Solvent-free microwave extraction and hydrodistillation of essential oils from endemic Origanum husnucanbaseri H. Duman, Aytac & A. Duran: comparison of antibacterial activity and contents

The essential oils (EOs) obtained by solvent-free microwave extraction (SFME) and hydrodistillation (HD) from endemic Origanum husnucanbaseri H. Duman, Aytac & A. Duran were investigated using the gas chromatography-mass spectrometry system. The main constituents of both oils obtained from SFME and HD from O. husnucanbaseri are borneol (15.2-12.8%), α-terpineol (12.3-10.8%) and trans-sabinene hydrate (11.8-9.92%). The EO obtained from SFME contained substantially higher amounts of oxygenated compounds and lower amounts of monoterpenes than that from HD. The antibacterial activities of the EOs from SFME and HD were evaluated by the disc diffusion method against six bacterial strains. The EO extracted by SFME was more effective than the EO extracted by HD against the tested bacteria, except for Klebsiella pneumoniae American type culture collection (ATCC) 13883. Streptococcus pyogenes ATCC 19615 and Staphylococcus aureus ATCC 25923 in particular were more sensitive against the EO extracted by SFME.     

Chemical composition and antibacterial activity of Origanum saccatum P.H. Davis essential oil obtained by solvent-free microwave extraction: comparison with hydrodistillation

The components of the essential oils (EOs) obtained by solvent-free microwave extraction (SFME) and hydrodistillation (HD) from endemic Origanum saccatum P.H. Davis were identified by using GC/MS. The main constituents of both EOs obtained by SFME and HD, respectively, from O. saccatum were p-cymene (72.5 and 70.6%), thymol (9.32 and 8.11%), and carvacrol (7.18 and 6.36%). The EO obtained by SFME contained substantially higher amounts of oxygenated compounds and lower amounts of monoterpenes than did the EO obtained by HD. The antibacterial activities of the EOs obtained by SFME and HD were evaluated with the disc diffusion method by comparison with 10 different bacterial strains. The antibacterial activity of the EO extracted by SFME was found to be more effective than that of the EO extracted by HD against seven of the tested bacteria.     

Antibacterial activities of essential oils extracted from leaves of Murraya koenigii by solvent-free microwave extraction and hydro-distillation

Solvent-free microwave extraction (SFME) for the isolation of essential oil from leaves of Murraya koenigii L. (Rutaceae) has been compared with the conventional hydro-distilled oil (HD) in terms of yield, composition, antioxidant activity, and antibacterial activity against Listeria innocua. The yield of essential oil obtained from 30 min of SFME was similar to that of HD for 180 min. By GC-MS analysis, the major compounds of the essential oil extracted by SFME, which were obtained in somewhat lower amounts than in the essential oil obtained by HD, were alpha-copaene (44.3%), beta-gurjunene (25.5%), isocaryophyllene (12.1%), beta-caryophyllene (8.7%) and germacrene D (2.9%). The content of oxygenated terpenes, slightly higher for the SFME-essential oil (2.3%) than the HD-essential oil (1.4%), were much lower than that of nonoxygenated terpenes in both oils. DPPH radical scavenging activities of both essential oils were relatively low (10%-24%). Complete inhibition of growth of L. innocua was observed with both SFME and HD essential oils, at 400 and 600 microg/mL (minimum inhibitory concentration), respectively. The SFME-essential oil at 300 microg/mL provided 92% inhibition, indicating its potential as a natural antimicrobial agent.     

Solvent-free microwave extraction of essential oil from aromatic herbs: comparison with conventional hydro-distillation

Solvent-free microwave extraction (SFME) is a combination of microwave heating and dry distillation, performed at atmospheric pressure without added any solvent or water. Isolation and concentration of volatile compounds are performed by a single stage. SFME has been compared with a conventional technique, hydro-distillation (HD), for the extraction of essential oil from three aromatic herbs: basil (Ocimum basilicum L.), garden mint (Mentha crispa L.), and thyme (Thymus vulgaris L.). The essential oils extracted by SFME for 30min were quantitatively (yield) and qualitatively (aromatic profile) similar to those obtained by conventional hydro-distillation for 4.5 h. The SFME method yields an essential oil with higher amounts of more valuable oxygenated compounds, and allows substantial savings of costs, in terms of time, energy and plant material. SFME is a green technology and appears as a good alternative for the extraction of essential oils from aromatic plants.     

