Comparative study of the phenolic profile,antioxidant and antimicrobial activities of leaf extracts of five Juniperus L. (Cupressaceae) taxa growing in Turkey

Abstract

The purpose of this study was to conduct a comparative evaluation of some biological properties of methanol and water extracts of leaves of five Juniperus taxa growing in Turkey: J. communis L. var. communis (Jcc), J. communis L. var. saxatilis Pall. (Jcs), J. drupacea Labill. (Jd), J. oxycedrus L. subsp. oxycedrus (Joo), J. oxycedrus L. subsp. macrocarpa (Sibth. & Sm.) Ball. (Jom). The antioxidant properties were examined in vitro; both in the DPPH and in the reducing power tests, Joo methanol extract resulted the most active (IC₅₀?=?0.09?±?0.01mg/mL and ASE/mL?=?2.56?±?0.06). In the TBA assay, Jcs methanol extract exhibited the highest activity (IC₅₀?=?4.39?±?0.47?μg/mL). The extracts displayed bacteriostatic activity against Staphylococcus aureus, and Jd methanol extract resulted the most effective (MIC?=?19.53?μg/mL); no effect on the S. aureus biofilm formation was observed. The extracts resulted non-toxic in the Artemia salina lethality bioassay. Finally, the phenolic profile of the methanol extracts was characterized by HPLC-PDA/ESI-MS.     

A comparison between different techniques for the isolation of rosemary essential oil

Traditional hydrodistillation (HD), supercritical fluid extraction (SFE), organic solvent extraction (SE), and water microwave assisted hydrodistillation (MAHD) techniques were compared and evaluated for their effectiveness in the isolation of rosemary essential oil. The microwave assisted hydrodistillation technique was optimized in terms of both delivered power and time duration. The extracts/distillates were analyzed by GC and GC-MS. Microwave distillation, which exploits the physical action of microwaves on plants, showed a series of advantages over the other approaches: low cost, use of water in sample pre-treatment step, greatly reduced isolation time, and attainment of high quality essential oil distillate. Moreover, the absence of environmental impact of this innovative technique was also emphasized.     

Fast GC for the analysis of citrus oils

In this investigation, the gas chromatographic (GC) analysis of citrus essential oils is carried out in 3.3 min, with a speed gain of almost 14 times in comparison with traditional GC procedures. The fast method that is developed requires the application of severe experimental conditions (accelerated temperature program rates, high inlet pressures, and split ratios) and, thus, the support of adequate instrumentation. The samples investigated can be considered to be rather complex and, although a slight loss in peak resolution is observed, the overall analytical result is excellent. All data obtained are compared with that of a conventional application on the same matrices. This is done in order to evaluate the effectiveness and advantages of fast GC achieved with narrow bore columns.     

High-throughput analysis of bergamot essential oil by fast solid-phase microextraction-capillary gas chromatography-flame ionization detection

The advantages of using a narrow-bore column in headspace solid-phase microextraction-gas chromatographic (HS-SPME-GC) analysis are investigated. An automated rapid HS-SPME-GC method for the determination of volatile compounds in a complex sample (bergamot essential oil) was developed. A low-capacity (7 microm) SPME fibre was employed, enabling a short equilibration time (15 min). The absorbed volatile compounds were then separated in 12.5 min on a 10 m x 0.1 mm I.D. capillary. The fast GC method was characterized by relatively moderate GC parameters (head pressure: 173 kPa; temperature program rate: 12 degrees C/min). The employment of the low-capacity fibre also suited the reduced sample capacity of the capillary employed, hence column overloading was avoided. Analytical repeatibility was determined in terms of retention times (maximum RSD: 0.32%) and peak areas (maximum RSD: 9.80%). The results obtained were compared to those derived from a conventional HS-SPME-GC (a 30 microm SPME fibre and 0.25 mm I.D. capillary were used) application on the same sample. In this respect, a great reduction of analytical time was obtained both with regard to the conventional SPME equilibration and GC run times, which both required 50 min. Peak resolution was altogether comparable in both applications. Although a slight loss in terms of sensitivity was observed in the rapid approach (generally within the 25-50% range), this did not impair the detection of all peaks of interest. Finally, the selectivities of the 30 and 7 microm fibres were evaluated and, as expected, these were in good agreement.     

Separation of triacylglycerols in a complex lipidic matrix by using comprehensive two-dimensional liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometric detection

The present investigation describes the employment of a comprehensive 2-D HPLC system, based on the combination of a silver ion and an RP column, for the characterization of the triacylglycerol (TAG) fraction of a very complex lipidic sample: donkey milk fat. The TAGs were grouped on the resulting bidimensional contour plot according to their double bond numbers (aligned along vertical bands) and according to their partition numbers (aligned along horizontal bands). Peak assignment was supported by using atmospheric pressure chemical ionization mass spectrometric (APCI-MS) detection. The combination of the enhanced resolving power of comprehensive multidimensional LC, the formation of ordered 2-D patterns, and APCI-MS detection proved to be an effective tool for the characterization of the complex matrix, enabling the separation and identification of nearly 60 TAGs.     

