Mentha Canadensis Research Articles

Linarine inhibits inflammatory responses in dry eye disease mice by modulating purinergic receptors.

Linarine is a natural chemical component widely found in Buddleja officinalis Maxim., Chrysanthemum indicum L., Mentha canadensis L., and other medicinal plants. Modern pharmacological studies have shown that linarine with good anti-inflammatory and antioxidant activities can inhibit the proliferation and induce apoptosis of many kinds of tumor cells. Moreover, linarine showed protective effect on the liver, kidneys, and other organs. Inflammation model of human corneal epithelial cell (HCEC) was constructed using NaCl induction, and cytotoxicity was detected by the CCK8 assay. The levels of inflammatory factors tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β) were measured using Enzyme-linked immunoassay (ELISA). Chronic painful stimulation (tail clamping) in combination with Benzalkonium Chloride Solution drops in a desiccator established a mouse model of dry eye disease (DED). The following parameters were recorded: body mass, anal temperature, tear secretion, tear film rupture time, and corneal fluorescein staining. The levels of inflammatory factors mitogen activated protein kinase (MAPK), nuclear factor kappa-B (NF-kB), c-Jun N-terminal kinase (JNK), IL-1β, Interleukin 18(IL-18), A2A, A3, P2X4, P2X7, P2Y1 were measured by using immunofluorescence (IF) staining. Linarine can inhibit the secreation of TNF-α, and IL-1β in HCECs. Linarine prolonged tear film rupture time, promoted tear secretion, repaired corneal damage, and reduced the levels of inflammatory factors of MAPK, NF-kB, JNK, IL-1β, IL-18, and modulated the levels of the purinergic receptor. Linarine is effective in treating dry eye in mice by inhibiting purinergic receptors-mediated inflammatory response.

Transcriptional regulation and functional validation analysis of the McbZIP1 in Mentha canadensis L.

Monoterpenoids are the main components of Mentha canadensis essential oil. Monoterpene biosynthetic pathways have been explored, but the regulatory mechanisms remain unclarified. We identified an abscisic acid (ABA)-inducible A-type basic leucine zipper (bZIP) transcription factor McbZIP1 that was localized in the nucleus and positively regulates monoterpene synthesis. McbZIP1 was expressed in most M. canadensis tissues and was induced under ABA, mannitol, and NaCl treatments. McbZIP1 had transcriptional activity in yeast and the N terminus (amino acids 75–117) was sufficient for transactivation. Yeast one-hybrid and Dual-Luciferase assays showed that McbZIP1 binds to ABA-responsive elements in the promoter region of limonene synthase gene. Yeast two-hybrid and biomolecular fluorescence complementation assays revealed that McbZIP1 interacts with McSnRK2.4. Overexpression of McbZIP1 in peppermint resulted in dramatically up-regulated monoterpene biosynthesis gene levels and increased menthol contents. The results support a transcriptional regulation mechanism in which McbZIP1 serves as a positive regulator of menthol biogenesis. These findings contribute to the molecular mechanism of monoterpenoid biogenesis, which may have uses in genetic engineering and menthol production.

Exploring anti-inflammatory non-essential oil metabolites in Mentha canadensis: Insights into neutrophil extracellular trap inhibition for functional health promotion

Mentha canadensis, commonly known as Canadian mint, has been utilized in herbal medicine for its menthol content, addressing digestive and respiratory issues. It also serves as a popular culinary herb, adding a refreshing minty flavor to dishes and beverages. However, research on its non-essential oils and their anti-inflammatory potential is lacking. This study utilized multi-informative molecular networking to comprehensively profile the non-essential oils of M. canadensis. Cinnamic acid derivatives were identified as potent anti-inflammatory agents, with high activity ratings. By analyzing the Molecular Networking (MN) database, fourteen metabolites were identified. Compounds within the bioactive MN clusters demonstrate significant inhibition of reactive oxygen species generation, playing a crucial role in the management of oxidative stress. These compounds also effectively suppressed the formation of neutrophil extracellular traps. In conclusion, salvianolic acid B (IC50: 0.08 μM) was promoted as the chemical marker of M. canadensis for its potential anti-inflammatory effect. This study pioneers the identification of anti-inflammatory metabolites in M. canadensis' non-essential oils, offering insights into its therapeutic properties and potential for health-centric culinary applications.

