Menthol Content Research Articles

Insecticidal activity of the Mentha arvensis L. essential oil on stored grain pest Callosobruchus maculatus F.

Stored grain insect pests are becoming the foremost threat for reducing nutritional quality and quantity of grains in the storages worldwide. The pulse beetle, Callosobruchus maculatus F. is one the most serious post-harvest pest threat to stored legumes in tropical and subtropical regions. Today, for their control using eco-friendly and sustainable methods over the traditional chemical control are very crucial. In our study, an attempt was made to find the potency of the essential oil by two physical methods to control the beetle by using a common pulse grain – Vigna radiata L. (green gram). The repellency, fumigant and contact toxicity of the essential oil extracted from Mentha arvensis L. were checked by direct and indirect methods. Indirect method showed better results as the oil had prevented the pest from feeding on the grains. The Mentha arvensis essential oil was further screened for its chemical constituents by the technique of Gas Chromatography. The essential oil had high content of Menthol along with other constituents such as l-Menthone, Isomenthone, Menthol acetate, D-Limonene. Menthol which could all be responsible for the essential oil’s significant insecticidal property against Callosobruchus maculatus.

A Method to Amend Cigarettes With Menthol for Use in Research.

Studies have evaluated the role of menthol cigarettes on various addiction-related outcomes; however, the effect of varying menthol content on these outcomes has not been evaluated. We developed a method to amend non-menthol SPECTRUM Research Cigarettes to contain menthol at four different levels. SPECTRUM Research Cigarettes, NRC 600 (0.8 mg nicotine; 10 mg tar), were modified to contain target menthol amounts at 3, 6, and 12 mg/cigarette by injecting 25 µL ethanol/triacetin/menthol solutions of varying concentrations (120 mg menthol/mL, 240 mg/mL, and 480 mg/mL) into four distinct locations in the filter and tobacco rod. Menthol content was tested in triplicate in the whole cigarette and in the tobacco rod and filter at 1, 24, 48, and 72 hours for each target menthol level using an extraction solution of quinoline in methyl-tert-butyl ether and measured using gas chromatography with flame ionization detection. Injections into the filter and tobacco rod (12.5 µL each) yielded equal menthol distribution up to 72 hours. However, total menthol content decreased from an average of 90.3% of the target menthol concentration at 1 hour to 80.7% at 72 hours in cigarettes stored individually in glass tubes at room temperature. Analysis of urinary menthol glucuronide confirmed that amended cigarettes used within 24 hours of injection delivered dose-related menthol levels to participants in a clinical laboratory setting. This method can be used to modify cigarettes with a range of reliable menthol levels in both filter and tobacco rod for use in laboratory and clinical research. This study presents a technique for modifying cigarettes with different levels of menthol that can reliably deliver dose-related menthol levels to participants when smoked in a clinical study. The technique can be used to quickly amend cigarettes to examine the independent effects of varying flavor and additive levels on smoking behavior, nicotine pharmacokinetics, mainstream smoke emissions, and other laboratory or clinical research outcomes.

Light spectra of biophilic LED-sourced system modify essential oils composition and plant morphology of Mentha piperita L. and Ocimum basilicum L.

Investigating morphological and molecular mechanisms that plants adopt in response to artificial biophilic lighting is crucial for implementing biophilic approaches in indoor environments. Also, studying the essential oils (EOs) composition in aromatic plants can help unveil the light influence on plant metabolism and open new investigative routes devoted to producing valuable molecules for human health and commercial applications. We assessed the growth performance and the EOs composition of Mentha x piperita and Ocimum basilicum grown under an innovative artificial biophilic lighting system (CoeLux®), that enables the simulation of natural sunlight with a realistic sun perception, and compared it to high-pressure sodium lamps (control) We found that plants grown under the CoeLux® light type experienced a general suppression of both above and belowground biomass, a high leaf area, and a lower leaf thickness, which might be related to the shade avoidance syndrome. The secondary metabolites composition in the plants' essential oils was scarcely affected by both light intensity and spectral composition of the CoeLux® light type, as similarities above 80% were observed with respect to the control light treatments and within both plant species. The major differences were detected with respect to the EOs extracted from plants grown under natural sunlight (52% similarity in M. piperita and 75% in O. basilicum). Overall, it can be speculated that the growth of these two aromatic plants under the CoeLux® lighting systems is a feasible strategy to improve biophilic approaches in closed environments that include both plants and artificial sunlight. Among the two plant species analyzed, O. basilicum showed an overall better performance in terms of both morphological traits and essential oil composition. To increase biomass production and enhance the EOs quality (e.g., higher menthol concentrations), further studies should focus on technical solutions to raise the light intensity irradiating plants during their growth under the CoeLux® lighting systems.

