Chemical constituents and biological activities of essential oil from Mentha longifolia: effects of different extraction methods

Comparison of quantity, quality and antibacterial activity of essential oil Mentha longifolia (L.) L. under different traditional and modern extraction methods

Extraction is the first and most important step in obtaining the effective ingredients of medicinal plants. Mentha longifolia (L.) L. is of considerable economic importance as a natural raw material for the food and pharmaceutical industries. Since the effect of different extraction methods (traditional and modern methods) on the quantity, quality and antimicrobial activity of the essential oil of this plant has not been done simultaneously; the present study was designed for the first time with the aim of identifying the best extraction method in terms of these features. For this purpose, extracting the essential oil of M. longifolia with the methods of hydrodistillation with Clevenger device (HDC), steam distillation with Kaiser device (SDK), simultaneous distillation with a solvent (SDE), hydrodistillation with microwave device (HDM), pretreatment of ultrasonic waves and Clevenger (U+HDC) and supercritical fluid (SF) were performed. Chemical compounds were identified by gas chromatography coupled with mass spectrometer (GC-MS). Antimicrobial activity of essential oils against various clinical microbial strains was evaluated by agar diffusion method and determination of the minimum inhibitory concentration and minimum bactericidal concentration (MIC and MBC). The results showed that the highest and lowest yields of M. longifolia leaf essential oil belonged to HDC (1.6083%) and HDM (0.3416%). The highest number of compounds belonged to SDK essential oil and was equal to 72 compounds (with a relative percentage of 87.13%) and the lowest number of compounds was related to the SF essential oil sample (7 compounds with a relative percentage of 100%). Piperitenone (25.2-41.38%), piperitenone oxide (22.02-0%), pulegone (10.81-0%) and 1,8-cineole (5-35.0%) are the dominant and main components of M. longifolia essential oil were subjected to different extraction methods. Antimicrobial activity results showed that the lowest MIC value belonged to essential oils extracted by HDM, SDK, SDE and U+HDC methods with a value of 1000 μg/mL was observed against Gram-negative bacteria Shigella dysenteriae, which was 5 times weaker than rifampin and 7 times weaker than gentamicin. Therefore, it can be concluded that in terms of efficiency of the HDC method, in terms of the percentage of compounds of the HDM method, and in terms of microbial activity, the SDK, HDM and U+HDC methods performed better.

Exploring anti-inflammatory and antioxidant-related quality markers of Artemisia absinthium L. based on spectrum-effect relationship

INTRODUCTION

Artemisia absinthium L. is a well-known medicinal, aromatic, and edible plant with important medicinal and economic properties and a long history of use in treating liver inflammation and other diseases; however, there has been insufficient progress in quality control.

OBJECTIVE

This study aimed to investigate the quality markers for the anti-inflammatory and antioxidant activities of A. absinthium based on spectrum-effect relationship analysis.

MATERIALS AND METHODS

Eighteen batches of A. absinthium from different origins were used. Chemical fingerprints were obtained by ultra-performance liquid chromatography (UPLC). The chemical compositions were identified by quadrupole-Orbitrap high-resolution mass spectrometry. Anti-inflammatory activity was assessed by inhibition of cyclooxygenase-2 and 15-lipoxygenase in vitro and inhibition of nitric oxide release in lipopolysaccharide-induced BV-2 cells. Antioxidant activity was assessed by DPPH and ABTS radical scavenging assays. The relationship between bioactivity and chemical fingerprints was then analyzed using chemometrics including gray relational analysis, bivariate correlation analysis, and orthogonal partial least squares analysis.

RESULTS

Different batches of A. absinthium extracts possessed significant anti-inflammatory and antioxidant activities to varying degrees. Eighty compounds were identified from A. absinthium, and 12 main common peaks were obtained from the UPLC fingerprints. P3 (chlorogenic acid), P5 (isochlorogenic acid A), and P6 (isochlorogenic acid C) were screened as the most promising active compounds by correlation analysis and further validated for their remarkable anti-inflammatory effects.