Insecticidal Activity of Essential Oils and Their Synergistic Effect on Improving the Efficacy of β-Cypermethrin against Blattella germanica.

We screened the contact activity of 32 commercial essential oils (EOs) and their synergistic effect with β-cypermethrin against Blattella germanica. Results showed that the most effective EOs against B. germanica were from Illicium verum, Syzygium aromaticum, and Cinnamomum camphora, with LD50 values of less than 500 μg/insect. The most potent synergistic effects of β-cypermethrin on B. germanica were from Dysphania ambrosioides and Mentha canadensis. Both oils have a co-toxic factor of 133.33. The results of the major compound testing of the EOs showed that trans-anisaldehyde and thymol have the best insecticidal activity against B. germanica, with LD50 values of 141.30 and 138.61 μg/insect, respectively. The compounds with the best synergistic effect on β-cypermethrin were γ-terpinene and linalool at a concentration of 0.5%. The co-toxic factors for γ-terpinene and linalool were 150 and 133.33, respectively, which were similar to the synergistic effect observed with 2% piperonyl butoxide.

Behavioral preferences of Solenopsis invicta Buren to essential oils and active compounds from amiaceae plants

The red imported fire ant (RIFA) (Solenopsis invicta Buren) has caused serious ecological and public safety problems in invasive areas. While extensive use of pesticides to control RIFA may negatively affect human health and environment, essential oils (EOs) of Lamiaceae possessing aromatic smell and multiple biological activities are potential alternatives of chemical pesticides. In this study, we evaluated the behavioral preferences of different castes of RIFA towards the EOs from five species of Lamiaceae plants (Salvia miltiorrhiza, Perilla frutescens, Pogostemon cablin, Schizonepeta tenusfolia, Mentha canadensis), and then investigated the active compounds in these EOs that trigger insect behavioral preferences by gas chromatography-electroantennographic detection (GC-EAD). The results of behavioral experiment indicated that three EOs strongly altered the behavior of RIFA. Notably, all concentrations of P. frutescens EO showed a significant repellent activity on virgin queen ants, with a repellent rate of 62.50% at the lowest concentration of 2 μg/ml. The repellent effect of S. tenusfolia EO against small worker ants reached a very significant difference between control and treatment groups, with the highest repellent rate of 85.00% observed at 1000 μg/ml. Save for the lowest concentration 2 μg/ml, other doses of M. canadensis EO showed a remarkable repellent effect on small worker ants, demonstrating a positive dose-effect relationship (with repellent rates of 77.50% and 65.00% at 1000 and 8 μg/ml, respectively). A total of 39 EAD-active compounds were detected in these EOs, and 12 of them were subsequently evaluated for behavioral preferences of RIFA. Our findings indicated that six compounds (menthone, menthol, caryophyllene oxide, pulegone, 3-methylcyclopentanol, eugenol) consistently triggered behavioral preferences in worker ants. Meanwhile, six compounds, including borneol, eugenol, phenylethyl alcohol, perilla ketone, 3-methylcyclopentanol, α-guaiene, were found to significantly alter the behavioral selectivity of virgin queen ants. These results may help to develop application value of selected Lamiaceae plants EOs and contribute to the exploration of new green control methods for invasive pests.