Standardization of post-harvest practices for best quality essential oil production of Mentha arvensis L.

Mentha species belongs to Lamiaceae family is an important industrial crop, cultivated commercially on large scale. In this study, a common cultivar of M. arvensis with a high essential oil content (Cim Kranti) was investigated to determine the impact of drying techniques for 10 days immediately following harvest on the essential oil content and its chemical profile under three conditions: open field (S1), shade (S2), and ventilated chamber (S3). According to results, significantly higher essential oil (0.723%) with 77.58 % of menthol content was observed in freshly harvested crop on same /1st day of harvest (T1) than any other conditions. M. arvensis was harvested and drying in open field condition (S1) has showed 0.68% of essential oil having rich amount of menthol (76.86 % ) content on fresh sample (T1) which decline to 0.51% essential oil content with menthol content 76.88% at 10th days after harvest. M. arvensis dying in ventilated room (S3) showed essential oil (0.71%) and menthol content 76.58 % on same day of harvest, which later decreases upto 0.6% essential oil with menthol content 74.32% on 10th day after harvest. Results concluded that the best quality and high yield of essential oil of M. arvensis should willingly be distilled fresh just after harvest. It also indicates that postharvest processes should immediately followed harvesting with appropriate drying method to minimize the loss of high quality essential oil.

Optimizing Antioxidant Activity and Phytochemical Properties of Peppermint (Mentha piperita L.) by Integrative Application of Biofertilizer and Stress-Modulating Nanoparticles under Drought Stress Conditions

Drought stress (DS) negatively affects plant growth, productivity, and quality in semi-arid and arid regions. Nowadays, application of biofertilizers and stress-modulating nanoparticles (NPs) improves plant performance under stressful conditions. The study evaluated the impacts of arbuscular mycorrhizal fungi (Myco-Root) and TiO2 NPs on the nutrient uptake, dry yield, essential oil (EO) productivity, and EO quality of peppermint (Mentha piperita L.) under different irrigation regimes. The treatments included three irrigation regimes containing irrigation after 20% (I20, well-watered), 40% (I40, mild DS), and 60% (I60, severe DS) maximum allowable depletion (MAD) percentage of the soil's available water as well as four fertilizer sources contain no fertilization (control), Myco-Root biofertilizer, TiO2 NPs, and an integrative application of Myco-Root + TiO2 NPs. The results demonstrated that the highest (195.72 g m-2) and the lowest dry yield (78.76 g m-2) of peppermint was obtained in well-watered conditions with integrative application of Myco-Root + TiO2 NPs and severe drought stress (I60) without fertilization, respectively. The dry yield of peppermint was reduced by 27.7 and 53.4% in mild (I40) and severe drought stress (I60), respectively. The maximum EO content (1.49%) and EO yield (2.30 g m-2) was recorded in mild drought stress (I40) treated with Myco-Root + TiO2 NPs. Based on the GC-MS and GC-FID analysis, 29 constituents were identified in peppermint EO, with the major constituents being menthol (38.99-52%), menthone (12.72-20.13%), 1,8-cineole (6.55-7.84%), and neo-menthol (3.14-4.52%), respectively. The maximum content of menthol, 1,8-cineole, and neo-menthol was obtained under mild drought stress (I40) fertilized with Myco-Root + TiO2 NPs. The results indicate that the integrative application of Myco-Root + TiO2 NPs could be used as an alternative method of using chemical fertilizers in sustainable agricultural systems for improving the EO quantity and quality of peppermint grown under drought stress conditions.

