Microwave-assisted Hydrodistillation Research Articles

Chemical constituents and biological activities of the seed essential oil from Michelia tonkinensis grown in Thanh Hoa province, Viet Nam

AbstractEssential oils (EOs) from the seed of Michelia tonkinensis were extracted in four ways hydrodistillation (HD), microwave‐assisted hydrodistillation (MHD), ultrasound‐assisted hydrodistillation (UHD) and enzyme‐assisted hydrodistillation (EHD). The chemical constituents of these EOs were analysed by gas chromatography (GC‐FID) and gas chromatography/mass spectrometry (GC/MS). Phenylpropanoids were the main components in which safrole is the dominant constituent (82.98‐91.53%), followed by monoterpene hydrocarbons (5.26‐11.94%). In comparison with traditional hydrodistillation method (HD only), the EOs obtained from the MHD, UHD and EHD methods have the higher safrole contents (91.32%, 90.96% and 90.25%, respectively). The essential oils were also tested for their antioxidant, anti‐imflammatory, antimicrobial and cytotoxic activities. The HD essential oil sample showed inhibitory activity against 6/8 tested microorganisms, i.e., Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Bacillus subtillis, Candida albicans, and Saccharomyces cerevisiae. The MHD and EHD exhibited the inhibitory activity against three strains E. coli, A. niger and F. oxysporum. The UHD inhibited E. coli and F. oxysporum.

A COMPREHENSIVE REVIEW ON LEMONGRASS (CYMBOPOGON CITRATUS) OIL EXTRACTION AND ITS APPLICATIONS

This article presents a comprehensive review of methods of extraction, properties, compositions and industrial application of lemongrass essential oil. Lemongrass (Cymbopogon citratus) essential oil has been used traditionally since ancient days in medicine as remedy to improve blood circulation, treat fever and malaria, promote digestion and as well used to increase immune system of the human body. Essential Oils of lemongrass are used in various industries. Some of the industries in which they are used extensively include Aromatherapy, Food and drink industry, Pharmaceuticals industry, Fragrance and Flavour industry, Agriculture and Livestock industry, Cosmetic and Soaps industry, House hold and Domestic. The quality of the essential oil from lemongrass strongly depends on the extraction method and operating conditions. Basically lemongrass essential oil can be obtained by various extraction methods, such as steam distillation, conventional solvent extraction, Soxhlet extraction, ultrasound-assisted extraction (UAE), hydrodistillation (HD), microwave-assisted hydrodistillation (MAHD), Simultaneous-distillation-extraction technique (SDE), Solvent-Free-Microwave-Extraction Technique (SFME) and supercritical fluid extraction (SFE) with CO2. The composition of essential oil of Cympobogon citratus contains α-pinene, β-pinene, delta-3-catrene, myrcene dipentene, β-phellandrene, β-cymene , methyl heptanene, citronellal, β-elemene, β-caryophyllene, citronellyl acetate, geranyl acetate , citral A , citral B, geraniol, elemol , and β-caryophyllene oxide, etc. In addition, lemongrass oil also contains essential minerals such as Fe, Zn, Mg, Na, K, Ca, Mn, P etc. The most important physicochemical properties of lemongrass oil includes specific gravity, Optical rotation, refractive index, percentage of citral, freezing point, moisture content, acid value, ester value, carbonyl value and phenol content . Nevertheless, the chemical composition of the essential oil of Lemongrass also varies with the geographical origin, cultivation practices, plant age, photoperiod, harvest period, cultivars, and extraction methods. However, for extraction of lemongrass oil, green technology such SFE, SDE, SFME and MAHD that are consumer and environmental friendly in industrial-scale essential oil production should be considered as a method to overcome the limitations of traditional distillation methods. KEYWORDS: Essential Oil, Lemongrass, Microwave-Assisted-Hydrodistillation. Solvent Extraction, Steam Distillation, Supercritical Fluid Extraction

Conventional vs. Microwave-Assisted Hydrodistillation: Influence on the Chemistry of Sea Fennel Essential Oil and Its By-Products.

