Effect of multifactorial free and liposome-coated of bay laurel (Laurus nobilis) and rosemary (Salvia rosmarinus) extracts on the behavior of Listeria monocytogenes and Vibrio parahaemolyticus in silver carp (Hypophthalmichthys molitrix) stored at 4 °C.

In this study, the effect of bay laurel (Laurus nobilis) (LE) and rosemary (Salvia rosmarinus) (RE) extracts, in two free forms and loaded with liposome, on the behavior of Listeria monocytogenes and Vibrio parahaemolyticus in silver carp (Hypophthalmichthys molitrix) minced, were examined. After extraction, the extracts were evaluated for phenolic, flavonoid, and antibacterial compounds (determination of MIC and MBC). The treatments studied included control treatment, treatments containing 1 and 1.5% of free extracts, and treatments containing 1 and 1.5% of liposome-coated extracts of LE and RE which were examined at times of 0, 4, 8, and 12 days with 3 replications. The findings indicated that the amount of flavonoid and phenolic compounds and the results of antibacterial tests (MIC and MBC tests) in RE extract were more favorable than LE extract. The aqueous extract of rosemary had higher levels of phenolic (344.66 mg gallic acid/g extract) and flavonoid (245.33 mg Catechin/g extract) compounds compared to the bay laurel extract (257.66 mg gallic acid/g extract) and (151.26 mg Catechin/g extract) respectively. The results of the behavior of L. monocytogenes and V. parahaemolyticus in fish showed that with increasing the storage time at 4 °C, these parameters increased, but in the treatment containing the coated forms of LE and RE extracts (concentration 1.5%), changes were significantly slower than other treatments. According to the obtained results, it can be concluded that in general, adding extracts of bay laurel and rosemary in a concentration of 1.5% reduces the proliferation of bacteria that cause food poisoning.

Laurel essential oil: biological activities and application for semolina preservation against the red flour beetle Tribolium castaneum (Tenebrionidae).

The phytochemical composition of Laurus nobilis essential oil and their anticholinesterase, antioxidant, and insecticidal potential were studied. Also, the oil volatile fraction was compared in semolina at the beginning and after storage periods. For that, a headspace solid-phase-microextraction analysis (HS-SPME) coupled with gas chromatography and mass spectrometry was undertaken. Significant quantitative and qualitative differences of the oil volatile fraction were detected according to storage periods and occupation space ratios. Additionally, anti-acetylcholinesterase activity of L. nobilis oil against T. castaneum adults was evaluated. Results revealed that insecticide activity varied according to storage duration and occupation space. Besides, the oil acts on acetylcholine hydrolysis by inhibiting the activity of acetylcholinesterase. These results highlighted that L. nobilis essential oil may be recommended as an eco-friendly alternative for preserving semolina during storage.

Biological control of Citrus brown spot pathogen, "Alternaria alternata" by different essential oils.

The antifungal effects of laurel, myrtle and peppermint essential oils and their combinations were investigated in vitro on two strains of Alternaria alternata mycelial growth and in vivo on detached Citrus leaf disease incidence. Myrtle essential oil was rich in α-pinene and 1,8-cineole while peppermint essential oil in menthol and menthone. 1,8-Cineole was the main component of the essential oils from laurel, laurel + myrtle and peppermint + laurel. The combined peppermint and myrtle essential oil was characterized by the predominance of menthol and 1,8-cineole. All tested essential oils, incorporated in potato-dextrose agar, inhibited A. alternata mycelial growth and had a fungistatic effect at concentration 3 mg/mL of medium. A great synergism was detected between peppermint and laurel essential oils against the two strains of A. alternata. The combined laurel and peppermint essential oil reduced mycelial growth rates of inoculated detached leaves at concentration above 1.5 mg/mL.

Anticandidal effectiveness of greenly synthesized zinc oxide nanoparticles against candidal pathogens.

