Comparison of Essential Oils from Marchantia paleacea Obtained by Traditional and Microwave-Assisted Hydrodistillation Methods

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

Chemical composition and antioxidant activity of essential oils from barks of Pinus pumila using microwave-assisted hydrodistillation after screw extrusion treatment

Microwave-assisted hydrodistillation (MAHD) is a promising and advanced technology that uses microwave heating to extract essential oils from dry leaves. Currently available conventional methods are time consuming, thermally unsafe and require costly solvents. In the current study, MAHD and traditional hydrodistillation (HD) techniques were compared and their effectiveness in the separation of the essential oil from dry patchouli leaves have been studied. The patchouli oil that obtained from MAHD and HD extraction methods were characterized using gas chromatography-mass spectrometry (GC-MS) analysis and the impact of the two extraction methods on the plant morphology were observed using scanning electron microscopy (SEM) analysis. The results indicated that MAHD method extracted 5 % of essential oil at solid to solvent ratio of 1:12 g/ml from patchouli leaves as compared to 4 % obtained using HD method at 45 minutes of extraction time. In addition, MAHD method can retain 16 compounds while only 11 chemical compounds were extracted using HD. Thus, MAHD showed a greater potential for better production of the essential oil from patchouli leaves as compared to HD method.

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) 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.

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.

Kinetics of mace (Myristicae arillus) essential oil extraction using microwave assisted hydrodistillation: Effect of microwave power

Chemical profiles of the essential oils and volatile compounds from the aerial parts of Achillea wilhelmsii C. Koch (Compositae) obtained through hydrodistillation (HD), solvent-free microwave extraction (SFME), microwave assisted hydrodistillation (MAHD) and headspace solid-phase microextraction (HS-SPME) methods were subsequently investigated by means of GC and GC-MS instruments. A total of 22, 18, 22 and 22 components were identified in the chemical profiles, representing 93.6 %, 93.0 %, 92.4 % and 94.9 % of the total compositions when using the HD, HS-SPME, SFME and MAHD methods, respectively. In all samples, more than forty percent of the total structure consisted of oxygenated monoterpenes. In addition, the second rank of natural compounds are due to monoterpene hydrocarbons by SFME, MAHD and HS-SPME approaches while in the oil obtained by HD, oxygenated sesquiterpenes are the next most common ones. Moreover, 1,8-cineole was the main constituent of the hydrodistilled oil whereas camphor was the most frequently occurred compound using SFME, MAHD and HS-SPME methods.

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

A microwave-assisted hydrodistillation (MAHD) method was investigated for extraction of essential oils from lavender. The essential oil extracts at optimized MAHD conditions was compared with hydrodistillation (HD). Response surface methodology coupled with Box-Behnken design was applied to optimize the parameters for MAHD. The optimized MAHD conditions were 500 W microwave power, 17 mL/g liquid-to-solid ratio and 40 min microwave time. The ANOVA results revealed that microwave time had the greatest impact on the essential oil yield followed by liquid-to-solid ratio and microwave power. Under the MAHD optimized conditions, the essential oil yield was 3.19%, approximating the predicted yield (3.20%). MAHD was superior in terms of saving energy and extraction time (40 min, compared to 120 min in HD). The essential oil analyzed by GC-MS, presented 39 compounds constituting 98.37% and 97.51% of the essential oils obtained through MAHD and HD, respectively. No obvious differences were found in composition between MAHD oil and HD oil. Antimicrobial study showed that the lavender essential oil exhibited broad-spectrum antibacterial activity and the MAHD oil showed a higher antimicrobial activity than the HD oil. This study revealed that MAHD could be a good method for extracting essential oil in lavender and other aromatic plants.

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.

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.

Isolation of essential oil using microwave-assisted hydro-distillation (MAHD) method could enhance the yield compared to steam-distillation or conventional hydro-distillation methods. This study explored the isolation of essential oil from Citronella (Cymbopogon nardus L.) using the MAHD method with several parameters, such as solid-to-liquid ratio, power of the microwave, and extraction time. The essential oils produced were evaluated based on yield, density, refractive index, and composition. The result showed that the density of the essential oil product was in the range of 0.866–0.902 g/mL, while the refractive index was in the range of 1.470–1.475, which met the ISO standard. Chemical compounds were identified using Gas Chromatography-Mass Spectrometry (GC-MS) analysis. It was found that the total amount of citronellal, citronellol, and geraniol in the product obtained by MAHD is higher than the one from conventional methods. This study aims to identify the most efficient operating conditions to maximize yield while analyzing energy consumption to determine the most cost-effective conditions.

Extraction of essential oils of Ferulago angulata with microwave-assisted hydrodistillation

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.