High performance liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry for sensitive determination of bioactive amines in donkey milk

In the present study we report on the optimization and validation of a sensitive high performance liquid chromatography atmospheric pressure chemical ionization mass spectrometry (HPLC–APCI–MS) method for the determination of 8 bioactive amines (histamine, tyramine, tryptamine, 2-phenylethylamine, cadaverine, putrescine, spermidine and spermine) in donkey milk samples. The method involves donkey milk pre-treatment to remove proteins and pre-column dansylation of the amines. HPLC in reversed phase mode has been used for bioactive amines separation and the operating condition of the APCI–MS system proved to be powerful and very efficient for peak assignment. The separation was accomplished in a short time with an excellent resolution for all the amine peaks. Quantification was carried out by monitoring the characteristic [M+H]⁺ ion of each amine derivative. The method sensitivity, linearity and repeatability were assayed with satisfactory results. The detection limits of the analysed amines ranged from 0.5 μg L⁻¹ to 15 μg L⁻¹; the highest LOD was for spermine. Also remarkably good recovery values were obtained; at the lowest spiking level (1 μg L⁻¹) the percent mean recoveries ranged from 77.7 to 109.7. Furthermore, as the investigations relate to a complex matrix as donkey milk, suitable studies on matrix effect were performed. Finally, the developed and validated method was applied to analyse 13 donkey milk samples. Among the identified bioactive amines, putrescine, spermine and spermidine proved to be the main amines in donkey milk. Their concentration levels in the present study were lower than the values determined in mature human, cow and sow milk.     

Detailed analysis and group-type separation of natural fats and oils using comprehensive two-dimensional gas chromatography

Comprehensive gas chromatography (GC x GC) is an adequate methodology for the separation and identification of very complex samples. It is based on the coupling of two capillary columns that each give a different but substantial contribution to the unprecedented resolving power of this technique. The 2D space chromatograms that derive from GC x GC analysis have great potential for identification. This is due to the fact that the contour plot positions, pinpointed by two retention time coordinates, give characteristic patterns for specific families of compounds that can be mathematically translated. This investigation concerned the application of this principle to fatty acid methyl esters that were grouped on an equal double bond number basis. The ester samples were derived from various lipids and all underwent bidimensional analysis on two sets of columns. Peak attribution was supported by mass spectra, linear retention indices and information reported in the literature.     

Multidimensional Capillary GC-GC for the Analysis of Real Complex Samples. Part IV. Enantiomeric Distribution of Monoterpene Hydrocarbons and Monoterpene Alcohols of Lemon Oils

This paper describes a fully automated, multidimensional, double-oven GC-GC system, developed in our laboratory. The system is based on the use of mechanical valves which allow the multitransfer of different fractions during the same GC analysis and the use of the two GC independently when the multitransfer options is not used. Pneumatic and electronic circuits permit maintenance of constant retention times in the pre-column, even for the components eluted after numerous transfers. The system has been used for the determination of the enantiomeric distribution of β-pinene, sabinene, limonene, linalol, terpinen-4-ol, and α-terpineol in lemon oils. The results obtained allowed the characterization of cold-pressed lemon oils.     

Elucidation of Analytical–Compositional Fingerprinting of Three Different Species of Chili Pepper by Using Headspace Solid-Phase Microextraction Coupled with Gas Chromatography–Mass Spectrometry Analysis,and Sensory Profile Evaluation

The aim of the present study was to determine the volatile compounds of three different species of chili peppers, using solid-phase microextraction (SPME) methods in combination with gas chromatography–mass spectrometry (GC-MS). The detection of marker aroma compounds could be used as a parameter to differentiate between species of chili peppers for their detection and traceability in chili pepper food. The sensorial contribution was also investigated to identify the predominant notes in each species and to evaluate how they can influence the overall aroma. Three different pepper species belonging to the Capsicum genus were analyzed: Chinense, Annuum, and Baccatum. A total of 269 volatile compounds were identified in these species of chili peppers. The Capsicum annum species were characterized by a high number of acids and ketones, while the Capsicum chinense and Capsicum baccatum were characterized by esters and aldehydes, respectively. The volatile profile of extra virgin olive oils (EVOOs) flavored with chili peppers was also investigated, and principal component analysis (PCA) and hierarchical cluster analysis (HCA) of the volatile profiles were demonstrated to be a powerful analytical strategy for building a model that highlights the potential of a volatile characterization approach for use in evaluating food traceability and authenticity.