Chemical and Antimicrobial Characterization of Mentha piperita L. and Rosmarinus officinalis L. Essential Oils and In Vitro Potential Cytotoxic Effect in Human Colorectal Carcinoma Cells.

Colorectal cancer is one of the most frequently diagnosed forms of cancer, and the therapeutic solutions are frequently aggressive requiring improvements. Essential oils (EOs) are secondary metabolites of aromatic plants with important pharmacological properties that proved to be beneficial in multiple pathologies including cancer. Mentha piperita L. (M_EO) and Rosmarinus officinalis L. (R_EO) essential oils are well-known for their biological effects (antimicrobial, antioxidant, anti-inflammatory and cytotoxic in different cancer cells), but their potential as complementary treatment in colorectal cancer is underexplored. The aim of the present study was to investigate the M_EO and R_EO in terms of chemical composition, antioxidant, antimicrobial, and cytotoxic effects in a colorectal cancer cell line-HCT 116. The gas-chromatographic analysis revealed menthone and menthol, and eucalyptol, α-pinene and L-camphor as major compounds in M_EO and R_EO respectively. M_EO exhibited potent antimicrobial activity, moderate antioxidant activity and a low cytotoxic effect in HCT 116 cells. R_EO presented a significant cytotoxicity in colorectal cancer cells and a low antimicrobial effect. The cytotoxic effect on non-cancerous cell line HaCaT was not significant for both essential oils. These results may provide an experimental basis for further research concerning the potential use of M_EO and R_EO for anticancer treatment.

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.

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.

GC-MS analysis and nutra-pharmaceutical potential of Mentha piperita essential oil extracted by supercritical fluid extraction and hydro-distillation.

This study reports the comparative evaluation of yield, physico-chemical composition and biological attributes (antioxidant activity, antimicrobial activity, biofilm inhibition and hemolytic activity) of peppermint (Mentha piperita L.) essential oil (EO) obtained by hydro-distillation (HD) and supercritical fluid (CO2) extraction (SCFE) methods. The yield (%) of EO obtained by HD (0.20 %) was significantly (p < 0.05) higher than that of SCFE (0.13 %) while the variation in the physical parameters like solubility, color, density (at 25 °C) and refractive index (at 25 °C) was not significant between the tested oils. The data of chemical compositional analysis revealed that menthol was the key component in the EO obtained by HD (52.85 %) and SCFE (45.51 %), followed by menthone [HD (25.93 %) and SCFE (27.3 %)] and eucalyptol [HD (8.59 %); SCFE (8.92 %)]. The EO extracted with supercritical fluid (SCFE-EO) exhibited superior (p < 0.05) DPPH free radical inhibition potential (52 %) with an IC50 value of 15.65 µg/mL and reducing power compared to that of HD-EO. The highest antimicrobial activity was exhibited by SCFE-EO against Pasturella multocida with an inhibition zone of 18.00 mm (MIC value of 86 µg/mL). The results of biofilm inhibition and hemolytic activity revealed that the SCFE method was superior to recover high quality EO in comparison to the HD method. The peppermint EO obtained by SCFE, owing to potent bioactive components, can be a potential candidate to develop nutra-pharmaceuticals.

Modulation of Phytochemical Pathways and Antioxidant Activity in Peppermint by Salicylic Acid and GR24: A Molecular Approach.

This study uncovers the potential of salicylic acid (SA) and synthetic Strigolactone (GR24) in enhancing menthol biosynthesis and antioxidant defense mechanisms in Mentha piperita L. Our comprehensive analysis, which included a series of controlled experiments and data analysis of the effects of these phytohormones on enzymatic antioxidants catalase (CAT) and ascorbate peroxidase (APX) and non-enzymatic antioxidants, including carotenoids and proline, revealed promising results. The study also examined their impact on lipid peroxidation, hydrogen peroxide levels, and the expression of genes critical to menthol and menthofuran synthesis. The results indicated that SA and GR24 significantly increased menthol production and reduced the levels of menthofuran and pulegone, suggesting upregulation in the plant's innate defense systems. Furthermore, the activities of CAT and APX were elevated, reflecting a strengthened antioxidant response. Interestingly, the menthofuran synthase (MFS) was higher in the control group. At the same time, pulegone reductase (PR) genes and menthol dehydrogenase (MDH) gene expression were upregulated, highlighting the protective effects of SA and GR24. These findings underscore the potential of SA and GR24 to serve as effective bio-stimulants, improving the quality and resilience of peppermint plants and thereby contributing to eco-friendly agricultural practices in pollution-stressed environments.