Drug resistance of pathogenic candidal strains to conventional antifungal agents represents a significant health issue contributing to high morbidity worldwide. Hence, the aim of the current study focused on evaluating the antifungal and synergistic activities of the green synthesized zinc oxide nanoparticles formulated using Laurus nobilis leaf extract. The biogenic ZnONPs were hexagonal in shape with average particle size diameter of 37.98 nm and pure crystalline structure as detected by XRD data. The highest antifungal activity of biogenic ZnONPs was detected against Candida parapsilosis strain demonstrating relative inhibitory zone diameters of 17.13 ± 0.74 and 25.78 ± 0.47 mm, at the concentrations of 100 and 200 µg/disk, respectively. Moreover, the biogenic ZnONPs demonstrated the highest synergistic activity with clotrimazole antifungal agent against Candida glabrata followed by Candida auris strains. MTT assay revealed that the biogenic ZnONPs showed low toxicity demonstrating relative IC50 value of 774.45 µg/mL against normal lung fibroblast cells which further affirmed their biosafety for application. In conclusion, the bioinspired ZnONPs could be utilized for the formulation of effective antifungal agents against drug resistant candidal strains and also could be combined with antifungal agents to boost their antifungal efficiency.

Lipids in xylem sap of woody plants across the angiosperm phylogeny.

Lipids have been observed attached to lumen-facing surfaces of mature xylem conduits of several plant species, but there has been little research on their functions or effects on water transport, and only one lipidomic study of the xylem apoplast. Therefore, we conducted lipidomic analyses of xylem sap from woody stems of seven plants representing six major angiosperm clades, including basal magnoliids, monocots and eudicots, to characterize and quantify phospholipids, galactolipids and sulfolipids in sap using mass spectrometry. Locations of lipids in vessels of Laurus nobilis were imaged using transmission electron microscopy and confocal microscopy. Xylem sap contained the galactolipids di- and monogalactosyldiacylglycerol, as well as all common plant phospholipids, but only traces of sulfolipids, with total lipid concentrations in extracted sap ranging from 0.18 to 0.63 nmol ml-1 across all seven species. Contamination of extracted sap from lipids in cut living cells was found to be negligible. Lipid composition of sap was compared with wood in two species and was largely similar, suggesting that sap lipids, including galactolipids, originate from cell content of living vessels. Seasonal changes in lipid composition of sap were observed for one species. Lipid layers coated all lumen-facing vessel surfaces of L. nobilis, and lipids were highly concentrated in inter-vessel pits. The findings suggest that apoplastic, amphiphilic xylem lipids are a universal feature of angiosperms. The findings require a reinterpretation of the cohesion-tension theory of water transport to account for the effects of apoplastic lipids on dynamic surface tension and hydraulic conductance in xylem.

Antibacterial activity of essential oils extracted from the unique Chinese spices cassia bark, bay fruits and cloves.

Spices are widely used in daily life such as diet and have certain activity. Especially in China, spices have been mainly used as condiments for thousands of years in order to improve the sensory quality of food; in addition, they and their derivatives can also be used as preservatives. In this study, three spices with unique Chinese characteristics widely used were selected: cassia bark (bark of Cinnamomum camphora Presl), bay fruits (Laurus nobilis), and cloves (Syzygiumaromaticum). The main components and antibacterial ability of these three spices were analyzed by simulated extraction method. Through headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) analysis, it was determined that the main active compounds in the essential oils of cassia bark, bay fruits and cloves were cinnamaldehyde (78.11%), cinnamaldehyde (61.78%) and eugenol (75.23%), respectively. The agar plate diffusion test and the simulated food culture medium experiment confirmed that the essential oils extracted from the three flavors have antibacterial effects on Listeria monocytogenes, Listeria innocua, Listeria welshimeri, Listeria ivanovii, Listeria grayi and Vibrio parahaemolyticus. The antibacterial activity of different strains has different optimal extraction conditions. Generally speaking, cinnamon essential oil has the strongest antibacterial activity, while laurel fruit has the lowest antibacterial activity. The study proved the antibacterial activity of these three Chinese-specific spices and provided some new ideas and methods for the subsequent research and preparation of natural food additives and food antibacterial agents.

Prevention of Saprolegniasis in rainbow trout (Oncorhynchus mykiss) eggs using oregano (Origanum onites) and laurel (Laurus nobilis) essential oils.

The present study investigated the antifungal effects of essential oils of oregano (Origanum onites) and laurel (Laurus nobilis) on Saprolegniasis, a disease that occurs in rainbow trout eggs during the incubation period. Oregano and laurel were ground after drying, and essential oils were obtained by water distillation method using a Clevenger apparatus. The essential oils were added to potato dextrose agar (PDA) at the rates of 1-1000 ppm, and the minimum inhibitory concentration (MIC) was determined as 250 ppm whereas the minimum lethal concentration (MLC) was determined to be 500 ppm for both plants. In the in vivo trials, fertilized eggs were treated with predetermined doses either by bathing during water hardening and incubation period or only during incubation period, and death rates were monitored during embryological development. The best larvae hatching rate was determined in 500 ppm oregano and 500 ppm laurel groups treated during water hardening plus daily as 82.11% and 79.87%, respectively. According to the results, it was determined that oregano and laurel essential oils exhibited better results in all doses compared with the negative control group, and 500 ppm dose had a better effect than the positive control group treated with formalin.