Improved solvent-free microwave extraction of essential oil from dried Cuminum cyminum L. and Zanthoxylum bungeanum Maxim

Solvent-free microwave extraction (SFME) is a recently developed green technique which is performed in atmospheric conditions without adding any solvent or water. SFME has already been applied to extraction of essential oil from fresh plant materials or dried materials prior moistened. The essential oil is evaporated by the in situ water in the plant materials. In this paper, it was observed that an improved SFME, in which a kind of microwave absorption solid medium, such as carbonyl iron powders (CIP), was added and mixed with the sample, can be applied to extraction of essential oil from the dried plant materials without any pretreatment. Because the microwave absorption capacity of CIP is much better than that of water, the extraction time while using the improved SFME is no more than 30 min using a microwave power of 85 W. Compared to the conventional SFME, the advantages of improved SFME were to speed up the extraction rate and need no pretreatment. Improved SFME has been compared with conventional SFME, microwave-assisted hydrodistillation (MAHD) and conventional hydrodistillation (HD) for the extraction of essential oil from dried Cuminum cyminum L. and Zanthoxylum bungeanum Maxim. By using GC-MS system the compositions of essential oil extracted by applying four kinds of extraction methods were identified. There was no obvious difference in the quality of essential oils obtained by the four kinds of extraction methods.     

Comparative analysis of the oil and supercritical CO(2) extract of Schinus molle L. growing in Yemen

In this study, we report the preliminary data on the chemical composition of Yemeni Schinus molle L. volatile oil obtained by supercritical extraction with carbon dioxide (40°C and 90?bar), SFE, and by hydrodistillation (HD). The composition of the volatile oil has been analysed by GC and GC-MS. The content of the major constituents in the oils from leaves varied in the following ranges: germacrene D 3.7% in SFE and 16.7% in HD; β-caryophyllene 19.1% in SFE and 13.5% in HD. The amount of monoterpenes constituted 4%, in all the analysed samples, while the number of sesquiterpenes was 44% in supercritical and 67% in HD oil. Some compounds were not identified by GC-MS and it will require further analysis using other analytical techniques.     

莪术中挥发性成分的微波辅助固相顶空气相色谱法分析

将微波无溶剂提取(SFME)与顶空气相色谱(HS-GC)在线联用,建立了中药材的微波辅助固相顶空气相色谱法(MASP-HSGC),并用该方法快速直接分析了莪术药材中的挥发性成分。研究中对色谱条件、微波作用时间、微波作用功率等因素进行了考察,并以莪术醇为标准品考察了回收率和检出限,同时测定了莪术醇在莪术药材中的含量。对采用水蒸气蒸馏法(HD)和SFME法获得的莪术挥发油进行了气相色谱-质谱（GC-MS）分析,所得结果与所建立方法的结果进行对比。结果表明: HD-GC、SFME-GC和MASP-HSGC法所测得的化合物分别为35、33和40种;3种方法测得的莪术醇含量分别为（0.294±0.015）、（0.331±0.023）和（0.297±0.009） mg/g。该法简便快速,可用于莪术中挥发性成分的分离分析。     

Microwave-Assisted and Conventional Extractions of Volatile Compounds from Rosa x damascena Mill. Fresh Petals for Cosmetic Applications

Rosa x damascena Mill. essential oil is mainly used in the cosmetics and perfumery industry, but it also finds application in the food industry as a flavoring agent. The chemical composition of essential oils is affected by environment, soil, harvesting technique, storage condition, and extraction methods. Nowadays, the study and design of greener, more efficient, and sustainable extractive procedures is the main and strategic focus in the chemical research and development of botanical derivatives, especially as regards fragrances and essential oils. Several technologies are available, and the best method to use depends on the desired chemicals, but conventional extractive processes are often laborious and time-consuming, involve large amounts of solvents, and may cause the partial loss of volatiles, affecting the quality of the final product. In the last decade, microwave irradiation has been successfully applied to classical techniques, often improving the general extractive efficiency and extract quality. In the present paper, as a preliminary analytical screening approach, two microwave-mediated techniques, Solvent-Free Microwave Extraction (SFME) and Microwave Hydrodiffusion and Gravity (MHG), and two conventional procedures, Hydrodistillation (HD) and Steam Distillation (SD), were applied and compared for the extraction of volatile compounds from R. x damascena fresh petals to highlight differences and advantages of the selected procedure and of the obtained extracts useful in a cosmetic context as fragrances or active ingredients. The chemical composition of the extracts was investigated by GC-MS and GC-FID. Sixty-one components, distributed in the four techniques, were identified. SD and HD are dominated by oxygenated terpenes (59.01% and 50.06%, respectively), while MHG and SFME extracts are dominated by alcohols (61.67% and 46.81%, respectively). A relevant variability in the composition of the extracts relating to the extraction techniques used was observed. To point out the correlation between the process and composition of the obtained natural products, principal component analysis (PCA) of the data extracted from GC-FID was used. Taking into account a cosmetic application, SFME shows several advantages when compared with the other procedures. The extract (obtained in a significantly higher amount) contains a meaningful lower level of potential fragrance allergenic compounds and quite a double amount of benzyl alcohol and 2-phenyl ethanol that can also enhance the preservative action in personal care products.     

