Changes in Physiological Traits, Gene Expression and Phytochemical Profile of Mentha piperita in Response to Elicitor.

Peppermint (Mentha piperita) is a perennial medicinal plant containing active ingredients that can be used for treating liver and prostate cancers, acute respiratory infections, allergies, digestive problems, neuralgia, and migraines. The objective of this research is to investigate the expression of essential genes in the menthol pathway of Mentha piperita, including Pulegone reductase (Pr), Menthofuran synthase (Mfs), and limonene synthase (Ls) using qPCR, physiological analysis and essential oil composition in response to methyl jasmonate (MeJA) (0.5 mM) elicitation. Physiological analysis showed that 0.5 mM MeJA triggers defensive responsiveness in Mentha piperita by increasing superoxide dismutase (SOD) and Peroxidase (POD) enzymes activity. The highest transcript levels of Pr and Mfs genes were observed during 8 and 12 h after treatment respectively, but following 24 h, they were down-regulated. Essential oil analysis indicated that the percentage of constituents in the essential oil was changed using MeJA at 48 h and 96 h after post-treatment. Effective antimicrobial compounds, α-pinene, ß-pinene, linalool and methyl acetate, were induced after 48 h. A non-significant positive relationship was detected between menthol content, and expression of the Pr and Mfs genes. Due to the significant change in the expression of Pr and Mfs genes in the menthol pathway, role of Pr gene in directing the pathway to the valuable compound menthol and deviation of the menthol pathway to the menthofuran as an undesirable component of essential oil by Mfs gene, it can be deduced that they are the most critical genes in response to MeJA treatment, which are appropriate candidates for metabolite engineering. In addition, MeJA improved defensive responsiveness and percentage of some constituents with antimicrobial properties in Mentha piperita.

Peppermint and menthol: a review on their biochemistry, pharmacological activities, clinical applications, and safety considerations.

In this manuscript, we conducted a comprehensive review of the diverse effects of peppermint on human health and explored the potential underlying mechanisms. Peppermint contains three main groups of phytochemical constituents, including essential oils (mainly menthol), flavonoids (such as hesperidin, eriodictyol, naringenin, quercetin, myricetin, and kaempferol), and nonflavonoid phenolcarboxylic acids. Peppermint exhibits antimicrobial, antioxidant, anti-inflammatory, immunomodulatory, anti-cancer, anti-aging, and analgesic properties and may be effective in treating various disorders, including gastrointestinal disorders (e.g., irritable bowel syndrome, dyspepsia, constipation, functional gastrointestinal disorders, nausea/vomiting, and gallbladder stones). In addition, peppermint has therapeutic benefits for psychological and cognitive health, dental health, urinary retention, skin and wound healing, as well as anti-depressant and anti-anxiety effects, and it may improve memory. However, peppermint has paradoxical effects on sleep quality and alertness, as it has been shown to improve sleep quality in patients with fatigue and anxiety, while also increasing alertness under conditions of monotonous work and relaxation. We also discuss its protective effects against toxic agents at recommended doses, as well as its safety and potential toxicity. Overall, this review provides the latest findings and insights into the properties and clinical effects of peppermint/menthol and highlights its potential as a natural therapeutic agent for various health conditions.

Phytochemical analysis of carotenoid profile in Mentha piperita and Artemisia vulgaris: cytotoxicity in tumoral cells and evaluation of plasmid DNA cleavage.

Several medicinal plants have been administered to cancer patients attributed to their anticarcinogenic and chemoprotective properties, in addition to lower toxicity compared to traditional therapies. The aim was to investigate the antioxidant properties and carotenoid composition of aqueous extracts of Mentha piperita or Artemisia vulgaris which were previously found to exert beneficial effects on human health through diet. aqueous extracts exhibited potent antioxidant activity. A diversity of carotenoids was identified in these extracts using HPLC-PDA-MS/MS. Both extracts contained predominantly all-trans-lutein as the main component within this class. In order to investigate antioxidant properties, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) techniques were used. The (3-4,5 dimethylthiazol-2, 5 diphenyl tetrazolium bromide) (MTT) and Crystal Violet assays assessed cellular cytotoxicity. Assessments of presence of reactive species were carried out following exposure of oral squamous cell carcinoma cell line (SCC-4) to various aqueous extracts of M piperita or A vulgaris utilizing dichlorofluorescein diacetate (DCFH-DA) and nitric oxide (NO) assays. Exposure to these extracts induced severe cytotoxic effects, which led to investigation of the biochemical and molecular mechanisms underlying this observed effect. Data demonstrated that both solutions induced oxidative stress and DNA damage, especially at higher concentrations using agarose gel subjected to electrophoresis. It is known that exposure to excess amounts of antioxidants results in a prooxidant effect which is beneficial in cancer therapy. Further, the extracts were found to reduce viability of SCC-4 in culture, indicating that this antitumoral activity may be of therapeutic importance and requires further study.