Molecular dynamics analysis of a flavoring drum combining numerical simulation and experimental evaluation

The tobacco flavoring process is an important procedure in production stage. During the flavoring process, the cut tobacco is endowed with a unique flavor to stabilize the production quality. Most of the flavoring process in tobacco enterprises is finished in the drum, and the internal structure of the drum (including the number, angle and installation position of the baffle plate) will affect the flavoring effect and efficiency. Therefore, this paper studied the particle behavior of the cut tobacco in the drum based on molecular dynamics analysis to explore the influence of the drum structure on the flavoring effect and to find the optimal structure parameters. Based on the discrete element simulation, an original rotary drum is structurally modified twice, and the corresponding field test is carried out to evaluate the performance of the modified drum. The results suggest that the flavoring effect is significantly improved through the structural modification, the content of menthol and citronellol are increased by 24.70% and 23.74% in the first test after modification, and reached 83.2% and 85.4% of the theoretical value respectively, and the error of the running time in the drum between the simulation and the test result is only 6.3%

Effects of Green Manures (in the Form of Monoculture and Intercropping), Biofertilizer and Organic Manure on the Productivity and Phytochemical Properties of Peppermint (Mentha piperita L.).

Nowadays, the application of sustainable and eco-friendly fertilizers plays an important role in improving the essential oil (EO) quantity and quality of medicinal and aromatic plants. Hence, the study aimed to investigate the effects of green manures, organic manures and biofertilizers on the nutrient content, dry matter yield, EO productivity and quality of peppermint. The treatments included green manures [barley monoculture (Bm), hairy vetch monoculture (HVm) and replacement intercropping of 75%HV + 25%B, 50%HV + 50%B and 25%HV + 75%B], arbuscular mycorrhizal fungi (AMF) and vermicompost (VC). A 50%HV + 50%B green manure appears to be the most effective treatment, since it provides the greatest amount of nutrients (N and K, 18.8 g kg-1, and 18.1 g kg-1, respectively), the tallest plants (61.5 cm), the most nodes per plant (17.5), the lateral branches (24.4), the highest leaf greenness index (45.5) and dry yield (266.7 g m-2) in peppermint. Moreover, this treatment evidenced the larger EO content (1.8%) and EO yield (4.84 g m-2). Regardless of the treatments, the chemical composition of peppermint EO was characterized by menthol (32.35-37.73%), menthone (16.96-20.64%) and 1,8-cineole (6.18-7.78%). The maximum content of menthol and 1,8-cineole was obtained by the application of 50%HV + 50%B. Additionally, the highest content of menthone was observed in AMF treatment. These results indicate that the application of 50%HV + 50%B green manures could be suggested as an environmentally friendly strategy for improving EO quantity and quality of peppermint.

Botanical discrimination and classification of Mentha plants applying two-chiral column tandem GC–MS analysis of eight menthol enantiomers

The concentration and distribution of menthol enantiomers have great significance in discriminating natural mint varieties and evaluating the origin of foodstuffs containing menthol additives. However, the chiral separation of eight chiral menthol enantiomers in Mentha plants offers an easy approach to eliminating or reducing the identification technology problem. The application of derivatized β-cyclodextrin capillary chiral column coupled with derivatized γ-cyclodextrin capillary chiral column, and gas chromatography–mass spectrometry (GC–MS) technology, to isolate and analyze eight chiral menthol enantiomers in 23 natural Mentha plants was investigated. The results showed that the two-chiral columns tandem technology enabled the baseline separation of the eight menthol enantiomers. Four different menthol compounds were only detected in seven out of the 23 natural mint plants. (1R,3R,4S)-(−)-menthol and (1R,3S,4S)-(+)-neomenthol were detected in the seven mint plant samples, while (1S,3S,4R)-(+)-menthol and (1S,3R,4R)-(−)-neomenthol could not be detected in the seven mint plant samples. For the two enantiomer couples of (+/−)-isomenthol and (+/−)-neoisomenthol, only (+)-isomers were detected in field mint, candy mint, and peppermint. The Mentha plant samples were distinguished and identified by principal component analysis and radar chart statistical analysis based on the data of the menthol content and isomer ratio. Furthermore, the presence or absence of (1S,3S,4R)-(+)-menthol in the samples can be used as an identification factor for discriminating between synthetic menthol and natural sources of menthol.