Enhancement of yogurt functionality by adding Mentha piprita phenolic extract and evaluation of its quality during cold storage.

New functional food products with health benefits are currently in high demand among health-conscious consumers. The present research aims to improve the functional properties of yogurt by adding peppermint hydroethanolic extract (PHE) at different doses. The impact of PHE (0%, 2%, 4%, and 6%) on yogurt was studied for acidity, pH, organoleptic quality, antioxidant activity, lipid peroxidation, and fatty acid profile. The results revealed that PHE is rich in phenolic compounds, of which rosmarinic acid was the main one (339.88 mg/g lyophilized extract) and has considerable antioxidant potential, which remarkably (p < .01) increased antioxidant capacity in yogurt by over 39.51%, even at a low dose of 2%, giving the product better protection against lipid peroxidation and preserving its physicochemical and sensory quality. At 4%, PHE increased significantly (p < .01) the content of omega-3 fatty acids, notably alpha-linolenic acid, in fortified yogurt compared with the control, and reduced (p < .01) the ratio of omega-6/omega-3, which dropped from 5.21 to 4.11. It looks feasible to prepare a yogurt with health-giving properties by adding Mentha piperita hydroethanolic extract at a concentration of up to 4% as an alternative to synthetic antioxidants, which would also extend its shelf life.

Comprehensive quality assessment of peppermint oils and commercial products: An integrated approach involving conventional and chiral GC/MS coupled with chemometrics.

Peppermint essential oil (EO) has a multitude of applications, such as a fragrance in cosmetics, personal care and industrial products, or as a flavoring ingredient in food and beverages. Despite its popularity and economic significance, peppermint EO is often adulterated to reduce production costs and to increase profits. Although the ISO standard for peppermint EO exists, detecting sophisticated forms of adulteration remains challenging.The current study used conventional and chiral GC/MS analysis of volatiles compounds, and chemometric techniques to evaluate an extensive set of authentic peppermint EO (n = 22) and commercial products (n = 36) purported to contain peppermint EO. Specifically, thirty-six terpenoids were examined in each sample and compared with the ISO standard. Fifty-three percent of the selected commercial products did not meet the ISO specifications and the ratio between menthone/isomenthone was proven to be a good indicator for authentication and adulteration detection. Chiral GC/MS was further employed to measure eight terpenoids: α-pinene, ß-pinene, limonene, menthol, menthone, isomenthone, pulegone, and menthyl acetate. The enantiomeric compositions of 27 commercial products were above or below the norm measured from authentic peppermint EOs. Of the 27 samples, eight met the ISO standard. A sample class prediction (SCP) model based on partial least squares-discriminant analysis (PLS-DA) of conventional GC/MS data was constructed using authentic peppermint EOs and cornmint EOs. The model can distinguish the most common types of peppermint EOs (US, India, and US/India blend) and cornmint EOs sold in the US market. After construction, the SCP model was then used to analyze commercial samples. One sample, which passed both ISO specification and chiral analysis, was identified as outlier by the SCP model. Overall, the applicability of combining both conventional and chiral GC/MS along with chemometric tools has been successfully demonstrated to address the overall quality of peppermint EOs in commerce and may help combat sophisticated adulteration.

Kinetics of Microwave-Assisted Extraction Process Applied on Recovery of Peppermint Polyphenols: Experiments and Modeling.

The aim of this work was to investigate the microwave-assisted extraction (MAE) kinetics of polyphenolic compounds from organic peppermint leaves. The phytochemicals of peppermint (Mentha piperita L.) are increasingly used in food technology due to their numerous biological activities. The processing of various plant materials by MAE and the production of high-quality extracts is becoming increasingly important. Therefore, the influence of microwave irradiation power (90, 180, 360, 600, and 800 W) on total extraction yield (Y), total polyphenols yield (TP), and flavonoid yield (TF) were investigated. Common empirical models (first-order, Peleg's hyperbolic, Elovich's logarithmic, and power-law model) were applied to the extraction process. The first-order kinetics model provided the best agreement with the experimental results in terms of statistical parameters (SSer, R2, and AARD). Therefore, the influences of irradiation power on the adjustable model parameters (k and Ceq) were investigated. It was found that irradiation power exerted a significant influence on k, while its influence on the asymptotic value of the response was negligible. The highest experimentally determined k (2.28 min-1) was obtained at an irradiation power of 600 W, while the optimal irradiation power determined by the maximum fitting curve determination predicted the highest k (2.36 min-1) at 665 W.

Effect of Adding Matricaria recutita L., Cymbopogon citratus, or Mentha piperita L. Extracts to Fermented Orange Beverage: Sensory Evaluation, Physicochemical Characterization, and Prediction of Toxic Risks and Biological Activity In Silico.

