields (0.24% vs. 0.21% for HD and 0.054% for CP); environmental impact (energy charge is noticeably superior for performing HD and for mechanical motors (CP) than that necessary for quick MAD assay); cleaner features (as no remains creation and no solvent or water used); raises antibacterial properties ; and offers a more precious EO (with high amounts of oxygenated compounds)

    Composition of the essential oils of Thymus and Origanum species from Algeria and their antioxidant and antimicrobial activities

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    The composition of the essential oils of Origanum and Thymus species restricted to Algeria and the North Africa region was determined. Antioxidant and antibacterial activities of the isolated essential oils were also determined. The oils of oregano plants were strongly characterized by p-cymene (16.8-24.9%), gamma-terpinene (16.8-24.9%), thymol (8.4-36.0%), and carvacrol (1.1-29.7%), a thymol chemotype for Origanum floribundum and a R-terpineol chemotype for Thymus numidicus being described for the first time. The strains of Listeria monocytogenes tested were relatively resistant to the action of essential oils of either Origanum or Thymus species. All essential oils possessed antioxidant activity, but this was dependent on the specific chemical composition and the method employed to determine such activity

    Rapid extraction of volatile compounds from Citrus fruits using a microwave dry distillation

    No full text
    Three different extraction methods were used for a comparative study of essential oil (EO) from fresh Citrus peels: Traditional hydrodistillation (HD), cold pressing (CP) and innovative microwave ‘dry’ distillation or microwave-accelerated distillation (MAD). The microwave process offers significant advantages over conventional alternatives, viz. shorter distillation period (30 min vs. 3 h for hydrodistillation and 1 h for cold pressing); better yields (0.24% vs.0.21% for HD and 0.054% for CP); environmental impact (energy charge is noticeably superior for performing HD and for mechanical motors (CP) than that necessary for quick MAD assay); cleaner features (as no remains creation and no solvent or water used); raises antibacterial properties ; and offers a more precious EO (with high amounts of oxygenatedcompounds)

    Chemical composition and biological activities of Algerian Thymus oils

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    The compositions of essential oils isolated from nine samples of three Thymus species (Thymus algeriensis, Thymus pallescens and Thymus dreatensis) were analysed by GC and GC-MS, and a total of 114 components were identified. T. pallescens collected from various regions showed a great similarity in their compositions and were characterised by carvacrol (44.4-57.7%), p-cymene (10.3-17.3%) and gamma-terpinene (10.8-14.2%) as the major components for four samples; only one sample was thymol-rich (49.3t) with a small amount of carvacrol (9.0%). On the other hand, T. algeriensis showed a chemical polymorphism, even for samples from the same location, and two new chemotypes for this species were proposed. Oxygen-containing monoterpenes were the predominant class (76.3%) in T. dreatensis oil, with linalool (30.4%), thymol (20.2%) and geraniol (19.6%) as the principal constituents. The oils were screened for their possible antioxidant activities by four complementary assays, namely DPPH free radical scavenging, hydroxyl radical scavenging, inhibition of lipid peroxidation and reducing power. The two new chemotypes of T algeriensis exhibited strong hydroxyl radical scavenging (IC(50) = 2.2-3.3 mu g/ml), but were not or only slightly active against the other radicals and exhibited a weak reducing power. Despite their chemical similarity, T. pallescens oils sometimes produced significant differences in their antioxidant activities. The essential oils were also screened for their antimicrobial activity against five bacteria (three Gram-positive and two Gram-negative) and one yeast (Candida albicans). The tested essential oils showed antimicrobial activity against the microorganisms used, in particular against two important pathogens, C. albicans and Helicobacter pylori. (C) 2009 Elsevier Ltd. All rights reserved
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