Rapid analysis of the essential oils from dried Illicium verum Hook. f. and Zingiber officinale Rosc. by improved solvent-free microwave extraction with three types of microwave-absorption medium

A new method of extracting essential oils from dried plant materials has been studied. By adding a microwave-absorption medium (MAM) to a reactor, solvent-free microwave extraction (SFME) was improved and can be used to extract essential oils from dried plant material without pretreatment. With a microwave irradiation power of 85 W it took only approximately 30 min to extract the essential oils completely. The whole extraction process is simple, rapid, and economical. Three types of MAM, iron carbonyl powder (ICP), graphite powder (GP), and activated carbon powder (ACP), and two types of dried plant material, Illicium verum Hook. f. and Zingiber officinale Rosc., were studied. The results were compared with those obtained by use of conventional SFME, microwave-assisted hydrodistillation (MAHD), and conventional hydrodistillation (HD), and the conclusion drawn was that improved SFME was a feasible means of extracting essential oils from dried plant materials, because there were few differences between the composition of the essential oils extracted by improved SFME and by the other methods.     

一种简易同时蒸馏萃取方法用于八角茴香挥发油提取及其GC-MS分析

设计了一种简易同时蒸馏萃取(SSDE)装置并用于八角茴香挥发油提取及其气相色谱-质谱法(GC-MS)分析。 该装置由圆底烧瓶、恒压滴液漏斗和回流冷凝管构成。 通过对八角茴香挥发油组分的GC-MS分析,比较SSDE法和水蒸汽蒸馏提取法(HD)提取植物源挥发油的效果。 结果表明,SSDE法所得挥发油相对含量在0.1%以上的19种化合物占挥发油总量的98.84%(相对标准偏差(RSD)(n=3)均不大于5.59%,其中RSD﹤5%的17种化合物占鉴定组分89.5%。SSDE法和HD法挥发油平均收率分别为7.30%(RSD=2.37%(n=5))和6.67%(RSD=5.26%(n=5))。 SSDE法简便、快速,适用于八角茴香挥发油的提取。     

Rapid Extraction and Analysis of Essential Oil from Cinnamomum Cassia Presl.

An improved solvent-free microwave extraction（ISFME） was used for the extraction of essential oil from dried Cinnamomum cassia Presl. Two kinds of solid microwave absorption media[carbonyl iron powder（CIP） and graphite powder（GP）] were used. When ISFME was applied, the heating rate was enhanced and the extraction time was obviously shorter than that consumed in conventional solvent-free microwave extraction（CSFME）. Twenty-eight kinds of compounds in the essential oil were identified, and the total content fractions of the compounds obtained by CIP-ISFME, GP-ISFME, CSFME, and hydrodistillation（HD） were 96.65%, 96.06%, 97.22%, and 96.29%, respectively. The compounds in the essential oil obtained from Cinnamomum cassia Presl. by ISFME, CSFME, and HD were compared and the quantity of the essential oil was almost the same. The ISFME has been proved to be a feasible way to extract essential oil from dried samples, and there are several obvious advantages in ISFME over those of HD and CSFME, for example, shorter extraction time（30 min） and lower energy consumption.     

Comparing the effect of sub-critical water extraction with conventional extraction methods on the chemical composition of Lavandula stoechas

