Laurel Extracts Research Articles

Composition and antifungal effects of aqueous extracts of Cymbopogon citratus, Laurus nobilis and Santolina chamaecyparissus on the growth of Fusarium oxysporum f. sp. lentis

Aqueous extracts of three aromatic and medicinal plants, viz. lemongrass (Cymbopogon citratus), laurel (Laurus nobilis) and cotton-lavender (Santolina chamaecyparissus) were tested against the growth of Fusarium oxysporum f. sp. lentis. The aqueous extracts concentrations were evaluated from 0.05 to 20 mg/mL. Ultra-High-Performance Liquid Chromatography (UHPLC)-Quadrupole-Time-of-Flight-Mass Spectrometer and UHPLC-potato dextrose agar were used to identify and quantify the major phenolic compounds. Lemongrass extract revealed the best antifungal activity; a concentration of 0.05 mg/mL inhibited 67% of conidial germination and 77% sporulation, 5 mg/mL restrain 70% of mycelial growth and 20 mg/mL stopped almost completely the pathogen. The extracts of laurel and cotton-lavender exhibited a moderate inhibition on conidial germination and mycelial growth even at 20 mg/mL, while laurel extracts inhibited 75% of sporulation at 0.05 mg/mL. Four phenolic acids and 16 flavonoids were identified and quantified in the three aqueous extracts. Luteolin derivatives represent 96% of the phenolic compounds identified in lemongrass while procyanidin and caffeic acid derivatives represent 76% and 96% in laurel and cotton-lavender, respectively. Our investigation demonstrates that lemongrass was an actual source of aqueous extract with a biomolecule content that could effectively be used for the control of lentil Fusarium wilt.

Application of Plant Extracts to Control Postharvest Gray Mold and Susceptibility of Apple Fruits to B. cinerea from Different Plant Hosts

Sustainable plant protection can be applied on apples against fungal pathogens such as Botrytis cinerea (which is responsible for gray mold)—a significant global postharvest disease. This pathogen can affect a wide range of hosts; and fruits may have variable susceptibilities to B. cinerea from different plant hosts. New possibilities to control gray mold in food production are under demand due to the emergence of resistance against antifungal agents in fungal pathogens. Cinnamon, pimento, and laurel extracts were previously assessed for antifungal activities under in vitro conditions and were found to have the potential to be effective against postharvest gray mold. Therefore, this study aimed to investigate the antifungal activity of cinnamon, pimento, and laurel extracts in vitro and against postharvest gray mold on apples to determine the susceptibility of apple fruits to B. cinerea from different plant hosts, and to analyze the chemical composition of the extracts. Apples (cv. “Connell Red”) were treated with different concentrations of extracts and inoculated with B. cinerea isolates from apple and strawberry followed by evaluation of in vitro antifungal activity. The results reveal that most of the concentrations of the extracts that were investigated were not efficient enough when assessed in the postharvest assay, despite having demonstrated a high in vitro antifungal effect. Apples were less susceptible to B. cinerea isolated from strawberry. To conclude, cinnamon extract was found to be the most effective against apple gray mold; however, higher concentrations of the extracts are required for the efficient inhibition of B. cinerea in fruits during storage.

Laurel extracts inhibit Quorum sensing, virulence factors and biofilm of foodborne pathogens

Antimicrobial, antibiofilm, anti-Quorum sensing (QS) and virulence factors inhibitory capacity of different polarity Laurus nobilis extracts against several pathogenic microorganisms were studied. Some extracts exhibited antibiotic effect against Staphylococcus aureus multidrug-resistant strains. However, all extracts (100 μg/mL) inhibited to some extent the biofilm of most bacteria tested (until 40% for Gram-negative and 76% for Gram-positive). Hexane (HE) and chloroform extract (CE) were potent inhibitors of S. aureus biofilm and the microscopies further confirmed an important reduction in adherent cells. Polystyrene surfaces coated with these extracts showed a decrease in bacterial adhesion with the resulting inhibition of S. aureus biofilm formation and biofilm activity. Moreover, they also interfere with the coagulase and hemolysin activities of this bacterium. With respect to Gram-negative bacteria, these extracts showed anti-QS activity against Chromobacterium violaceum and inhibited biofilm formation, swarming motility, pyocyanin production, and elastase activity of Pseudomonas aeruginosa. Chemical analysis of HE and CE revealed that the fatty acids were the main compounds, particularly linolenic, oleic and hexadecanoic acids followed by the oxygenated monoterpenes. Non-toxic laurel extracts offer a natural alternative to control contamination and/or spoilage of food, as well as infectious diseases, by attacking the biofilm and the virulence of Gram-positive and Gram-negative bacteria.