The main objectives of this study were to investigate the effects of the applied essential oil (EO) isolation method, conventional hydro-distillation (HD), and microwave-assisted hydro-distillation (MHD) on the chemical profile of sea fennel (Crithmum maritimum L.) essential oil and to investigate the main constituents present in the liquid by-products of EOs isolation (hydrolate and residual wastewater). Headspace-solid phase microextraction (HS-SPME) was used to isolate hydrolate components, while gas chromatography coupled with mass spectrometry (GC-MS) was used to detect and analyse the chemical constituents of the essential oils and hydrolates. The phenolic composition of the wastewater extracts was analysed by high performance liquid chromatography (HPLC). The EO obtained by MHD had a higher yield of limonene and sabinene. The chemical composition of the hydrolates differed from the EO compositions. The content of terpinen-4-ol in the MHD hydrolate was higher, while several compounds were detected in relatively high proportions only in the HD hydrolate. MHD also resulted in a higher phenolic content of the wastewater, where an increase in the concentration of chlorogenic acid was also observed. It can be concluded that the isolation method had a great influence on the profile of sea fennel EOs, especially on their corresponding hydrolates and residual wastewater extracts. Due to their valuable chemical composition, these by-products can be a cost-effective source of bioactive compounds that have great potential for use in various industries.

Extraction of citronella oil from lemongrass (Cymbopogon winterianus) by sequential ultrasonic and microwave-assisted hydro-distillation

The Ultrasonic and Microwave-Assisted Hydro-Distillation (US-MAHD) method is a process combination of ultrasonic-assisted extraction (UAE) and microwave-assisted hydro-distillation (MAHD) carried out sequentially. This method aims to improve the UAE and MAHD methods in extracting citronella oil. This study evaluates the performance of US-MAHD in the extraction of citronella oil from the citronella plant. Extraction is conducted for 90 min at various solvent-plant ratios (v/m) (10:1, 12:1, 14:1), ultrasonic bath temperature (30 °C, 40 °C, 50 °C), and power of microwave oven (150 W, 300 W, 450 W). US-MAHD yields a maximum yield of citronella oil of 1.82 mg/g when extracting lemongrass plant with a combination of ultrasonic bath temperature of 30 °C, a solvent-plant ratio of 10:1, microwave power of 300 W, and time of 90 min. All quality parameters of the oil produced have met ISO 3848:1976 standard. Extraction of citronella oil using the US-MAHD method produces higher yields than the UAE and MAHD methods under the same operating conditions. The yields of citronella oil from the US-MAHD, UAE, and MAHD methods are 1.82, 0.92, and 1.48 mg/g, respectively. SEM analysis of residual lemongrass plant shows more cell wall damage which indicates more oil release from the plant matrix.

Essential Oil of Cestrum diurnum L.: GC/MS Analysis, in Vitro and in Silico Anti-HCoV-229E Effects and Inhibitory Activity against LPS-Induced Inflammation.

Cestrum diurnum L. (Solanaceae) is a fragrant ornamental tree cultivated in different parts around the world. In this study, the essential oil (EO) of the aerial parts was extracted by hydrodistillation (HD), steam distillation (SD) and microwave-assisted hydro-distillation (MAHD). GC/MS analysis of the three EOs revealed that phytol represents the major component in SD-EO and MAHD-EO (40.84 and 40.04 %, respectively); while in HD-EO it only represented 15.36 %. The SD-EO showed a strong antiviral activity against HCoV-229E with IC50 of 10.93 μg/mL, whereas, MAHD-EO and HD-EO showed a moderate activity with IC50 values of 119.9 and 148.2 μg/mL, respectively. The molecular docking of EO major components: phytol, octadecyl acetate and tricosane showed a strong binding to coronavirus 3-CL (pro). Moreover, the three EOs (50 μg/mL) decreased the levels of NO, IL-6 and TNF-α and suppressed IL-6 and TNF-α gene expression in LPS-induced inflammation model in RAW264.7 macrophage cell lines.

