Investigation of peel and leaf essential oils of Citrus clementina Hort. ex Tan. growing in the south of Vietnam

The essential oils from Marchantia paleacea obtained by microwave-assisted hydro-distillation (MAHD) and conventional hydrodistillation (HD) methods were compared. For MAHD method, the effects of different parameters, such as extraction time, the moisture of the matrix and the irradiation power, on the yield of essential oils were investigated. Maximum global yields were obtained using the following conditions: extraction time, 40 min; the irradiation power, 450 V and the moisture of the matrix, 80 %. MAHD was superior in terms of saving energy and extraction time (40 min, compared with 3 h for HD). The yield of essential oils by MAHD method was ten-fold higher than that of HD method. The extracts of essential oils were analyzed by GC-MS. The obtained results were compared with references. The result also indicated that the using microwave irradiation did not change the composition of essential oils.

Essential oils from sugarcane molasses: Chemical composition, optimization of microwave-assisted hydrodistillation by response surface methodology and evaluation of its antioxidant and antibacterial activities

Due to the increased demand and importance of essential oils in medicinal applications, advanced essential oil extraction techniques have been employed. Both conventional hydrodistillation (HD) and microwave-assisted hydrodistillation (MAHD) were employed to extract the essential oils from the hibiscus flower. Extraction time and solvent polarity were the most critical factors. Scanning electron microscopy (SEM) was used to investigate the surface morphologies of raw powdered hibiscus flowers (not exposed to any pretreatment) and pretreated powdered hibiscus flowers (exposed to methanol absorption for 60 minutes prior to extraction). Extractive chemistry analysis utilizing Fourier transform infrared (FTIR) spectroscopy was performed on the volatile oil obtained by MAHD. Different peaks in the gas chromatography/mass spectrometry (GC/MS) analysis indicated the presence of thirty-seven different compositions. MAHD was more energy efficient, had higher yield production, and was environmentally friendly, reducing HD’s overall carbon footprint by 40%. Oxygenated monoterpene, sesquiterpene, and sesquiterpene hydrocarbons were found in the hibiscus flower’s crude extract. Moreover, the methanolic extract of Hibiscus rosa-sinensis has potent antioxidant properties. A hibiscus flower extract had scavenging activities of 51.2% at 0.2 mg/mL, 0.3% at 0.6 mg/mL, 0.8% at 1.0 mg/mL, and 68.5% at 1.2 mg/mL against DPPH free radicals. Therefore, the MAHD method is well-suited to extracting essential oils from hibiscus flowers, and the resulting oil has the potential to provide significant therapeutic advantages.

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

The demand of essential oil in current industry has increased due to its bioactive compound that shows various therapeutic effects. Therefore, the qualities of essential oil mainly depend on its constituents. This study was carried out to determine the effects of Microwave-assisted hydrodistillation (MAHD) and hydrodistillation (HD) methods on yield, chemical composition and toxicity of essential oil from Lemongrass (Cymbopogon citratus). A pale yellow oil yield of 1.46 % (90 min) and 1.38% (180 min) were obtained from MAHD and HD methods, respectively. GC-MS results shows a total of twenty compounds in MAHD oil and seven compound in HD oil. MAHD oil contained slightly higher amount of citral, which is the key component of Lemongrass (Cymbopogon citratus), compared to HD oil, 86.48% and 83.15%, respectively. However, hydrodistilled oil showed the presence of higher β-Myrcene, 9.91%, and only 3.96% were found in the MAHD oil. Other identified constituents, include Linalool, 1,6-Octadiene,3,5-dimethyl-,trans, Pinane, Geranic acid and 1,5-Octadiene. Cytotoxicity study was also carried out by using Artemia Salina (Brine shrimp) lethality bioassay. The Lemongrass (Cymbopogon citratus) oil extracted using MAHD and HD gives LC50 value of 0.35µg/ml and 0.29µg/ml, respectively. A minor variation in the total chemical composition of essential oil may contribute for different level of biological activity expression.

This study investigated the effectiveness of microwave-assisted hydrodistillation (MAHD) and solvent-less microwave extraction (SLME) for extracting essential oil (EO) from lemon peels in comparison with conventional hydrodistillation (HD) in terms of extraction time, extraction yield, physical properties, chemical composition, operation cost, and antioxidant activity. The results showed that MAHD and SLME methods required an extraction time of 15 minutes while the required extraction time in HD was 120 minutes. There were no significant differences among physical properties (refractive index, specific gravity, and color) of extracted EOs by the three methods. Gas chromatography analysis did not indicate any noticeable change in the composition of EOs extracted by microwave-assisted extraction methods (MAHD and SLME) and HD method. DPPHº analysis of the extracted EOs indicated that microwave irradiation did not adversely influence antioxidant activity of the extracted EOs. The results of this study introduced MAHD and SLME as rapid, economical, and environmentally friendly extraction methods.