Amended Safety Assessment of Mentha piperita (Peppermint)-Derived Ingredients as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) reviewed the safety of M piperita (peppermint)-derived ingredients. The Panel reviewed data relevant to the safety of these ingredients. Because final product formulations may contain multiple botanicals, each containing the same constituent(s) of concern, formulators are advised to be aware of these constituents and avoid reaching levels that may be hazardous to consumers. Industry should continue to use good manufacturing practices to limit impurities that could be present in botanical ingredients. The Panel concluded that M piperita (Peppermint) Oil, Extract, Leaf, and leaf-derived ingredients are safe in cosmetics in the present practices of use and concentration when formulated to be non-sensitizing, and that the available data are insufficient for determining that M piperita (Peppermint) Flower/Leaf/Stem Extract, M piperita (Peppermint) Flower/Leaf/Stem Water, and M piperita (Peppermint) Meristem Cell Culture are safe under the intended conditions of use in cosmetic formulations.

In Vitro Antiglycation and Methylglyoxal Trapping Effect of Peppermint Leaf (Mentha × piperita L.) and Its Polyphenols.

The most significant reactive α-dicarbonyl RCS involved in the pathomechanism of glycation and related diseases is methylglyoxal (MGO). Hyperglycemia promotes the generation of MGO and leads to the formation of advanced glycation end products (AGEs). Therefore, MGO trapping and glycation inhibition appear to be important therapeutic targets in prediabetes, diabetes, and in the early prevention of hyperglycemic complications. Peppermint leaf is commonly used as herbal tea, rich in polyphenols. Eriocitrin, its predominant component, in a double-blind, randomized controlled study reversed the prediabetic condition in patients. However, the antiglycation activity of this plant material and its polyphenols has not been characterized to date. Therefore, the aim of this study was to evaluate the ability of a peppermint leaf dry extract and its polyphenols to inhibit non-enzymatic protein glycation in a model with bovine serum albumin (BSA) and MGO as a glycation agent. Peppermint polyphenols were also evaluated for their potential to trap MGO in vitro, and the resulting adducts were analyzed by UHPLC-ESI-MS. To relate chemical composition to glycation inhibitory activity, the obtained peppermint extract was subjected to qualitative and quantitative analysis. The capability of peppermint leaf polyphenols to inhibit glycation (27.3-77.2%) and form adducts with MGO was confirmed. In the case of flavone aglycones, mono- and di-adducts with MGO were observed, while eriodictyol and eriocitrin effectively produced only mono-adducts. Rosmarinic acid and luteolin-7-O-glycosides did not reveal this action. IC50 of the peppermint leaf dry extract was calculated at 2 mg/mL, equivalent to a concentration of 1.8 µM/mL of polyphenols, including ~1.4 µM/mL of flavonoids and ~0.4 µM/mL of phenolic acids. The contribution of the four major components to the anti-AGE activity of the extract was estimated at 86%, including eriocitrin 35.4%, rosmarinic acid 25.6%, luteolin-7-O-rutinoside 16.9%, luteolin-7-O-ß-glucuronoside 8.1%, and others 14%. The effect of peppermint dry extract and polyphenols in inhibiting MGO-induced glycation in vitro was comparable to that of metformin used as a positive control.

The Influence of Microwave Treatments on Bioactive Compounds and Antioxidant Capacity of Mentha piperita L.