Extraction of Cinnamomum longepaniculatum deciduous leaves essential oil using solvent-free microwave extraction: Process optimization and quality evaluation

The optimal process conditions for solvent-free microwave extraction (SFME) of essential oils from Cinnamomum longepaniculatum deciduous leaves after moisture conditioning were established by response surface methodology (RSM). A Box-Behnken design (BBD) was applied to evaluate the effects of three independent variables: moisture content (A: 54%–74%), microwave power (B: 300–500 ​W) and microwave time (C: 20–40 ​min), on the extraction yield of essential oil. The compounds of the essential oils obtained by SFME, hydro-distillation and microwave-assisted hydro-distillation (MADE) were identified by gas chromatography-mass spectrometry (GC-MS), and the total lipids of C. longepaniculatum fresh leaves and deciduous leaves were analyzed. The correlation analysis of the response regression model indicated that quadratic polynomial model could be employed to optimize the extraction of essential oil. The optimal extraction condition was A: 58%, B: 400 ​W and C: 28 ​min. In the optimal condition, the maximum extraction yield was 4.475 mL/100 ​g dw and higher than that by MADE. The main compound of the essential oil was eucalyptol (63.54%), and total oxygenated compounds was 78.95%, mainly caused by SFME and the metabolism of endophytic bacteria with decreasing content of phospholipids and fatty acids. Analysis of variance under the extraction condition illustrated high fitness of the model and the success of RSM for optimizing and reflecting the expected process condition. SFME combined with moisture regulation was an effective method for extracting essential oil from C. longepaniculatum deciduous leaves.

Optimization of microwave-assisted hydro-distillation essential oil extracted from Rumex Crispus leaves using definitive screening design

Conversion of nonfood natural products to value-added products is an important work, which is going on worldwide. In addition, to obtain a product with better quality, a sufficient separation method is helpful to improve its utilization value by using effective, rapid and environmentally friendly techniques. Thus in this work, the microwave-assisted hydrodistillation (MAHD) process of essential oils from important natural plant Rumex Crispus leaves was investigated. The experimental design and extraction conditions were optimized using a definitive screening design. The yield of essential oils of 4.67 ± 0.02 % was investigated under the optimum conditions; 534.89 W of microwave power, 23.48 min of hydrodistillation time and 4.5 mL/g of the volume of water to plant mass ratio. Under these conditions, the essential oils were analyzed using gas chromatography-mass spectrometry (GC–MS). Results revealed that the essential oil extracted by MAHD possessed high quality as proved by its higher percentage of oxygenated compounds. In addition, α-santol (29.63 %) and β-santol (25.60 %) are the primary components of oxygenated compounds in essential oils. In conclusion, the MAHD was successfully employed to obtain mainly Oxygenated compounds-rich essential oil that may be used in several industrial applications. Subsequently, a definitive screening design may be regarded as an alternative and reliable method for the prediction of experimental parameters. It was concluded that the weeds plant (Rumex Crispus) contains a reliable quantity of oils that is extremely feasible to use and recommended as good feedstock for possible use in industrial applications.

Microwave-Assisted Hydrodistillation of Essential Oil from Plectranthus amboinicus: Evaluation of Its Antifungal Effect and Chemical Composition

Fusarium wilt, a vascular syndrome in a wide range of plants, is caused by the pathogen Fusarium Oxysporum. The objective of this investigation was to evaluate the antifungal effect of four essential oils (EOs) (Plectranthus amboinicus, Syzygium aromaticum, Lippia alba, and Rosmarinus officinalis), which were obtained by using microwave-assisted hydrodistillation (MAH), against F. oxysporum. The yield obtained from P. amboinicus with the use of MAH was 0.2%, which was higher than that of a conventional extraction; its extraction time was also shorter. For concentrations of 100 and 300 μL/L, P. amboinicus caused an inhibition rate of 27.2 and 55.7%, respectively, while S. aromaticum caused an inhibition rate of 23.1 and 87.3%, respectively. It was observed that increasing the concentration also increased the % inhibition rate. The extracts of L. alba and R. officinalis caused an inhibition rate of 14.5 and 14.7% at 500 µL/L, respectively, at 10 days of incubation, while at this concentration, P. amboinicus and S. aromaticum achieved 100%. The major chemical compounds of P. amboinicus were carvacrol (41.20%), o-cymene (11.61%), caryophyllene (11.45%), α-bergamotene (7.71%), and caryophyllene oxide (4.62%), and these monoterpene hydrocarbons were responsible for the biological activity. The essential oil of P. amboinicus in appropriate concentrations is a potent antifungal agent that could be used for the control of F. oxysporum.

