| In vitro: |
| Sci Rep . 2020 Apr 29;10(1):7199. | | Standardised comparison of limonene-derived monoterpenes identifies structural determinants of anti-inflammatory activity[Pubmed: 32350292] | | Mint species are widely used in traditional and conventional medicine as topical analgesics for osteoarthritic pain and for disorders of the gastrointestinal and respiratory tracts which are all associated with chronic inflammation. To identify the structural determinants of anti-inflammatory activity and potency which are required for chemical optimization towards development of new anti-inflammatory drugs, a selected group of monoterpenes especially abundant in mint species was screened by measuring bacterial lipopolysacharide (LPS)-induced nitric oxide (NO) production in murine macrophages. Nine compounds significantly decreased LPS-induced NO production by more than 30%. IC50 values were calculated showing that the order of potency is: (S)-(+)-carvone > (R)-(-)-carvone > (+)-dihydrocarveol > (S)-8-hydroxycarvotanacetone > (R)-8-hydroxycarvotanacetone > (+)-dihydrocarvone > (-)-carveol > (-)-Dihydrocarveol > (S)-(-)-pulegone. Considering the carbon numbering relative to the common precursor, limonene, the presence of an oxygenated group at C6 conjugated to a double bond at C1 and an isopropenyl group and S configuration at C4 are the major chemical features relevant for activity and potency. The most potent compound, (S)-(+)-carvone, significantly decreased the expression of NOS2 and IL-1β in macrophages and in a cell model of osteoarthritis using primary human chondrocytes. (S)-(+)-carvone may be efficient in halting inflammation-related diseases, like osteoarthritis. | | Planta Med . 2014 Feb;80(2-3):165-170. | | Acaricidal activities against house dust mites of spearmint oil and its constituents[Pubmed: 24488719] | | The aim of this study was to evaluate the acaricidal activities of spearmint oil and carvone derivatives against house dust mites using contact and fumigant toxicity bioassays to replace benzyl benzoate as a synthetic acaricide. Based on the LD50 values, the contact toxicity bioassay revealed that dihydrocarvone (0.95 and 0.88 μg/cm2) was 7.7 and 6.8 times more toxic than benzyl benzoate (7.33 and 6.01 μg/cm2) against Dermatophagoides farinae and Dermatophagoides pteronyssinus, respectively, followed by carvone (3.78 and 3.23 μg/cm2), spearmint oil (5.16 and 4.64 μg/cm2), carveol (6.00 and 5.80 μg/cm2), and dihydrocarveol (8.23 and 7.10 μg/cm2). Results of the fumigant toxicity bioassay showed that dihydrocarvone (2.73 and 2.16 μg/cm2) was approximately 4.0 and 4.8 times more effective than benzyl benzoate (11.00 and 10.27 μg/cm2), followed by carvone (6.63 and 5.78 μg/cm2), carveol (7.58 and 7.24 μg/cm2), spearmint oil (9.55 and 8.10 μg/cm2), and dihydrocarveol (9.79 and 8.14 μg/cm2). Taken together, spearmint oil and carvone derivatives are a likely viable alternative to synthetic acaricides for managing house dust mites. | | Br J Pharmacol . 2007 Jun;151(4):530-540. | | Monoterpenoid agonists of TRPV3[Pubmed: 17420775] | | Background and purpose: Transient receptor potential (TRP) V3 is a thermosensitive ion channel expressed predominantly in the skin and neural tissues. It is activated by warmth and the monoterpene camphor and has been hypothesized to be involved in skin sensitization. A selection of monoterpenoid compounds was tested for TRPV3 activation to establish a structure-function relationship. The related channel TRPM8 is activated by cool temperatures and a number of chemicals, among them the monoterpene (-)-menthol. The overlap of the receptor pharmacology between the two channels was investigated.
Experimental approach: Transfected HEK293 cells were superfused with the test substances. Evoked currents were measured in whole cell patch clamp measurements. Dose-response curves for the most potent agonists were obtained in Xenopus laevis oocytes.