Cloning and expression pattern analysis of abscisic acid receptor gene McPYL4 in Mentha canadensis

Mentha canadensis is a traditional Chinese herb with great medicinal and economic value. Abscisic acid(ABA) receptor PYLs have important roles in plant growth and development and response to adversity. The M. canadensis McPYL4 gene was cloned, and its protein characteristics, gene expression, and protein interactions were analyzed, so as to provide genetic resources for genetic improvement and molecular design breeding for M. canadensis resistance. Therefore, the protein characteristics, subcellular localization, gene expression pattern, and protein interactions of McPYL4 were analyzed by bioinformatics analysis, transient expression of tobacco leaves, RT-qPCR, and yeast two-hybrid(Y2H) techniques. The results showed that the McPYL4 gene was 621 bp in length, encoding 206 amino acids, and its protein had the conserved structural domain of SRPBCC and was highly homologous with Salvia miltiorrhiza SmPYL4. McPYL4 protein was localized to the cell membrane and nucleus. The McPYL4 gene was expressed in all tissue of M. canadensis, with the highest expression in roots, followed by leaves, and it showed a pattern of up-regulation followed by down-regulation in leaves 1-8. In both leaves and roots, the McPYL4 gene responded to the exogenous hormones ABA, MeJA, and the treatments of drought, AlCl_3, NaCl, CdCl_2, and CuCl_2. Moreover, McPYL4 was up-regulated for expression in both leaves and roots under the MeJA treatment, as well as in leaves treated with AlCl_3 stress for 1 h, whereas McPYL4 showed a tendency to be down-regulated in both leaves and roots under other treatments. Protein interactions showed that McPYL4 interacted with AtABI proteins in an ABA-independent manner. This study demonstrated that McPYL4 responded to ABA, JA, and several abiotic stress treatments, and McPYL4 was involved in ABA signaling in M. canadensis and thus in the regulation of leaf development and various abiotic stresses in M. canadensis.

Identification and functional analysis of jasmonic acid signaling repressor McJAZ8 gene in Mentha canadensis

Mentha canadensis, as a plant with medicinal and culinary uses, holds significant economic value. Jasmonic acid signaling repressor JAZ protein has a crucial role in regulating plant response to adversity stresses. The M. canadensis McJAZ8 gene is cloned and analyzed for protein characterization, protein interactions, and expression patterns, so as to provide genetic resources for molecular breeding of M. canadensis for stress tolerance. This experiment will analyze the protein structural characteristics, subcellular localization, protein interactions, and gene expression of McJAZ8 using bioinformatics, yeast two-hybrid(Y2H), transient expression in tobacco leaves, qRT-PCR, and other technologies. The results show that:(1)The full length of the McJAZ8 gene is 543 bp, encoding 180 amino acids. The McJAZ8 protein contains conserved TIFY and Jas domains and exhibits high homology with Arabidopsis thaliana AtJAZ1 and AtJAZ2.(2)The McJAZ8 protein is localized in the nucleus and cytoplasm.(3)The Y2H results show that McJAZ8 interacts with itself or McJAZ1/3/4/5 proteins to form homologous or heterologous dimers.(4)McJAZ8 is expressed in different tissue, with the highest expression level in young leaves. In terms of leaf sequence, McJAZ8 shows the highest expression level in the fourth leaf and the lowest expression level in the second leaf.(5) In leaves and roots, the expression of McJAZ8 is upregulated to varying degrees under methyl jasmonate(MeJA), drought, and NaCl treatments. The expression of McJAZ8 shows an initial upregulation followed by a downregulation pattern under CdCl_2 treatment. In leaves, the expression of McJAZ8 tends to gradually decrease under CuCl_2 treatment, while in roots, it initially decreases and then increases before decreasing again. In both leaves and roots, the expression of McJAZ8 is downregulated to varying degrees under AlCl_(3 )treatment. This study has enriched the research on jasmonic acid signaling repressor JAZ genes in M. canadensis and provided genetic resources for the molecular breeding of M. canadensis.