CONCLUSION

This is the first study to screen the quality markers of A. absinthium by establishing the spectrum-effect relationship, which can provide a reference for the development of quality standards and further research on A. absinthium.

Vasorelaxant effects of biochemical constituents of various medicinal plants and their benefits in diabetes

Endothelial function plays a pivotal role in cardiovascular health, and dysfunction in this context diminishes vasorelaxation concomitant with endothelial activity. The nitric oxide-cyclic guanosine monophosphate pathway, prostacyclin-cyclic adenosine monophosphate pathway, inhibition of phosphodiesterase, and the opening of potassium channels, coupled with the reduction of calcium levels in the cell, constitute critical mechanisms governing vasorelaxation. Cardiovascular disease stands as a significant contributor to morbidity and mortality among individuals with diabetes, with adults afflicted by diabetes exhibiting a heightened cardiovascular risk compared to their non-diabetic counterparts. A plethora of medicinal plants, characterized by potent pharmacological effects and minimal side effects, holds promise in addressing these concerns. In this review, we delineate various medicinal plants and their respective biochemical constituents, showcasing concurrent vasorelaxant and anti-diabetic activities.

Effects of MhMYB1 and MhMYB2 transcription factors on the monoterpenoid biosynthesis pathway in l-menthol chemotype of Mentha haplocalyx Briq

MAIN CONCLUSION

Transcription factors MhMYB1 and MhMYB2 correlate with monoterpenoid biosynthesis pathway in l-menthol chemotype of Mentha haplocalyx Briq, which could affect the contents of ( -)-menthol and ( -)-menthone. Mentha haplocalyx Briq., a plant with traditional medicinal and edible uses, is renowned for its rich essential oil content. The distinct functional activities and aromatic flavors of mint essential oils arise from various chemotypes. While the biosynthetic pathways of the main monoterpenes in mint are well understood, the regulatory mechanisms governing different chemotypes remain inadequately explored. In this investigation, we identified and cloned two transcription factor genes from the M. haplocalyx MYB family, namely MhMYB1 (PP236792) and MhMYB2 (PP236793), previously identified by our research group. Bioinformatics analysis revealed that MhMYB1 possesses two conserved MYB domains, while MhMYB2 contains a conserved SANT domain. Yeast one-hybrid (Y1H) analysis results demonstrated that both MhMYB1 and MhMYB2 interacted with the promoter regions of MhMD and MhPR, critical enzymes in the monoterpenoid biosynthesis pathway of M. haplocalyx. Subsequent virus-induced gene silencing (VIGS) of MhMYB1 and MhMYB2 led to a significant reduction (P < 0.01) in the relative expression levels of MhMD and MhPR genes in the VIGS groups of M. haplocalyx. In addition, there was a noteworthy decrease (P < 0.05) in the contents of ( -)-menthol and ( -)-menthone in the essential oil of M. haplocalyx. These findings suggest that MhMYB1 and MhMYB2 transcription factors play a positive regulatory role in ( -)-menthol biosynthesis, consequently influencing the essential oil composition in the l-menthol chemotype of M. haplocalyx. This study serves as a pivotal foundation for unraveling the regulatory mechanisms governing monoterpenoid biosynthesis in different chemotypes of M. haplocalyx.

Chemical Composition and Biocontrol Activity of Different Essential Oils against Soil-Borne Fungal Pathogens

In this study, the efficacy of the essential oil of Mentha longifolia, Achillea arabica and Artemisia absinthium plants were evaluated against important soil-borne fungal pathogens as Verticillium dahliae, Rhizoctonia solani, and Fusarium oxysporum. Essential oils were obtained from plants by hydrodistillation method and the chemical components of essential oils were determined by analyzing by gas chromatography-mass spectrometry. The main components found as piperitone oxide (13.61%), piperitenone oxide (15.55%), pulegone (12.47%), 1-menthone (5.75%), and camphor (5.75%) in M. longifolia, á-selinene 13.38%, camphor 13.34%, L-4-terpineneol 8.40%, (-)-á-Elemene 7.01%, 1,8-cineole 4.71%, and (-)-spathulenol 3.84% in A. arabica, and á-thujone (34.64%), 1,8-cineole (19.54%), pulegone (7.86%), camphene (5.31%), sabinene (4.86%), and germacrene-d (3.67%) in A. absinthium. The antifungal activities of the oils were investigated 0.05, 0.1, 0.25, 0.5, 1.00, and 2.00 μl/ml concentrations with the contact effect method. M. longifolia oil (1.00 and 2.00 μl/ml) has displayed remarkable antifungal effect and provided 100% inhibition on mycelial growth of V. dahliae, R. solani and F. oxysporum. The results obtained from this study may contribute to the development of new alternative and safe methods against soil-borne fungal pathogens.