Microwave extraction is becoming a popular option in many fields, especially for bioactive compounds from medicinal plants. This paper addresses the application of microwaves in the process of extracting bioactive compounds (phenols, flavonoids, chlorophyll) from peppermint with antioxidant capacity in order to highlight the influence of the microwave field on the quality of the final product in comparison with the control samples. The Mentha piperita L. is a rich source of phenols. The total phenol content after applying the MW treatments significant increased and varied between 25.000 ± 1.992 and 391.687 ± 20.537 mg GAE/100 g dw compared to the untreated sample (8.089 ± 2.745 mg GAE/100 g dw). The same trend was also recorded in the case of the flavonoid and pigment content in peppermint leaves following the application of microwave treatments. The obtained results were investigated using chemometric multivariate analysis. The main purpose of our research was to compare the possibilities of total or partial substitution of conventional extraction technologies with the microwave extraction technology, and also to highlight the existing differences in the amount of total phenols and flavonoids extracted from peppermint plants in different processing conditions. Through microwave processing, a significant increase in polyphenolic compounds is obtained.

The Influence of Phytosociological Cultivation and Fertilization on Polyphenolic Content of Menthae and Melissae folium and Evaluation of Antioxidant Properties through In Vitro and In Silico Methods.

Since medicinal plants are widely used in treating various diseases, phytoconstituents enrichment strategies are of high interest for plant growers. First of all, we investigated the impact of phytosociological cultivation on polyphenolic content (total flavonoids-TFL, and total polyphenols-TPC) of peppermint (Mentha piperita L.) and lemon balm (Melissa officinalis L.) leaves, using spectrophotometric methods. Secondly, the influence of chemical (NPK) and organic (BIO) fertilization on polyphenolic content and plant material quality was also assessed. Dry extracts were obtained from harvested leaves using hydroethanolic extraction solvents for further qualitative and quantitative assessment of phytoconstituents by FT-ICR MS and UHPLC-MS. Furthermore, the antioxidant activity of leaf extracts was determined in vitro using DPPH, ABTS and FRAP methods. Molecular docking simulations were employed to further evaluate the antioxidant potential of obtained extracts, predicting the interactions of identified phytochemicals with sirtuins. The concentration of polyphenols was higher in the plant material harvested from the phytosociological culture. Moreover, the use of BIO fertilizer led to the biosynthesis of a higher content of polyphenols. Higher amounts of phytochemicals, such as caffeic acid, were determined in extracts obtained from phytosociological crops. The antioxidant activity was dependent on polyphenols concentration, more potent inhibition values being observed for the extracts obtained from the phytosociological batches. Molecular docking studies and MM/PBSA calculations revealed that the obtained extracts have the potential to directly activate sirtuins 1, 5 and 6 through several polyphenolic compounds, such as rosmarinic acid, thus complementing the free radical scavenging activity with the potential stimulation of endogenous antioxidant defense mechanisms. In conclusion, growing medicinal plants in phytosociological cultures treated with biofertilizers can have a positive impact on plant material quality, concentration in active constituents and biological activity.

Effective treatment of resistant opportunistic fungi associated with immuno-compromised individuals using silver biosynthesized nanoparticles.

Drug resistance in filamentous fungus to antifungal medicines is a huge problem in biomedical applications; so, an effective strategy for treating opportunistic fungal infections is needed. Mentha piperita is a very fascinating plant to treat a variety of ailments as home remedies. Eighteen strains of Aspergillus species were used for this study which are having a unique antifungal resistance profile in presence of silver nanoparticles (AgNPs). AgNPs were prepared, using an aqueous extract of M. Piperita and characterized it by various techniques. Structural properties of AgNPs were systematically studied using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FT-IR), and Raman measurement, which emanate the single-phase fcc structure of silver nanoparticles. The spherical nature and elemental analysis of as-synthesized AgNPs were confirmed using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy, respectively. The optical study has been analyzed using UV-Vis spectroscopy and band gap was calculated as 2.51 eV, using Tauc plot. To analyze and validate the good efficacy of the disc approach, antifungal activity of AgNPs nanoparticles in different concentrations against isolates was achieved in both disc and broth microdilution. The extracellular enzymatic activity of A. fumigatus was found to explore the precise impact of nanoparticles on fungal metabolism. The antifungal efficacy of AgNPs against all fungi was highly successful in disc method. The broth approach underlined the favorable results of the disc method. It provided more precise results in determining the minimum inhibition concentration (MIC), as well as the minimum effective concentration (MEC). A. fumigatus (AM6) enzymatic activity was boosted by AgNPs. Also, ß-galactosidase, ß-glucuronidase, and ß-glucosidase are necessary enzymes whose activity has been boosted. Consequently, M. piperita AgNPs can play a major and intriguing function against resistant Aspergillus species with a significant shift in the enzymatic activity profile of fungi due to this action.