Efficacy and safety of a food supplement with standardized menthol, limonene, and gingerol content in patients with irritable bowel syndrome: A double-blind, randomized, placebo-controlled trial.

BackgroundIrritable bowel syndrome (IBS) affects 9,2% of the global population and places a considerable burden on healthcare systems. Most medications for treating IBS, including spasmolytics, laxatives, and antidiarrheals, have low efficacy. Effective and safe therapeutic treatments have yet to be developed for IBS.PurposeThis study assessed the efficacy and safety of a food supplement containing standardized menthol, limonene, and gingerol in human participants with IBS or IBS/functional dyspepsia (FD).DesignA double-blind, randomized, placebo-controlled trial.MethodsWe randomly assigned 56 patients with IBS or IBS/FD to an intervention group (Group 1) or control group (Group 2) that were given supplement or placebo, respectively, in addition to the standard treatment regimen for 30 d. Three outpatient visits were conducted during the study. Symptom severity was measured at each visit using a 7×7 questionnaire. Qualitative and quantitative composition of the intestinal microbiota were assessed at visits 1 and 3 based on 16S rRNA gene sequencing.ResultsAt visit 1 (before treatment), the median total 7×7 questionnaire score was in the moderately ill range for both groups, with no difference between the groups (p = 0.1). At visit 2, the total 7×7 score decreased to mildly ill, with no difference between the groups (p = 0.4). At visit 3, the total score for group 1 indicated borderline illness and for group 2 remained indicated mild illness (p = 0.009). Even though we observed some variations in gut microbiota between the groups, we did not find any statistically significant changes.ConclusionThe food supplement with standardized menthol, limonene, and gingerol content increased the efficacy of standard therapy in IBS and FD patients. The use of the supplement did not cause any obvious side effects.RegistrationClinicalTrials.gov Identifier: NCT04484467

Synthetic Cooling Agents in US-marketed E-cigarette Refill Liquids and Popular Disposable E-cigarettes: Chemical Analysis and Risk Assessment.

Menthol, through its cooling and pleasant sensory effects, facilitates smoking and tobacco product initiation, resulting in the high popularity of mint/menthol-flavored E-cigarettes. More recently, E-cigarette vendors started marketing synthetic cooling agents as additives that impart a cooling effect but lack a characteristic minty odor. Knowledge about content of synthetic coolants in US-marketed E-cigarette products and associated health risks is limited. E-liquid vendor sites were searched with the terms "koolada", "kool/cool", "ice", or WS-3/WS-23, denoting individual cooling agents, and relevant refill E-liquids were purchased. "Ice" flavor varieties of Puffbar, the most popular disposable E-cigarette brand, were compared with non-"Ice" varieties. E-liquids were characterized, and synthetic coolants quantified using GC/MS. Margin of exposure (MOE), a risk assessment parameter, was calculated to assess the risk associated with synthetic coolant exposure from E-cigarette use. WS-3 was detected in 24/25 refill E-liquids analyzed. All Puffbar flavor varieties contained either WS-23 (13/14) or WS-3 (5/14), in both "Ice"- and non-"Ice" flavors. Modeling consumption of WS-3 from vaped E-liquids, resulted in MOEs below the safe margin of 100 for most daily use scenarios. MOEs for WS-23 were <100 for 10/13 Puffbar flavors in all use scenarios. Puffbar power specifications are identical to Juul devices. Synthetic cooling agents (WS-3/WS-23) were present in US-marketed E-cigarettes, at levels that may result in consumer exposures exceeding safety thresholds set by regulatory agencies. Synthetic coolants are not only found in mint- or menthol-flavored products but also in fruit- and candy-flavored products, including popular disposable E-cigarette products such as Puffbar. Synthetic cooling agents are widely used in "kool/cool"- and "ice"-flavored E-liquids and in E-liquids without these labels, both as a potential replacement for menthol or to add cooling "notes" to nonmenthol flavors. These agents may be used to bypass current and future regulatory limits on menthol content in tobacco products, and not just E-cigarettes. Because synthetic cooling agents are odorless, they may not fall under the category of "characterizing flavor", potentially circumventing regulatory measures based on this concept. Regulators need to consider the additional health risks associated with exposure to synthetic cooling agents.

