Supercritical fluid extraction of antioxidant and antimicrobial compounds from Laurus nobilis L. Chemical and functional characterization

Evaluation of the antimicrobial effects of Capsicum, Nigella sativa, Musa paradisiaca L., and Citrus limetta: A review

The extensive use of antibiotics and vaccines against microbial infections can result in long-term negative effects on humans and the environment. However, there are a number of plants that have antimicrobial effects against various disease-causing microbes such as bacteria, viruses, and fungi without negative side effects or harm to the environment. In this regard, four particular plants- Capsicum, Nigella sativa, Musa paradisiaca L., and Citrus limetta have been widely considered due to their excellent antimicrobial effect and ample availability. In this review, we discuss their antimicrobial effects due to the presence of thymoquinone, p-cymene, pinene, alkaloids, limonene, camphene, and melanin. These antimicrobial compounds disrupt the cell membrane of microbes, inhibit cellular division, and form biofilm in bacterial species, eventually reducing the number of microbes. Extraction of these compounds from the respective plants is carried out by different methods such as soxhlet, hydro-distillation, liquid-liquid extraction (LLE), pressurized liquid extraction (PLE), solid-phase extraction (SPE), supercritical fluid extraction (SFE), pulsed electric field (PEF), microwave-assisted extraction (MAE), enzyme-assisted extraction (EAE), ultrasound-assisted extraction (UAE), and high-voltage electrical discharge. Suitable selection of the extraction technique highly depends upon the associated advantages and disadvantages. In order to aid future study in this field, this review paper summarizes the advantages and disadvantages of each of these approaches. Additionally, the discussion covers how antimicrobial agents destroy harmful bacteria. Thus, this review offers in-depth knowledge to researchers on the antibacterial properties of Capsicum, Nigella sativa, Musa paradisiaca L. peels, and Citrus limetta.

Greenness of lab-on-a-chip devices for analytical processes: Advances & future prospects

Lab-on-a-chip devices have now-a-days become an important aspect of analytical/bioanalytical chemistry having wide range of applications including clinical diagnosis, drug screening, cell biology, environmental monitoring, food safety analysis etc. Conventional lab-on-a-chip devices generally employ chemicals that are not environmentally friendly and were commonly fabricated on hard plastic platform which are non-degradable and hence ignore the importance of green analytical chemistry. In today's scenario, it is highly imperative to protect our environment by using less toxic and environmentally friendly chemicals/solvents and biocompatible platforms. Accordingly, the present article comprehensively reviews on the various green aspects of lab-on-a-chip devices for analytical processes which aim at fabricating environmentally friendly and cost-effective downsized devices so that the risk factor at the user's end upon longer exposure as well as to the environment can be reduced. The decisive factors for the accomplishment of green aspects of lab-on-a-chip devices including sample preparation using lab-on-a-chip systems to minimize the amount of sample/solvents to few microliters only, substitution of harmful solvents with green alternatives, minimal waste generation or proper treatment of waste and biodegradable and biocompatible platforms for fabricating lab-on-a-chip devices have been discussed in details. Additionally, the challenges that may hinder their commercialization are also critically discussed.

A Review of the Botany, Volatile Composition, Biochemical and Molecular Aspects, and Traditional Uses of Laurus nobilis

Laurus nobilis L. is an aromatic medicinal plant widely cultivated in many world regions. L. nobilis has been increasingly acknowledged over the years as it provides an essential contribution to the food and pharmaceutical industries and cultural integrity. The commercial value of this species derives from its essential oil, whose application might be extended to various industries. The chemical composition of the essential oil depends on environmental conditions, location, and season during which the plants are collected, drying methods, extraction, and analytical conditions. The characterization and chemotyping of L. nobilis essential oil are extremely important because the changes in composition can affect biological activities. Several aspects of the plant’s secondary metabolism, particularly volatile production in L. nobilis, are still unknown. However, understanding the molecular basis of flavor and aroma production is not an easy task to accomplish. Nevertheless, the time-limited efforts for conservation and the unavailability of knowledge about genetic diversity are probably the major reasons for the lack of breeding programs in L. nobilis. The present review gathers the scientific evidence on the research carried out on Laurus nobilis L., considering its cultivation, volatile composition, biochemical and molecular aspects, and antioxidant and antimicrobial activities.