Exploring insecticidal properties and acetylcholinesterase inhibition by three plant essential oils against the cheese skipper Piophila casei (Diptera: Piophilidae)

Piophila casei is a highly problematic pest in the food industry, specifically ham processing. However, given the specific requirements of the food industry, there is an urgent requirement for environmentally friendly, more efficient and safer approaches to manage the P. casei. This study aimed to assess the fumigant and contact toxicity of three plant essential oils (EOs) against P. casei by examining their impact on P. casei acetylcholinesterase (AChE) activity and investigating the potential mode of action of their primary constituents using molecular docking and molecular dynamics simulations. The results indicate that Mentha canadensis EO exhibited substantial contact toxicity against P. casei, with the LC50 of 2.98 μL/cm2 after 48-h contact with second instar larvae and an IC50 of 4.99 μL/cm2 for inhibiting pupation in third instar larvae over a 5-day period. Moreover, M. canadensis and Jasminum sambac EOs demonstrated their significant fumigant toxicity, with LT50 of 7.06 and 17.55 h, respectively, at an air concentration of 0.5 mL/L. Among the three EOs, M. canadensis EO displayed the most effective inhibition of P. casei AChE activity, while the other two EOs also exhibited certain levels of activity inhibition, shedding light on the insecticidal mechanisms of EOs against P. casei. Additionally, the molecular docking and molecular dynamics simulations were employed to investigate the mechanisms of action and binding capacity of menthol and limonene, the major constituents of M. canadensis EO. The experimental validation verified the efficacy of menthol. Overall, the results demonstrate that M. canadensis EO and its components exhibit remarkable insecticidal properties and high safety profiles, rendering them suitable for insecticide deployment in pest management within the food industry.

Flora of six Lower Mississippi River islands (U.S.A.)

Lower Mississippi River islands are part of the last remaining floodplain habitat of the river, and studying their biodiversity is important to understand the river ecosystem. We conducted a floristic survey of six Lower Mississippi River islands between river miles 668 and 526 in southern Arkansas and northern Mississippi. These islands contain a variety of habitats and span a range of sizes, from 106 to 697 vegetated hectares. We identified 491 taxa (485 species plus six infraspecific taxa) from 2,310 specimens collected from June 2020 to December 2021. These taxa are within 89 families and 282 genera, and 100 (20.6%) species are not native to the Mississippi River drainage basin. Nine taxa found on Arkansas islands are tracked by the Arkansas Natural Heritage Commission for conservation. Five taxa found in Mississippi are tracked by the Mississippi Natural Heritage Program. We found five taxa that had not previously been reported in Arkansas (Equisetum variegatum, Achyranthes japonica var. hachijoensis, Stellaria aquatica, Potentilla paradoxa, Cyperus diandrus) and seven previously unreported in Mississippi (Euploca convolvulacea, Sisymbrium loeselii, Chaiturus marrubiastrum, Mentha canadensis, Potentilla norvegica, P. paradoxa, Physalis mollis). Additionally, we collected 266 Arkansas county records, including 132 in Phillips, 64 in Desha, and 28 in Chicot counties, respectively, and 42 in Washington County, Mississippi. The high number of new encounters and tracked species found emphasizes the need for more botanical study on Lower Mississippi River islands. Of the 485 species in the flora, we found 110 species on all six islands (22.7%), 43 on five of the six islands, 47 on four islands, 75 on three islands, 72 on two islands, and 138 on only one island (28.5%). The number of unique species found on only one island illustrates how variable and dynamic these islands are in this riparian zone.

Isolation of Anti-SARS-CoV-2 Natural Products Extracted from Mentha canadensis and the Semi-synthesis of Antiviral Derivatives.