Fermentation is an important tool in producing functional beverages through agro-industrial wastes, and medicinal and aromatic plants due to the specific content of bioactive molecules. Therefore, this study evaluated the contribution of Matricaria recutita (chamomile), Cymbopogon citratus (lemongrass), or Mentha piperita (peppermint) extracts to the phytochemical profile and potential biological effects of a functional fermented orange beverage in vitro and in silico. The concentrations of aromatic herbal extracts that yielded the best sensory performance for fermented beverages were selected for analyses that involved characterizing the fermented beverages. The beverages that received the extracts (2%) had the highest phenolic and flavonoid content and antioxidant potential compared to the control. Hesperidin (124-130 mg L-1), narirutin (66-70 mg L-1), chlorogenic (11-16 mg L-1), caffeic (5.3-5.5 mg L-1), and ferulic (1-1.7 mg L-1) acids were found in the different formulations. The in silico analysis suggested that the evaluated compounds do not present a toxicity risk (mutagenicity, carcinogenicity, hepatotoxicity, and ability to penetrate the blood-brain barrier). Additionally, they can contribute to the biological effects of therapeutic importance, such as antioxidant, gastroprotective, and anti-ulcerative properties, and the Mentha piperita L. extract presented the greatest potential among the evaluated herbs for use in functional fermented beverages.

Detoxification of monoterpenes by a family of plant glycosyltransferases.

Plant monoterpenes are challenging compounds, since they often act as solvents, and thus have both phytotoxic and antimicrobial properties. In this study an approach is developed to identify and characterize enzymes that can detoxify monoterpenoids, and thus would protect both plants and microbial production systems from these compounds. Plants respond to the presence of monoterpenes by expressing glycosyltransferases (UGTs), which conjugate the monoterpenoids into glycosides. By identifying these enzymes in a transcriptomics approach using Mentha × piperita, a family of UGTs was identified which is active on cyclic monoterpenoids such as menthol, and on acyclic monoterpenoids such as geranic acid. Other members of this family, from tomato, were also shown to be active on these monoterpenoids. In vitro and in vivo activity of different UGTs were tested with different substrates. We found that some glycosyltransferases significantly affect the toxicity of selected monoterpenoids in Escherichia coli, suggesting that glycosyltransferases can protect cells from monoterpenoid toxicity.

Phytochemical, in vitro radical scavenging and in vivo oxidative stress analysis of peppermint (Mentha piperita L.) leaves extract.

This current work aims to determine phytochemicals, in vitro radical scavenging, and in vivo oxidative stress reduction activities of peppermint (Mentha piperita L.) ethanolic extract (PEE). The Clule method was used to determine the phytochemical content. An in vitro antioxidant with radical scavenging activity was measured using 2,2-diphenyl-1-picrylhydrazyl. An in vivo antioxidant with oxidative stress reduction was carried out for 10 days on 25 male Sprague-Dawley rats (divided into five groups). Every day, each group was given positive control, negative control, 5, 10, and 20 mg/200 gr of body weight (BW) of the extract. The blood plasma was taken for malondialdehyde analysis. A phytochemical identification of PEE revealed more compounds, such as flavonoids, alkaloids, steroids, essential oils, and tannin. PEE exhibits significant in vitro radical scavenging activity, with an IC50 value of 126.695 µg/mL. In the in vivo antioxidant with oxidative stress reduction experiments, 5 mg/200 gr BW was the most effective dose, as evidenced by a considerable drop in malondialdehyde level (0.312 nmol/mL) after and before treatment. In conclusion, PPE has the potential to be developed as a herbal antioxidant based on in vitro and in vivo test results.

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.

Eco-friendly pesticide based on peppermint oil nanoemulsion: preparation, physicochemical properties, and its aphicidal activity against cotton aphid.

Using organic insecticides including plant oils, it is possible to design a new perspective for the control of insect pests. In this research, nanoemulsion formulations of Mentha piperita, wild-type essential oil (EO) were prepared utilizing high-energy ultrasonication process. Physicochemical properties of nanoemulsions were precisely studied by measurement various parameters including pH, viscosity, conductivity, and zeta potential. Experimental design by the aid of response surface methodology (RSM) was used to highlight the physicochemical roles of EO percentage (1% to 5% (v/v)) and surfactant concentration (3% to 15% (v/v)) for achieving minimum droplet diameter with high physical stability. The nanoemulsion formulations were then characterized using dynamic light scattering, transmission electron microscopy, and optical clarity. Afterward, an appropriate model between the variable factors (EO percentage and surfactant concentration) and the response (hydrodynamic particle size) was statistically developed. Under the optimum conditions, nanoemulsion with hydrodynamic particle size less than 10 nm with high physical stability is obtainable. Bioassay experiments were carried out to elucidate the effects of nanoemulsion on the cotton aphid. Synthesized nanoemulsion formulations showed relatively high contact toxicity (average value of LC50 was about 3879.5 ± 16.2 µl a.i./L) against the pest. On the basis of the obtained results, prepared nanoemulsion using M. piperita is potentially applicable as organic insecticides against cotton aphid. Graphical abstract.