COMPARISON OF LAURUS NOBILIS EXTRACTS COMPOSITION OBTAINED BY MICROWAVE EXTRACTION, SUPERCRITICAL FLUID EXTRACTION AND STEAM DISTILLATION

A comparison of chemical composition of bay laurel extracts obtained by microwave extraction, supercritical fluid extraction and steam distillation was performed. Microwave extraction and steam distillation were shown to give similar essential oils. Microwave extract contains more monoterpenoid components, especially hydrocarbons. Steam distillation oil contains more sesquiterpenoid compounds, mostly oxygenated. SFE extract composition differs substantially from the ones obtained by two other methods. According to GC-MS data they contain much more sesquiterpenoid components, namely sesquiterpene lactones. This makes SFE a perspective candidate for isolation of biologically active compounds from laurel leaves. However, apart from valuable compound SFE extracts also contain substantial amounts of waxes as well as large quantities of some non-volatile component undetectable via GC-MS. In order to implement SFE into the practice of laurel processing one has to develop an approach for the fractionation of SFE extracts allowing isolating sesquiterpene lactone enriched fraction.

Effects of drying method on the phenolics content and antioxidant activities of cherry laurel (Prunus laurocerasus L.)

Cherry laurel fruit is a good source of phenolics together with considerable antioxidant activity. However, it is only available for a short period of time during the year. Drying could offer long-time preservation however it harms the bioactive compounds due to the high temperatures applied during the process. The aim of this study is to determine the most proper drying method for cherry laurel in terms of preserving its bioactive compounds. The phenolics contents, antioxidant and antibacterial activities, and color properties of cherry laurel dried via lyophilization, vacuum drying, and fan oven-drying were compared. Lyophilized cherry laurel had the highest phenolics content (315.51 Gallic acid equivalent mg/100 g dried cherry laurel) and color intensity (C*). The antioxidant activity was determined using both DPPH and ABTS assays. The highest antioxidant activity (6.16 mM TE/g in DPPH and 28.83 mM TE/g in ABTS) thus, the lowest half-maximal inhibitory concentration (IC50) was detected for lyophilized samples in both DPPH and ABTS assays in methanolic (1.59 mg dried cherry laurel) and aqueous (0.30 mg dried cherry laurel) extracts, respectively. In general, vacuum- and fan oven-dried cherry laurel presented similar phenolics contents and antioxidant activities. None of the dried cherry laurel extracts showed antibacterial activity against the selected bacteria. Although lyophilization is a high-cost technology, it could be applied as an alternative method in the drying of cherry laurel since it provides high-quality products while maintaining its bioactivity.

Investigations on Apoptotic Activities of Cherry Laurel Extracts in HCT-116 Human Colon Carcinoma Cells

Investigations on Apoptotic Activities of Cherry Laurel Extracts in HCT-116 Human Colon Carcinoma Cells

Influence of phenolic profile on the RP-HPLC detection and anti-carcinogenic potential of cherry laurel extracts from Black Sea Region-Turkey

Cherry laurel produces edible dark colored fruits that are anticipated to have strongly antioxidative properties. Various studies dealt with the phenolic composition of cherry laurel fruits or concentrated juice to analyze the antioxidative potential. Here, in addition to polyphenol analysis, anti-proliferative activities of cherry laurel components have been investigated. Using an RP-HPLC method, phenolic content of the fruits were analyzed and 14 different polyphenolic compounds were determined in three varieties (55K06, 61K04 and 61K05), some of which were detected for the first time in cherry laurel fruits. Chlorogenic acid was found to be the major phenolic compound. In cell culture studies, polyphenolic extracts demonstrated anti-carcinogenic activity against HCT-116 colon carcinoma cells, potentially due to apoptotic activity of the extracts as demonstrated by flow cytometry. The composition and concentration of phenolic compounds largely determined the extent of cellular viability and apoptotic potential.