Pressurized Liquid Extraction as a Novel Technique for the Isolation of Laurus nobilis L. Leaf Polyphenols.

Laurus nobilis L., known as laurel or bay leaf, is a Mediterranean plant which has been long known for exhibiting various health-beneficial effects that can largely be attributed to the polyphenolic content of the leaves. Pressurized liquid extraction (PLE) is a green extraction technique that enables the efficient isolation of polyphenols from different plant materials. Hence, the aim of this research was to determine optimal conditions for PLE (solvent, temperature, number of extraction cycles and static extraction time) of laurel leaf polyphenols and to assess the polyphenolic profile of the optimal extract by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) as well as to evaluate the antioxidant activity determined by FRAP, DPPH and ORAC assays. The optimal PLE conditions were 50% ethanol, 150 °C, one extraction cycle and 5 min static time. The polyphenolic extract obtained at optimal PLE conditions comprised 29 identified compounds, among which flavonols (rutin and quercetin-3-glucoside) were the most abundant. The results of antioxidant activity assays demonstrated that PLE is an efficient green technique for obtaining polyphenol-rich laurel leaf extracts with relatively high antioxidant activity.

Evaluation of daily Laurus nobilis tea consumption on anxiety and stress biomarkers in healthy volunteers.

Laurus nobilis is known in the field of herbal medicine and in vitro studies for its antibacterial, antifungal, anti- diabetes, and anti-inflammatory beneficial effects. Laurus nobilis tea consumption was investigated with regard to its effects on anxiety and stress in healthy individuals, measured by subjective tools and by plasmatic cortisol levels. The study included thirty healthy Tunisian volunteers aged between 20 and 57 years consuming Laurus nobilis infusion, prepared from 5g of dried Laurus nobilis leaves in 100 ml boiled water, once a day during 10 days. Plasma concentrations of serum cortisol were measured before Laurus nobilis consumption and at the end of the experiment. Laurus nobilis tea consumption significantly decreased the concentration of plasmatic cortisol ([cortisol] D0= 93.5± 43.01ng/mL, D11=72.23± 25.37, p=0.001). A statistically significant decrease in PSS and STAI scores (p=0.006 and p=0.002 respectively) was also noted.These findings highlight the decrease in blood cortisol levels, which means a possible positive effect on reducing the risk of stress related-diseases in healthy volunteers consuming Laurus nobilis tea. However, more powerful studies with extended treatment periods are required.

Genetic relationships and diversity analysis in Turkish laurel (Laurus nobilis L.) germplasm using ISSR and SCoT markers.

Laurel (Laurus nobilis L.) has been used in the Mediterranean basin since ancient ages. Nowadays, Turkey, Mexico, Portugal, Italy, Spain, France, Algeria, and Morocco use aromatic leaves for commercial purposes, and Turkey is the largest exporter in the world. In this study, molecular characterization, and genetic relationships of 94 Turkish laurel genotypes were determined by ISSR and SCoT markers. The experiment was conducted with 16 ISSR and 10 SCoT markers. While 348 of 373 bands were polymorphic with a 93.3% polymorphism rate, Nei's genetic distances ranged between 0.17 and 0.70 with 0.39 mean in ISSR. In SCoT, 175 of 227 bands were polymorphic with 77.1% polymorphism rate, and Nei's genetic distances varied between 0.12 and 0.51. Sufficient genetic diversity determined with diversity parameters consisting of the average Shannon's information index (ISSR: 0.46, SCoT:0.35), the overall gene diversity (ISSR:0.19, SCoT:0.18), and the effective number of alleles (ISSR:1.52, SCoT:1.38). AMOVA (Analysis of molecular variance) revealed most of the variation was within genotypes (96%). Neighbor-joining algorithms, principal coordinate analysis (PCoA), and model-based structure resulted in harmony and clustered according to the geographical regions and provinces they collected. Genotypes were divided into two groups in ISSR and SCoT with UPGMA clustering resulting in a similar polymorphism distribution. The correlation coefficient (r) determined by marker systems' Nei's genetic distances was 0.25. The results of the study put forward resources for advanced breeding techniques, contribute to the preservation of genetic diversity, and management of genetic resources for the breeders.