Activity of Mentha piperita L. Ethanol Extract against Acetic Acid Bacteria Asaia spp.

Acetic acid bacteria belonging to the genus Asaia spp. are relatively new microbial contaminants in the beverage industry. These bacteria cause organoleptic changes such as increased turbidity, haziness and sour odor. In addition, they are able to form biofilms on the inner parts of production lines, and finally they can cause secondary contamination of final products. For this reason, new methods using effective and safe preservatives are being developed to improve microbial stability of soft beverages. The aim of the research was to investigate the effects of Mentha piperita L. ethanol extract against Asaia spp. biofilm formation. The bacterial adhesion was evaluated by a plate count method and luminometry, as well as fluorescence microscopy. The polyphenolic profile of the mint extract was determined on the basis of high-performance liquid chromatography (HPLC). The obtained microbiological results indicate bacteriostatic effect of mint extract at 10% (v/v) concentration. The plant extract also reduces the number of adhered bacterial cells on polystyrene surface.

In vitro antiviral, anti-inflammatory, and antioxidant activities of the ethanol extract of Mentha piperita L.

The objective of this study is to investigate the antiviral, anti-inflammatory, and antioxidant effects of the ethanol extract of Mentha piperita L. leaves (MPE). M. piperita L. leaves were extracted by reflux with ethanol. Total phenolic acid and total flavonoid content were determined. The antiviral activity of MPE against the respiratory syncytial virus (RSV) and the anti-inflammatory activity were evaluated in vitro. The levels of key pre-inflammatory mediators and cytokines including nitric oxide (NO), tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, and prostaglandin E2 (PGE2) were determined. The antioxidant activities were also evaluated using a colorimetry method. MPE contained high levels of phenolic acid and flavonoid, showed antiviral activity against RSV with a high selectivity index, and significantly decreased the production of NO, TNF-α, IL-6, and PGE2 in lipopolysaccharide-stimulated RAW 264.7 cells. Meanwhile, MPE showed potential free-radical scavenging activities. These results indicate that Mentha piperita L. might be a good source of medicinal plants.

Performance of Broilers Supplemented With Peppermint ( Mentha piperita L.) Powder.

This study was conducted to determine the effects of dietary supplementation of peppermint ( Mentha piperita L.) on the performance of broiler chicks. 500 Ross broiler chicks were divided into 5 treatment groups of 4 replications in a completely randomized design format. The diets were ISO-caloric and ISO-nitrogenous ones and contained 1.5, 3, 4.5, and 6 g/kg of peppermint powder. At start, growing, and end periods, the effects of peppermint powder on average daily weight gain, feed conversation ratio, and mortality rate were studied. The results of the present study showed that over a production period of 42 days peppermint had a significant effect on average daily weight gain and feed conversation ratio when compared with the control group ( P < .05). The level of 4.5 g/kg had the highest average daily weight gain (52.78 g), and control treatment with 46.98 g had the least average daily weight gain among different levels of peppermint. The level of 4.5 g/kg and 6 g/kg of peppermint had the least mortality compared to control treatment during training period ( P < .05). From this experiment, we can conclude that treatment with 4.5 g/kg peppermint powder has better performance and carcass characteristics in broilers.

Anti-Inflammatory Properties of Menthol and Menthone in Schistosoma mansoni Infection.

Schistosomiasis is a parasitic disease caused by several species of trematode worms and it is believed that more than 261 million people are affected worldwide. New drug development has become essential because there is a risk of the parasite becoming resistant to Praziquantel, the only drug available for this infection. This study evaluated parasitological, immunological and histological parameters in mice infected with Schistosoma mansoni and treated with an herbal commercial medicine. This drug consists of menthol (30-55%) and menthone (14-32%). A 60 day treatment regimen with the herbal medicine decreased the number of S. mansoni eggs in the feces, liver, and intestine and reduced the number of hepatic granulomas. We observed a reduction of 84% in blood eosinophilia and a decrease in the IL-4 and IL-10 blood levels after treatment. Therefore, we propose that schistosomiasis treatment with this herbal medicine for 60 days has an immunomodulatory and anti-inflammatory action in this animal model for schistosomiasis thus contributing to the decrease in physio pathological effects caused by S. mansoni infection.

