Molecular response of Musca domestica L. to Mintostachys verticillata essential oil, (4R)+-pulegone and menthone.

Intense applications of synthetic insecticides for the control of adult Musca domestica have led to the insects developing resistance to most of them. In consequence, there is interest in new active ingredients as alternatives to conventional insecticides. Essential oils (EO) are potential tools for controlling M. domestica because of their effectiveness and their minimal environmental effects. In a fumigant assay, M. domestica adults treated with Minthostachys verticillata EO [LC(50)=0.5 mg/dm(3); majority components by SPME-GC: (4R)(+)-pulegone (67.5%), menthone (22.3%) and (4R)(+)-limonene (3.8%)], died within 15 min or less. The terpenes absorbed by the flies and their metabolites, analyzed using SPME fiber, were (4R)(+)-limonene (LC(50)=6.2 mg/dm(3)), menthone (LC(50)=1.9 mg/dm(3)), (4R)(+)-pulegone (LC(50)=1.7 mg/dm(3)) and a new component, menthofuran (LC(50)=0.3 mg/dm(3)), in a relative proportion of 12.4, 6.5, 35.9 and 44.2% respectively. Menthofuran was formed by oxidation of either (4R)(+)-pulegone or menthone mediated by cytochrome P450, as demonstrated by a fumigation assay on flies previously treated with piperonyl butoxide, a P450 inhibitor, which showed a decrease in toxicity of the EO, (4R)(+)-pulegone and of menthone, supporting the participation of the P450 oxidizing system in the formation of menthofuran. The enzymatic reaction of isolated fly microsomes with the EO or the (4R)(+)-pulegone produced menthofuran in both cases. Contrary to expectations, the insect detoxification system contributed to enhance the toxicity of the M. verticillata EO. Consequently, resistant strains overexpressing P450 genes will be more susceptible to either M. verticillata EO or (4R)(+)-pulegone and menthone.

Monoterpenes isolated from Minthostachys verticillata (Griseb.) Epling essential oil modulates immediate-type hypersensitivity responses in vitro and in vivo.

In a previous work, we have demonstrated that Minthostachys verticillata essential oil has immunomodulatory effects in vitro on cells from allergic patients. Here we characterized main components of M. verticillata essential oil and also tested if these compounds modulate In vitro and in vivo the immediate-type allergic reaction. Gas chromatography was used to identify main components of the essential oil. Pulegone (63.4 %), menthone (15.9 %), and limonene (2.1 %) were found as main classes. IL-13 levels were evaluated from lymphocytes cultures stimulated with allergen alone or combined with monoterpenes. All compounds stimulated cell proliferation but, interestingly, promoted a reduction of IL-13 values, limonene and the mixture of the three compounds being the most active. ß-Hexosaminidase release was determined from basophils to which essential oil or monoterpenes were added. We observed that, whichever combination of monoterpenes was used, ß-hexosaminidase release was diminished in all cases. Obtained values were even lower than those of antiallergic drug desloratadine. Essential oil and limonene inhibited mast cell activation and degranulation in the skin when testing passive cutaneous anaphylaxis, limonene being the most active. In conclusion, limonene was the compound that showed the most potent immunomodulatory activity. This fact suggests that it constitutes a promising natural alternative for a novel treatment of allergic diseases.

[Determination of the antibacterial and antiviral activity of the essential oil from Minthostachys verticillata (Griseb.) Epling]. / Determinación de la actividad antibacteriana y antiviral del aceite esencial de Minthostachys verticillata (Griseb.) Epling.

The in vitro antiviral activity of the essential oil from Minthostachys verticillata was investigated against herpes simplex virus type 1 (HSV-1) and pseudorabies virus (PrV). The viral inhibition was assayed employing viral plaque reduction assay. The antiviral activity of the essential oil specifically affects PrV and HSV-1 multiplication, since it was found that non toxic effects on cells were observed at the concentrations assayed. The therapeutic index values were 10.0 and 9.5 for HSV-1 and PrV, respectively. The antibacterial activity was studied using a diffusion assay and the broth tube dilution method. Gram-positive bacteria were more sensitive to inhibition by plant essential oil than the gram-negative bacteria. The essential oil of M. verticillata was analyzed by gas chromatography (GC) technique. Of the six components identified in the volatile oil, pulegone (44.56%) and menthone (39.51%) were the major constituents. The antimicrobial activity can be explained to some extent by the presence of pulegone. Results suggest that further investigations concerning the isolation of the substance responsible for the antimicrobial activity and an effort to define the mechanisms of action are warranted.

Determinación de la actividad antibacteriana y antiviral del aceite esencial de Minthostachys verticillata (Griseb. ) Epling / Determination of the antibacterial and antiviral activity of the essential oil from Minthostachys verticillata (Griseb. ) Epling

The in vitro antiviral activity of the essential oil from Minthostachys verticillata was investigated against herpes simplex virus type 1 (HSV-1) and pseudorabies virus (PrV). The viral inhibition was assayed employing viral plaque reduction assay. The antiviral activity of the essential oil specifically affects PrV and HSV-1 multiplication, since it was found that non toxic effects on cells were observed at the concentrations assayed. The therapeutic index values were 10.0 and 9.5 for HSV-1 and PrV, respectively. The antibacterial activity was studied using a diffusion assay and the broth tube dilution method. Gram-positive bacteria were more sensitive to inhibition by plant essential oil than the gram-negative bacteria. The essential oil of M. verticillata was analyzed by gas chromatography (GC) technique. Of the six components identified in the volatile oil, pulegone (44.56) and menthone (39.51) were the major constituents. The antimicrobial activity can be explained to some extent by the presence of pulegone. Results suggest that further investigations concerning the isolation of the substance responsible for the antimicrobial activity and an effort to define the mechanisms of action are warranted.(AU)

Linalool and cineole type glucosides from Cunila spicata.

The leaves of Cunila spicata yielded a monoterpenetriol and six glycosidic terpenoids derived from linalool, hydroxylated linalool and 1,8-cineole: 3,7-dimethyl-oct-1-ene-3,6,7-triol, linalool-O-beta-D-glucopyranoside, 3,7 dimethyl-octa-1,6-diene-3,8-diol-3-O-beta-D-glucopyranoside as well as 3,7-dimethyl-octa-1,5-diene-3,7-diol-3-O-beta-D-glucopyranoside, 3,7-dimethyl-octa-1,7-diene-3,6-diol-7-O-beta-D-glucopyranoside, 3,7- dimethyl-oct-1-ene-3,6,7-triol-6-O-beta-D-glucopyranoside and (1S,4R,6R)-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-6-O-beta- glucopyranoside. The structures of the glucosides were established by chemical and spectroscopic methods especially high field NMR techniques.