Phytosynthesis of CuONPs via Laurus nobilis: Determination of antioxidant content, antibacterial activity, and dye decolorization potential.

Copper oxide nanoparticles (CuONPs) were phytosynthesized by Laurus nobilis leaf extract, which was used as a reducing and capping agent. UV-vis spectroscopy was applied, and the spectrum of CuONPs gave a peak around 300 and 325 nm. An intense Fourier transform infrared spectroscopy between 4000 and 500 cm-1 wavelengths exhibited exterior functional groups of CuONPs. The results of scanning electron microscopy and transmission electron microscopy revealed that the green synthesized CuONPs were spherical in shape with sizes between 90 and 250 nm. Antibacterial activity of CuONPs was evaluated against both Gram-positive and Gram-negative bacteria. Brilliant Blue R-250 was employed in the dye decolorization studies, and CuONPs achieved 69% decolorization in 60 Min. The antioxidant activity of CuONPs was calculated by analyzing total phenolic compounds and flavonoid content. Furthermore, the reducing power of extract and nanoparticles was determined. Total phenolic compounds of CuONPs were determined as 6.7 µg of pyrocatechol equivalent/mg, while total flavonoids were measured as 236.62 µg catechin/mg sample. Results indicated that the method of CuONP formation is simple and low cost and the phytosynthesized CuONPs had antibacterial, antioxidant, and dye decolorization activity.

Suggestions on the Contribution of Methyl Eugenol and Eugenol to Bay Laurel (Laurus nobilis L.) Essential Oil Preservative Activity through Radical Scavenging.

The present study examined the radical scavenging potential of the two benzene derivatives found in the bay laurel essential oil (EO), namely methyl eugenol (MEug) and eugenol (Eug), theoretically and experimentally to make suggestions on their contribution to the EO preservative activity through such a mechanism. Calculation of appropriate molecular indices widely used to characterize chain-breaking antioxidants was carried out in the gas and liquid phases (n-hexane, n-octanol, methanol, water). Experimental evidence was based on the DPPH• scavenging assay applied to pure compounds and a set of bay laurel EOs chemically characterized with GC-MS/FID. Theoretical calculations suggested that the preservative properties of both compounds could be exerted through a radical scavenging mechanism via hydrogen atom donation. Eug was predicted to be of superior efficiency in line with experimental findings. Pearson correlation and partial least square regression analyses of the EO antioxidant activity values vs. % composition of individual volatiles indicated the positive contribution of both compounds to the radical scavenging activity of bay laurel EOs. Eug, despite its low content in bay laurel EOs, was found to influence the most the radical scavenging activity of the latter.

Lower COVID-19 mortality in Italian forested areas suggests immunoprotection by Mediterranean plants.

The COVID-19 pandemic has induced dramatic effects on the population of the industrialized north of Italy, whereas it has not heavily affected inhabitants of the southern regions. This might be explained in part by human exposure to high levels of fine particulate matter (PM) in the air of northern Italy, thus exacerbating the mortality. Since trees mitigate air pollution by intercepting PM onto plant surfaces and bolster the human immune system by emitting bioactive volatile organic compounds (VOCs), we hypothesize a protective role of evergreen forested areas in southern Italy. We compared the mortality rate  due to COVID-19, the death number, the positivity rate and the forest coverage per capita in various Italian regions. Hectares of forest per capita and prevalence of deciduous versus evergreen forestal species were also estimated. In silico docking studies of potentially protective compounds found in Laurus nobilis L., a typical Mediterranean plant, were performed to search for potential antivirals. We found that the pandemic's severity was generally lower in southern regions, especially those with more than 0.3 hectares of forest per capita. The lowest mortality rates were found in southern Italy, mainly in regions like Molise (0.007%) and Basilicata (0.005%) where the forest per capita ratio is higher than 0.5 Ha/person. Our findings suggest that evergreen Mediterranean forests and shrubland plants could have protected the southern population by emission of immuno-modulating VOCs and provision of dietary sources of bioactive compounds. Moreover, in silico studies revealed a potential anti-COVID-19 activity in laurusides, which are unexplored glycosides from bay laurel. Overall, our results highlight the importance of nature conservation and applications to the search for natural antivirals.