The volatile extract composition of Lavandula stoechas flowers obtained by hydrodistillation (HD), subcrtical water extraction (SbCWE) and organic solvent extraction under ultrasonic irradiation (USE) were estimated by gas chromatography-mass spectrometry (GC-MS). One hundred and twenty four components were detected in SbCWE extracts while 94 and 65 signals were gained from HD and USE extracts, respectively. Most of the constituents were identified. The major compounds in all three extracts were fenchon, camphor, myrtenyl acetate, myrtenol and 1,8-cineol, but they differ in quantitatively. The total monoterpene hydrocarbons are higher in HD and USE extracts than those of SbCWE extract. However, SbCWE extract had higher concentration of light oxygenated compounds which contributes to the fragrance of the oil in a major extension. Heavy-oxygenated compounds was also in higher abundance in SbCWE extract (9.90%) than those of HD and USE extracts (3.19 and 4.78%, respectively). Effect of temperature on the extraction yield of SbCWE was investigated and while oil yield was increasing with an increase in temperature, a decrease in the extraction ability of sub-critical water toward the more polar compounds such as, 1,8-cineol, camphor and fenchon, was observed. Kinetic studies shown that SbCWE is clearly quicker than conventional alternatives. Most of components of volatile compounds were extracted at 15min.     

Identification of bioactive compounds in the leaves and stems of Aegopodium podagraria by various analytical techniques

The composition of essential oils of the leaves and stems of the Aegopodium podagraria growing wild in Estonia was determined using gas chromatography-flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS). A total of 69 compounds representing over 95% of the total oil were identified. The oil from the stems of A. podagraria was rich in monoterpenes (92.0%). In the leaves oil mainly monoterpenes (43.8%) and sesquiterpenes (29.8%) were identified. The total and extractable content of six mineral elements and two trace elements of the leaves and stems of A. podagraria were determined by atomic absorption spectroscopy (AAS). Capillary electrophoresis (CE) was employed in the fingerprint analysis of A. podagraria extracts.     

Comparative study of chemical composition,antibacterial and antioxidant activity of essential oils isolated from the seeds of Amomum subulatum by using microwave extraction and hydro-distillation methods

Microwave assisted hydro-distillation (MAHD) and conventional hydro-distillation (HD) techniques were compared in the extraction of essential oils from Amomum subulatum seeds. The time required for MAHD method (70 ​min) is lesser than that for HD method (4 ​h). There is a slight increase in the yield of extracted oil in MAHD method (3.35%) compared to HD (3%). Gas chromatography–mass spectrometry GC-MS results show that MAHD extracted essential oil was wealthier in oxygenated compounds. 1, 8-Cineole was found to be a major compound in case of both the essential oil, followed by α-pinene. In MAHD the percentage of the major oxygenated monoterpene (1, 8- cineol) slightly increases from 88% to 89% as compared to hydrodistillation. Contrarily to this, the percentage of monoterpene hydrocarbon was decreased in MAHD than HD extracted oil. MAHD and HD extracted oils show good antibacterial activities against gram-negative and gram-positive bacteria. MAHD extracted oil shows better antibacterial activity than HD extracted against both gram positive and gram-negative bacteria. 2, 2-diphenyl-1-picrylhydrazyl (DPPH•) radical scavenging antioxidant activities show that MAHD extract has better inhibition percentage than HD extract, and the half-maximal inhibitory concentration IC50 value of MAHD was less than HD extracted oil.     

Chemical composition and antibacterial activity of the essential oil of Moroccan Juniperus phoenicea

The antibacterial activity of the essential oil from leaves of Juniperus phoenicea (Cupressaceae) and its chemical constituents were investigated in this study. The essential oil was obtained by hydro-distillation and analyzed by gas chromatography equipped with a flame ionisation detector (GC-FID), and gas chromatography coupled to a mass spectrometer (GC-MS). Sixty-three volatile compounds were identified representing 52 to 92% of the total oil compositions. The main monoterpenes were a-pinene (26.7-78.7%) and 6-3carene (7.6-15.4%). The antibacterial activity of J. phoenicea essential oil, when tested against both Gram-positive and Gram-negative bacteria, showed high activity against all bacteria tested, except Pseudomonas.     

Comparative analysis of the oil and supercritical CO2 extract of Ridolfia segetum (L.) Moris

Supercritical carbon dioxide extraction allowed to obtain the volatile oil of different aerial parts of Ridolfia segetum (L.) Moris. Extraction conditions were as follows: pressure, 90 bar; temperature, 50 degrees C and carbon dioxide flow, Phi = 1.0 kg h(-1). Waxes were entrapped in the first separator set at 90 bar and -10 degrees C. The oil was recovered in the second separator working at 15 bar and 10 degrees C. The main components of the flower oil were alpha-phellandrene (19.4%), terpinolene (20.5%), piperitenone oxide (11.6%), beta-phellandrene (8.2%), (Z)-beta-ocimene (7.8%), myristicin (7.5%) and p-cymene (4.4%). The comparison with the hydrodistilled (HD) oil reveal that the significative difference was the content of sesquiterpenes which are higher in the supercritical fluid extraction (SFE) products. Collection of samples at different extraction times during supercritical extraction, allowed to monitor the change of the oil composition. Lighter compounds, as hydrocarbon monoterpenes, were extracted in shorter times than the heavier hydrocarbon and oxygenated sesquiterpenes. The oil from the steams was characterized by a high content of alpha-phellandrene (12.9%), terpinolene (11.6%), myristicin (11.0%), p-cymene (9.9%), beta-phellandrene (8.2%) and (Z)-beta-ocimene (6.0%) while the main components of the fruits were found to be myristicin (70.8%), piperitenone oxide (19.9%) and dill apiole (4.2%).     