Microwave assisted hydrodistillation (MAHD) and conventional hydrodistillation 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 hr). There is a slight increase in the yield of extracted oil in MAHD method (3.35%) compared to HD (3%). 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 were 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 IC50 value of MAHD was less than HD extracted oil.

The chemical composition of the curry leaf essential oils obtained from curry trees growing in the South of Vietnam was studied for the first time. Two methods of extraction were used, conventional hydrodistillation (CHD) and microwave-assisted hydrodistillation (MAHD), thus leading consequently to the isolation of two oils of moderately different composition. The oils were obtained in the yields of 0.83 % and 0.39 % by CHD (480 minutes) and MAHD (50 minutes), respectively. The main chemical compositions of the oils were completely dominated by hydrocarbons. The extracted oils were determined by GC/FID and GC/ MSD to contain 76 and 62 identifiable components for the CHD and the MAHD methods, respectively. The oil extracted by MAHD displayed a higher anti-microbial activity than the oil extracted by means of CHD.

Microwave-assisted hydro distillation (MAHD) protocol, applied optimal extraction condition (650 W, 35 min) was used to extract an essential oil from the aerial part of Echinophora platylabo DC, which was collected from the Binaloud Mountain- Nishapor city. To evaluate the effect of microwave energy on the yield and composition of essential oil, MAHD method results were compared to those obtained by conventional hydro distillation (HD). The volatile compounds obtained by both methods were analyzed by Gas chromatography (GC) and GC-MS. It was indicated that, the yield of extracted essential oil using MAHD method is about 40% higher than regular HD method. In addition, the use of microwave irradiation not only influence the composition of the essential oil and the quantity of major compounds (trans-β- ocimene and γ –decalactone) but the extraction time in comparison to the HD method is shorter (35 min compared to 3 hours in HD). It was found that MAHD method is a good alternative for the extraction of essential oil in terms of the quality of the essential oil cost of the operation and saving energy. Thus we suggest that MAHD method can be considered as a green technology. Key words: Microwave, essential oil, E-β- ocimene and γ–decalactone, Echinophora platyloba DC.

Microwave assisted hydrodistillation (MAHD) was applied for the extraction of the essential oil from the aerial parts (tops) of Thymus pubescens. The MAHD method has been compared with conventional hydrodistillation (HD) technique, in terms of extraction time, yields and chemical compositions of the essential oils. The obtained results show similar chemical profiles for both methods. The extracted essential oils involved 14 components constituting 94.1 % and 96.3 % of the chemical profiles for the HD and MAHD methods, respectively. In the water distilled oil, carvacrol (30.3 %), thymol (27.1 %), α-terpineol (19.9 %), β-caryo-phyllene (3.3 %) and geraniol (2.2 %) constitute most of the composition while in the oil separated using the MAHD approach, carvacrol (32.2 %), thymol (29.3% ), α-terpineol (18.5 %), β-caryophyllene (2.9 %), linalool (2.3 %) and geraniol (2.2 %) contribute as dominant compounds. Based on the respective profiles, in all of the oils, oxygenated monoterpenes such as alcoholic and phenolic ones contribute as dominant compounds. Also, the effect of microwave powers was investigated on extraction of some major constituents of T. pubescens essential oils. Our results confirm that main oxygenated monoterpenes such as carvacrol, thymol and α-terpineol require an optimum microwave power and time to enhance their isolated contents and to save energy.

The demand of essential oil in current industry has increased due to its bioactive compound that shows various therapeutic effects. Microwave-assisted hydrodistillation (MAHD) is an advanced hydrodistillation (HD) technique, in which a microwave oven is used as the heating source. MAHD extraction of essential oil from Lemongrass (Cymbopogon Citratus) was studied. The effect of different parameters, such as water to plant material ratio (6:1, 8:1,10:1), microwave power (200 W,250W) and extraction time (30min,60min, 90min,120min) on the extraction yield and its major constituents were investigated and the results were compared with those of conventional HD. These essential oils were further analyzed by gas chromatography/mass spectrometric (GC-MS) to evaluate the effect of extraction method on the content of its main constituents which were neral, geranial and myrcene and some minor compounds such as linalool, geranic acid and citronellol. The optimum parameters were found at water to plant material ratio of 8:1, microwave power of 250W and 90 minutes of extraction and the yield obtained under this condition was 1.46%. GC-MS analysis has proved that the use of microwave irradiation did not adversely influence the composition of essential oils as the main constituents found through both methods were almost similar in term of quality and quantity. The results obtained indicate that MAHD method provided a good alternative for the extraction of essential oil from Lemongrass (Cymbopogon Citratus). I. INTRODUCTION Essential oils are botanical extracts of various plant materials, and do not only originate from flowers, but from herbs, trees and various other plant material. It is estimated that the global number of plants is of the order of 300,000 and about 10% of these contains essential oils and could be used as a source for their production (1).Their extracts are formed by combination of diverse and complex volatile mixtures of chemical compounds, with predominance of terpene associated to aldehydes, alcohols, and ketones which were accumulated in various structure of the plant (2). In industry, the essential oils are typically extracted from fresh or partially dried leaves using various method of extraction and the most common will be hydrodistillation. The use of medicinal plants extracts is part of a competitive market, which includes pharmaceuticals, food, cosmetics, and perfumery markets, mainly to use their active substance. The Asian continent with its diversity of climates appears to be the most vital producer of essential oils. China and India play a major role followed by Indonesia, Sri Lanka, and Vietnam