Potassium humate and cobalt enhance peanut tolerance to water stress through regulation of proline, antioxidants, and maintenance of nutrient homeostasis

Water stress is an important factor that substantially impacts crop production. As a result, there is a need for various strategies that can mitigate these negative effects. One such strategy is the application of potassium humate (Kh) and cobalt (Co), which have been reported to enhance the resistance of crop plants. Therefore, the present experiment was designed to investigate whether the application of Kh and Co could positively affect proline, chlorophyll and mineral elements contents, and antioxidant defense systems which in turn will mitigate the negative impact of water stress under different irrigation strategies. In 2021 and 2022, an open-field experiments were conducted by using a split-plot design. The main plots were divided to represent different irrigation strategies (ST), with additional control of full irrigation requirements (ST1). Four STs were implemented, with ST1, followed by the application of 75%, 50%, and 25% irrigation strategies in ST2, ST3, and ST4 respectively, in the next irrigation, followed by the full requirements, and so on. In the subplots, peanut plants were treated with tap water (Control), Kh at 2 g l-1 and 3 g l-1, Co, Co + Kh 2 g l-1 and Co + Kh 3 g l-1. The yield was negatively affected by the implementation of ST4, despite the increase in proline contents. Furthermore, there was a decrease in relative water content, chlorophyll content, antioxidant enzymes, protein, and mineral nutrient elements. However, the application of Kh or Co showed better improvements in most of the studied parameters. It is worth noting that there was an antagonistic relationship between Co and iron/manganese, and the intensity of this relationship was found to depend on the STs implemented. The highest mineral nutrient accumulation, chlorophyll content, relative water content, protein content, oil content, seed yield, and water productivity were observed when peanut plants were treated with Kh 3 g l-1 + Co under the ST2 water strategy.

Impact of different sowing dates and irrigation levels on NPK absorption, yield and water use efficiency of maize

Upper Egypt experiences high temperatures during summer and low temperatures during winter, which significantly impacts the sowing dates of maize in this region. The productivity of maize crops and water use efficiency can be greatly affected by water stress and sowing dates (SDs). Therefore, it is crucial to determine the optimal irrigation level and SDs based on local conditions. To assess the effects, two irrigation levels were employed: (1) control (full irrigation water applied) and (2) 70% of irrigation water. Field experiments were conducted at the National Water Research Center's water studies and research complex station in Toshka. The aim was to evaluate two irrigation levels (full and limited irrigation) across five SDs (early: mid-February and March, normal: mid-June, and late: mid-August and September) in both 2019 and 2020, in order to identify the ideal sowing date (SD) and irrigation level. The normal SD resulted in an increased the growth season length between plant emergence and maturity. Conversely, the late SD reduced the number of days until plant maturity, resulting in higher grain yields and water use efficiency (WUE). Notably, the SD in September, coupled with the 70% irrigation level, yielded the highest productivity and WUE, with a productivity of 7014 kg ha-1 and a WUE of 0. 9 kg m-3. Based on the findings, it is recommended that regions with similar conditions consider cultivating maize seeds in September, adopting a 70% irrigation level, to achieve optimal N uptake, growth traits (plant height, ear length, ear weight, number of rows per ear, and grain index weight), yield, and WUE.