Constraints analysis of mint plant (Mentha spp.) growers in central Avadh region (Barabanki) of Uttar Pradesh

India is the largest cultivator of mint plant and market leader in mentha oil production. Uttar Pradesh occupies major area under mint cultivation as well as highest mentha oil producer among all the states of India. Present study was conducted in central avadh region, under this region Barabanki district accounts 90-95 per cent area under mentha cultivation and mentha oil production. Research study is fully based on primary data which was collected with the help of well-organized structured schedule for the agricultural year. Major constraints related with mint production faced by mint growers were unstable yield of mentha, lower productivity of mentha, high cost of mentha roots/suckers, less supply of farm yard manure, high labor cost, labour scarcity during peak time, high cost of fertilizer, high incidence of disease, distance from input supply center, poor quality of irrigation water, inadequate credit supply, less supply of recommended pesticide, high cost of growth regulators, erratic electricity supply. Marketing related constraints were frequent price fluctuation, collusion among traders/trade and malpractices, lack of MSP/government procurement, non-availability of storage facility, lack of market infrastructure, lack of availability of market information, lack of awareness of direct marketing practices, lack of information about government schemes and subsidies, quality deterioration during storage, poor road network for transportation, delay in sale and payment, distance from market, high transportation cost. Problems faced by farmers related to processing infrastructure were lack of technology related to distillation unit, lack of testing facility of menthol content in oil, lack of training related to package of practices, lack of regulated market, high costing in distillation machine, cost related to processing incurred by farmer, lack of small processing units. Existing constraints related to trade and export policy faced by farmers were illegal trade practices, unauthorized traders, unaware about export market, government subsidies.

Yield and oil composition of peppermint cultivars grown in the Isparta climate of Turkey

Peppermint, Mentha piperita L. belonging to the Lamiaceae family, contains a valuable essential oil known for its high menthol and menthone content. During the vegetation seasons of 2016 and 2017, field studies were conducted in Turkey?s Isparta climate by using randomized blocks to examine the yield and oil composition of the new peppermint cultivars. In these studies, Multimentha produced the highest herb yield even though the quality of its essential oil is relatively poor due to its low menthol content. Yield levels of other cultivars were similar to each other with the same statistical group. In the study, Citaro, Tokat CL-8, and Chocolate varieties had high menthol contents and were within the same chemical group. Varieties reacted differently to years and harvesting seasons, including summer and autumn. The menthol content of Citaro and Tokat CL-8 cultivars was higher in the fall harvest compared to the summer harvest. On the other hand, the menthol content of the Chocolate cultivar remained stable throughout the seasons. The study has revealed that the yields of the varieties with high menthol are low, and the oils obtained from all these varieties except Multimentha conform to the European pharmacopoeia.

Enhanced stability and controlled release of menthol using a β-cyclodextrin metal-organic framework

Menthol inclusion complexes (ICs) have addressed a range of opportunities in food applications due to their volatile resistance. However, previous protocols used for their synthesis give low yields and high industrial application costs. In the present investigation, metal–organic frameworks based on β-cyclodextrin (β-CD-MOF) have been prepared for the molecular encapsulation of menthol. Menthol/β-CD-MOF-IC was synthesized under the optimized parameters, after which release behavior was studied. In this optimized manner, a higher menthol capacity was obtained in which the menthol content and encapsulation efficiency were 27.1 and 30.6%, respectively. Compared with menthol/β-CD-IC, menthol/β-CD-MOF-IC is resistant to high temperature, but sensitive to moisture. In a simulated oral release experiment, the rate of menthol release from different samples followed the order of: pure menthol > β-CD > β-CD-MOF, which can be attributed to two mechanisms: non-specific binding and site preference. We propose that β-CD-MOF can be used as a promising delivery system for aroma compounds.

