Larvicidal and adulticidal activity of essential oils from plants of the Lamiaceae family against the West Nile virus vector,Culex pipiens (Diptera: Culicidae)

Culex pipiens mosquitoes are the most widely distributed primary vector of the West Nile virus worldwide. Many attempts for investigation of botanical pesticides to avoid the development of pesticide resistance to conventional synthetic pesticides that are recognized as a threat to the diversity of ecosystems. The study aimed to determine the components of three essential oils of Lamiaceae family, lavender (Lavandula angustifolia), peppermint (Mentha piperita L.), and rosemary (Rosmarinus officinalis L.) by gas chromatography-mass spectrometry (GC–MS) analysis. Furthermore, aimed to validate the insecticidal activities of these oils as larvicidal agents against the third instar larvae of Culex pipiens using five different concentrations (62.5, 125, 250, 500, and 1000 ppm) for each oil in five replicates and as an adulticidal agent against approximately three-day-old female adults of Cx. Pipiens using 0.5, 1, 2, 4, and 5% concentrations in three replicates. The results generally showed a dose-related response. At 1000 ppm, rosemary oil showed the highest larvicidal (100%) (LC₅₀, 214.97 ppm), followed by peppermint oil (92.00% mortality and LC₅₀ (269.35 ppm). Lavender oil showed the lowest efficacy with 87.20% mortality and LC₅₀ (301.11 ppm). At 5% oil concentration, the highest knockdown rate at 1 h was recorded for lavender oil (95.55%), followed by peppermint oil (88.89%) and lastly rosemary oil (84.44%). After 24 h, rosemary oil showed the lowest adult mortality rate (88.89%; LC₅₀, 1.44%), while lavender and peppermint oils both showed a 100% mortality rate, with (LC₅₀, 0.81% and 0.91%, respectively). The chemical constituents of the oils consisted of monoterpenes and sesquiterpenes that determined their insecticidal activities against the target insect stage. The study proposed that rosemary essential oil may be useful for the control of Cx. pipiens larvae as part of an integrated water treatment strategy, and lavender and peppermint oils may be used in an integrated plan for adult’s control.     

<Emphasis Type="Italic">Lysmata rafa</Emphasis>, a new species of peppermint shrimp (Crustacea,Caridea, Hippolytidae) from the subtropical western Atlantic

Lysmata rafa n. sp. is described from freshly collected specimens from the Keys West Lakes, Florida Keys, and from a museum specimen collected at Bear Cut, Biscayne Bay, Florida. The new species is morphologically most similar to the western Atlantic Lysmata rathbunae Chace, 1970 and the eastern Pacific Lysmata gracilirostris Wicksten, 2000, but can be distinguished from them by the number of carpal segments in the second pereiopod; the length and dentition of the rostrum; the shape and number of spines on the dactylus of the third to fifth pereiopods; and the absence of a tooth on the pterygostomial margin of the carapace. Despite being a shallow-water species, L. rafa n. sp. has extremely elongate walking legs and third maxilliped that are more typical to deep-water or cave dwelling carideans.     

Highly efficient <Emphasis Type="Italic">in vitro</Emphasis> adventitious shoot regeneration of peppermint (<Emphasis Type="Italic">Mentha</Emphasis> x <Emphasis Type="Italic">piperita</Emphasis> L.) using internodal explants

An in vitro regeneration system with a 100% efficiency rate was developed in peppermint [Mentha x piperita] using 5- to 7-mm-long second internode stem segments of 3-wk-old stock plants. Shoots developed at sites of excision on stem fragments either directly from the cells or via primary calluses. The optimal medium for maximum shoot initiation and regeneration contained Murashige and Skoog (MS) salts, B5 vitamins, thidiazuron (TDZ, 11.35 μM), ZT (4.54 μM), 10% coconut water (CW), 20 g l⁻¹ sucrose, 0.75% agar, adjusted to pH 5.8. A frequency of 100% shoot initiation was achieved, with an average of 39 shoots per explant. This regeneration system is highly reproducible. The regenerated plants developed normally and were phenotypically similar to Black Mitcham parents.     