Mentha: Nutritional and Health Attributes to Treat Various Ailments Including Cardiovascular Diseases

A poor diet, resulting in malnutrition, is a critical challenge that leads to a variety of metabolic disorders, including obesity, diabetes, and cardiovascular diseases. Mentha species are famous as therapeutic herbs and have long served as herbal medicine. Recently, the demand for its products, such as herbal drugs, medicines, and natural herbal formulations, has increased significantly. However, the available literature lacks a thorough overview of Mentha phytochemicals' effects for reducing malnutritional risks against cardiovascular diseases. In this context, we aimed to review the recent advances of Mentha phytochemicals and future challenges for reducing malnutritional risks in cardiovascular patients. Current studies indicated that Mentha species phytochemicals possess unique antimicrobial, antidiabetic, cytotoxic, and antioxidant potential, which can be used as herbal medicine directly or indirectly (such as food ingredients) and are effective in controlling and curing cardiovascular diseases. The presence of aromatic and flavor compounds of Mentha species greatly enhance the nutritional values of the food. Further interdisciplinary investigations are pivotal to explore main volatile compounds, synergistic actions of phytochemicals, organoleptic effects, and stability of Mentha sp. phytochemicals.

Process Optimization for Supercritical Carbon Dioxide Extraction of Origanum vulgare L. Essential Oil Based on the Yield, Carvacrol, and Thymol Contents

Background

Origanum vulgare L. essential oil (OEO) is widely known for its good biological activity, but different extraction methods with significant implications on the yield of OEO and the content of the thymol and carvacrol. As an efficient method for extracting essential oils (EO), the supercritical carbon dioxide extraction (SC-CO2) can improve the yield of EOs while protecting their main active components from loss.

Objective

In this study, the process optimization of SC-CO2 of OEO was carried out. The effects of extraction pressure, temperature, time, and modifier concentration on the composite score of OEO extraction process were investigated.

Method

Response surface analysis was performed using a Box-Behnken design with three levels and four independent variables. Steam distillation (SD) and lipophilic solvents (n-hexane) extraction (LSE) were compared with SC-CO2 for OEO yields. OEOs extracted by the three methods were qualitatively and semi-quantitatively analyzed by gas chromatography quadrupole-time-of-flight mass spectrometry and gas chromatography-flame ionization detector.

Results

The results showed that extraction pressure was the most significant factor affecting the OEO yield, thymol, and carvacrol content. In the optimal conditions (pressure: 217 bar, temperature: 54°C, time: 2 h, modifier concentration: 14%), the yield of OEO reached up to 1.136%, and the contents of thymol and carvacrol reached 53.172  and 41.785 mg/g, respectively.

Conclusions

SC-CO2 was the best extraction method compared to the other two methods. Under the optimal conditions, yield and the content of main components can be effectively improved. It can provide a theoretical basis for the industrial extraction of OEO.

Highlights

Taking the comprehensive score as the index, the interaction between the four independent variables in the supercritical fluid extraction process was evaluated by the response surface method. The effects of extraction parameters on the yield of EOs and the contents of thymol and carvacrol were comprehensively investigated.

Antioxidant, Antimicrobial and Antibiofilm Properties of Glechoma hederacea Extracts Obtained by Supercritical Fluid Extraction, Using Different Extraction Conditions

Glechoma hederacea var. longituba is a herbaceous plant from the Lamiaceae family, used in herbal medicine. In this work, we aimed to assess the total phenolic content, antioxidant, antimicrobial and antibiofilm activity of extracts obtained from G. hederacea via supercritical dioxide extraction with methanol as a co-solvent under different extraction conditions. The results showed that the activity of the obtained SC-CO2 extracts is strongly dependent on the extraction temperature. Significantly higher total polyphenol content, as well as antioxidant and antimicrobial activity towards bacteria and yeasts, was observed in the extract obtained at 40 °C, compared to extracts obtained at 50 °C and 60 °C; however, antifungal activity against filamentous fungi was not dependent on the extraction conditions. Antimicrobial activity also depended on the microorganism type. Higher sensitivity was exhibited by Gram-positive bacteria than by Gram-negative bacteria, with S. aureus and P. aeruginosa being the most sensitive species among each group. The most susceptible fungi were Candida albicans and Sclerotinia sclerotiorum. The antibiofilm activity was differentiated and depended on the extraction conditions, the microorganism and the method of biofilm treatment. All tested extracts inhibited biofilm formation, with the extract obtained at 40 °C showing the highest value, whereas only extract obtained at 60 °C efficiently removed mature biofilm.