Topical Mentha piperita Effects on Cutaneous Wound Healing: A Study on TGF-ß Expression and Clinical Outcomes.

BACKGROUND: Wound healing is a critical clinical concept. We aimed to evaluate the effects of topical Mentha piperita essence on cutaneous wound healing. METHODS: This randomized controlled trial was conducted in Tehran University of Medical Sciences, Tehran, Iran in 2019. Square-shaped 1.5×1.5 cm wounds were made on the neck of 60 male Wistar rats in a sterile condition. Samples were randomly divided into a control group and three experimental groups. Group A treated with M. piperita essence and Vaseline. The second group received the M. piperita essence, and the third group received Vaseline. Histological specimens were obtained in 4th, 7th, and 14th days and were explored for fibroblasts, epithelial cells, inflammatory cells, and vessels. RT-PCR was performed for molecular and gene expression evaluation of TGF-ß. RESULTS: The M. piperita essence increases TGF-ß gene expression as an important factor in wound healing. After 14 d, group A, who received M. piperita and Vaseline, had 99.73% of wound healing with the mean wound size of 0.006 cm2 while wound healing in the control group was only 52%. Samples treated with M. piperita have 74.58% wound healing following by group treated with Vaseline, which was 67.02% (P<0.05), respectively. CONCLUSION: The application of the M. piperita essence for wound healing accelerates the process and improves outcomes.

Expression profiling of rosmarinic acid biosynthetic genes and some physiological responses from Mentha piperita L. under salinity and heat stress.

Peppermint is of great economic importance, mainly due to its valuable essential oils. The present study aimed to compare the expression level of genes coding for proteins involved in the rosmarinic acid biosynthesis pathway and some physiological responses in peppermint under three levels of salinity (0, 60 and 120 mM) and two levels of thermal stresses (at 25 °C, optimal plant heat, and 35 °C, for thermal stress). The results showed that salinity at 25 °C resulted in an increased relative level of phenolic compounds, proline and antioxidant activity by 1.88, 1.92 and 2.58 times after 72 h respectively at salinity of 120 mM. Rosmarinic acid as well as soluble sugar, chlorophyll and K+/N+ ratio showed a decreasing trend by 3.2, 1.8, 4.6 and 9 times after 72 h respectively at salinity of 120 mM at 35 °C. Gene expression analysis showed a significant increase in HPPR and C4H expression and a significant decrease in RAS expression in plants subjected to simultaneous stresses. The higher levels of C4H and HPPR expression indicate the roles of these genes in defense processes and the effects of phenolic compounds in inhibiting oxidative stress. Our results may help increase knowledge about the stress-dependent alterations in gene expression profiles and physiological patterns in plants. This information may be used for medicinal plant improvement programs aimed at increasing rosmarinic acid production.

Poly(vinyl alcohol)/Plant Extracts Films: Preparation, Surface Characterization and Antibacterial Studies against Gram Positive and Gram Negative Bacteria.

In this study, we aim to obtain biomaterials with antibacterial properties by combining poly(vinyl alcohol) with the extracts obtained from various selected plants from Romania. Natural herbal extracts of freshly picked flowers of the lavender plant (Lavandula angustifolia) and leaves of the peppermint plant (Mentha piperita), hemp plant (Cannabis sativa L.), verbena plant (Verbena officinalis) and sage plant (Salvia officinalis folium) were selected after an intensive analyzing of diverse medicinal plants often used as antibacterial and healing agents from the country flora. The plant extracts were characterized by different methods such as totals of phenols and flavonoids content and UV-is spectroscopy. The highest amounts of the total phenolic and flavonoid contents, respectively, were recorded for Salvia officinalis. Moreover, the obtained films of poly(vinyl alcohol) (PVA) loaded with plant extracts were studied concerning the surface properties and their antibacterial or cytotoxicity activity. The Attenuated Total Reflection Fourier Transform Infrared analysis described the successfully incorporation of each plant extract in the poly(vinyl alcohol) matrix, while the profilometry demonstrated the enhanced surface properties. The results showed that the plant extracts conferred significant antibacterial effects to films toward Staphylococcus aureus and Escherichia coli and are not toxic against fibroblastic cells from the rabbit.