Traditional herbal medicine offers opportunities to discover novel therapeutics against SARS-CoV-2 mutation. The dried aerial part of mint (Mentha canadensis L.) was chosen for bioactivity-guided extraction. Seven constituents were isolated and characterized by nuclear magnetic resonance (NMR) and mass spectrometry (MS). Syringic acid and methyl rosmarinate were evaluated in drug combination treatment. Ten amide derivatives of methyl rosmarinate were synthesized, and the dodecyl (13) and 3-ethylphenyl (19) derivatives demonstrated significant improvement in the anti-SARS-CoV-2 plaque reduction assay, achieving IC50 of 0.77 and 2.70 μM, respectively, against Omicron BA.1 as compared to methyl rosmarinate's IC50 of 57.0 μM. Spike protein binding and 3CLpro inhibition assays were performed to explore the viral inhibition mechanism. Molecular docking of compounds 13 and 19 to 3CLpro was performed to reveal potential interaction. In summary, natural products with anti-Omicron BA.1 activity were isolated from Mentha canadensis and derivatives of methyl rosmarinate were synthesized, showing 21- to 74-fold improvement in antiviral activity against Omicron BA.1.

The non-specific lipid transfer protein McLTPII.9 of Mentha canadensis is involved in peltate glandular trichome density and volatile compound metabolism.

Mentha canadensis L. is an important spice crop and medicinal herb with high economic value. The plant is covered with peltate glandular trichomes, which are responsible for the biosynthesis and secretion of volatile oils. Plant non-specific lipid transfer proteins (nsLTPs) belong to a complex multigenic family involved in various plant physiological processes. Here, we cloned and identified a non-specific lipid transfer protein gene (McLTPII.9) from M. canadensis, which may positively regulate peltate glandular trichome density and monoterpene metabolism. McLTPII.9 was expressed in most M. canadensis tissues. The GUS signal driven by the McLTPII.9 promoter in transgenic Nicotiana tabacum was observed in stems, leaves, and roots; it was also expressed in trichomes. McLTPII.9 was associated with the plasma membrane. Overexpression of McLTPII.9 in peppermint (Mentha piperita. L) significantly increased the peltate glandular trichome density and total volatile compound content compared with wild-type peppermint; it also altered the volatile oil composition. In McLTPII.9-overexpressing (OE) peppermint, the expression levels of several monoterpenoid synthase genes and glandular trichome development-related transcription factors-such as limonene synthase (LS), limonene-3-hydroxylase (L3OH), geranyl diphosphate synthase (GPPS), HD-ZIP3, and MIXTA-exhibited varying degrees of alteration. McLTPII.9 overexpression resulted in both a change in expression of genes for terpenoid biosynthetic pathways which corresponded with an altered terpenoid profile in OE plants. In addition, peltate glandular trichome density was altered in the OE plants as well as the expression of genes for transcription factors that were shown to be involved in trichome development in plants.

Overexpression of a WRKY transcription factor McWRKY57-like from Mentha canadensis L. enhances drought tolerance in transgenic Arabidopsis

BackgroundDrought has become a major environmental problem affecting crop production. Members of the WRKY family play important roles in plant development and stress responses. However, their roles in mint have been barely explored.ResultsIn this study, we isolated a drought-inducible gene McWRKY57-like from mint and investigated its function. The gene encodes a group IIc WRKY transcription factor, McWRKY57-like, which is a nuclear protein with a highly conserved WRKY domain and a C2H2 zinc-finger structure, and has transcription factor activity. Its expression levels were examined in different tissues of mint and under the treatment of mannitol, NaCl, abscisic acid, and methyl jasmonate. We found that McWRKY57-like overexpression in Arabidopsis significantly increased drought tolerance. Further studies showed that under drought stress, McWRKY57-like-overexpressing plants had higher chlorophyll, soluble sugar, soluble protein, and proline contents but lower water loss rate and malondialdehyde content than wild-type plants. Moreover, the activities of antioxidant enzymes catalase, superoxide dismutase, and peroxidase were enhanced in McWRKY57-like transgenic plants. Furthermore, qRT-PCR analysis revealed that the drought-related genes AtRD29A, AtRD29B, AtRD20, AtRAB18, AtCOR15A, AtCOR15B, AtKIN2, and AtDREB1A were upregulated in McWRKY57-like transgenic plants than in wild-type Arabidopsis under simulated drought conditions.ConclusionThese data demonstrated that McWRKY57-like conferred drought tolerance in transgenic Arabidopsis by regulating plant growth, osmolyte accumulation and antioxidant enzyme activities, and the expression of stress-related genes. The study indicates that McWRKY57-like plays a positive role in drought response in plants.