Yield, chemical composition, and antioxidant activity of essential oil obtained from Ferula persica oleo-gum-resin: Effect of the originated region, type of oleo-gum-resin, and extraction method

In the present study, we investigated the effect of extraction methods (hydro-distillation, microwave-assisted hydro-distillation, and solvent-free microwave extraction), oleo-gum-resin types (Kokh and Shir), and regions (Sepidan and Darb-e-Behesht) on yield, composition and antioxidant activity of essential oils obtained from oleo-gum-resin of Ferula persica. The results showed that oleo-gum-resins originating from Darb-e-Behesht produced more essential oil than oleo-gum-resins of Sepidan using each of the extraction methods. Each of the extraction methods isolated more essential oil from Kokh samples as compared with Shir. The highest essential oil was achieved by the solvent-free microwave extraction method from Kokh samples. A total of 51 compounds were identified in essential oil samples. Monoterpene hydrocarbons and sulfur compounds were dominant in all essential oils. The main compounds of essential oil in the samples were β-pinene, α-pinene, (E)− 1-Propenyl sec-butyl disulfide, and (Z)− 1-Propenyl sec-butyl disulfide. The antioxidant activity of the essential oils was affected by the region and type of oleo-gum-resin. The essential oils showed less antioxidant activity than butylated hydroxyanisole. The research suggests that the area of oleo-gum-resin collection, type of oleo-gum-resin collected, and essential oil extraction method should be selected and optimized based on the intended purpose and the desired active ingredients. Also, the results show that microwave-assisted hydro-distillation and solvent-free microwave extraction methods can be introduced as quick and suitable alternative methods for extracting essential oils from oleo-gum-resins of F.persica.

Effect of Extraction Methods on Essential Oil Composition: A Case Study of Irish Bog Myrtle-Myrica gale L.

Myrica gale is an aromatic peatland shrub that has reported traditional use as an insect repellent. Different extraction methodologies were used in this study to isolate the essential oil of Myrica gale L., including Clevenger hydrodistillation (CH) and microwave-assisted hydrodistillation (MAH). The oils, isolated from different plant parts (leaves, fruit and branches) collected in summer and autumn, were analysed by GC-MS and the volatiles from plant tissue were directly analysed by headspace-GC-MS. A total of 58 components were identified, including 15 monoterpene hydrocarbons (22.78–98.98%), 14 oxygenated monoterpenes (0.91–43.02%), 13 sesquiterpene hydrocarbons (0.05–24.98%), 3 oxygenated sesquiterpenes (0.07–13.16%) and 13 other compounds (0.05–5.21%). Headspace sampling furnished monoterpenes, while CH and MAH extracted monoterpenes and sesquiterpenes, with α-pinene (6.04–70.45%), eucalyptol (0.61–33.80%), limonene (2.27–20.73%) and α-phellandrene (2.33–15.61%) as major components in all plant parts. Quantitative differences occurred between extraction methodologies, with MAH yielding higher quantities of monoterpene and sesquiterpene hydrocarbons and CH targeting oxygenated counterparts. Leaves gave more complex chemical fingerprints than branches and fruit, and the summer collection yielded more components than the autumn collections. An OPLS-DA model was applied to the GC-MS data to compare the chemical profiles based on the extraction techniques and plant parts, and molecular networks were obtained for monoterpenes and sesquiterpenes connected via biosynthetic pathways. The essential oil profile of Myrica gale was influenced by the season of collection, plant part and extraction method.

Microwave-Assisted Hydrodistillation of the Insecticidal Essential Oil from Carlina acaulis: A Fractional Factorial Design Optimization Study.