Efficacy of Gold Nanoparticles against Drug-Resistant Nosocomial Fungal Pathogens and Their Extracellular Enzymes: Resistance Profiling towards Established Antifungal Agents.

Drug resistance of filamentous fungi to the commonly used antifungal agents is a major concern in medicine. Therefore, an effective approach to treat several opportunistic fungal infections is the need of the hour. Mentha piperita is used in home remedies to treat different disorders. Isolates of fungi were taken from hospitals in Riyadh, Saudi Arabia, and identified using molecular tools. Amphotericin B, Voriconazole, and Micafungin were applied to screen the resistance of these isolates using both disc and broth microdilution techniques. An aqueous extract of Mentha piperita was utilized to synthesize AuNPs and the nanoparticles were characterized using UV-Vis, FTIR, TEM, EDAX, and XRD. The AuNPs were tested for antifungal activity against the nosocomial fungal pathogens and the activity of extracellular enzymes of such pathogens were analyzed after treatment with AuNPs. We conclude that AuNPs synthesized using Mentha piperita do not possess especially effective antifungal properties against multi-drug resistant Aspergillus species. Five out of eighteen isolates were inhibited by AuNPs. When inhibition was observed, significant alterations in the activity profile of extracellular enzymes of the nosocomial fungi were observed.

Peppermint Essential Oil and Its Major Volatiles as Protective Agents against Soft Rot Caused by Fusarium sambucinum in Cera Pepper (Capsicum pubescens).

Cera pepper (Capsicum pubescens) is an exotic fruit considered as a rich source of nutraceuticals with known benefits for human health and also an economic resource for local producers in Mexico. The present investigation reports on the in vitro and in situ antifungal activity of the essential oil from Mentha piperita and its two major volatiles (menthol and menthone) against Fusarium sambucinum, which is a causal agent of soft rot in cera pepper. The application of these components in pepper fruits previously infected with F. sambucinum caused a significant delay (p<0.05) in the emergence of soft rot symptoms. This effect was reflected in the maintenance of pH and fruit firmness during a period of 10 days. The nutrimental content of the fruits (protein, fiber, fat and other proximate parameters) was conserved in the same period of time. The nutraceutical content of these fruits was estimated by the quantification of seven carotenoids (violaxanthin, cis-violaxanthin, luteoxanthin, antheraxanthin, lutein, zeaxanthin and ß-carotene), ascorbic acid and capsaicinoids (capsaicin and dihydrocapsaicin). According to our results, the essential oil from M. Piperita and its major volatiles exerted a preservative effect on these metabolites. Our findings demonstrated that the essential oil of M. Piperita and its major volatiles represent an ecological alternative for the control of fusariosis caused by F. sambucinum in cera peppers under postharvest conditions.

Antimicrobial synergism and antibiofilm activities of Pelargonium graveolens, Rosemary officinalis, and Mentha piperita essential oils against extreme drug-resistant Acinetobacter baumannii clinical isolates.

Rosemary officinalis L., Pelargonium graveolens L., and Mentha piperita L., essential oils are used by complementary medicine specialists simultaneously with traditional antibiotics for treatment purposes. The chemical composition of essential oils was analyzed by the gas chromatography-mass spectrometry method. In vitro antibacterial and antibiofilm activities of the essential oils were tested against extreme drug-resistant (XDR) colistin-resistant and colistin susceptible Acinetobacter baumannii clinical strains. The synergistic activities between essential oils and colistin antibiotics were investigated by the checkerboard method. The highest antibacterial effect was detected in mint essential oil (2.5-5 µl/ml), followed by pelargonium essential oil (5-20 µl/ml) and rosemary essential oil (5-20 µl/ml). The combination of rosemary essential oil or pelargonium essential oil with colistin showed strong synergistic activity in most of the bacterial strains tested (fractional inhibitory concentration index ≤ 0.5; synergy). As a result of the combination of mint essential oil and colistin, an indifferent effect was observed in only two bacterial strains, and other strains could not be evaluated. No antagonistic effects were observed in any of the tested essential oils. As a result of the effectiveness of the combination, the minimum inhibitory concentration (MIC) values of colistin in XDR-A. baumannii clinical isolates decreased 2-32 fold. Additionally, the sub-MIC concentration of essential oils exhibited an inhibitory effect (48-90%) against the biofilm layer of tested A. baumannii strains.