Transgenic peppermint (Mentha×piperita L.) plants obtained by cocultivation with Agrobacterium tumefaciens

The first transgenic peppermint (Mentha×piperita L. cultivar Black Mitcham) plants have been obtained by Agrobacterium-mediated transformation by cocultivation with morphogenically responsive leaf explants. Basal leaf explants with petioles, from leaves closest to the apex of in-vitro-culture-maintained shoots (5 cm), exhibited optimal shoot organogenetic responsiveness on medium supplemented with thidiazuron (8.4 μm). Shoot formation occurred at sites of excision on the leaf blade and petiole either directly from cells of the explant or via a primary callus. Analyses of transient GUS activity data indicated that DNA delivery by microprojectile bombardment was more effective than Agrobacterium infection. However, no transgenic plants were obtained from over 22,000 leaf explants after particle bombardment. Cocultivation of leaf explants with Agrobacterium strain EHA 105 and kanamycin selection produced transgenic plants. Greater transient and stable -glucuronidase (GUS) activities were detected in explants or propagules transformed with the construct where gusA was driven by the pBISN1 promoter rather than a CaMV 35S promoter. Eight plants were subsequently regenerated and verified as transgenic based on detection of the nptII transgene by PCR and Southern blot analyses. The Southern analyses indicated that the plants were derived from eight unique transformation events. All transgenic plants appeared morphologically normal. Analyses of GUS activities in leaves sampled from different portions of these transgenic plants, 10 months after transfer to the greenhouse, indicated that six out of the eight original regenerants were uniformly transformed, i.e., did not exhibit chimeric sectors. Received: 12 December 1997 / Revision received: 3 June 1997 / Accepted: 18 July 1997     

Pharmacology and preclinical pharmacokinetics of peppermint oil

The principal pharmacodynamic effect of peppermint oil relevant to the gastrointestinal tract is a dose-related antispasmodic effect on the smooth musculature due to the interference of menthol with the movement of calcium across the cell membrane. The choleretic and antifoaming effects of peppermint oil may play an additional role in medicinal use. Peppermint oil is relatively rapidly absorbed after oral administration and eliminated mainly via the bile. The major biliary metabolite is menthol glucuronide, which undergoes enterohepatic circulation. The urinary metabolites result from hydroxylation at the C-7 methyl group at C-8 and C-9 of the isopropyl moiety, forming a series of mono- and dihydroxymenthols and carboxylic acids, some of which are excreted in part as glucuronic acid conjugates. Studies with tritiated I-menthol in rats indicated about equal excretion in feces and urine. The main metabolite indentified was menthol-glucuronide. Additional metabolites are mono- or di-hydroxylated menthol derivatives.     

Antifungal activities of essential oils applied by dip-treatment on areca palm (Areca catechu) leaf sheath and persistence of their potency upon storage

The antifungal activities of cinnamon oil, clove oil, anise oil, and peppermint oil, and their main components (cinnamaldehyde, eugenol, trans-anethole, and menthol, respectively) against molds identified from areca palm leaf sheath (Mucor dimorphosporus, Penicillium sp., Aspergillus niger, and Rhizopus sp.) were investigated. An agar dilution method was employed to determine the minimum inhibitory concentration (MIC) of essential oils and their main components. Zone inhibition tests and the inhibitory effect of the leaf sheath dip-treated with essential oils against those molds were examined. Major components of essential oils on the leaf sheath during storage were quantified by gas chromatography analysis. The MIC values of essential oils on agar and on the leaf sheath were identical. With an MIC of 50 ??g ml⁻¹, cinnamon oil had the strongest inhibitory effect. At their MICs the oils were capable of providing protection against mold growth on the leaf sheath for at least 12 weeks during storage at 25 °C and 100% RH. Scanning electron microscope examination showed that essential oils prevented spore germination. Except for menthol in peppermint oil, the main components of the essential oils, which were fairly stable over the storage period, largely contributed to the antifungal activity.     