The present work mainly describes the relative abilities of two different extraction techniques, namely hydrodistillation (HD), and microwave assisted hydrodistillation (MAHD) to separate the essential oils from the aerial parts of Artemisia sieberi, in combination with analysis by GC and GC-MS. By means of the HD method, 47 components were identified in the aerial parts oils, representing 98.6 % of the total composition, whereas by the MAHD method, 30 components were identified, constituting 99.7 % of the oil. The major constituents of the HD method were camphor (22.0 %), 1,8-cineole (19.3 %), cis-davanone (15.0 %), camphene (4.6 %) and terpinene-4-ol (3.2 %), whereas the profile of the oil isolated by the MAHD technique was characterized by cis-davanone (29.8 %), camphor (20.8 %), 1,8-cineole (13.8 %), geranyl acetate (5.7 %) and terpinene-4-ol (3.0 %) as the dominant compounds.

The present study aimed to evaluate the chemical analysis and antimicrobial effects of the Thamnobryum alopecurum (Hedw.) Gangulee essential oils were obtained by different distillation methods (Clevenger apparatus hydrodistillation (HD) and microwave-assisted hydrodistillation (MD)). In this study obtained volatile oils were analyzed by gas chromatography-mass spectrometry which revealed the presence of forty-five compounds present in the essential oil obtained by HD method representing 99.48 % of the total identified compounds and thirty-four compounds were identified in the essential oil extracted by MD method representing 95.39 % of the total identified compounds. 3-octanone was the major constituent of the essential oils extracted by both HD (14.28 %) and MD (20.07 %). Terpenes were the major constituents in the essential oil extra-cted by both methods (54.41 % in HD and 52.21 % in MD) followed by oxygenated terpenoids (17.16 % in HD and 14.94 % in MD). The other major compounds of the essential oil in HD was limonene (9.65 %) followed by β-pinene (9.13 %), cuparene (6.04 %), gymnomitrone (5.72 %) and 4-epi-abietal (5.59 %). While in MD essential oil the other major compounds were β-pinene (12.20 %) followed by limonene (8.56 %), α-pinene (9.01 %), cupa-rene (6.44 %), abietadiene (5.97 %). The antimicrobial effects of the essential oils were determined tested quantitatively in respective broth media by using double microdilution and the minimal inhibition concentration (MIC) values (μg/mL). The isolated essential oils of T. alopecurum showed effective antimicrobial activities against Escherichia coli, Yersinia pseudotuberculosis, Staphylococcus aureus, Enterococcus faecalis, Bacillus cereus, Mycobacterium smegmatis and Candida albicans. However, no activity was not observed against Pseudomonas aeruginosa. The hydrodistillation method was found to be more effective than the microwave method in iden-tifying the chemical composition of the structure of T. alopecurum essential oil. While for antimicrobial study MD method was found to be more effective in terms of antimicrobial effect. The T. alopecurum thus is a potential source of an antimicrobial agent with a wide range of chemical compounds that could be responsible for their activity.

:In this investigation, conventional hydrodistillation (HD) and microwave assisted hydrodistillation (MAHD) were used for extraction of essential oil from roots of Rosa canina, also, the effect of a chemical modifier was investigated. At first, magnetic nanoparticles were modified with a thermosensitive polymer. Then its effect on microwave extraction efficiency was investigated. The results obtained from the conventional HD extraction showed that the quantity and number of extracted compounds is low (30 compounds). Extraction yields were 0.47, 0.78 and 1.12 by hydrodistillation, microwave and microwave assisted hydrodistillation, respectively. Thus, the percent of the extraction yield was significantly increased through the MAHD method, particularly in the presence of the modified magnetic nanoparticles. In addition, extracted compounds were increased from 46 to 80 compounds by adding modified magnetic nanoparticles, respectively. Modified magnetic nanoparticles with cell compatible polymer could increase the efficiency of the extraction significantly. As simultaneous use of microwave and modified magnetic nanoparticles significantly increase the quality and quantity of volatile essential oils of Rosa canina L.

Comparative seasonal variation and chemical composition of essential oils from the leaves and stems of Schefflera heptaphylla using microwave-assisted and conventional hydrodistillation