Optimization of microwave-assisted hydrodistillation for essential oil extraction from Cinnamomum tamala leaves: A comparative study of response surface methodology (RSM) and artificial neural network (ANN).

This study evaluates the chemical profile and antifungal efficacy of essential oils from Piper glabratum, Piper friedrichsthalii, and Piper cumanense against the cocoa pathogens Moniliophthora roreri and Phytophthora palmivora. Microwave-assisted hydrodistillation followed by GC-MS analysis identified 80 constituents, predominantly monoterpenes and sesquiterpenes, which exhibited significant mycelial inhibition comparable to commercial fungicides. Beyond basic characterization, a comprehensive chemoinformatic analysis was conducted to elucidate the molecular mechanisms driving this bioactivity. The computed physicochemical landscape reveals a dominant lipophilic profile (average LogP 3.4) and low polarity (TPSA 11.5 Å2), characteristics essential for effective fungal membrane penetration. Structural mining identified conserved benzene and cyclohexene scaffolds alongside specific 1,3-benzodioxole moieties, while Maximum Common Substructure (MCS) analysis uncovered high similarity clusters among phenylpropanoids and sesquiterpenes. These findings suggest a synergistic mode of action where conserved structural backbones and interchangeable diastereomers facilitate membrane destabilization and ion leakage. Consequently, the integrative chemoinformatic profiling elucidates the molecular basis of this efficacy, positioning these Piper essential oils not merely as empirical alternatives, but as sources of rationally defined synergistic scaffolds for next-generation sustainable fungicides.

Eucalyptus citriodora (lemon eucalyptus) is a medicinal plant commonly used as an antiseptic agent to prevent infection and promote healing. The aim of this exploration was to investigate for the first time the antibacterial mode of action of a gas chromatography-mass spectrometry chemically characterized E. citriodora essential oil (EO) obtained by microwave-assisted hydrodistillation. First, the chemical investigation revealed citronellal (30.67%) and citronellol (19.14%) as the major components. E. citriodora EO represented remarkable antibacterial properties, as demonstrated by significant zone of inhibition in the disc-diffusion test against all tested bacterial pathogens, including Listeria innocua ATCC 33090, L. monocytogenes ATCC 13932, Proteus mirabilis ATCC 25933, Salmonella typhimurium ATCC 700408, and Pseudomonas aeruginosa ATCC 27853. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values confirmed these findings showing antibacterial efficacy at low concentrations ranging 5.75-92 µg/mL for MICs and 11.5-184 µg/mL for MBCs. These results were comparable with gentamicin. The MICindex revealed that E. citriodora EO has bactericidal effects. We evaluated the antibacterial properties of E. citriodora EO and determined its mode of action using advanced tests with P. aeruginosa as a typical pathogen. The time-kill test revealed dose-dependent inhibitory effects on the cell proliferation of P. aeruginosa, affecting its membrane permeability based on the time and concentration of the EO. E. citriodora EO also caused damage to the cell membrane, resulting in leakage of cellular constituents, including RNA and DNA. Anti-quorum sensing activity was tested by inhibiting biofilm formation, showing that E. citriodora EO effectively inhibited biofilm formation. The UV-visible investigation on the release of cellular materials absorbed at 260 nm showed significant leakage of cytoplasmic substances, including proteins, DNA, and RNA, indicating devastation to bacterial cell membrane integrity. In addition, the use of E. citriodora EO significantly inhibited P. aeruginosa adhesion on 304 L stainless-steel surface, making it more suitable for applications requiring better wetting ability and surface interactions, particularly in food production. [Figure: see text].

Utilization of Pinus pumila seed scales as forestry residues: Green microwave-assisted hydrodistillation for essential oil extraction and its antibacterial activity.

Process optimization of microwave-assisted hydrodistillation for Andaliman (Zanthoxylum acanthopodium DC.) extraction: Investigating solvent volume, power, and time effects on yield