Oxidative stability of microencapsulated fish oil with rosemary, thyme and laurel extracts: A kinetic assessment

Antioxidant activity of rosemary (R), thyme (T) and laurel (L) extracts was evaluated for protection of fish oil during microencapsulation and heat-induced degradation. For this purpose, oil stability was optimised by comparing oxidation levels of fish oils which are exposed to high temperatures ie., 23 °C, 40 °C, and 60 °C in the presence of natural and commercial antioxidants ie., 1000 (1) 1500 (2) ppm extracts and two control groups without and with BHT (250 ppm) (C1, C2). Then, peroxide formation kinetics of the microcapsules were also determined. Peroxide values (PV) of microencapsulated fish oil in the presence of 1500 ppm rosemary (R2) were lower (3.08 mEq O2/kg oil) than the control group with commercial antioxidant (C2, 4.25 mEq O2/kg oil). Thiobarbituric acids (TBA) of R2, R1, and L2 (0.36 mmol MDA/kg oil, 0.56 mmol MDA/kg oil, 0.59 mmol MDA/kg oil respectively) were also lower than C2 (0.64 mmol MDA/kg oil). Besides, R2 and R1 (31.62 kJ/mol, and 30.82 kJ/mol) had higher activation energies than C2 (30.46 kJ/mol). As a result, it is revealed that rosemary and laurel extracts can successfully be applied to anchovy oil for improving the oxidative stability in microencapsulation by spray drying.

Combined effects of plant and cell-free extracts of lactic acid bacteria on biogenic amines and bacterial load of fermented sardine stored at 3 ± 1 °C

Effects of cell-free extracts (CFE, 8%) prepared using Lactobacillus plantarum FI8595 or Pediococcus acidolactici ATCC 25741 alone or in combination with thyme and laurel extracts (0.5%) on physical, sensory, microbiological and chemical quality of fermented and vacuum packaged sardine fillets were investigated during 8 wk of chilled storage (3 ± 1 °C). Sardine fillets were divided into 7 groups with the control being untreated. The other groups were treated with CFE of Lb. plantarum (LP group) and P. acidolactici (PA group). In addition, thyme with LP CFE (THLP) or PA CFE (THPA); and laurel with LP CFE (LALP) or PA CFE (LAPA) were also prepared. According to the sensory and physical assessment, shelf life of fermented fish was 5 wk for the control, 6 wk for LP, PA, LALP and LAPA, and 7 wk for THPA and THLP, although chemical and microbiological results exhibited longer shelf life. THPA and THLP had the lowest bacterial growth and TBA values. TVB-N values remained below 35 mg/100 g until 7 wk for all groups. THPA significantly reduced TMA formation. The study suggested that cell-free extracts of Lb. plantarum and P. acidolactici with thyme extract was the most effective way to improve the shelf-life of fermented sardines stored at chilled temperature.

Laurus nobilis L. Extracts against Paenibacillus larvae: Antimicrobial activity, antioxidant capacity, hygienic behavior and colony strength.

The aim of this work was to compare the antimicrobial activity against Paenibacillus larvae and the antioxidant capacity of two Laurus nobilis L. extracts obtained by different extraction methods. The hydroalcoholic extract was moreover added as supplementary diet to bees in field conditions to test behavioural effects and colony strength. Both laurel extracts were subjected to different phytochemical analysis to identify their bioactive compounds. Antimicrobial activity was analyzed by the minimal inhibitory concentration (MIC) determination by means the agar dilution method. The hydroalcoholic extract (HE) was able to inhibit the bacterial growth of all P. larvae strains, with 580 µg/mL mean value. This better antibacterial activity in relation to the essential oil (EO) could be explained by the presence of some phenolic compounds, such as flavonoids, evidenced by characteristic bands resulting from the Fourier Transform Infrared Spectroscopy (FTIR) analysis. Antioxidant activities of the extracts were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging ability and ferric reducing antioxidant power (FRAP) assays. The HE showed the highest antioxidant activity as measured by DPPH, with IC50 values of 257 ± 12 μg/mL. The FRAP assay method showed that the HE was 3-fold more effective reducing agent than the EO. When the bee colonies were supplied with laurel HE in sugar paste an improvement in their general condition was noticed, although neither the hygienic behavior nor the proportions of the breeding cells varied statistically due to the treatment. In conclusion, the inhibition power against P. larvae attributable to the phenolic compounds, the antioxidant capacity of the HE, and the non-lethal effects on adult honey bees on field trials suggest the HE of laurel as a promising substance for control American foulbrood disease.

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.

