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At least 19 recordsLinked to original sources
PubMed1992

Purification of 4S-limonene synthase, a monoterpene cyclase from the glandular trichomes of peppermint (Mentha x piperita) and spearmint (Mentha spicata).

The p-menthane monoterpenes of the Mentha species are biosynthesized from geranyl pyrophosphate via the monocyclic olefin 4S-limonene. A monoterpene cyclase was isolated from both Mentha x piperita (peppermint) and Mentha spicata (spearmint) that catalyzes the cyclization of geranyl pyrophosphate to 4S-limonene. This enzyme, 4S-limonene synthase, was purified to apparent homogeneity by dye ligand, anion exchange, and hydrophobic interaction chromatography. Since the monoterpenes of Mentha are synthesized and secreted in modified epidermal hairs called glandular trichomes, an extract of isolated glandular trichome cells was used as the source of this enzyme. A combination of gel permeation chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that purified 4S-limonene synthase had a native molecular weight of 56,000 and was monomeric. The principal product of the enzyme was enantiomerically pure (-)-4S-limonene, and a catalytic constant of 0.3/s was determined. The basic properties of 4S-limonene synthase from both M. x piperita and M. spicata are identical and, in general, are similar to those of other monoterpene, sesquiterpene, and diterpene cyclases isolated from microorganisms and higher plants.

Chromatography, Liquid↗
PubMed2026

Comprehensive plastome variation and RNA editing in Mentha: insights into phylogenetic relationships and candidate DNA barcodes.

INTRODUCTION: Mentha is an economically and medicinally important genus in Lamiaceae, but its taxonomy and species delimitation remain challenging because of frequent hybridization, polyploidy, and marked morphological plasticity. METHODS: In this study, we comparatively analyzed 12 plastomes representing major Mentha species, hybrid taxa, and unresolved accessions, including four newly assembled genomes, to characterize plastome structure, repeat composition, sequence divergence, phylogenetic relationships, and plastid RNA editing. The M. arvensis plastome and RNA-seq datasets originated from independent Swiss and Indian accessions, respectively. RESULTS: The plastomes were highly conserved in overall organization, ranging from 151,824 to 152,154 bp and displaying the typical quadripartite structure. Gene content and order were largely stable across taxa, with only minor variation likely associated with annotation differences at IR/SC boundary regions. Codon usage analysis revealed a clear bias toward A/U-ending synonymous codons, and most shared protein-coding genes showed low Ka/Ks ratios, indicating predominant purifying selection. Repeat analyses showed that simple sequence repeats were mainly composed of A/T-rich mononucleotide motifs, whereas long repeats were concentrated in the 30-40 bp size class. Comparative analyses identified six hypervariable regions, namely ccsA-ndhD, ycf1, ndhD, rpl32-trnL-UAG, rbcL-accD, and petA-psbJ, which represent promising candidate plastid markers for species discrimination. Phylogenetic analysis based on complete plastomes provided strong support for relationships among the sampled taxa and recovered a close affinity among M. aquatica, M. arvensis, and M. canadensis. In addition, RNA-seq analysis of M. arvensis identified 17 candidate plastid RNA editing sites, most of which were C-to-U conversions and nonsynonymous events. DISCUSSION: Together, these results expand plastid genomic resources for Mentha and provide a useful framework for phylogenetic inference, species identification, and future germplasm utilization.

RNA editing↗
PubMed1976

Studies on the metabolism of d-limonene (p-mentha-1,8-diene). IV. Isolation and characterization of new metabolites and species differences in metabolism.

1. The main route of elimination of d-limonene administered orally was via the urine in animals and man, 75-95% of the administered radioactivity being excreted in the urine during 2-3 days. Faecal excretion accounted for less than 10% of the dose in animals during 2-3 days. 2. In addition to six metabolites, namely p-mentha-1,8-dien-10-ol (M-I), p-menth-1-ene-8,9-diol (M-II), perillic acid (M-III), perillic acid-8,9-diol (M-IV), p-mentha-1,8-dien-10-yl-beta-D-glucopyranosiduronic acid (M-V) and 8-hydroxy-p-meth-1-en-9-yl-beta-D-glucopyranosiduronic acid (M-VI) isolated from rabbit urine previously (Kodama et al., 1974), five new metabolites have been isolated from dog and rat urine, and which were characterized as 2-hydroxy-p-menth-8-en-7-oic acid (M-VII), perillylglycine (M-VIII), perillyl-beta-D-glucopyranosiduronic acid (M-IX), p-mentha-1,8-dien-6-ol (M-X) and probably p-menth-1-ene-6,8,9-triol (M-XI). 3. The major metabolite of d-limonene in the urine was M-IV in rat and rabbit, M-IX in hamster, M-II in dog and M-VI in guinea pig and man.