This study evaluated the efficacy of an environmentally friendly degreasing agent formulated from orange peel extract as both a cleaning agent and corrosion inhibitor for surgical instruments manufactured from 316LVM stainless steel. The extract was obtained via microwave-assisted hydrodistillation and subsequently blended with biodegradable surfactants. Its performance was compared against a benchmark commercial cleaner (West Oxyclean®) through Tafel polarization, Electrochemical Impedance Spectroscopy (EIS), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and X-Ray Diffraction (XRD). FTIR analysis confirmed the presence of terpenic compounds, predominantly limonene, alongside ethers, alcohols, and unsaturated structure characteristics of citrus essential oils. Polarization and EIS results showed that the formulation containing 0.12% extract exhibited the highest charge-transfer resistance and the lowest corrosion current density (0.093 μA/cm2), achieving an inhibition efficiency of 81.29%, whereas the 0.08% formulation showed greater corrosive response than the commercial cleaner. SEM imaging demonstrated a progressive decline in both the severity and density of localized corrosion attacks with increasing extract concentration, while XRD diffractograms indicated a marked reduction in corrosion-product formation—completely absent at the optimal concentration. These findings demonstrate that orange peel extract functions as an effective and environmentally sustainable corrosion inhibitor, capable of preserving the structural and surface integrity of surgical-grade steel. Its technical performance, combined with its biodegradable profile, positions it as a promising alternative to conventional industrial cleaners within medical and hospital applications.

Background: The processing of kinnow (Citrus reticulata) juice generates 30–34% peel waste, which is loaded in bioactive compounds like phenolics, limonin, and pectin. This study examined the antibacterial efficacy and storage stability of essential oil (EO) derived from kinnow peel, emphasizing its prospective use in the food, pharmaceutical, and cosmetic sectors. Methods: Kinnow peels were collected from juice venders of Hisar and Sirsa between December 2022 and January 2023. EO was extracted using four methods: Hydrodistillation (HD), Microwave Assisted Hydrodistillation (MAHD), Ultrasonic Assisted Hydrodistillation (UAHD), and Ohmic Heating Assisted Hydrodistillation (OHHD). The antimicrobial activity was assessed by the well diffusion technique against established bacterial and fungus strains. For the storage study, oils were kept in amber-colored bottles at refrigerator and freezer temperatures for 12 months. Fresh and stored oils were characterized using FTIR and GC-MS analysis. Data were evaluated utilizing ANOVA in SPSS 25.0, with statistical significance established at p<0.05. Results: The EO extracted from kinnow peel exhibited the strongest antimicrobial activity against Staphylococcus aureus, followed by Pseudomonas aeruginosa. It also exhibits antifungal effects against Aspergillus niger and Candida albicans. FTIR and GC-MS analyses confirmed limonene as the dominant compound. The highest concentrations were found in freshly extracted samples: HD (92.04%), MAHD (85.19%), UAHD (86.09%), and OHHD (85.12%). After 12 months of storage, the limonene content decreased slightly but remained more stable at –10°C: HD (88.11%), MAHD (84.23%), UAHD (85.24%), and OHHD (84.48%), compared to storage at 4°C: HD (87.06%), MAHD (85.61%), UAHD (84.90%), and OHHD (84.12%). Conclusion: The EO shown greater efficacy against gram-positive bacteria compared to gram-negative pathogens. Prolonged storage led to a reduction in low-molecular-weight compounds, with better retention observed at lower temperatures. These findings suggest that kinnow peel EO holds promise for applications in food preservation and natural antimicrobial formulations.

Background: This study aimed to optimize the conditions of microwave assisted hydro distillation (MAHD) for maximizing the essential oil yield and DPPH radical scavenging activity from Alpinia blepharocalyx K. Schum. leaves. Methods: Using the central composite design (CCD) of response surface methodology (RSM) with factors that affect the yield of essential oil and DPPH obtained: Microwave power (W), liquid-to-material ratio (mL/g) and extraction time (min). Result: The optimal extraction conditions determined by the RSM model were a microwave power of 600 W, a liquid-to-material ratio of 7.0:1 mL/g and an extraction time of 45 min. Under these conditions, the experimental essential oil yield was 3.35±0.02% and the DPPH antioxidant activity was 87.05±0.05%. The chemical composition of the essential oil was also characterized by gas chromatography-mass spectrometry (GC-MS), revealing β-Pinen, 1,8-Cineol and α-Pinen as the major compounds.

This study presents an innovative design of a reactor vessel for Microwave-Assisted Hydro Distillation (MAHD), optimized for household-scale essential oil production. MAHD, as an energy-efficient alternative to conventional distillation methods, was applied through a newly designed reactor that emphasizes heat transfer optimization and energy efficiency. The reactor was constructed from stainless steel 304 with a capacity of 30–50 liters, integrated with a microwave heating system (500–2000 W), and equipped with a copper pipe condenser. Experimental results demonstrated an increase in essential oil yield of up to 30% compared to conventional hydrodistillation, with extraction times significantly reduced (reaching 100 °C in less than 15 minutes at 1000 W). Further analysis identified optimal operating conditions at 450 W with a feed-to-solvent (F/S) ratio of 0.35 g/mL. This design provides a significant solution for enhancing the efficiency of essential oil production in household industries, with potential implications for reducing energy consumption and improving product quality.

