Antioxidant and Antimicrobial Activities of Essential Oils Extracted from Laurus nobilis L.Leaves by Using Solvent-Free Microwave and Hydrodistillation

In this study, laurel essential oils were obtained by using solvent-free microwave extraction (SFME) and hydrodistillation (HD) methods from Laurus nobilis leaves and determined their antioxidant and antimicrobial activity. Extraction time was reduced by about 43% in SFME at 622 W and 67% in SFME at 249 W compared to hydrodistillation. Essential oil of laurel was extracted by SFME at 622 W (100%) and 249 W (40%) power levels and HD inhibited oxidation generated by ABTS radical by 93.88%, 94.13% and 92.06%, respectively. Trolox equivalent antioxidant capacities (TEAC) of essential oils were 0.18 mM/mL oil for SFME at 622 W, 1.36 mM/mL oil for SFME at 249 W and 2.40 mM/mL oil for HD (p < 0.05). Essential oils of L. nobilis were extracted by SFME at 100% and 40% power levels and HD inhibited linoleic acid peroxidation by 70.57%, 63.53% and 89.18% respectively. Inhibition effects of laurel essential oils obtained by SFME at different power levels and HD on DPPH radical cation oxidation were not significantly different. The strongest antioxidant activity against DPPH radical was found in the essential oil obtained by SFME at 100% power level. Essential oils displayed antimicrobial activity against Staphylococcus aureus 6538P, Escherichia coli O157:H7 and Salmonella typhimurium NRRL E 4463 except for Listeria monocytogenes. The inhibitory effect on Staphylococcus aureus 6538P survival of laurel oil obtained from SFME by using lower power level was found to be lower than that obtained from SFME at 100% power level and HD

Antibiotic Activity of the Essential Oil of Laurel （Laurus nobilis L,） on Eight Bacterial Strains

The recent studies unveil more and more therapeutic properties of the essential oil of Bay leaf （Laurus nobilis L.）. The aim of this study is to determine the chromatographic profile of the essential oil of Bay leaf cultivated under the climatic conditions of the Algerian East and to test its antibiotic activity, against 8 bacterial strains （Escherichia coil, Serratia sp., Proteus sp., Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus D, Pseudomonas aeruginosa and Acinetobacter baumanii）, by using different concentrations. The GC/MS analysis showed that the essential oil is rich in eucalyptol （35.31%）, [3 linalool （22.52%）, eugenol methyl ether （9.17%）, camphene （7.37%） and 3 carene （5.39%）. The antibiotic activity of the essential oil was determined by the diffusion on agar method. Measuring diameters of inhibition method of Vincent [1] indicated that bacterial strains which are very sensitive to even very diluted essential oil are Pseudomonas aeruginosa, Streptococcus D, Serratia sp. and Klebsiella pneumoniae. Staphylococcus aureus, E. coli and Acinetobacter baumanii exhibit less sensitivity and Proteus sp. is especially sensitive to the pure oil. Laurus nobilis L. is a Mediterranean endemic that presents an interesting antibacterial activity and its culture should be encouraged and expanded in Algeria.

Seasonal Variation in Volatile Oil, Polyphenol Content and Antioxidant Activity in Extract of Laurus nobilis Grown in Iran

The leaves ofLaurus nobilis were collected in the middle of four seasons （spring, summer, autumn, and winter） to determine the best harvesting time for obtaining the highest oil yield, 1,8-cineole and polyphenol content and antioxidant activity. After drying the plant materials in shade, their EOs （essential oils） were obtained by hydro-distillation method. Analysis of variance showed harvesting time had significant effect on the oil yields of L. nobilis. Seventy one components were identified in the oils of L. nobilis with 1, 8-cineole （5.7%-42.6%）, ot-terpinyl acetate （3.2%-13.1%）, sabinene （2.3%-12.0%）, beta-elemene （0.2%-17.7%） and （E）-caryophyllene （0.2%-16.9%） as the main constituents in different seasons. The predominant phenolic constituents in L. nobilis were cinnamic acid, carvacrol, quercetin and coumarin, respectively. Gallic acid, catechin, caffeic acid, chloregenic acid, p-Comaric acid and rutin were not detected in any seasons. The best antioxidant activity was in spring （268.6μg/mL） and the lowest one was in winter （702.1μg/mL）.

Composition analysis and antimicrobial activity of essential oil from leaves of Laurus nobilis grown in Oman

Traditionally,Laurus nobilis is used for the treatment of earaches and skin rashes as well as rheuma-tism.The most common technique to isolate the oil is hydro-distillation and steam-distillation.The investigation presented in this paper was aimed to unravel the antimicrobial activity and chemical composition of essential oil in the leaves of L.nobilis grown in Oman.The essential oil was extracted from the leave of the selected plant species by hydro distillation using Clevenger type apparatus.The antimicrobial assay was done by disc diffusion methods against three bac-terial strains,Staphylococcus aureus,Pseudomonas aeruginosa and Escherichia coli,and one fungal strain:Candida albicans.The isolated essential oil was analyzed by gas chromatography-mass spectrometry(GC-MS).The percentage yield of the essential oil was 0.064%(w/w).The essen-tial oil was found actively against the applied bacterial and fungal strains.The highest activity was found against S.aureus and the lowest was against E.coli,and the order was S.aureus>P.aeruginosa>E.coli.The essential oil was also active against the fungus C.albicans.The range of inhibition zones was 6-14 mm.The results of GC-MS analysis showed(E)-𝛽-caryophyllene to be the major component about 59.62%.Other major components included𝛼-selinene(14.03%),𝛼-humulene(8.65%),𝛽-selinene(4.99%),and𝛼-pinene(4.98%).In addition,several minor com-ponents were found in the essential oil of L.nobilis.Based on the experimental results,it showed that the plant species that grown in Oman were a potential source of therapeutic agents.In con-clusion,the essential oil and the plant could be used as natural and potential therapeutic agents to treat earaches,skin rashes,and rheumatism.