Recently, microwave-assisted hydrodistillation (MAH) has been reported as an innovative technique leading to increased essential oil (EO) extraction yield, coupled with reduced extraction time and energy costs. The EO of Carlina acaulis L. (Asteraceae), mainly constituted by carlina oxide (>95%) and conventionally obtained through traditional hydrodistillation (HD), has been reported as extremely effective against several arthropod vectors and pests of medical and economic importance with limited impact on non-target species, including mammals. This study aimed to the optimization of the EO extraction through MAH by using a one-step design of experiments (DoE) approach that allowed us to relate the characteristics of the produced EOs with the applied experimental conditions using mathematical models. The preliminary screening allowed us to optimize the protocol only by the extraction time, skipping complex data analysis. Moreover, the comparison of the optimized MAH conditions with traditional HD pointed out the higher efficiency of MAH in terms of EO yield (0.65 and 0.49% for MAH and HD, respectively) and extraction time (210 min for MAH). The results obtained confirmed the promising role that MAH could have in C. acaulis EO extraction, with increased yield and reduced extraction time, water consumption, and energy costs, and being employable on an industrial scale, with special reference to insecticidal and acaricidal formulations.

Enhancing Yields and Antioxidant Activities of Caraway Seeds Essential Oil by Ultrasonic Treatment Combined with Hydro-distillation, and Microwave-assisted Hydro-distillation

This study examined the effects of ultrasonic treatment on the amount and quality of essential oils extracted from caraway seeds using ultrasonic treatment followed by hydro-distillation and ultrasonic treatment followed by microwave-assisted hydro-distillation. Afterward, the obtained results were compared with those of untreated extracts issued from conventional hydro-distillation and microwave-assisted hydro-distillation. The essential oil yields ranged from 1.18 ± 0.09 to 1.36 ± 0.09% w/w, depending on the extraction technique. Analysis by gas chromatography coupled with mass spectrometry showed the presence of 21 compounds in all the extracts. Produced essential oils consisted of 9.65 ± 1.742 % to 18.59 ± 1.377 % monoterpenes hydrocarbons and 77.20 ± 2.847 to 84.60 ± 1.909 % oxygenated monoterpenes. The main components were limonene and carvone, but the amounts of each component depend on the methods. Additionally, the antioxidant activity of caraway seeds essential oils was determined using the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. The antioxidant ability of the examined oils was moderate, and the USMAHD oil median inhibitory concentration (IC50) value was the lowest. Moreover, a statistical investigation paved the way for a possible correlation between the carvone/limonene ratio and IC50. Consequently, this aspect, which is the potential for improving the extract’s quality by modifying the ratio of the target components known for their high antioxidant effects, made this study novel.

Mini-Review: Extraction of Patchouli Oil from Pogostemon cablin Benth. Leaves

Pogostemon cablin Benth. var ‘Sidikalang’ leaves are the main source of patchouli oil which is used in the cosmetics and perfume industry because of its better fixative nature and provides the foreign exchange of around 60 % of Indonesia’s essential oil export revenues and is the largest patchouli oil supplier in the world with a contribution of 90 %. But apparently, several studies found that patchouli oil also has pharmacological activity such as aromatherapy, anti-influenza, antioxidants, and anti-microbial. This proves that leaves patchouli oil can be used as alternative medicine. Patchouli oil is composed of 20 main constituents, but the most important role as a determinant of the quality of patchouli oil is sesquiterpene patchouli alcohol (PA). The right extraction method is the most important factor so that the quality of patchouli oil is well maintained during the extraction process. Some methods that have been used for patchouli oil extraction include soxhlet, hydrodistillation, microwave-assisted hydrodistillation, microwave–air hydrodistillation, and water–bubble distillation. Microwave-assisted hydrodistillation and water–bubble distillation methods are more efficient methods for patchouli oil extraction. The microwave-assisted hydrodistillation method produces a yield of 1.9437 to 2.7227 % with a PA content of 26.32 % within 120 min to 126 min, and the water–bubble distillation method produces a yield of 2.40 % with a PA content of 61.53 % within 360 min.