Animals↗
PubMed1992

[Aromatic and polyphenolic composition of infused peppermint, Mentha x piperita L].

The qualitative and quantitative composition of the main aromatic and polyphenolic constituents of Mitcham type peppermint (Mentha x piperita L.) tisane, were examined and compared with those of leaves before and after infusion. The original peppermint leaves contained 2.4% essential oil of which menthol was 0.99%, total polyphenolic compounds 19% and total flavonoid compounds 12% comprising eriocitrin 7%, luteolin-7-rutinoside 1.5%, hesperidoside 0.6% and total hydroxycinnamic compounds 7% (rosmarinic acid 1.4%). The tisane contained 21% of the original essential oil corresponding to 25 mg/l, with increased alcohol and ketone contents and lower contents of hydrophobic terpenecarbons, oxides and esters. It contained also a high proportion of the polyphenolic compounds (about 750 mg/l) corresponding to an extraction yield of 75%. In consequence the monograph "Peppermint leaf" of the Pharmacopoeia should be amended.

Oils, Volatile↗
PubMed1975

Studies on the metabolism of d-Limonene (p-Mentha-1,8-diene). III. Effects of d-Limonene on the lipids and drug-metabolizing enzymes in rat livers.

1. After a single oral dose of d-limonene (200-1200 mg/kg) no effects were observed on liver triglyceride, microsomal protein, cytochrome b5, and the drug-metabolizing enzymes. Glycogen content was slightly decreased at doses higher than 800 mg/kg, and cytochrome P-450 and delta-aminolaevulinic acid synthetase activity was slightly increased at 1200 mg/kg. 2. After repeated treatment (400 mg/kg/day) for 30 days, the relative liver weight and hepatic phospholipid content were only slightly increased, and liver and serum cholesterol were decreased 49 and 8%, respectively. Of the phospholipid fatty acids, palmitic, linoleic and arachidonic acids were increased, and stearic acid was decreased. Aminopyrine demethylase and aniline hydroxylase were increased 26 and 22%, respectively, and cytochrome P-450 and b5 were likewise increased 31 and 30%.

5-Aminolevulinate Synthetase↗
PubMed2026

Establishment of a CRISPR/Cas9-mediated system for targeted editing of the MFS gene in mint.

The key message of this study is that we established a CRISPR/Cas9-mediated genome-editing system for Mentha haplocalyx "738" by optimizing protoplast transient assay and screening effective regulatory elements. Targeted knockout of the MFS gene generated edited mint plants with reduced menthofuran content, offering a strategy for quality improvement of mint essential oil. The commercial value of mint (Mentha spp.) essential oil is often diminished by the presence of undesirable metabolites, notably menthofuran, which impairs flavor and raises safety concerns. This study aimed to develop a robust CRISPR/Cas9 gene editing system for mint 738 (Mentha haplocalyx "738") and apply it to disrupt the menthofuran synthase (MFS) gene, thereby redirecting metabolic flux to enhance oil quality. We established an optimized system for high-efficiency protoplast isolation and transient transformation from young mint leaves. Key parameters for enzymatic digestion (1.5% cellulase R10, 0.2% macerozyme R-10, 3 h) and PEG-mediated transformation (40% PEG6000, 0.4 M mannitol, 0.4 M CaCl₂) were systematically determined. Using this platform, we screened endogenous regulatory elements, identifying a truncated mint U6 promoter (HmU6.1-3P) and the tomato SlEF1α promoter as the most effective drivers for sgRNA and Cas9 expression, respectively. A CRISPR/Cas9 vector targeting the MFS gene was constructed and used for Agrobacterium-mediated stable transformation. The positive transgenic mint lines were obtained. Sequencing confirmed heritable mutations at the target sites within the MFS gene in multiple independent lines. The results revealed a substantial decrease in menthofuran content in the essential oil of the edited line #10 compared to the wild-type control, thereby demonstrating a viable strategy for improving mint essential oil quality through genome-editing.