Functional Characterization and Structural Insights Into Stereoselectivity of Pulegone Reductase in Menthol Biosynthesis.

Monoterpenoids are the main components of plant essential oils and the active components of some traditional Chinese medicinal herbs like Mentha haplocalyx Briq., Nepeta tenuifolia Briq., Perilla frutescens (L.) Britt and Pogostemin cablin (Blanco) Benth. Pulegone reductase is the key enzyme in the biosynthesis of menthol and is required for the stereoselective reduction of the Δ2,8 double bond of pulegone to produce the major intermediate menthone, thus determining the stereochemistry of menthol. However, the structural basis and mechanism underlying the stereoselectivity of pulegone reductase remain poorly understood. In this study, we characterized a novel (-)-pulegone reductase from Nepeta tenuifolia (NtPR), which can catalyze (-)-pulegone to (+)-menthone and (-)-isomenthone through our RNA-seq, bioinformatic analysis in combination with in vitro enzyme activity assay, and determined the structure of (+)-pulegone reductase from M. piperita (MpPR) by using X-ray crystallography, molecular modeling and docking, site-directed mutagenesis, molecular dynamics simulations, and biochemical analysis. We identified and validated the critical residues in the crystal structure of MpPR involved in the binding of the substrate pulegone. We also further identified that residues Leu56, Val282, and Val284 determine the stereoselectivity of the substrate pulegone, and mainly contributes to the product stereoselectivity. This work not only provides a starting point for the understanding of stereoselectivity of pulegone reductases, but also offers a basis for the engineering of menthone/menthol biosynthetic enzymes to achieve high-titer, industrial-scale production of enantiomerically pure products.

Extraction of Peppermint Essential Oils and Lipophilic Compounds: Assessment of Process Kinetics and Environmental Impacts with Multiple Techniques.

Consumers are becoming more mindful of their well-being. Increasing awareness of the many beneficial properties of peppermint essential oil (EO) has significantly increased product sales in recent years. Hydrodistillation (HD), a proven conventional method, and a possible alternative in the form of microwave-assisted hydrodistillation (MWHD) have been used to isolate peppermint EO. Standard Soxhlet and alternatively supercritical fluid (SFE), microwave-assisted, and ultrasound-assisted extraction separated the lipid extracts. The distillations employed various power settings, and the EO yield varied from 0.15 to 0.80%. The estimated environmental impact in terms of electricity consumption and CO2 emissions suggested that MWHD is an energy efficient way to reduce CO2 emissions. Different extraction methods and solvent properties affected the lipid extract yield, which ranged from 2.55 to 5.36%. According to the corresponding values of statistical parameters, empiric mathematical models were successfully applied to model the kinetics of MWHD and SFE processes.

Toxic Metals (As, Cd, Ni, Pb) Impact in the Most Common Medicinal Plant (Mentha piperita).

This study aimed to evaluate the behavior of Mentha piperita under Cd, Pb, Ni, and As soil contamination and their transfer from soil in plants as well as translocation in the roots/stems/leaves system compared with a control without metal addition. The mint seedlings were exposed for a three-month period using two metal mixtures in the same concentrations such as AsCd and AsCdNiPb (23.7 mg/kg As, 5 mg/kg Cd, 136 mg/kg Ni, and 95 mg/kg Pb). The results of metal concentration in plants showed that Cd, Ni, and Pb were accumulated in different parts of the plant, except for As. In plants organs, the order of metal accumulation was roots > stems > leaves. No significant impact on the growth, development, and chlorophyll content compared to the control was observed in the first month of exposure. After three months of exposure, phytotoxic effects occurred. Generally, the transfer coefficients and translocation factors values were less than 1, indicating that Mentha piperita immobilized the metals in root. The laboratory experiments highlighted that for a short period of time, Mentha piperita has the capacity to stabilize the metals at the root level and was a metal-tolerant plant when using a garden rich-substrate.

Anti-osteoarthritis potential of peppermint and rosemary essential oils in a nanoemulsion form: behavioral, biochemical, and histopathological evidence.