Sugarcane molasses essential oils: mesoporous silica nanoparticles as carriers to improve their slow-release activity and the study on their anti-inflammatory activities in vivo.

In this study, sugarcane molasses essential oils (SMEOs) were extracted by microwave-assisted hydrodistillation (MAHD); the components of SMEOs were identified and analyzed by gas chromatography-mass spectrometry (GC-MS). SMEOs were loaded into mesoporous silica nanoparticles (MSNPs) and their sustained-release activity was evaluated. In vivo anti-inflammatory activity assays pertained to inhibiting the auricle swelling caused by xylene in mice, the peritoneal permeability increased inflammation in mice induced by acetic acid and the inflammation caused by granuloma hyperplasia in mice. We demonstrated that the main components of SMEOs were isoamylol, ethyl acetate, isobutanol, isovaleraldehyde, 2-methyl-butanal, furfural and 2-acetylpyrrole. The SMEOs loaded into MSNPs formed MSNP-SMEOs, which enhanced the stability and slow-release performance compared with SMEOs. The main components of SMEOs can inhibit inflammation, and the development and application of SMEOs in the fields of food and medicine have certain potential.

Bioactive Profile of Distilled Solid By-Products of Rosemary, Greek Sage and Spearmint as Affected by Distillation Methods.

By-products of essential oils (EOs) in the industry represent an exploitable material for natural and safe antioxidant production. One representative group of such by-products is distilled solid residues, whose composition is properly modulated by the distillation method applied for the recovery of EOs. Recently, in terms of Green Chemistry principles, conventional extraction and distillation processes are considered outdated and tend to be replaced by more environmentally friendly ones. In the present study, microwave-assisted hydro-distillation (MAHD) was employed as a novel and green method for the recovery of EOs from three aromatic plants (rosemary, Greek sage and spearmint). The method was compared to conventional ones, hydro-distillation (HD) and steam-distillation (SD), in terms of phytochemical composition of distilled solid residues, which was estimated by spectrophotometric and chromatographic methods. Total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity (ABTS, DPPH and FRAP) results highlighted the distilled solid residues as good sources of antioxidants. Moreover, higher antioxidant activity was achieved for MAHD extracts of solid residues in comparison to HD and SD extracts. A metabolomics approach was carried out on the methanolic extracts of solid residues obtained by different distillation methods using LC-MS analysis followed by multivariate data analysis. A total of 29 specialized metabolites were detected, and 26 of them were identified and quantified, presenting a similar phenolic profile among different treatments, whereas differences were observed among different species. Rosmarinic acid was the most abundant phenolic compound in all extracts, being higher in MAHD extracts. In rosemary and Greek sage extracts, carnosol and carnosic acid were quantified in significant amounts, while trimers and tetramers of caffeic acid (salvianolic acids isomers) were identified and quantified in spearmint extracts, being higher in MAHD extracts. The obtained results pointed out that MAHD extracts of distilled solid by-products could be a good source of bioactives with potential application in the food, pharmaceutical and cosmetic industries, contributing to the circular economy.

Optimization of microwave-assisted hydrodistillation of essential oils from fennel seeds

Fennel seeds are a medicinal plant in species Foeniculum vulgare. Essential oils are commonly used for flavoring or in the cosmetic industry and also have antibacterial properties. The purpose of this research was to increase the yield of essential oils by studying the optimize conditions for microwave-assisted hydrodistillation of essential oils from fennel seeds using response surface methodology in combination with central composite design (CCD). The factors used in this study consisted of extraction time (60–120 min), microwave power (300–500 W), and solid–liquid ratio (1:10–1:20 g/mL). The experimental data obtained were fitted to quadratic equation due to high coefficient of determination (R2 = 0.9624). It was found that the microwave power factor and the square factor of microwave power were significant (p < 0.05) for the percentage yield of fennel seeds essential oil. The predicted conditions for extraction were time 96.36 min, microwave power 400 W and solid to liquid ratio 1:14.85 g/mL. The predicted percentage yield was 0.94. The actual yield percentage of essential oils was 0.98. In addition, GC–MS analysis revealed that major components of fennel seeds were anethole (46.12 %) and estragole (36.39 %). The compounds were classified in the group of phenylpropanoid compounds 83.47 %, oxygenated monoterpene 10.62 %, monoterpene 4.81 %, sesquiterpene 0.06 % and ester 0.04 %. Due to its shorter duration and higher yield, MAHD is a good alternative to extracting essential oils from fennel seeds.