Nanotized kinetin enhances essential oil yield and active constituents of mint via improvement in physiological attributes

Often mint (Mentha arvensis L.) faces unforeseen limitations, resulting in a low yield and quality of essential oil (EO), especially menthol content necessitating the need to explore the potential of modern technology to overcome this predicament. One of such techniques is the use of nanomaterials. The bulk (un-nanotized) form of PGRs (plant growth regulators) has been considered as a potential tool for crop improvement. Utilizing the top-down approach of nanotization, bulk PGR kinetin was ball-milled to the nano-scale range. A pot experiment was conducted on mint applying bulk- and nano-kinetin through foliar application. The concentrations of spray-treatments included 0 (de-ionized water, control), 10, 20, and 30 μM of bulk-as well as nanotized-kinetin. Both forms of kinetin manifested their patterns in the plant. Treatment N2 (20 μM of nanotized-kinetin) excelled in all other treatments for most of the parameters studied. As compared with De-ionized water-spray control, it resulted in the highest improvement in photosynthetic efficiency, Carbonic anhydrase activity, EO content (46.6 %), EO yield (50.8 %), and density as well as the diameter of PGTs (peltate glandular trichomes). Treatment N2, equalled by treatment B2 (20 μM of bulk-kinetin), maximally improved the menthol yield. The highest content and yield of EO, as a result of N2 application, was attributed to its manifestation in terms of the improved photosynthetic machinery, enzyme activity, and vigour (density and diameter) of PGTs. Since treatment N2 increased the most desirable EO-traits, viz. content and yield of EO along with yield of menthol, it might be recommended for successful production of mint.

Isotope-Dilution Gas Chromatography-Mass Spectrometry Method for the Selective Detection of Nicotine and Menthol in E-Cigarette, or Vaping, Product Liquids and Aerosols.

We developed a quantitative method for analyzing nicotine and menthol in e-cigarette, or vaping, products (EVPs). These products may adversely impact health through inhalational exposure to addictive and harmful chemicals. The presence of unknown substances in do-it-yourself e-liquids, counterfeits, or unregulated products may increase exposure to harmful chemicals, as underscored by the 2019 EVP use-associated lung injury (EVALI) outbreak. To minimize these risks, it is important to accurately quantify nicotine and menthol in e-liquids and aerosol emissions to evaluate EVP authenticity, verify product label accuracy, and identify potentially hazardous products. We developed a simple, versatile, high-throughput method using isotope-dilution gas chromatography-mass spectrometry for quantifying nicotine and menthol concentrations in both e-liquid contents and machine-generated aerosol emissions of EVPs. Rigorous validation has demonstrated that the method is specific, precise (CV<2.71%), accurate (percent error ≤7.0%), and robust. Linear calibration ranges from 0.01 to 1.00 mg/ml for both analytes was achieved, corresponding to expected analyte levels in e-liquids and machine-generated EVP aerosols. Limits of detection (LODs) in the final 10-ml sample extract were 0.4 μg/ml for nicotine and 0.2 μg/ml for menthol. The method was used to analyze aerosol emissions of 141 EVPs associated with the 2019 EVALI outbreak; detectable levels of nicotine (2.19–59.5 mg/g of aerosol) and menthol (1.09–10.69 mg/g of aerosol) were observed in 28 and 11%, respectively, of the samples analyzed. Nicotine was not detected in any of the tetrahydrocannabinol (THC), cannabidiol (CBD), or oil-based products, while menthol (2.95 mg/g of aerosol) was only detected in one of these products (THC-labeled). The analytical method can be used to quantify nicotine and menthol concentrations in the e-liquids and aerosols from a range of EVPs, and these findings highlight a difference between e-cigarette and other vaping products.