Laurus nobilis L. Essential Oil-Loaded PLGA as a Nanoformulation Candidate for Cancer Treatment

The aim of this study was to obtain essential oil (LNEO) from the Laurus nobilis L. plant, and to prepare LNEO-loaded poly lactic-co-glycolic acid (PLGA) nanoparticles (NPs) as an approach in cancer treatment. The components of the obtained LNEO were analyzed using GC-MS. The LNEO-NPs were synthesized by the single-emulsion method. The LNEO-NPs were characterized using UV-Vis spectrometry, Dynamic Light Scattering (DLS), Scanning Electron Microscopy (SEM), and a DNA binding assay, which was performed via the UV-Vis titration method. According to the results, the LNEO-NPs had a 211.4 ± 4.031 nm average particle size, 0.068 ± 0.016 PdI, and −7.87 ± 1.15 mV zeta potential. The encapsulation efficiency and loading capacity were calculated as 59.25% and 25.65%, respectively, and the in vitro drug release study showed an LNEO release of 93.97 ± 3.78% over the 72 h period. Moreover, the LNEO was intercalatively bound to CT-DNA. In addition, the mechanism of action of LNEO on a dual PI3K/mTOR inhibitor was predicted, and its antiproliferative activity and mechanism were determined using molecular docking analysis. It was concluded that LNEO-loaded PLGA NPs may be used for cancer treatment as a novel phytotherapeutic agent-based controlled-release system.

Isolation of Laurus nobilis Leaf Polyphenols: A Review on Current Techniques and Future Perspectives

In recent years, the market demand for products enhanced with ingredients derived from natural products, such as polyphenols, is rapidly increasing. Laurus nobilis L., known as bay, sweet bay, bay laurel, Roman laurel or daphne is an evergreen Mediterranean shrub whose leaves have traditionally been used in cuisines and folk medicine due to their beneficial health effects, which can nowadays be scientifically explained by various biological activities of the leaf extracts. Many of these activities can be attributed to phenolic compounds present in L. nobilis leaves which include flavonoids, phenolic acids, tannins (proanthocyanidins) and lignans. In order to enable efficient industrial utilization of these valuable compounds, it is crucial to establish optimal extraction procedures resulting in the highest yields and quality of the extracts. This paper offers the first systematic review of current literature on the influence of conventional and advanced extraction techniques, including microwave-assisted, ultrasound-assisted, enzyme-assisted, supercritical-CO₂ and mechanochemical-assisted extraction on the phenolic content of L. nobilis leaf extracts, allowing more efficient planning of further research and simplifying the steps towards industrial utilization of this plant.

Chemical Composition, Antioxidant Activity, and Antifungal Effects of Essential Oil from Laurus nobilis L. Flowers Growing in Morocco

In this study, the chemical composition and the antioxidant and antifungal activities of essential oil from Laurus nobilis flowers were examined. The essential oil was prepared using steam distillation in a modified Clevenger-type apparatus. The chemical composition of the obtained essential oil and chemotypes was determined using gas chromatography coupled with mass spectrometry (GC/MS) and gas chromatography with flame ionization detection (GC-FID). Twenty-five volatile compounds were identified, which made up 92.07% of the total essential oil content. The essential oil yield was 1.06% and the most abundant compounds were 1.8-cineole (45.01%), α-caryophyllene (7.54%), germacradienol (6.13%), limonene (4.69%), α-pinene (3.04%), and germacrene D (3.14%). The antifungal activity of the obtained essential oil was tested against seven fungal strains: Aspergillus clavatus, A. niger, Chaetomium globosum, Cladosporium cladosporioides, Myrothecium verrucaria, Penicillium citrinum, and Trichoderma viride. The results indicated that essential oil from L. nobilis flowers exhibited significant antifungal activity against the tested fungal strains with minimum inhibitory concentrations (MICs) ranging from 0.05 to 0.46 mg/mL. The essential oil of L. nobilis also exhibited strong total antioxidant capacity (TAC) as indicated by its ability to scavenge free radical DPPH. Taken together, this study indicates that the essential oil from L. nobilis flowers possesses significant antifungal and antioxidant activities, possibly due to the high level of 1,8-cineole.