Isolation of essential oil from Mosla chinensis Maxim by surfactant-enzyme pretreatment in high-solid system and evaluation of its biological activity

Plant essential oil (EO) is an important natural active product, and the development of efficient and green EO separation technique has been one of the research hotspots. In this work, surfactant-enzyme pretreatment in high-solid system followed by microwave-assisted hydrodistillation (SEHS-MHD) was developed for the isolation of EO from Mosla chinensis Maxim. Through kinetic curve fitting, pretreatment of raw materials with combined enzyme (cellulase and hemicellulase of 1:1 in activity value) and surfactant (tween-20) in high-solid system (20% solid content) could provide a higher yield of EO. Compared with other reference methods, the yield of EO obtained by SEHS-MHD was significantly increased, which was mainly due to the synergistic interaction of enzyme and surfactant in the high-solid system. The results of gas chromatography-mass spectrometer analysis showed that the main components of M. chinensis EO were thymol and carvacrol, the contents of which were 75.38% and 17.20%, respectively. Additionally, the inhibitory enzyme activity and antifungal activity of M. chinensis EO were evaluated, the results of which indicated that EO had no obvious inhibitory activity on α-amylase and acetylcholinesterase, but had spectral antifungal activity. In general, the SEHS-MHD developed in this work is a potential and powerful alternative to traditional techniques for the sufficient isolation of EO from natural plant and crop materials. • Surfactant and enzyme were combined to pretreat raw materials in high-solid system. • Synergistic interaction of surfactant and enzyme in high-solid system was produced. • Kinetics and composition of essential oils under various conditions were studied. • Essential oil showed excellent inhibitory activity against plant pathogenic fungi.

Recent advances of kinetic model in the separation of essential oils by microwave-assisted hydrodistillation

To better design and optimize the separation process of plant essential oils obtained by microwave-assisted hydrodistillation , it is necessary to fully understand the kinetic mechanism and appropriate mathematical representation of the separation process. In this paper, the kinetic models, including first-order kinetic models, second-order kinetic models, two-site kinetic models, power-law models, Peleg models, and Elovich model, for the separation of essential oils by microwave-assisted hydrodistillation are introduced, and try to explain the kinetic behavior of this method for the separation of essential oils through the assumptions, parameters and application examples of the kinetic model. Meanwhile, the most suitable kinetic models were screened according to the kinetic mechanism of essential oils obtained by this method, although these kinetic models all showed a high coefficient of determination, only first- and second-order kinetic models can reproduce the kinetic mechanism of this method under specific conditions. In addition, the effects of microwave irradiation power, liquid-solid ratio, moisture content, and particle size on the kinetic model parameters are discussed and analyzed, then the extraction rate constants, equilibrium yields, and coefficients of determination in the kinetic models all change with these factors. Therefore, it is necessary to explore new kinetic models to more comprehensively understand the kinetic mechanism of the separation of essential oils by this method, which has guiding significance for the optimal design of essential oil separation methods and the utilization of high-value processing. • The MHD method can be approximated as only two simultaneous mechanisms. • First- and second-order kinetic models can well fit the MHD under certain conditions. • Kinetic model parameters are affected by the essential oil separation conditions. • Essential oils isolated by the MHD method are mainly derived from broken plant cells. • Adverse results such as thermal decomposition affect the kinetic mechanism of MHD.