Identification of essential oil components of Marrubium thessalum Boiss. & Heldr., growing wild in Greece

The essential oil of the Greek endemic species Marrubium thessalum Boiss. & Heldr. (Lamiaceae) was obtained by the hydrodistillation of its aerial parts during the flowering stage. The composition of the oil was analysed by GC and GC-MS. Thirty compounds were identified. The oil was devoid of monoterpenes, while sesquiterpenes constituted the major fraction. The main components of the oil were caryophyllene oxide (21.7%), β-caryophyllene (17.6%), germacrene D (15.3%), β-bisabolene (12.6%) and trans-β-farnesene (8.1%).     

Analysis of the essential oil of Teucrium polium ssp. capitatum from the Balkan Peninsula

The chemical composition of the essential oil of the aerial parts of Teucrium polium ssp. capitatum collected during the flowering period from rocky places and dry pastures, (Serbia, Nis, Kamenica), and dunes along the sea-side, (Bulgaria, Burgas, Primorsko) has been studied by GC and GC/MS. The identified compounds, 45 for the oil from Serbia and 44 for that from Bulgaria, amounted to 97.3% and 96.4% of the oils, respectively. The dominant constituents of the Serbian oil were sesquiterpenes {59.6%, the most abundant components being germacrene D (31.8%), trans-caryophyllene (8.8%) and bicyclogermacrene (6.2%)}, while monoterpenes accounted for 37.5% {the most abundant components being linalool (14.0%) and beta-pinene (10.7%)}. The essential oil from Bulgaria was characterized by a high percentage of monoterpenes, amounting to 62.9% {the most abundant components being beta-pinene (26.8%), alpha-pinene (9.3%) and limonene (6.4%)}, while sesquiterpenes accounted for 33.5% (the most abundant component was germacrene D 17.7%)}.     

A study on the essential oil of Ferulago campestris: How much does extraction method influence the oil composition?

The essential oil of different parts of Ferulago campestris (Bess.) collected in Sicily has been extracted by microwave-assisted hydrodistillation (MAHD) and by classic hydrodistillation (HD). A comparative qualitative-quantitative study on the composition of the oils was carried out. A total of 100 compounds were identified in the oils obtained by MAHD, whereas 88 compounds characterized the HD oils. The most prominent components were, in all different parts of F. campestris and in both extraction methods, 2,4,5-trimethylbenzaldehyde and 2,4,6-trimethylbenzaldehyde isomers; the latter was not previously found. The attempt to evaluate where the oil components are located in all parts of the plant was carried out by means of a kinetic study. Then, electron microscopy observation on the different parts before and after MAHD and HD was performed.     

Chemical investigation of the essential oil from berries and needles of common juniper (Juniperus communis L.) growing wild in Estonia

The essential oils obtained by simultaneous distillation and extraction (SDE) from the fresh and dried needles and dried berries of Juniperus communis L. of Estonian origin were subjected to GC-FID and GC-MS analyses. The yields of the oils ranged between 0.2% and 0.6% from juniper berries and between 0.5% and 1.0% from needles (dried weight). A total of 87 compounds were identified, representing over 95% of the oil. The major compounds in the needle oil were monoterpenes α-pinene (33.3-45.6%), sabinene (0.2-15.4%), limonene (2.8-4.6%) and sesquiterpenes (E)-β-caryophyllene (0.8-10.3%), α-humulene (0.8-6.2%) and germacrene D (3.0-7.8%). The juniper berry oil was rich in α-pinene (53.6-62.3%), β-myrcene (6.5-6.9%) and germacrene D (4.5-6.1%). The main oxygenated terpenoids found in the needle oil were germacrene D-4-ol (0.4-4.0%) and α-cadinol (to 2.7%). The oil from fresh needles contained high amounts of (E)-2-hexenal (3.7-11.7%).