Biostimulating effect of chitosan and acetic acid on the growth and profile of the essential oil of Mentha arvensis L

Elicitors are molecules that can induce responses in plants, such as the production of secondary metabolites. Mentha arvensis L. is a medicinal plant belonging to the Lamiaceae family with great importance for the worldwide production of essential oil. This work aimed to evaluate the response of elicitor application to the growth and essential oil production of M. arvensis. Two experiments were carried out at different times under nursery conditions with 50 % shading. The preliminary experimental design was completely randomized with three replications and five treatments (distilled water; 1% glacial acetic acid solution; and 0.25 %, 0.5 % and 0.75 % chitosan), and a second experiment (distilled water, 0.25 % glacial acetic acid and 0.06 % and 0.125 % chitosan) was also conducted. In the preliminary experiment, samples were collected 7 days after treatment application and 0 h, 12 h, 24 h, and 7 days after treatment application in the second experiment. Both experiments were evaluated at 7 days concerning the content, yield, and chemical composition of the essential oil. The use of 1% acetic acid to dissolve chitosan caused aerial plant injury, reducing the essential oil yield. The 4-fold reduction in the concentration of acetic acid and low concentrations of chitosan showed biostimulating action. In conclusion, the growth and essential oil and menthol content of M. arvensis undergo changes dependent on the concentration of acetic acid and chitosan. The 0.125 % concentration of chitosan provides greater accumulation of shoots, roots and total dry weights. Plant pulverizes with 0.25 % acetic acid had a higher essential oil content, while maximum menthol content is reached with 0.06 % chitosan.

Menthol as anesthetic for juvenile Lophiosilurus alexandri: Induction and recovery time, ventilatory frequency, hematology and blood biochemistry

Anesthesia is an indispensable procedure during the handling of fish. This work evaluated the effects of menthol as anesthetic for juvenile Lophiosilurus alexandri. Menthol concentrations of 0 (control), 25, 50, 150, 300 and 450 mg L−1 were tested using 14 animals for each concentration, with each fish being a replicate. Blood was sampled from seven of the juveniles in each group shortly after anesthetic induction and from the other seven at 24 h post-anesthesia and procedures to collect biometric measures, i.e., handling and air exposure. Induction time showed a linear response plateau effect (LRP) with an inflection point of 142 mg L−1, while a dose-response relationship was observed among concentrations for recovery time. Ventilatory frequency (VF) during anesthetic induction had a LRP effect with an inflection point of 127 mg L−1, while during recovery it had a quadratic effect with a maximum point of 305.45 mg L−1. Fish anesthetized with 50 mg L−1 of menthol had the lowest hematocrit values (P < 0.05), while those exposed to 450 mg L−1 had the lowest erythrocyte values (P < 0.001). Other changes in hemato-biochemical parameters are discussed. Concentrations between 50 and 300 mg L−1 of menthol were able to induce deep anesthesia in juvenile L. alexandri with induction and recovery times considered ideal for fish. The use of 50 mg L−1 of menthol was able to reduce VF during induction and recovery and also prevent increased plasma glucose, with little influence on hematological and biochemical parameters after handling.

Evaluation of the chemical components and some bioactive compounds of the peppermint essential oil (Mentha arvensis L.) cultivated in Vietnam

Vietnam has diverse plant resources and many species are considered to be valuable medicinal sources. Studying, seeking, and evaluating the bioactive compounds from plants is a valuable research endeavor for producing human healthcare products. Peppermint (Mentha arvensisL.) is widely cultivated in Vietnam as a raw material for the production of essential oils serving local needs and exports. This study compared the chemical components and some bioactive compounds in essential oil from Mentha arvensisL. cultivated in Thai Binh, Binh Thuan, and An Giang provinces. The essential oil yields in all samples ranged from 0.69 to 0.84%. Gas chromatography analyses identified 29 substances in total. Menthol and menthone were the two main ingredients in the oils, accounting for 53.62-62.61% and 18.81-21.06%, respectively. Furthermore, all essential oils exhibited free radical scavenging capacity in vitroand antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli. The plants collected in Thai Binh had the highest content of essential oil, menthol, and menthone, as well as the strongest bioactivities.