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.

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.

Bioactive compounds from bay leaves (Laurus nobilis) extracted by microwave technology

Laurus nobilis leaves contain flavored and bioactive components with relevant biological properties for human health that are attributed to an abundant presence of highly bioactive secondary metabolites. However, the separation process for these bioactive molecules from plant matrix is seriously limited by the presence of a physical barrier (cell wall). Thus, the use of novel extraction procedures to enhance their release is particularly important. In this work, the potential use of microwave-assisted extraction (MAE) as a tool to improve the extraction efficiency of bioactive compounds from bay leaves and their characterization was evaluated. The effects of irradiation time (3, 6 and 9 min) and aqueous ethanol concentration (0, 25 and 50%) on the extraction of phenolic compounds were evaluated. A response surface methodology was applied to determine the best extraction conditions by MAE. The maximum total phenolic compound under the best conditions (9 min time irradiation and aqueous ethanol 50%) was 10.63±0.91 mg gallic acid equivalent/g plant using MAE. Also, the antioxidant potential of the extracts obtained was evaluated.

Laurus nobilis: Composition of Essential Oil and Its Biological Activities

Laurus nobilis is native to the southern Mediterranean region and cultivated mainly in Europe and the USA as an ornamental and medicinal plant. The chemical composition of the essential oil (EO) from leaves of L. nobilis, collected in Southern Italy, was studied by GC and GC-MS. In all, 55 compounds were identified, accounting for 91.6% of the total essential oil. 1,8-Cineole (31.9%), sabinene (12.2%), and linalool (10.2%) were the main components. Antimicrobial and antifungal activities of EO and 1,8-cineole were determined in vitro. The cytotoxicity of the EO was evaluated against SH-SY5Y cell line, as well as the influence of the EO on the expression of adenylate cyclase 1 (ADCY1), suggesting possible essential oil effects on the Central Nervous System.

Phytochemicals and Biological Activities of Laurel Tree (Laurus nobilis)

This review summarizes the chemical composition reported up to date on Laurus nobilis L. (Lauraceae), an evergreen shrub or tree cultivated for its aromatic leaves and ornamental interest. It has been focused on non-volatile phytochemicals such as sesquiterpene lactones, flavonoids and proanthocyanidins, among others. Moreover, biological activities of laurel extracts and pure compounds have also been reviewed.

Two-dimensional PCA highlights the differentiated antitumor and antimicrobial activity of methanolic and aqueous extracts of Laurus nobilis L. from different origins

Natural matrices are important sources of new antitumor and antimicrobial compounds. Species such as Laurus nobilis L. (laurel) might be used for this purpose, considering its medicinal properties. Herein, in vitro activity against human tumor cell lines, bacteria, and fungi was evaluated in enriched phenolic extracts. Specifically, methanol and aqueous extracts of wild and cultivated samples of L. nobilis were compared considering different phenolic groups. Principal component analysis (PCA) was applied to understand how each extract acts differentially against specific bacteria, fungi, and selected human tumor cell lines. In general, the extract type induced the highest differences in bioactivity of laurel samples. However, from the PCA biplot, it became clear that wild laurel samples were higher inhibitors of tumor cell lines (HeLa, MCF7, NCI-H460, and HCT15). HepG2 had the same response to laurel from wild and cultivated origin. It was also observed that methanolic extracts tended to have higher antimicrobial activity, except against A. niger, A. fumigatus, and P. verrucosum. The differences in bioactivity might be related to the higher phenolic contents in methanolic extracts. These results allow selecting the extract type and/or origin with highest antibacterial, antifungal, and antitumor activity.

Nutritional and antioxidant contributions of Laurus nobilis L. leaves: would be more suitable a wild or a cultivated sample?