Key results: Six monoterpenes significantly more potent than camphor were identified: 6-tert-butyl-m-cresol, carvacrol, dihydrocarveol, thymol, carveol and (+)-borneol. Their EC(50) is up to 16 times lower than that of camphor. All of these compounds carry a ring-located hydroxyl group and neither activates TRPM8 to a major extent.
Conclusions and implications: Terpenoids have long been recognized as medically and pharmacologically active compounds, although their molecular targets have only partially been identified. TRPV3 activation may be responsible for several of the described effects of terpenoids. We show here that TRPV3 is activated by a number of monoterpenes and that a secondary hydroxyl-group is a structural requirement. | | J Pathog . 2015;2015:916305. | | Chemical Composition and In Vitro Antibacterial Activity of Mentha spicata Essential Oil against Common Food-Borne Pathogenic Bacteria[Pubmed: 26351584] | | The aim of the present study was to investigate chemical composition and antibacterial activity of essential oil from the leaf of Mentha spicata plant against common food-borne pathogenic bacteria (Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, Listeria monocytogenes, Salmonella typhimurium, and Escherichia coli O157:H7). Chemical composition of the essential oil was identified by gas chromatography coupled with mass spectrometer detector (GC-MS). The antibacterial activity of the essential oil was evaluated by broth microdilution method and agar disk diffusion assay. According to the result of GC-MS analysis, 18 components were identified, accounting for 99.89% of the whole essential oil. The main components were carvone (78.76%), limonene (11.50%), β-bourbonene (11.23%), cis-dihydrocarveol (1.43%), trans-caryophyllene (1.04%), menthone (1.01%), menthol (1%), and terpinen-4-ol (0.99). The essential oil exhibited moderate level of antibacterial activity against all test microorganisms. In general, Gram-positive bacteria were more susceptible to M. spicata essential oil than Gram-negative bacteria. L. monocytogenes was the most sensitive of the microorganisms to the antibacterial activity of M. spicata essential oil (inhibition zone = 22 mm and MIC and MBC = 2.5 μL/mL). Based on our results, the essential oil of M. spicata plant collected from Kermanshah province, west of Iran, has a potential to be applied as antibacterial agent. | | Int J Food Microbiol . 2001 Aug 5;67(3):227-239. | | Modelling the effects of (green) antifungals, droplet size distribution and temperature on mould outgrowth in water-in-oil emulsions[Pubmed: 11518432] | | Prevention of fungal spoilage is a key microbiological issue for the shelf life of fat spreads. Our aim was to assess and model the scope of (natural) antimicrobials for extending shelf life of spreads (water-in-oil emulsions). Production conditions were established to make 60% model fat spreads with reproducible droplet size distributions. The mould vulnerabilities ranged from 1 to 20 weeks. The system allowed feasibility testing of lytic enzymes (Novozym 234) and LMW compounds against Penicillium roqueforti, a key-spoilage mould. The action of Novozym 234, carvacrol, undecanol and dihydrocarveol was benchmarked against sorbate and preservative-free controls under ambient and chilled conditions. Novozym 234 was ineffective to prevent outgrowth of P. roqueforti. Carvacrol, undecanol and dihydrocarveol had limited effects on shelf-life extension compared to sorbate. Fungal growth boundaries of (un-)preserved spreads were modelled. The emulsion droplet size distribution (DSD) was first captured in a mechanistic parameter DSD-I (I = Influence). DSD-I was a move away from the mean droplet diameter D3,3 as sole quantitative droplet-size distribution parameter for mould susceptibility of emulsions. DSD-I is a combination of available water droplets and surface area to initiate and sustain fungal outgrowth. Followup experiments showed that modelling D3,3 and distribution width (e(sigma)) instead of DSD-I gave better results for emulsions with high e(sigma). Empirical predictive models were subsequently developed for the effects of D3,3, e(sigma) and undissociated sorbic acid (HSO) on the shelf life of emulsions. |
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