Genetic identification of the original plant species for Mentha Herb listed in the Japanese Pharmacopoeia and analyses of their essential oil composition

Mentha arvensis Linné var. piperascens Malinvaud is an original plant species for "Mentha Herb (Hakka, ハッカ)" and "Mentha Oil (Hakka-yu, ハッカ)" listed in the Japanese Pharmacopoeia, whereas Mentha canadensis L. is that of "Mint oil, partly dementholised" listed in the European Pharmacopoeia. Although these two species are thought to be taxonomically identical, there are no data on whether the source plants of the Mentha Herb products distributed in the Japanese market are actually M. canadensis L. This is an important issue for international harmonization of the Japanese Pharmacopoeia and European Pharmacopoeia. In this study, 43 Mentha Herb products collected from the Japanese market and two plant samples of the original species of Japanese Mentha Herb harvested in China were identified by sequence analyses of the rpl16 regions in the chloroplast DNA, and the composition of their ether extracts was analyzed by GC-MS. Almost all samples were identified as M. canadensis L., and the main component of their ether extracts was menthol, although there were variations in their composition. However, there were some samples thought to be derived from other Mentha species, even though their main component was menthol. For quality control of Mentha Herb, it is important to be sure of not only the original plant species but also the composition of the essential oil and amount of menthol as the characteristic compound.

Effects of thermal-olfactory interactions on emotional changes in urban outdoor environments

We selected three representative spaces on a university campus with different olfactory stimuli (Lavandula officinalis, Rosa rugosa, and Mentha canadensis) to investigate the effects of thermal-olfactory interactions on emotional responses to outdoor environments in Xi'an, China. Meteorological measures combined with electroencephalograms (EEG) of 81 respondents were examined before and after fragrance stimuli. Respondents' subjective perception and emotional responses were determined using subjective questionnaires and Positive and Negative Affect Schedule (PANAS). EEG changes were analyzed among physiological equivalent temperature (PET) ranges and fragrance types. We demonstrated that: 1) fragrance comfort vote (FCV) had a significant crossover effect on thermal sensation vote and thermal comfort vote (TCV). Increasing FCV could relieve thermal discomfort caused by high air temperature in summer. 2) Stimulated by R. rugosa and L. officinalis, thermal discomfort may produce a “revenge effect” resulting in fragrance discomfort. 3) After fragrance stimuli, fragrance pleasantness vote, FCV and TCV were positively related to positive affect (PA), but negatively related to negative affect (NA). M. canadensis and L. officinalis resulted in an increase in PA and decrease in NA, while R. rugosa always decreased PA. 4) When 30.80 °C ≤ PET < 44.53 °C, the beta-band (13–30 Hz) increased significantly due to olfactory stimuli. When 44.53 °C ≤ PET < 58.27 °C, the alpha-band (8–13 Hz) clearly decreased. Under different PETs, theta-band (4−8 Hz) was largely influenced by olfactory stimuli.

Mentha canadensis attenuates adiposity and hepatic steatosis in high-fat diet-induced obese mice.