The objective of this study was to optimize the extraction of essential oil from Baeckea frutescens leaves using microwave-assisted hydro-distillation (MAHD) combined with response surface methodology (RSM). This approach aimed to improve extraction efficiency and maximize essential oil yield. The chemical composition of the extracted oil was subsequently analyzed using gas chromatography-mass spectrometry (GC-MS) to identify its principal constituents. The optimal extraction conditions were determined to be a microwave power of 550 W, an extraction time of 89 min and a liquid-to-material ratio of 9.5:1. Under these conditions, the essential oil yield was 3.96 ± 0.02 % (w/w), which represents a high extraction efficiency. GC-MS analysis revealed that the major constituents of the essential oil were α-thujene (26.81 %), α-humulene (15.35 %), trans-caryophyllene (12.29 %) and 3-carene (10.20 %). In addition, biological activity assays indicated that the essential oil exhibited notable antibacterial and antioxidant activities. It significantly inhibited the growth of Escherichia coli and Salmonella typhi, with minimum inhibitory concentrations (MICs) below 100 µg/mL. These findings suggest that Baeckea frutescens essential oil has strong potential as a natural antimicrobial and antioxidant agent, supporting its application in pharmaceutical and industrial products.

Microwave-assisted hydro-distillation (MAHD) and hydro-distillation (HD) were performed for the analysis of volatile constituents in the aerial parts of both Chiliadenus montanus (Vahl.) Brullo and Chiliadenus candicans (Delile) Brullo. Aerial parts were distilled using a microwave oven modified to fit a Clevenger apparatus. The study examines how different levels of microwave energy (400, 600, and 800 watts) affect the amount and composition of the essential oil extracted, compared to traditional hydro-distillation methods. Essential oils of all samples were analyzed by gas chromatography-mass spectrometry (GC-MS). For C. montanus, 43, 38, 39 and 38 compounds were identified by HD and MAHD at 400, 600, 800 watts, respectively. For C. candicans, 40, 41, 35 and 36 compounds were identified by HD and MAE at 400, 600, 800 watts, respectively. Oxygenated sesquiterpenes were the predominant class in both the species by both extraction techniques. endo-Borneol followed by γ-eudesmol were the major constituents identified in C. montanus, whereas intermedeol and τ-cadinol represent the major constituents in C. candicans. The antimicrobial properties of essential oils obtained through HD and MAHD were tested against ten different pathogens. The hydro-distilled oil of both plants showed higher activity than the microwave obtained oil at 400, 600, 800 watts against all the test pathogens. In addition, the antimicrobial activity was more potent against Gram positive bacteria (80-1250 µg/mL) than Gram negative bacteria (80-2500 µg/mL), while it was less potent against fungi.

Essential oils from citrus peels, particularly Citrus jambhiri (Jungga orange), are gaining attention for their anticancer properties due to the presence of monoterpenes like D-limonene, γ-terpinene, and β-pinene. Despite its bioactive profile, CEO remains underexplored. This study evaluates the anticancer activity of Citrus jambhiri essential oil (CEO) using GC-MS profiling, network pharmacology, and in vitro testing on T47D breast cancer cells. CEO was extracted via microwave-assisted hydrodistillation, and its constituents were identified through GC-MS. Target genes were predicted using SwissTargetPrediction, PubChem, and CTD, while breast cancer-associated genes were retrieved from GeneCards and Open Targets. Protein-protein interaction and hub genes were analysed using STRING and Cytoscape, with pathway enrichment assessed using DAVID and ShinyGO. Bioactivity was evaluated via MTT, Annexin V/PI, cell cycle, ROS, and protein expression assays targeting PI3K/Akt/mTOR and BTK pathways. CEO was found to be rich in hydrocarbon monoterpenes, mainly D-limonene (35.68%), γ-terpinene (16.14%), and β-pinene (11.84%). Network pharmacology revealed 406 overlapping targets enriched in PI3K/Akt/mTOR and BTK signalling. Key hub genes included AKT1, EGFR, BTK, and TP53. CEO exhibited moderate cytotoxicity (IC50 = 68 µg/mL) with high selectivity (SI = 4.67) compared to doxorubicin. Cell-cycle analysis showed S-phase arrest and sub-G1 elevation, while Annexin V/PI confirmed apoptotic activity with minimal necrosis. ROS levels remained unchanged, and CEO significantly downregulated PI3K, mTOR, and BTK, sparing Akt. CEO demonstrates selective anticancer activity through S-phase arrest, non-oxidative apoptosis, and inhibition of PI3K/mTOR-BTK signalling in T47D cells, suggesting its promise as an adjuvant in breast cancer therapy alongside conventional drugs such as doxorubicin. HIGHLIGHTS GC-MS profiling revealed that Citrus jambhiri essential oil is rich in hydrocarbon monoterpenes, particularlys D-limonene, γ-terpinene, and β-pinene. Network pharmacology identified 406 gene targets associated with PI3K/Akt/mTOR and BTK signalling pathways. In vitro assays on T47D breast cancer cells showed Citrus jambhiri essential oil induces S-phase cell cycle arrest and apoptosis without elevating ROS levels. Protein expression analysis confirmed significant downregulation of PI3K, mTOR, and BTK, while Akt expression was spared. Citrus jambhiri essential oil exhibits selective, ROS-neutral anticancer activity and shows promise as an adjuvant agent in breast cancer therapy. GRAPHICAL ABSTRACT