Planting-date and cutting-time affect the growth and essential oil composition of Mentha × piperita and Mentha arvensis

Peppermint (Mentha × piperita L.) and Japanese mint (Mentha arvensis L.), as the prominent menthol bearing species are widely cultivated and have a considerable share in the global essential oil trade. In this research, the effects of two different planting dates (spring and autumn), diverse cutting time, and alluvial soil conditions were investigated on the growth and essential oil compounds of M. × piperita L. var. Black Mitcham and M. arvensis var. piperascens Holmes in Çukurova Region/Turkey, during 2011−2014. According to the results, despite the relative superiority of M. arvensis; no significant difference was recorded in the growth potential of two species. However, the content and yield of M. arvensis essential oil (4.8 % and 94 L ha−1) were substantially higher than M. × piperita (2.8 % and 43 L ha−1). In terms of plant height, dry biomass, leaf dry weight, and essential oil yield, the spring planting date was significantly superior to autumn. Among the six cuttings, the data of the first cuttings were significantly higher than the second cuttings for each year. The major essential oil constituents of M. × piperita were menthol (22.5–44.6 %) and menthone (13.8–37.4 %). Overall, menthol was more abundant in the spring cultivation of M. × piperita. In contrast, menthone amounts were higher in autumn cultivation. Menthol (53.6–70.5 %) was the major compound of M. arvensis. Isomenthone (4.5–17.7 %), menthone (3.3–14.5 %), and α- pinene (3.6–11.1 %) were the other major oil components of M. arvensis. Menthol content significantly decreased from the fourth cuttings. Although a declining trend in the yield of species was observed over time, the results were acceptable considering the restrictive conditions of the alluvial soils. All in all, without imposing the limits on the cultivation areas of the strategic agricultural crops; the cultivation of medicinal plants would be advisable with the plenty of alluvial lands.

Is there any relationship between agronomic traits, soil properties and essential oil profile of peppermint (Mentha piperita L.) treated by fertiliser treatments and irrigation regimes?

AbstractOne of the greatest challenges in recent years is providing enough food to feed the increasing world population, with limited freshwater resources. However, effective fertiliser management also has a fundamental role to improve yield quality and quantity. Organic fertiliser not only supplements nutrients but also improves physicochemical and biological soil properties. A 2‐year field experiment was conducted to examine the influence of urea and vermicompost fertiliser on oil phytochemical properties of peppermint pH, soil cation exchange capacity (CEC) and organic carbon of experimental site under three irrigation regimes in 2018 and 2019. The experiments had three water deficit regimes (no stress, moderate, and severe drought stress) as a main plot. The subplot division consisted of six fertiliser treatments: unfertilised (control); 140 kg urea ha−1; 105 kg urea ha−1 + 3.3 ton vermicompost ha−1; 70 kg urea ha−1 + 6.6 ton vermicompost ha−1; 35 kg urea ha−1 + 10 ton vermicompost ha−1; and 13.5 ton vermicompost ha−1. The maximum leaf area index (4.29) and dry matter weight (3,803 kg ha−1) were observed in control irrigation, while the highest essential oil content (0.97%) could be seen under mild water deficit stress. Additionally, the highest organic carbon and CEC were obtained under well‐watered conditions at 1.20% and 6.41 (meq 100 g soil−1), respectively. Dry matter weight and essential oil content increased considerably in response to increasing vermicompost in fertiliser treatments, and the highest content of these traits were observed in 2019 and with 13.5 ton vermicompost ha−1. The menthol content increases in response to deficit irrigation and integrated fertiliser. These data indicate that mild drought stress can increase the synthesis of medical compounds and vermicomposting can alleviate the impact of drought by conserving soil moisture as an acclimation mechanism to improve nutrient uptake and avoid yield losses.