Obesity is a major risk factor for metabolic syndrome, a global public health problem. Mentha canadensis (MA), a traditional phytomedicine and dietary herb used for centuries, was the focus of this study to investigate its effects on obesity. Thirty-five male C57BL/6J mice were randomly divided into 2 groups and fed either a normal diet (ND, n = 10) or a high-fat diet (HFD, n = 25) for 4 weeks to induce obesity. After the obesity induction period, the HFD-fed mice were randomly separated into 2 groups: one group continued to be fed HFD (n = 15, HFD group), while the other group was fed HFD with 1.5% (w/w) MA ethanol extract (n = 10, MA group) for 13 weeks. The results showed that body and white adipose tissue (WAT) weights were significantly decreased in the MA-supplemented group compared to the HFD group. Additionally, MA supplementation enhanced energy expenditure, leading to improvements in plasma lipids, cytokines, hepatic steatosis, and fecal lipids. Furthermore, MA supplementation regulated lipid-metabolism-related enzyme activity and gene expression, thereby suppressing lipid accumulation in the WAT and liver. These findings indicate that MA has the potential to improve diet-induced obesity and its associated complications, including adiposity, dyslipidemia, hepatic steatosis, and inflammation.

A stable method for Agrobacterium-mediated transformation of Mentha piperita and Mentha canadensis using internodal explants

A stable method for Agrobacterium-mediated transformation of Mentha piperita and Mentha canadensis using internodal explants

Novel Integrated Tiered Cumulative Risk Assessment of Heavy Metals in Food Homologous Traditional Chinese Medicine Based on a Real-Life-Exposure Scenario.

In order to serve population health better, the first integrated tiered decision tree for cumulative risk assessment of co-exposure of Pb-, Cd-, and As-associated health risks in food homologous traditional Chinese medicine (TCM) was designed, after measuring their concentrations by inductively coupled plasma-mass spectroscopy (ICP-MS). Basically, our three-step decision tree involving hazard quotient (HQ), hazard index (HI), and target-organ toxicity dose (TTD) modification of the HI method was developed to evaluate the potential risks of 949 batches of 15 types of food homologous TCM. To acquire a real-life exposure scenario, the cumulative risk assessment model was established by optimizing key parameters, such as ingestion rates, frequency, and duration of exposure to food homologous TCM based on questionnaire data. As a result, the mean concentrations of Pb, Cd, and As in 949 batches of food homologous TCM were 0.896, 0.133, and 0.192 mg/kg, respectively. The HQ values of As for Angelica sinensis (Oliv.) Diels and Houttuynia cordata Thunb. were 1.04 and 1.01, respectively, for females. Other HQs of Pb, Cd, or As in food homologous TCM were lower than 1 for both males and females. However, after rapid screening of the co-exposure health risks of heavy metals by the HI method, cumulative risk assessment results acquired by TTD modification of the HI method implied that the potential health risks associated with the co-exposure of Pb, Cd, and As in Lonicera japonica Thunb. and Houttuynia cordata Thunb. ingested as both TCM and food were of concern in the clinic. Additionally, the cumulative risks of Pb, Cd, and As in Mentha canadensis L., Chrysanthemum indicum L., and Zaocys dhumnades (Cantor) only used as food exceeded the human tolerance dose. Collectively, our innovation on the tiered strategy of decision tree based on a real-life exposure scenario provides a novel approach engaging in the cumulative risk assessment of heavy metals in food homologous TCM. All in all, such effort attempts to scientifically guide the rational use of TCM in the treatment of the complex diseases and the improvement of population health.

Characterisation of the Mentha canadensis R2R3-MYB transcription factor gene McMIXTA and its involvement in peltate glandular trichome development

BackgroundMentha canadensis L. has important economic value for the production of essential oils, which are synthesised, secreted and stored in peltate glandular trichomes. As a typical multicellular secretory trichome, glandular trichomes are important biological factories for the synthesis of some specialised metabolites. However, little is known about the molecular mechanism of glandular trichome development in M. canadensis.ResultsIn this study, the R2R3-MYB transcription factor gene McMIXTA was isolated to investigate its function in glandular trichome development. Bioinformatics analysis indicated that McMIXTA belonged to the subgroup 9 R2R3-MYB, with a R2R3 DNA-binding domain and conserved subgroup 9 motifs. A subcellular localisation assay indicated that McMIXTA was localised in the nucleus. Transactivation analysis indicated that McMIXTA was a positive regulator, with transactivation regions located between positions N253 and N307. Yeast two-hybrid and bimolecular fluorescence complementation assays showed that McMIXTA formed a complex with McHD-Zip3, a trichome development-related HD-ZIP IV transcription factor. Overexpression of McMIXTA in Mentha × piperita L. caused an increase in peltate glandular trichomes density of approximately 25% on the leaf abaxial surface.ConclusionsOur results demonstrated that the subgroup 9 R2R3-MYB transcription factor McMIXTA has a positive effect on regulating peltate glandular trichome development and the MIXTA/HD-ZIP IV complexes might be conserved regulators for glandular trichome initiation. These results provide useful information for revealing the regulatory mechanism of multicellular glandular trichome development.