Rhodomyrtus tomentosa (Aiton) Hassk. has been widely used in traditional medicine; however, limited attention has been paid to its essential oil's chemical profile and biological activities. In this study, essential oil was extracted from fresh leaves of R. tomentosa using microwave-assisted hydrodistillation. The oil yield was 0.72% (v/w), and gas chromatography-mass spectrometry (GC-MS) analysis revealed a composition highly enriched in monoterpene hydrocarbons, with α-pinene comprising approximately 79.73% of the total content. Minor constituents included β-caryophyllene, α-terpineol, and d-limonene. The cytotoxic potential of R. tomentosa essential oil (RtEO) was evaluated against three human cancer cell lines: breast adenocarcinoma (MCF-7), epidermoid carcinoma (KB), and lung carcinoma (A549) using the WST-1 assay. RtEO exhibited significant dose-dependent cytotoxicity, with IC50 values of 14.30 µg/mL, 19.91 µg/mL, and 20.63 µg/mL, respectively. These results suggest that RtEO possesses promising broad-spectrum anticancer activity, warranting further investigation as a potential natural source of bioactive compounds for cancer therapy.

Natural deep eutectic solvents (NADESs) are emerging green solvents widely applied to improve the extraction of essential oil (EO) through plant tissue pretreatment. Various NADESs, formulated from polyalcohols, sugars, and organic acids, were employed as pretreatment solvents prior to microwave-assisted hydrodistillation (MAHD) to facilitate plant cell wall breakdown and improve the efficiency of EO extraction. The findings revealed that the most effective pretreatment conditions for enhancing EO extraction involved using a NADES composed of choline chloride and glycerol (in a 1:2 molar ratio), applied to fennel seed powder at a solid-to-NADES ratio of 1:6 g/mL. Optimal performance was achieved with 20% water content in the NADES, microwave irradiation at 400 W for 6 min, followed by 96 min of MAHD. Under these conditions, the NADESs-based MAHD achieved the highest EO yield, increasing it from 1.33% with water-based MAHD to 2.70%. Fennel EO demonstrated the strongest antimicrobial activity against S. pyogenes and C. albicans., while the EO obtained from NADES-MAHD using Ch:Gly (1:2) showed the highest antioxidant activity, with 72.41% inhibition. Finally, GC-MS phytochemical analysis of the extracted EOs revealed anethole as the major compound. Notably, the application of NADES, particularly Ch:Gly (1:2), enhanced the relative content of monoterpene hydrocarbons. These findings highlight the superior effectiveness of deep eutectic solvents during the pretreatment stage in enhancing EO production.

This paper reflects the effect of grinding lavender (Lavandula angustifolia Mill.) flowers cultivated in Serbia for obtaining essential oil (LEO) by intensified microwave-assisted hydrodistillation (MWHD) and conventional hydrodistillation (HD). The LEO yield, chemical composition, and antimicrobial activity were greatly affected by incorporating the grinding pre-treatment. LEO isolated by MWHD from disintegrated and non-disintegrated plant material (oil yield 6.4502±0.02% and 5.9325±0.01%, respectively) was composed of 11 and 17 volatile components, respectively. On the other hand, LEO isolated by HD from disintegrated and non-disintegrated plant material (oil yield 5.7±0.1% and 5.1±0.1%, respectively) contained 29 and 51 compounds, respectively. Independent of extraction technique, the major constituents of LEOs were oxygenated monoterpenes, followed by oxygenated sesquiterpenes and sesquiterpene hydrocarbons. MWHD-provided LEOs were more potent antimicrobial agents than the HD-provided LEOs; the most sensitive microorganisms were B. subtilis and C. albicans. The suggested combination of grinding and intensified MWHD is promising approach for producing potent antimicrobial LEO with the potential to be used in different industries.