CRISPR-Cas Systems↗
PubMed1978

Efficacy of some essential oils and their constituents on few ubiquitous molds.

Six essential oils of Mentha arvensis, Mentha piperita, Anethum sowa, Cymbopogon winterianus, Nardostachys jatamansi, and Commiphora mukul were selected and tested for their efficacy against Aspergillus flavus, A. fumigatus, A. sulphureus, Mucor fragilis, and Rhizopus stolonifer. These oils were fungistatic or fungicidal to one or the other molds, depending upon the concentrations.

Antifungal Agents↗
PubMed1992

Evidence for an essential histidine residue in 4S-limonene synthase and other terpene cyclases.

(4S)-Limonene synthase, isolated from glandular trichome secretory cell preparations of Mentha x piperita (peppermint) leaves, catalyzes the metal ion-dependent cyclization of geranyl pyrophosphate, via 3S-linalyl pyrophosphate, to (-)-(4S)-limonene as the principal product. Treatment of this terpene cyclase with the histidine-directed reagent diethyl pyrocarbonate at a concentration of 0.25 mM resulted in 50% loss of enzyme activity, and this activity could be completely restored by treatment of the preparation with 5 mM hydroxylamine. Inhibition with diethyl pyrocarbonate was distinguished from inhibition with thiol-directed reagents by protection studies with histidine and cysteine carried out at varying pH. Inactivation of the cyclase by dye-sensitized photooxidation in the presence of rose bengal gave further indication of the presence of a readily modified histidine residue. Protection of the enzyme against inhibition with diethyl pyrocarbonate was afforded by the substrate geranyl pyrophosphate in the presence of Mn2+, and by the sulfonium ion analog of the linalyl carbocation intermediate of the reaction in the presence of inorganic pyrophosphate plus Mn2+, suggesting that an essential histidine residue is located at or near the active site. Similar studies on the inhibition of other monoterpene and sesquiterpene cyclases with diethyl pyrocarbonate suggest that a histidine residue (or residues) may play an important role in catalysis by this class of enzymes.

Binding Sites↗
PubMed1992

Antigenic cross-reactivity among monoterpene cyclases from grand fir and induction of these enzymes upon stem wounding.

A major wound response in grand fir (Abies grandis) sapling stems is the rapid increase in monoterpene production at the site of injury. Monoterpene cyclases (synthases) catalyze the formation of monoterpenes from geranyl pyrophosphate, and total cyclase activity increases markedly on wounding. At least six distinct cyclases, producing different monoterpene products, have been isolated from wounded grand fir saplings and characterized. The predominant wound-inducible cyclase produces both alpha- and beta-pinene. This pinene cyclase was purified, and polyclonal antibodies were generated in rabbits against the sodium dodecyl sulfate-denatured protein. The antibody preparation was found to cross-react by Western blotting with other grand fir monoterpene cyclases that produce different olefinic products, but not with monoterpene cyclases from related conifer species (Pinus contorta and P. ponderosa) or from angiosperms (Mentha piperita and M. spicata). The increase in monoterpene cyclase activity after wounding was closely correlated with the appearance of new cyclase protein as determined by immunoblotting. These results indicate that the wound-dependent increase in monoterpene cyclase activity is a consequence of de novo synthesis of cyclase protein.

Antibodies↗
PubMed1976

Hashish. Unsaturated side-chain analogues of delta8-tetrahydrocannabinol with potent biological activity.

Two delta8-THC derivatives, 4a and 4b, with functionalized side chains were synthesized. Treatment of (+)-trans-p-mentha-2,8-dien-1-ol with the resorcinal 2b followed by removal of the dithiol group with HgO--BF3-Et2O gave the aldehyde 3b. A Wittig reaction of dimethyl (2-oxoheptyl)phosphate with 3b furnished 4a, which was reduced to 4b. Compounds 4a and 4b showed potent cannabinoid-like activity in mice.

Animals↗
PubMed1992

Flushing technique in the management of retained common bile duct stones with a T tube in situ.