Bioacessibility of phenolic compounds and antioxidant capacity in organic peppermint leaves

ABSTRACT The objective of this study was to analyze the chemical composition and bioaccessibility of phenolic compounds as well as their antioxidant capabilities of organic peppermint leaves after each phase of simulated digestion. Moisture was determined until a constant weight was obtained in an oven at 105 °C; ash was determined after sample calcination in a muffle furnace at 550 °C. The protein concentration was determined by the Macro-Kjeldahl method and lipid content by hot-extraction in a Soxhlet apparatus. Carbohydrates were calculated from differences and energy values based on the Atwater conversion factors. Total phenolic, flavonoid content, and antioxidant activity were determined by spectrophotometry. A four-step procedure was used for in vitro digestion. Organic peppermint was found to contain the following: 78% moisture, 1.7% ash, 1.5% lipids, 0.3% proteins, 17.7% carbohydrates, and a total of 85.5 kcal/100 g. Values of 705 mg GAE/100 g of phenolic, 918 mg QE/100 g of flavonoids, and 58.8 mg/g of vitamin C were also measured. It was discovered that total phenolics had the highest bioaccessible fraction relative to flavonoids; the salivary phase was identified as that with the highest release of these compounds and thus the phase in which peppermint showed significant antioxidant activity (1509 μmol TEAC/100g). This study demonstrated that organic peppermint has a high content of phenolic compounds that can be extracted from the alimentary matrix in the salivary and intestinal phases of the digestive system. Because of the antioxidant activity of these compounds, the use of this aromatic plant as seasonings and spices is relevant.

RESUMEN El objetivo de este estudio fue analizar la composición química de hojas de menta orgánica y la bioaccesibilidad de los compuestos fenólicos así como su capacidad antioxidante. Se determinó la humedad hasta obtener un peso constante en el horno a 105 °C, la ceniza se determinó en un horno de mufla a 550 °C. La concentración de proteína se determinó mediante el método Macro-Kjeldahl y los lípidos mediante extracción en un aparato Soxhlet. Los carbohidratos se calcularon por diferencia y energía basadas en los factores de conversión de Atwater. El contenido fenólico y la actividad antioxidante se determinaron por espectrofotometría. Se usó un procedimiento de cuatro pasos para la digestión in vitro. La menta orgánica contiene 78% de humedad, 1,7% de cenizas, 1,5% de lípidos, 0,3% de proteínas, 17,7% de carbohidratos y 85,5 kcal/100 g. También se midieron valores de 705 mg GAE/100g de fenólico, 918 mg QE/100 g de flavonoides y 58,8 mg/g de vitamina C. Se descubrió que los fenólicos tenían la fracción bioaccesible más alta en relación con los flavonoides; la fase salival se identificó como aquella con la mayor liberación de estos compuestos y, por lo tanto, la menta mostró una actividad antioxidante significativa (1509 μmol de TEAC/100 g). La menta orgánica tiene un alto contenido de fenólicos que se pueden extraer en las fases salival e intestinal. Debido a la actividad antioxidante de estos compuestos, el uso de esta planta como condimentos y especias es relevante.

Glandular trichomes and essential oils in developing peppermint leaves: I. Variation of peltate trichome number and terpene distribution within leaves.

The trichome number and the variability in mono and sequisterpene distribution of peltate trichomes within a leaf was investigated during development of peppermint (Mentha×piperita L.) leaves. A larger number of peltate trichomes was initiated on adaxial epidermises than abaxial epidermises, but during leaf development a greater gland number was produced on abaxial epidermises. Evidence showed that the trichome number was not fixed at the time of leaf emergence. On both epidermises, the trichome distribution was found to change with its position on the leaf. A striking monoterpene composition variability was present among individual trichomes and between different parts of the leaf. Different rates of peltate trichome development and distribution as well as significant differences in trichome number and density were found between the epidermises. A clear and opposite trend was found between menthone and menthol percentages during development. Menthone and menthol were also found to be present in larger amounts on adaxial epidermises, whereas neomenthol and isomenthol had highest percentages on abaxial epidermises. Of the total oil collected from peltate trichomes, 60%, was composed of menthone. isomenthol, menthol and neomenthol and of the remaining 40 %, more than half was represented by other mono and sesquiterpenes while the final percentage was made up of a few unidentified early eluting compounds of high Volatility.