BACKGROUND: This study aimed to evaluate the effect of nanoemulsion containing peppermint and rosemary essential oils in rats with osteoarthritis (OA). METHODS: In this experimental study, we prepared a nanoemulsion containing peppermint and rosemary essential oils by spontaneous emulsification and evaluated the nanoemulsion's dermal irritation and toxicity. Investigating the analgesic effect of the nanoemulsion, we randomly assigned 36 male rats to 6 groups: Control (saline injection into the knee), osteoarthritis (intra-articular injection of 2 mg monosodium iodoacetate), and four groups of OA treated with nanoemulsion gel, nanoemulsion solution, rosemary and peppermint essential oil gel, or diclofenac sodium. Treatments were administered topically at a dose of 1 ml daily. Using behavioral tests, we assessed pain on days 1, 4, 7, and 14 after injection. Finally, we did the histopathological and biochemical evaluation of rats' knee joints. RESULTS: There were no irritation signs on the animals' skin after receiving the nanoemulsion and no changes in the hematological and biochemical parameters of rats' blood compared to the control group. Receiving nanoemulsion decreased the mechanical (P < 0.001) and thermal allodynia (P < 0.05), thermal hyperalgesia (P < 0.05), and ambulatory-evoked pain in comparison with the OA group. Also, the nanoemulsion receiving rats showed an increase in SOD and GPx activity and a decrease in MDA level. Histopathology of synovial tissues confirmed the results of behavioral and biochemical tests. CONCLUSION: The nanoemulsion containing essential oils of peppermint and rosemary reduces osteoarthritis pain via increasing antioxidant capacity and improving the histopathological features of the rats' knee joint.

Antioxidant and enzyme-inhibitory activity of peppermint extracts and essential oils obtained by conventional and emerging extraction techniques.

Peppermint is widely used medicinal plant with distinguished bioactive potential, therefore, the aim of present work was to develop novel peppermint extracts with high activity by application of traditional and emerging separation techniques. Conventional hydrodistillation and microwave-assisted hydrodistillation (MWHD) were applied for recovery of essential oil (EO), while organic solvent extraction using Soxhlet apparatus, microwave-assisted and ultrasound-assisted process and supercritical fluid extraction (SFE) were applied for non-selective recovery of peppermint lipophilic extracts. Extracts were characterized in terms of terpenoids profile with special emphasis on content of major compounds (mentol, menthone, isomenthol and eucalyptol). Antioxidant activity (DPPH, ABTS, CUPRAC, FRAP, chelating and phosphomolybdenum assay) and enzyme-inhibitory assays (acetylcholinesterase, butyrylcholinesterase, tyrosinase, amylase and glucosidase inhibition) were used for screening of peppermint bioactivity. MWHD was recognized as alternative for traditional process in EO recovery, while SFE extracts were useful for green production of solvent-free peppermint extracts rich in terpenoids and other lipophilic bioactives.

A simple method to determine antioxidant status in aromatic plants subjected to drought stress.

Drought is a major environmental stress factor that affects the growth and development of plants. All plants have to maintain the reactive oxygen species within certain levels for normal cellular homeostasis by means of their antioxidant systems, which can be classified as enzymatic and non-enzymatic. Plants under drought stress generate an excess production of reactive oxygen species. At high concentrations, this can be detrimental by producing damage to the protein structures and inhibiting enzymes, as well as oxidizing macromolecules, which may eventually lead to cell death. There has been increasing attention paid to the antioxidant capacity of aromatic/medicinal plants, with a high antioxidant content having been reported in some plant extracts, such as in Mentha piperita (peppermint). Peppermint plants cultivated under drought stress also present high levels of phenolic compounds, peroxidase enzyme activity and lipid peroxidation of membranes. A simple and inexpensive laboratory class is proposed for teaching some mechanisms that plants have evolved to avoid reactive oxygen species damage. The series of lab experiments described is aimed at demonstrating the antioxidant status in aromatic plants subjected to drought stress, by measuring total phenolic compound content (non-enzymatic antioxidant compound), peroxidase activity (enzymatic antioxidant) and malondialdehyde, as convenient biomarkers for lipid peroxidation. The proposed class will be carried out by undergraduate students of the advanced biochemistry course, as part of our biology and agronomy studies. The experiment presented is intended to be used as a vehicle to emphasize the concepts that students have learned in their lectures. This lab exercise to be carried out by the students has dual goals: to apply a methodology only learned superficially on previous courses, and also to increase their understanding of how plants developed resistance mechanisms in order to tolerate drought stress.