Gastrointestinal clinical pharmacology of peppermint oil

In nine studies, 269 healthy subjects or patients underwent exposure to peppermint oil (PO) either by topical intraluminal (stomach or colon) or oral administration by single doses or 2 weeks treatment (n = 19). Methods used to detect effects were oro-cecal transit time by hydrogen expiration, total gastrointestinal transit time by carmine red method, gastric emptying time by radiolabelled test meal or sonography, direct observation of colonic motility or indirect recording through pressure changes or relieve of colonic spasms during barium enema examination. The dose range covered in single dose studies is 0.1-0.24ml of PO/subject. With one exception, which show an unexplained potentiation of neostigmine stimulated colon activity, all other studies result in effects, indicating a substantial spasmolytic effect of PO of the smooth muscles of the gastrointestinal tract. Pharmacokinetic studies reveal that fractionated urinary recovery of menthol is dependent on the kind of formulation used for the application of PO. Optimal pH triggered enteric coated formulations start releasing PO in the small intestine extending release over 10-12 h thus providing PO to the target organ in irritable bowel syndrome, i.e. the colon. The hypothesis is supported by anecdotal observations in patients with achlorhydria or ileostoma, respectively.     

Cosuppression of limonene-3-hydroxylase in peppermint promotes accumulation of limonene in the essential oil

cDNA clones encoding limonene synthase and limonene-3-hydroxylase, both driven by the CaMV 35S promoter, were independently transformed into peppermint (Menthaxpiperita) to alter the production and disposition of (-)-limonene, the first committed intermediate of essential oil biosynthesis in this species. Although both genes were constitutively expressed in leaves of transformed plants, the corresponding enzyme activities were not significantly increased in the glandular trichome sites of essential oil biosynthesis; thus, there was no effect on oil yield or composition in the regenerated plants. Cosuppression of the hydroxylase gene, however, resulted in the accumulation of limonene (up to 80% of the essential oil compared to about 2% of the oil in wild type plants), without influence on oil yield. These results indicate that limonene does not impose negative feedback on the synthase, or apparently influence other enzymes of monoterpene biosynthesis in peppermint, and suggests that pathway engineering can be employed to significantly alter essential oil composition without adverse metabolic consequences.     

Monoterpene double-bond reductases of the (-)-menthol biosynthetic pathway: isolation and characterization of cDNAs encoding (-)-isopiperitenone reductase and (+)-pulegone reductase of peppermint

Random sequencing of a peppermint essential oil gland secretory cell cDNA library revealed a large number of clones that specified redox-type enzymes. Full-length acquisitions of each type were screened by functional expression in Escherichia coli using a newly developed in situ assay. cDNA clones encoding the monoterpene double-bond reductases (-)-isopiperitenone reductase and (+)-pulegone reductase were isolated, representing two central steps in the biosynthesis of (-)-menthol, the principal component of peppermint essential oil, and the first reductase genes of terpenoid metabolism to be described. The (-)-isopiperitenone reductase cDNA has an open reading frame of 942 nucleotides that encodes a 314 residue protein with a calculated molecular weight of 34,409. The recombinant reductase has an optimum pH of 5.5, and K(m) values of 1.0 and 2.2 microM for (-)-isopiperitenone and NADPH, respectively, with k(cat) of 1.3s(-1) for the formation of the product (+)-cis-isopulegone. The (+)-pulegone reductase cDNA has an open reading frame of 1026 nucleotides and encodes a 342 residue protein with a calculated molecular weight of 37,914. This recombinant reductase catalyzes the reduction of the 4(8)-double bond of (+)-pulegone to produce both (-)-menthone and (+)-isomenthone in a 55:45 ratio, has an optimum pH of 5.0, and K(m) values of 2.3 and 6.9 microM for (+)-pulegone and NADPH, respectively, with k(cat) of 1.8s(-1). Deduced sequence comparison revealed that these two highly substrate specific double-bond reductases show less than 12% identity. (-)-Isopiperitenone reductase is a member of the short-chain dehydrogenase/reductase superfamily and (+)-pulegone reductase is a member of the medium-chain dehydrogenase/reductase superfamily, implying very different evolutionary origins in spite of the similarity in substrates utilized and reactions catalyzed.     

用复方薄荷油预处理制作植物染色体标本的初步研究

报道了用复方薄荷油预处理制作植物染体标本的方法,共试验了３１种植物,效果良好,方法简便,有一定应用价值。