Evaluation of Daily Laurus nobilis Tea Consumption on Lipid Profile Biomarkers in Healthy Volunteers.

Introduction:Laurus nobilis is known in the field of herbal medicine and in vitro studies that it has beneficial effects such as antibacterial, antifungal, antidiabetes, and anti-inflammatory properties.Objective: We investigated whether L. nobilis tea consumption affects the plasma levels of lipid biomarkers in healthy volunteers.Methods: Thirty healthy Tunisian volunteers aged between 20 and 57 years old consumed L. nobilis infusion, prepared from 5 g of dried L. nobilis leaves in 100 ml boiled water, once a day during 10 days. Plasma concentrations of serum low-density lipoprotein (LDL) cholesterol, triglycerides and HDL (high-density lipoprotein) cholesterol were measured by Beckman Coulter D × 600 analyzer before L. nobilis consumption and at the end of the experiment.Results:L. nobilis tea consumption significantly increased the concentration of HDL cholesterol ([HDL cholesterol] D0 = 1.34 ± 0.25 pg/mL, D11=1.42 ± 0.29, p = 0.01). However, a slight decrease that was statistically non-significant in LDL cholesterol and triglycerides levels was observed (p < 0.05).Conclusions: These findings highlight the improving blood lipidic profiles, which means a possible positive effect on reducing the risk of cardiovascular disease of L. nobilis tea consumption in healthy volunteers. However, more powerful studies with an extended treatment period are required.

Mitigation of lead neurotoxicity by the ethanolic extract of Laurus leaf in rats.

The present study was conducted in order to assess the chemical composition of Laurus, its antioxidant activities, and benefit from the Laurus extract effect on neurotoxicity caused by lead acetate (Pb). Chemical profile was assayed by using liquid chromatography coupled with high-resolution mass spectrometry (LC-HR-MS). In this study, 40 male rats were divided into four groups (10 rats per each group): (1) control group, (2) Laurus group: rats treated with 250 mg/kg b. wt. of Laurus leaves extract, (3) Pb group: rats treated with 100 mg/kg b. wt. of lead acetate, (4) Pb + Laurus group: rats treated with 250 mg/kg b. wt. of Laurus leaves extract in addition to lead acetate for 30 days. At the end of experiment, some estimates were calculated from blood samples, brain tissue, and histological examination. The results showed that the extract is highly affluent in total flavonoids, total phenolic, and also has antioxidant activity. The LC-MS appeared a wide range of compounds in the extract. The oxidative stress resulted from exposure to lead acetate has been reported to cause reduction in body and brain weights, levels of RBCs, acetylcholinesterase (AChE), GSH, SOD, and CAT in addition to increase in levels of WBCs and MAD. Moreover, Laurus leaves extract notably lessened the biochemical changes caused by lead acetate in the blood, homogenate, and brain tissue (P < 0.05). The current study indicates the antioxidant activity of Laurus leaves extract and assumes that it has a defensive role against the oxidative damage caused by lead in a rat's brain.

Modeling heavy metal removal by retention on Laurus nobilis leaves biomass: linear and nonlinear isotherms and design.

Heavy metal industries pose a serious threat to the environment. Conventional methods used for heavy metal removal are generally not always low-cost and environmentally friendly. So, researchers focused to investigate alternative biosorbents for the uptake of heavy metal. In this study, Laurus nobilis leaves (LNL) were used as a biosorbent for the uptake of toxic metals such as Pb2+ and Cd2+ from aqueous solutions. Batch biosorption experiments under varied conditions, such as biosorbent dosage, solution pH, heavy metal concentration, biosorption time, ionic strength, humic acid effect and competitive metal ions (Cd(II), Pb(II), Cu(II) and Zn(II)) were performed. The biomass was characterized using FT-IR spectra and SEM images. The nonlinearized and linearized isotherm models were compared and discussed. A single-stage batch bioreactor system for each heavy metal based on the best fit nonlinear isotherm model also has been presented. The biosorption of Pb(II) on LNL fitted better in the Langmuir model and Cd(II) biosorption fitted better in the Freundlich model by nonlinearized equations. The LNL exhibited the maximum monolayer biosorption capacities (qmax) of 7.1 and 32.5 mg/g for cadmium and lead, respectively. LNL showed great potential especially in Pb(II) uptake. LNL may be promising for heavy metal removal from aqueous environment.