Preparation and Characterization of Polysaccharide-Based Hydrogels for Cutaneous Wound Healing.

Natural hydrogels are growing in interest as a priority for wound healing. Plant polysaccharides have a variety of biological pharmacological activities, and chitosan hydrogels have proven strong antimicrobial effects, but hydrogels prepared with polysaccharides alone have certain deficiencies. Polysaccharides from flowers of Lonicera japonica Thunb. (LP) and the aerial parts of Mentha canadensis L. (MP) were extracted and oxidized by sodium periodate (NaIO4) and then cross-linked with oxidized-carboxymethylated chitosan (O-CCS) to develop oxidized plant- polysaccharides-chitosan hydrogels (OPHs). SEM observation showed that OPHs had porous interior structures with interconnecting pores. The OPHs showed good swelling, water-retention ability, blood coagulation, cytocompatibility properties, and low cytotoxicity (classed as grade 1 according to United States Pharmacopoeia), which met the requirements for wound dressings. Then the cutaneous wound-healing effect was evaluated in BALB/C mice model, after 7 days treatment, the wound-closure rate of OPHs groups were all greater than 50%, and after 14 days, all were greater than 90%, while the value of the control group was only 72.6%. Of them, OPH-2 and OPH-3 were more favorable to the wound-healing process, as the promotion was more significant. The plant polysaccharides and CS-based hydrogel should be a candidate for cutaneous wound dressings.

Transcriptome-Wide Identification and Characterization of the JAZ Gene Family in Mentha canadensis L.

Jasmonate ZIM-domain (JAZ) proteins are the crucial transcriptional repressors in the jasmonic acid (JA) signaling process, and they play pervasive roles in plant development, defense, and plant specialized metabolism. Although numerous JAZ gene families have been discovered across several plants, our knowledge about the JAZ gene family remains limited in the economically and medicinally important Chinese herb Mentha canadensis L. Here, seven non-redundant JAZ genes named McJAZ1–McJAZ7 were identified from our reported M. canadensis transcriptome data. Structural, amino acid composition, and phylogenetic analysis showed that seven McJAZ proteins contained the typical zinc-finger inflorescence meristem (ZIM) domain and JA-associated (Jas) domain as conserved as those in other plants, and they were clustered into four groups (A-D) and distributed into five subgroups (A1, A2, B1, B2, and D). Quantitative real-time PCR (qRT-PCR) analysis showed that seven McJAZ genes displayed differential expression patterns in M. canadensis tissues, and preferentially expressed in flowers. Furthermore, the McJAZ genes expression was differentially induced after Methyl jasmonate (MeJA) treatment, and their transcripts were variable and up- or down-regulated under abscisic acid (ABA), drought, and salt treatments. Subcellular localization analysis revealed that McJAZ proteins are localized in the nucleus or cytoplasm. Yeast two-hybrid (Y2H) assays demonstrated that McJAZ1-5 interacted with McCOI1a, a homolog of Arabidopsis JA receptor AtCOI1, in a coronatine-dependent manner, and most of McJAZ proteins could also form homo- or heterodimers. This present study provides valuable basis for functional analysis and exploitation of the potential candidate McJAZ genes for developing efficient strategies for genetic improvement of M. canadensis.