Chemical constituents and antibacterial activity of essential oils in &lt;i&gt;Amomum longiligulare&lt;/i&gt; from Vietnam

This paper reports the chemical constituents and the antibacterial activity of essential oils from the leaves, rhizomes, and fruits of Amomum longiligulare T.L. Wu (Zingiberaceae) obtained by microwave-assisted hydrodistillation. The essential oils were analyzed by gas chromatography–mass spectrometry techniques. The minimum inhibitory concentration (MIC) values were measured by the broth microdilution assay. The oil yields of leaves, rhizomes and fruits from A. longiligulare were 0.23%, 0.27% and 1.93% (v/w), respectively, calculated on a dry weight basis. The leaf essential oil comprised mainly α-humulene (28.4%), α-pinene (24.9%), β-caryophyllene (17.3%), humulene epoxide II (7.3%), and β-pinene (4.7%). The major compounds of the rhizome essential oil were β-caryophyllene (28.7%), bicyclogermacrene (17.1%), humulene epoxide II (10.5%), camphene (7.9%), and α-pinene (5.7%). Camphor (40.7%) and bornyl acetate (34.2%) were the main constituents of the fruit oil. The essential oils demonstrated antimicrobial activities against Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Pseudomonas aeruginosa with the MIC values ranging from 200 to 400 μg/mL. In summary, the A. longiligulare essential oils are a source of promising antibacterial agents. This is the first report on the chemical composition and antibacterial activity of A. longiligulare essential oil obtained by microwave-assisted hydrodistillation.

Evaluation of Chemical Composition of Vaccaria oxyodontha Boiss Plant Essential Oils and Antioxidant and Antibacterial Effects on Gram-Negative and Gram-Positive Bacteria

Background &amp; Aims: Caryophyllaceae is a large family of about 2200 herbaceous or subshrub species. Vaccaria oxyodontha Boiss is of the family Caryophyllaceae. This plant grows as a weed in agricultural land of sugarcane, wheat, barley, forage, and summer crops such as sugar beet, potato, cotton, and onion. All parts of the V. oxyodontha Boiss plant, especially its root, contain a type of saponin, which shows its medicinal value. According to traditional Iranian medicine, this plant is a blood purifier and has anti-infective, utilized for cough, anti-rheumatism, and anti-inflammatory properties. This study first aimed to investigate the chemical composition of V. oxyodontha Boiss essential oil (EO) and the antioxidant and antibacterial properties of the hydroalcoholic extract of this plant on gram-positive and gram-negative bacteria. Materials and Methods: In this study, EOs were extracted from the aerial parts of V. oxyodontha Boiss using the combination of hydrodistillation and microwave-assisted hydrodistillation methods. Then, the antioxidant properties and antibacterial activity of the extract were evaluated, and the chemical compositions of the EOs of V. oxyodontha Boiss were determined using gas chromatography-mass spectroscopy (GC-MS). The extract’s antioxidant activity was studied by the 2,2-diphenyl-1- picrylhydrazyl-hydrate (DPPH) method. In addition, the plant antimicrobial effects were investigated by the agar disk diffusion method, and minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined as well. Finally, the antibacterial activity of the mentioned plant was compared with the antibiotic discs of gentamicin (10 mg) and vancomycin (30 mg). Results: The major compounds in the EOs were 2-Pentadecanone,6,10,14-trimethyl (10.52%) and 1,2-Benzenedicarboxylic acid (19.27%). Half maximal inhibitory concentration (IC50) of V. oxyodontha Boiss was 0.49 µg/mL, which was higher than that of vitamin C (IC50 value of 0.56 µg/mL). Further, MIC and MBC for the V. oxyodontha Boiss extract against Staphylococcus aureus and Escherichia coli were 62.5 and 125 mg/mL, as well as 31.25 and 62.5 mg/mL, respectively. Conclusion: The results of GC-MS demonstrated that the EO of the V. oxyodontha Boiss plant contains antioxidant and antibacterial compounds. Its antioxidant properties are higher than vitamin C. The highest diameter of the inhibition zone caused by the methanol extract of the V. oxyodontha Boiss plant was against S. aureus and E. coli (23.7±0.29 mm and 15.65±0.33 mm, respectively). Compared with the antibiotics vancomycin, the Vaccaria oxyodontha Boiss represented a stronger inhibitory effect in the inhibition of S. aureus (P&lt;0.05).