Chemical Composition of Natural Hydrolates and Their Antimicrobial Activity on Arcobacter-Like Cells in Comparison with Other Microorganisms.

Hydrolates obtained via the hydrodistillation and steam distillation of Lavandulaangustifolia Mill., Syzygiumaromaticum L., Foeniculumvulgare Mill., and Laurusnobilis L. were analyzed by gas chromatography with flame ionization detector (GC-FID) and gas chromatography coupled to mass spectrometry (GC-MS). Additionally, the hydrolates were evaluated for antimicrobial activity (disk-diffusion and microdilution method), influence on biofilm formation (Christensen method) and cytotoxicity of concentrated hydrolates against human cell lines (A549) by xCELLigence system. Using chemical analysis, 48, 9, 13 and 33 different components were detected in lavender, clove, fennel and laurel hydrolates, respectively. Lavender hydrolate contained the largest proportion of 1,8-cineol, linalool furanoxide, and linalool. The main components of laurel hydrolate were 1,8-cineol, 4-terpineol and α-terpineol. Fenchone and estragole were the most abundant in fennel hydrolate, and eugenol and eugenyl acetate in clove hydrolate. Concentrated hydrolates showed significant antimicrobial activity. Clove hydrolate was among the most antimicrobially active agents, most preferably against C. albicans, with an inhibition zone up to 23.5 mm. Moreover, concentrated hydrolates did not show any cytotoxic effect again8 st human A549 cells. In the presence of the non-concentrated hydrolates, significantly reduced biofilm formation was observed; however, with concentrated clove hydrolate, there was an increase in biofilm formation, e.g., of A. thereius, A. lanthieri, and A. butzleri. Research shows new findings about hydrolates that may be important in natural medicine or for preservation purposes.

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.

Diagnostic Potential of FT-IR Fingerprinting in Botanical Origin Evaluation of Laurus nobilis L. Essential Oil is Supported by GC-FID-MS Data.

The last years, non-targeted fingerprinting by Fourier-transform infrared (FT-IR) spectroscopy has gained popularity as an alternative to classical gas chromatography (GC)-based methods because it may allow fast, green, non-destructive and cost-effective assessment of quality of essential oils (EOs) from single plant species. As the relevant studies for Laurus nobilis L. (bay laurel) EO are limited, the present one aimed at exploring the diagnostic potential of FT-IR fingerprinting for the identification of its botanical integrity. A reference spectroscopic dataset of 97 bay laurel EOs containing meaningful information about the intra-species variation was developed via principal component analysis (PCA). This dataset was used to train a one-class model via soft independent modelling class analogy (SIMCA). The model was challenged against commercial bay laurel and non-bay laurel EOs of non-traceable production history. Overall, the diagnostic importance of spectral bands at 3060, 1380-1360, 1150 and 1138 cm-1 was assessed using GC-FID-MS data. The findings support the introduction of FT-IR as a green analytical technique in the quality control of these often mislabeled and/or adulterated precious products. Continuous evaluation of the model performance against newly acquired authentic EOs from all producing regions is needed to ensure validity over time.

Comparison of Chemical Composition and Biological Properties of Essential Oils Obtained by Hydrodistillation and Steam Distillation of Laurus nobilis L.

The purpose of this study was to compare the yield, chemical composition, antimicrobial and antioxidant properties of essential oils isolated from leaves of Laurus nobilis L. by two different distillation methods. The essential oils isolated by hydrodistillation (HD) and steam distillation (SD) were analyzed by gas chromatography coupled to mass spectrometry (GC-MS) and gas chromatography with flame ionization detector (GC-FID). Hydrodistillation produced a yield of 0.95 ± 0.06% which is slightly higher than yield obtained by steam distillation 0.79 ± 0.07%. Seventy three compounds in the bay leaves oil obtained by steam distillation were identified while in essential oil obtained by hydrodistillation were identified only 54 compounds. The antioxidant activity was evaluated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical method. Antimicrobial activity of obtained essential oils was evaluated by disc diffusion method in comparison with several chosen antimicrobials. The antimicrobial activity was tested on five microorganisms - Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Candida albicans. In general, oils produced by steam distillation had higher antimicrobial and antioxidant activities than hydrodistillation extracts. It seems that hydrodistillation is better for higher yield while steam distillation is better to use for more quality oils with stronger biological properties.