Medicinal and aromatic plants are used since ancient times in folk medicine and traditional food, but also in novel pharmaceutical preparations. The controversy lies in the use of cultivated and/or wild plants presenting both advantages and disadvantages in biological, ecological but also economic terms. Herein, cultivated and wild samples of Laurus nobilis L. were chemically characterized regarding nutritional value, free sugars, organic acids, fatty acids and tocopherols. Furthermore, the antioxidant activity (scavenging activity, reducing power and lipid peroxidation inhibition) and individual phenolic profile of L. nobilis extracts and infusions were evaluated. Data showed that the wild sample gave higher nutritional contribution related to a higher content of proteins, free sugars, organic acids, PUFA and tocopherols. It also gave better PUFA/SFA and n-6/n-3 ratios. Regarding antioxidant activity and phenolic compounds, it was the cultivated sample (mostly the infusion) that showed the highest values. The present study supports the arguments defending the use of wild and cultivated medicinal and aromatic plants as both present very interesting features, whether nutritional or antioxidant, that can be an assessed by their consumption. In vitro culture could be applied to L. nobilis as a production methodology that allows combination of the benefits of wild and cultivated samples.

Laurel leaf extracts for honeybee pest and disease management: antimicrobial, microsporicidal, and acaricidal activity

A diverse set of parasites and pathogens affects productivity and survival of Apis mellifera honeybees. In beekeeping, traditional control by antibiotics and molecules of synthesis has caused problems with contamination and resistant pathogens. In this research, different Laurus nobilis extracts are tested against the main honeybee pests through an integrated point of view. In vivo effects on bee survival are also evaluated. The ethanol extract showed minimal inhibitory concentration (MIC) values of 208 to 416 μg/mL, having the best antimicrobial effect on Paenibacillus larvae among all substances tested. Similarly, this leaf extract showed a significant antiparasitic activity on Varroa destructor, killing 50 % of mites 24 h after a 30-s exposure, and on Nosema ceranae, inhibiting the spore development in the midgut of adult bees ingesting 1 × 10(4) μg/mL of extract solution. Both ethanol extract and volatile extracts (essential oil, hydrolate, and its main component) did not cause lethal effects on adult honeybees. Thus, the absence of topical and oral toxicity of the ethanol extract on bees and the strong antimicrobial, microsporicidal, and miticidal effects registered in this study place this laurel extract as a promising integrated treatment of bee diseases and stimulates the search for other bioactive phytochemicals from plants.

Ultrasound-assisted extraction of phenolic compounds from Laurus nobilis L. and their antioxidant activity

Bay leaves (BL) (Laurus nobilis L., Family: Laureceae) are traditionally used to treat some symptoms of gastrointestinal problems, such as epigastric bloating, impaired digestion, eructing and flatulence. These biological properties are mainly attributed to its phenolic compounds. In this paper, ultrasound-assisted extraction of phenolic compounds from Laurus nobilis L. (Laureceae) was studied. Effects of several experimental factors, such as sonication time, solid/liquid ratio and concentration of solvent on extraction of phenolic compounds were evaluated through a randomized complete block design with factorial treatment arrangement (3(3)). The best extraction conditions were: 1g plant sample with 12 mL of 35% ethanol, for 40 min, obtaining a yield of phenolic compounds of 17.32±1.52 mg g(-1) of plant. In addition, free radical-scavenging potential of DPPH and lipid oxidation inhibition, by linoleic acid peroxidation of the selected extract was measured in order to evidence their antioxidant properties. Results indicated that high amounts of phenolic compounds can be extracted from L. nobilis by ultrasound-assisted extraction technology.

Supercritical fluid extraction of plant flavors and fragrances

Supercritical fluid extraction (SFE) of plant material with solvents like CO₂, propane, butane, or ethylene is a topic of growing interest. SFE allows the processing of plant material at low temperatures, hence limiting thermal degradation, and avoids the use of toxic solvents. Although today SFE is mainly used for decaffeination of coffee and tea as well as production of hop extracts on a large scale, there is also a growing interest in this extraction method for other industrial applications operating at different scales. In this review we update the literature data on SFE technology, with particular reference to flavors and fragrance, by comparing traditional extraction techniques of some industrial medicinal and aromatic crops with SFE. Moreover, we describe the biological activity of SFE extracts by describing their insecticidal, acaricidal, antimycotic, antimicrobial, cytotoxic and antioxidant properties. Finally, we discuss the process modelling, mass-transfer mechanisms, kinetics parameters and thermodynamic by giving an overview of SFE potential in the flavors and fragrances arena.