Antioxidant Activity and Bioactive Compounds of Lamium album Flower Extracts Obtained by Supercritical Fluid Extraction

In this research, supercritical CO2 extraction is applied to extract bioactive compounds from Lamium album (white dead nettle, Lamiaceae). Extraction was performed at various temperatures (40, 50, and 60 °C) using methanol as co-solvent at a constant flow rate of CO2, methanol, and pressure. The collected extracts were characterized in terms of antioxidant capacity by using DPPH, ABTS and FRAP in vitro antioxidant activity assays, whereas the Folin–Ciocalteu procedure was employed to estimate the total phenols content (TPC). On the other hand, phenolic compounds in the extracts were quantitated by liquid chromatography coupled with a photodiode array detector (UPLC-PDA) and confirmed with a mass detector (TQD). The extracts have shown high TPC ranged between 234.17 to 650.17 mg GAE/g extract. DPPH scavenging of the extracts was estimated and obtained EC50 values ranged from 0.12 to 0.37 mg/mL of solution. The ABTS radical scavenging activity ranged from 43.20 to 44.53 µg TE/g. The FRAP value was found within the range of 19.48 to 44.74 µmol TE/g of extract. Differences between extraction conditions were observed. In this research, 50 °C/250 bar was efficient for the TPC, DPPH, ABTS, and FRAP assays; moreover, statistically, TPCs and FRAP assay showed significant differences between the conditions at α = 0.05. The identification of phenolic compounds in the obtained extract of Lamium album flowers, using UPLC/PDA, revealed that chrysin, pinostrobin, myricetin, and trans-3-hydroxycinnamic acid were the significant molecules present, which may be responsible for the high content of polyphenols and antioxidant activity. The results obtained indicated that SC-CO2 could be considered an alternative method for extracting bioactive compounds of Lamium album. High antioxidant activity and the presence of various bioactive compounds indicate the potential of this plant from the Lamiaceae family and the possibility of its application in various industries, including agriculture, food technology, or pharmacy.

The Modulation of PCSK9 and LDLR by Supercritical CO2 Extracts of Mentha longifolia and Isolated Piperitone Oxide, an In Vitro Study

In the present study the ability of supercritical carbon dioxide (SCO₂) extracts of M. longifolia L. leaves to modulate low-density lipoprotein receptor (LDLR) and proprotein convertase subtilisin/kexin type 9 (PCSK9) expression was evaluated in cultured human hepatoma cell lines Huh7 and HepG2. Two SCO₂ extracts, one oil (ML-SCO₂) and a semisolid (MW-SCO₂), were subjected to detailed chemical characterization by mono- and bidimensional nuclear magnetic resonance (1D, 2D-NMR), gas chromatography coupled with mass spectrometry (GC-MS) and liquid chromatography coupled with mass spectrometry (LC-MS). Chemical analysis revealed significant amounts of fatty acids, phytosterols and terpenoids. ML-SCO₂ was able to induce LDLR expression at a dose of 60 µg/mL in HuH7 and HepG2 cell lines. Furthermore, ML-SCO₂ reduced PCSK9 secretion in a concentration-dependent manner in both cell lines. Piperitone oxide, the most abundant compound of the volatile constituent of ML-SCO₂ (27% w/w), was isolated and tested for the same targets, showing a very effective reduction of PCSK9 expression. The overall results revealed the opportunity to obtain a new nutraceutical ingredient with a high amount of phytosterols and terpenoids using the SCO₂ extraction of M. longifolia L., a very well-known botanical species used as food. Furthermore, for the first time we report the high activity of piperitone oxide in the reduction of PCSK9 expression.