Phytochemical composition of the Algerian Laurus nobilis L. leaves extracts obtained by solvent-free microwave extraction and investigation of their antioxidant activity

This paper focuses the phytochemical composition of bay leaves essential oils obtained by solvent-free microwave extraction (SFME) and by the hydrodistillation (HD) for comparison. Essential oils had similar qualitative but different quantitative composition. For HD and SFME, the main constituents on the oils differed respectively in 1,8-cineole (26.4–30.9)%, sabinene (9–9.6)%, alpha-terpinyl acetate (9.5–7.8)%, linalool (4.9–9.5)%, alpha-terpineol (3.3–7.6)%, alpha-pinene (9.2–4.6)%, methyl eugenol (5–6.2)% and eugenol (1.2–3.6)%. The HD essential oil and SFME volatile extract inhibited nitric oxide production by stimulated mice peritoneal neutrophils (IC50: 6.65 and 13.75) mg/mL and dose dependently scavenged superoxide anion (IC50: 0.048 and 0.058) mg/mL. Inversely, these volatile extracts enhanced myeloperoxidase release (EC50: 0.72 and 0.29) mg/mL. Moreover, the potentiating effect of laurel extracts on exocytosis granules could collaborate in trapping and killing of extracellular pathogens by neutrophils extracellular traps (NETs).

The Effects of Natural Extracts on the Quality Changes of Frozen Chub Mackerel (Scomber japonicus) Burgers

The effects of the use of natural antioxidants on the quality of frozen chub mackerel (Scomber japonicus) burgers stored at −18 °C were investigated in terms of sensory, biochemical (thiobarbituric acid reactive substances-TBARS, total volatile basic nitrogen, peroxide value and free fatty acids) and microbiological analyses (total viable count—TVC, total psychrotrophic count—TPC). Oregano, green tea, sage and laurel extracts were obtained by using steam distillation method. After that, thawed fish were headed, gutted and filleted. Fillets were then minced and divided into nine groups. These were the control without plant extract, O1 with 0.3% oregano extract, O2 with 0.6% oregano extract, G1 with 0.3% green tea extract, G2 with 0.6% green tea extract, S1 with 0.3% sage extract, S2 with 0.6% sage extract, L1 with 0.3% laurel extract and L2 with 0.6% laurel extract. Plant extracts together with burger ingredients were added to each group. All groups were stored at −18 °C for 9 months. According to the results of sensory analyses, the control at 7 months of storage, oregano and green tea at 9 months of storage, sage and laurel groups at 8 months of storage were rejected by panellists and considered as unaccepptable. Natural extracts were effective in controlling biochemical indices. TVC content of fish burgers did not exceed the limit during storage period for all groups (<6 log CFU/g). TPC slightly decreased with storage time. Additions of oregano, green tea and laurel extracts except sage extract reduced (P < 0.05) lipid oxidation in fish burger and have the potential to be incorporated into fish burgers.

Turmeric and Laurel Aqueous Extracts ExhibitIn VitroAnti-Atherosclerotic Activity andIn VivoHypolipidemic Effects in a Zebrafish Model

Culinary herbs and spices have been widely used for their hypoglycemic, lipid-lowering, and anti-inflammatory activities. This study examined the physiologic activity of hydrophilic components using extracts of turmeric or laurel leaf powder. Aqueous extracts of turmeric and laurel showed potent inhibitory activity against fructose-mediated glycation with antioxidant ability against low-density lipoprotein (LDL) oxidation and radical scavenging activity. The turmeric and laurel extracts had potent cholesteryl ester transfer protein (CETP) inhibitory ability (up to 23% and 40% inhibition, respectively) at a final concentration of 10 μg/mL. The turmeric and laurel extracts inhibited the cellular uptake of oxidized LDL into macrophages, which is the initial step in atherogenesis. For in vivo testing, zebrafish consumed a high cholesterol diet (HCD) (final concentration, 4% [wt/wt]) with or without turmeric or laurel powder (final concentration, 10% [wt/wt]). The turmeric and laurel groups had a 14% and 12% decrease, respectively, in the weight and height ratios compared to the HCD group. The plasma total cholesterol level was significantly lower in the turmeric and laurel groups (48% and 28% less, respectively, than in the HCD group). Plasma triglycerides were more markedly reduced in the turmeric and laurel groups than in the HCD group (68% and 56% less, respectively, than the HCD group). In conclusion, the hydrophilic extracts of turmeric and laurel potently suppressed the incidence of atherosclerosis via a strong antioxidant potential, prevention of apolipoprotein A-I glycation and LDL phagocytosis, and inhibition of CETP. Consumption of turmeric and laurel extracts exhibited hypolipidemic and antioxidant activities in a hypercholesterolemic zebrafish model.