The aim of this study was to identify the most suitable extraction methods for isolating essential oils and polyphenols from Ammodaucus leucotrichus. Essential oils were extracted using hydrodistillation (HD), microwave-assisted HD (MW-HD) and microwave-assisted steam distillation (MW-SD), while polyphenols were obtained via maceration (MAC), Soxhlet (SOX), ultrasonic extraction (ULTR), and microwave-assisted extraction (MW). HD yielded the highest amount of essential oil (1.95%), and GC/MS analysis revealed that perillaldehyde (56.80%-62.67%) and limonene (22.04%-62.50%) are the most abundant compounds in the essential oils obtained through all techniques. Although the microwave-assisted methods (MW-HD and MW-SD) resulted slightly lower yields, but they offer substantial advantages in terms of reduced extraction time, lower energy consumption, and preservation of essential oil quality. For polyphenol extraction, MW and ULTR techniques produced the richest extracts, with a concentration of 624.11mg EAG/g at 917.73mg EAG/g. LC/MS analysis of the polyphenol extracts revealed several bioactive compounds identified for the first time, including taxifolin (2.24-12.90mg/g), rutin (10.25mg/g), isorhamnetin (12.82-43.33mg/g), and 3-hydroxyflavone (0.85-5.21mg/g). DPPH radical scavenging assays revealed the high potent radical-scavenging activity of extracts, highlighting the potential of A. leucotrichus as a promising natural source of bioantioxidant.

This study aimed to develop food-grade microemulsions of laurel essential oil (L-EO) (MEs) stabilized with amylopectin (L-AP) and gum arabic (L-GA) and to determine characteristic properties of the MEs at different pH and temperatures during storage. L-EO was extracted using the microwave-assisted hydrodistillation technique. The prepared ME droplets ranged in size range from 328 to 347nm in L-AP (pH 6.0) and from 327 to 432nm in L-GA (pH 3.0). The total phenolic content and antioxidant capacity were 170.60mg/L gallic acid equivalent (GAE) and 0.93mM Trolox/mL in L-AP, respectively, while total phenolic content was 243.10mg/L GAE and antioxidant capacity was 1.19mM Trolox/mL in L-GA. Additionally, the MEs demonstrated relatively potent antimicrobial activity against Escherichia coli, Bacillus cereus, and Staphylococcus aureus strains. The main volatile compounds of L-EO were identified as 1,8-cineole (33.4%), sabinene (8.4%), and linalool L (6.6%).

Influence of extraction techniques on chemical composition, antioxidant and antifungal activities of Mentha spicata L. essential oil: A comparative study of microwave-assisted hydrodistillation and steam distillation

Leucaena leucocephala is known as ‘Petai Belalang’ in Malaysia and can be identified by its intermediate leaflets and large pods. The leaflets can be up to 16 mm long and 4.5 mm wide, while the pods occur in a crowded cluster of 5-20 pods per flower head and with 8-18 seeds per pod. Much literature has been published on the medical benefits of L. leucocephala, which exhibits antidiabetic and anti-inflammatory activities. Phytochemical compounds have received considerable attention because of their unique and vast spectrum of biological activities. The extraction of phytochemicals from L. leucocephala was carried out using microwave-assisted hydrodistillation (MAHD) at varying temperatures ranging from 30 °C to 70 °C at 10 °C intervals. The compounds extracted were then identified using gas chromatography-mass spectroscopy (GC-MS). Several bioactive compounds, including glycosides, phenols, terpenoids, and alkaloids, were identified, with glycosides predominantly present in the pods and seeds of L. leucocephala. The highest concentration of these compounds was identified at an extraction temperature of 50 °C, as determined by the peak area in the GC-MS chromatogram. The findings revealed that glycosides were the most abundant phytochemicals present in L. leucocephala, while other compounds, including phenolic acids, steroids, and terpenoids, were identified in lower amounts. In addition, most of the identified compounds exhibited antidiabetic, anti-inflammatory, antioxidant, antibacterial, and antifungal properties, while some compounds also demonstrated therapeutic potential against cancer. Among these compounds, 4-C-methyl- myo-inositol was present in significant quantities and potentially demonstrated both antidiabetic and anti-inflammatory agents. These results indicate that L. leucocephala holds significant promise as a medicinal plant due to its diverse pharmacological activities.

Optimization of Extraction of Volatile Compounds from Cinnamomum camphora (L.) J. S. Presl Leaves Using Microwave-Assisted Hydro-Distillation Method