Development of a new chromium reducing antioxidant capacity (CHROMAC) assay for plants and fruits

A chromium reducing antioxidant capacity (CHROMAC) assay was presented to measure antioxidant capacity of selected plants and fruits and compared its performance with other commonly used antioxidant capacity methods of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and cupric reducing antioxidant capacity (CUPRAC). The assay is based on the spectrophotometric measurement of colored a chelate complex of Cr(III) and diphenylcarbazone formed by the reaction of Cr(VI) and 1,5-diphenylcarbazid in acidic medium. Phenolic compounds react with excessive amounts of Cr(VI) at low pH values, causing reduction of Cr(VI) to Cr(III) and conversion of phenols to oxidized products. The assay comprises of the antioxidant with a chromium(VI) solution, a 1,5-diphenylcarbazid in acidic medium and subsequent measurement of the developed absorbance at 540 nm after 50 min. The color development is stable for phenolic compounds in plant and fruit. The selectivity of the assay for phenolic compounds was improved by adjusting pH to 2.8 and reduction potential between 0.2 and 0.9 V. The developed assay was successfully applied to the measurement of antioxidant capacity of three plants and one fruit (Prunus divaricata Ledeb.subsp. divaricata) samples and comparable results were obtained by ABTS and CUPRAC assays.

Antioxidant and antibacterial activity of essential oil and extracts of bay laurel Laurus nobilis Linnaeus (Lauraceae) from Portugal

Laurus nobilis L. is an aromatic plant frequently used as a spice in Mediterranean cookery and as a traditional medicine for the treatment of several infectious diseases. The aim of this study was to characterise the antibacterial and antioxidant activities of bay laurel essential oil (EO), ethanolic extract (EE) and hot/cold aqueous extract (AE). The major components detected in bay laurel EO were eucalyptol (27.2%), α-terpinenyl acetate (10.2%), linalool (8.4%), methyleugenol (5.4%), sabinene (4.0%) and carvacrol (3.2%). The EO exhibited strong antibacterial activity against all tested foodborne spoilage and pathogenic bacteria, whereas this activity was less pronounced or even nonexistent in the EE and AE. In contrast, EO exhibited low antioxidant activity compared to extracts (EX), and among the EX, the hot AE revealed the highest antioxidant ability. The results show that bay laurel EO and its EX have potential as natural alternatives to synthetic food preservatives, in order to enhance food safety and increase food shelf life.

Supercritical CO2 extract and essential oil of bay (Laurus nobilis L.): Chemical composition and antibacterial activity

The present study deals with the supercritical carbon dioxide (SC-CO2) extraction and hydrodistillation (HD) of dried bay leaves (Laurus nobilis L.). The chemical composition and antibacterial activity of the SC-CO2 extract and essential oil (EO) from dried leaves of bay were compared to each other and literature data. Qualitative and quantitative analyses of the SC-CO2 extract and EO were performed using GC-FID and GC-MS analytical methods. A significant difference in the chemical composition of the SC-CO2 extract and EO was observed. The EO comprised high contents of monoterpenes and their oxygenated derivates (98.4 %), principally 1,8-cineole (33.4 %), linalool (16.0 %) and ?-terpinyl acetate (13.8 %), sabinene (6.91 %) and methyl eugenol (5.32 %). The SC-CO2 extract comprised twice less monoterpenes and their oxygenated derivates (43.89 %), together with sesquiterpenes (12.43 %), diterpenes (1.33 %) and esters (31.13 %). The major components were methyl linoleate (16.18 %), ?-terpinyl acetate (12.88 %), linalool (9.00 %), methyl eugenol (8.67 %), methyl arachidonate (6.28 %) and eugenol (6.14 %). An investigation of the antibacterial activity of bay SC-CO2 extract and EO was completed on different Staphylococcus strains using the broth macrodilution method. Staphylococcus intermedius strains were the most susceptible to both the SC-CO2 extract and EO (MIC = 640 ?g/ml).

Use of compressed fluids for sample preparation: Food applications

This review attempts to provide an updated overview (including works published till June 2006) on the latest applications of compressed fluids as sample preparation techniques for food analysis. After a general review of the principles of supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE; also called accelerated solvent extraction, ASE or subcritical water extraction, SWE, when water is employed as extraction solvent), the principal applications of such techniques in the mentioned fields of food and natural products are described, discussing their main advantages and drawbacks.