In Vitro and in Vivo Effects of Laurus nobilis L. Leaf Extracts

The in vitro and in vivo antioxidant activities of different extracts of laurel leaves were studied. Free radical scavenging capacity (RSC) was evaluated measuring the scavenging activity on the DPPH, NO, O2•− and OH radicals. The effects on lipid peroxidation (LP) were also evaluated. Experimental results indicate that ethyl acetate extract of leaves has exhibited the largest RSC capacity in neutralization of DPPH, NO, O2•− and OH radicals. The same result was obtained in investigation of extracts impact on LP. The in vivo effects were evaluated on some antioxidant systems (activities of GSHPx, LPx, Px, CAT and XOD, and GSH content) in the mice liver and blood-hemolysate after treatment with the examined laurel extracts, or in combination with carbon tetrachloride (CCl4). On the basis of the results obtained it can be concluded that the examined extracts exhibited a certain protective effect, which is more pronounced on the liver than on blood-hemolysate parameters. The results obtained indicate toxicity of CCl4, probably due to the radicals involved in its metabolism. Combined treatments with CCl4 and the examined extracts showed both positive and negative synergism. Based on the experimental results, the strongest protective effect was shown by the EtOAc extract.

Determination of the effect of plant essential oils obtained by supercritical fluid extraction on the growth and viability of Listeria monocytogenes in broth and food systems using flow cytometry

The antimicrobial properties of oregano, rosemary and laurel extracts obtained by supercritical fluid extraction were investigated by examining their influence on the growth and viability of Listeria monocytogenes in laboratory medium and broccoli juice at 30 and 8 °C. Important decreases in the L. monocytogenes population were shown in presence of all the extracts obtained from rosemary and one oregano extract. The counts were reduced below the level of detection after 4 h of exposure at 30 °C in laboratory medium. A bactericidal effect was observed also when L. monocytogenes was exposed to rosemary at 30 °C and 8 °C in broccoli juice. Significant reductions in growth rate and an increase in lag phase of L. monocytogenes were observed in presence of some of the laurel and oregano extracts at both temperatures. Flow cytometry was used as a rapid method to determine the antibacterial effect of supercritical extracts and the physiological state of L. monocytogenes. Bacterial viability performed by dual staining of L. monocytogenes with SYTO 9 and propidium iodide revealed three different cell populations, specifically, living, dead and compromised cells. Live cell percentage decreased with the time of exposure, whereas the percentage of compromised cells remained constant and the dead cells increased in the same period.

Antimycotic Activity of Methanol Extracts of Sage (Salvia officinalis L.), Laurel (Laurus nobilis L.) and Thyme (Thymbra spicata L.)

Inhibitory effects of methanol-water (90:10; v/v) extract from sage (Salvia officinalis L.), laurel (Laurus nobilis L.) and thyme (Thymbra spicata L.) were tested in vitro on clinical isolates of eleven species of yeasts (C. krusei, C. clus, Rhodotorula rubra, C. albicans 10039, C. tropicalis, C. glabrata 70164, C. parasilosis, C. insane, C. rhodotonla, C. holmii and C. glabrata 13b). Preliminary experiment was carried out in vitro using the disc diffusion method to investigate antimycotic activity of the sage, laurel and thyme extracts. Thyme methanol extract showed very high antimycotic activity against all tested yeasts. Effect of laurel extract was as good as thyme extract for C. tropicalis at 40 ppm level. Generally, sage had no effect on the tested yeasts. Methanol extracts of thyme and laurel may be useful tools to control the yeasts growth.

Antioxidant activities of extracts from selected culinary herbs and spices

Recently, interest in plant-derived food additives has grown, mainly because synthetic antioxidants suffer from several drawbacks. Furthermore, plant extracts have been shown to possess health-promoting properties. In the present study, hydrodistilled extracts from basil, laurel, parsley, juniper, aniseed, fennel, cumin, cardamom, and ginger were assessed for their total phenol content, and antioxidant (iron(III) reduction, inhibition of linoleic acid peroxidation, iron(II) chelation, 1,1-diphenyl-2-picrylhydrazyl radical-scavenging and inhibition of hydroxyl radical-mediated 2-deoxy- d-ribose degradation, site and nonsite-specific) activities. The extracts from basil and laurel possessed the highest antioxidant activities except for iron chelation. Although parsley showed the best performance in the iron chelation assay, it was less effective at retarding the oxidation of linoleic acid. In the linoleic acid peroxidation assay, 1 g of the basil and laurel extracts were as effective as 177 and 212 mg of trolox, respectively. Thus, both extracts are promising alternatives to synthetic substances as food ingredients with antioxidant activity.