Over a 12-year-period, 6046 cholecystectomies and 918 common bile duct explorations were undertaken with 697 stone-positive choledochotomies (76 per cent). Forty patients (5.7 per cent) had retained common bile duct stones with a T tube in situ. Twenty-eight patients underwent flushing of the common bile duct with a continuous infusion of heparinized saline solution with parenteral aminophylline to induce relaxation of the sphincter of Oddi. Complete duct clearance was achieved in 17 patients; infusion was stopped in four patients and no deaths occurred. The use of percutaneous stone extraction (Burhenne's technique), gave an overall successful common bile duct clearance rate of 86 per cent. The flushing technique represents the first step in the non-operative management of retained common bile duct stones in patients with a T tube in place. It is a safe and effective method for use in the early postoperative period with a prolongation of hospital stay of not more than 1 week.

Adult↗
PubMed1992

Subchronic toxicity study of peppermint oil in rats.

Peppermint oil was given p.o. to four groups of 28 rats at dosage levels of 0, 10, 40, and 100 mg/kg body wt. per day for 90 days. At the highest dose histopathological changes consisting of cyst-like spaces scattered in the white matter of cerebellum were seen. No other signs of encephalopathy were observed. Nephropathy was seen in the male rats in the highest dose group. A no-observed-adverse-effect level of 40 mg/kg body wt. per day was determined.

Administration, Oral↗
PubMed1992

Recent results of elective open cholecystectomy in a North American and a European center. Comparison of complications and risk factors.

Results of elective open cholecystectomy in 1252 patients treated in a North American and a European center were examined using a recent standardized classification of complications. Although there were significant differences between centers in population age, rate of concomitant disorders, and numbers of operators, the frequency and severity of complications were comparable. There were no deaths, but 12% and 14% of the patients developed complications in the two centers. About 6% of the patients developed grade I complications. Grade II complications were noted in 6% and 8%, and grade III in 0% and 0.3%. Using univariate and multivariate analysis, individual risk factors for developing complications were found to be different in the two centers. Two preoperative scoring systems, ASA and a simplified APACHE II, were predictive for complications in both centers, but did not account for all risk in these patients. Data from the two centers could not be combined because of significant interaction between risk factors and center. Elective open cholecystectomy is a safe procedure, particularly in terms of highly morbid complications and death. Generalization of risk factors identified in a particular center may be misleading because local conditions may significantly affect risk factors for complications. The data also demonstrate the advantages of a uniform way of reporting surgical complications, which may permit meaningful comparisons among centers.

Adolescent↗
PubMed1992

Methods of debonding ceramic brackets.

The problem of debonding ceramic brackets is still one which concerns the orthodontist. It is advisable to use the manufacturers recommended method of debonding each particular type of bracket. The risks of using such brackets need to be carefully assessed against the benefits. Risks can be minimized by carefully assessing the patient and the dentition, avoiding heavily restored teeth with pre-existing enamel cracks. It would seem wise to obtain an informed consent from the patient having out-lined the potential problems.

Ceramics↗
PubMed1992

[Safety of cholecystectomy by laparotomy in elective situation and in emergency].

Cholecystectomy is the only effective treatment of gallbladder stones. A retrospective study was carried out on results of 658 cholecystectomies by laparotomy without choledochotomy performed between January 1987 and December 1989, to determine morbidity and mortality of elective and emergency surgery and by age. Operations for tumors of the gallbladder and choledolithiasis were not included in the analysis. During this period, cholecystectomy was performed electively in 387 cases and under emergency conditions in 261 patients. Mortality and post-operative morbidity were 0% and 14.7% respectively after elective surgery, increasing to 1.1% (Fisher = 0.0617) and 25.2 (p = 0.0004) respectively after emergency operations. This large increase in postoperative morbidity in urgent cases was due to an increase in systemic and not local complications, as a result of the higher proportion of emergency operations with advancing age. Since elective cholecystectomy is safe it can be proposed to patients with symptoms, including the elderly. It is difficult at present to compare results of cholecystectomy by laparotomy with those of laparoscopy since the average age of in the latter category is markedly lower and the number of acute cases still low. The principal advantage of celioscopy could be a long term reduction in systemic complications in emergency operations.

Adolescent↗