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At least 811 records · Page 45Linked to original sources
PubMed1991

Myrcene mimics the peripheral analgesic activity of lemongrass tea.

Oral administration of an infusion of lemongrass (Cymbopogon citratus) fresh leaves to rats produced a dose-dependent analgesia for the hyperalgesia induced by subplantar injections of either carrageenin or prostaglandin E2, but did not affect that induced by dibutyryl cyclic AMP. These results indicate a peripheral site of action which was confirmed with the essential oil obtained by steam distillation of the leaves. Silica gel column fractionation of the essential oil allowed the identification of myrcene as the major analgesic component in the oil. Identification of the components was made by thin-layer chromatography and checked by mass spectrometry. The peripheral analgesic effect of myrcene was confirmed by testing a standard commercial preparation on the hyperalgesia induced by prostaglandin in the rat paw test and upon the contortions induced by intraperitoneal injections of iloprost in mice. In contrast to the central analgesic effect of morphine, myrcene did not cause tolerance on repeated injection in rats. This analgesic activity supports the use of lemongrass tea as a "sedative" in folk medicine. Terpenes such as myrcene may constitute a lead for the development of new peripheral analgesics with a profile of action different from that of the aspirin-like drugs.

Acyclic Monoterpenes↗
PubMed2006

Substrate specificity of strictosidine synthase.

Strictosidine synthase catalyzes a Pictet-Spengler reaction in the first step in the biosynthesis of terpene indole alkaloids to generate strictosidine. The substrate requirements for strictosidine synthase are systematically and quantitatively examined and the enzymatically generated compounds are processed by the second enzyme in this biosynthetic pathway.

Alkaloids↗
PubMed2007

Toxaphene chemistry: separation and characterisation of selected enantiomers of the Polychloropinene mixtures.

The primary goal for the study presented here was the preparation and characterisation of enantiomeric pure chlorobornane standards (Toxaphene). In this context, we partially modeled the procedure for Polychloropinene production in the former USSR. The initial reaction was ionic addition of hydrogen chloride to (1S)-alpha-pinene resulting predominantly in (1S)-2-endo-chlorobornane. Further photochlorination gave mixtures of chlorinated terpenes with different average content of Cl per molecule. The resulting mixtures were separated on a silica-gel column and a number of known hepta to decachlorobornanes were identified in fractions with the help of NMR and GC (using electron capture and mass spectrometric detection)--but in very unusual ratios as compared to the technical Toxaphene mixture formerly produced by Hercules (USA). Also several previously unknown congeners were isolated or detected. Three of the isolated congeners were obtained in crystalline state and X-ray crystallography showed their enantiomeric purity.

Bicyclic Monoterpenes↗
PubMed2006

Optimization and evaluation of a procedure for the gas chromatographic-mass spectrometric analysis of the aromas generated by fast acid hydrolysis of flavor precursors extracted from grapes.

A procedure has been developed for the GC-MS analysis of the aromas released in fast acid hydrolysis of precursor fractions from grape musts and skins. Different sorbents for the extraction of the precursors were compared. The best results were obtained with LiChrolut EN polymeric resins which displayed two and six-fold more extraction capacity than Amberlite XAD-2 resins and C18 sorbents, respectively. C18 sorbents are more suitable for selective extraction of less polar precursors. The initial version of the method was imprecise and so the imprecision of the different steps was assessed. The maceration of the solid parts and the liquid-liquid extraction of the aromas released in the acid hydrolysis proved to be the critical steps. Greater crushing of the solid parts and solid-phase extraction (SPE) instead of liquid-liquid extraction (LLE) improved reproducibility. In the method finally proposed about 100 aromatic components belonging to four large groups (lipid derivatives, shikimic acid derivatives, norisoprenoids and terpenes) were determined with good reproducibility. Important aroma compounds, such as cis-rose oxide or wine lactone were detected in non-Muscat grapes.

Acids↗
PubMed2004

Comparison of cannabinoid ligands affinities and efficacies in murine tissues and in transfected cells expressing human recombinant cannabinoid receptors.

Affinities and efficacies of several reference cannabinoid ligands were investigated at central and peripheral cannabinoid receptors in three different species (rat, mouse, and human). The tested compounds belong to different chemical classes such as classical and non-classical terpene derivatives (Delta(8)-THC, Delta(9)-THC, HU 210, CP 55,940, CP 55,244, CP 55,243 and CP 47,947), aminoalkylindole (WIN 55,212-2, WIN 55,212-3) and diarylpyrazole cannabinoids (SR 141716A, SR 144528). As cannabinoid receptors have been shown to be mainly coupled to Gi/o type G- proteins, and by using the [(35)S]-GTPgammaS nucleotide binding modulation, we characterized the functional activity of these ligands which can act as agonists (positive intrinsic activity), partial agonists (partial positive intrinsic activity), antagonists (no intrinsic activity), or inverse agonists (negative intrinsic activity). To our knowledge, some derivatives (Delta(8)-THC, WIN 55,212-3, CP 55,243 and CP 47,947) have never been characterized in [(35)S]-GTPgammaS binding assays and up to now, this study represents the largest survey of reference cannabinoids performed in unique experimental conditions and in the same laboratory.

Animals↗
PubMed2007

Partial silencing of a hydroxy-methylglutaryl-CoA reductase-encoding gene in Trichoderma harzianum CECT 2413 results in a lower level of resistance to lovastatin and lower antifungal activity.

In the present article, we describe the cloning and characterization of the Trichoderma harzianum hmgR gene encoding a hydroxymethylglutaryl CoA reductase (HMGR), a key enzyme in the biosynthesis of terpene compounds. In T. harzianum, partial silencing of the hmgR gene gave rise to transformants with a higher level of sensitivity to lovastatin, a competitive inhibitor of the HMGR enzyme. In addition, these hmgR-silenced transformants produced lower levels of ergosterol than the wild-type strain in a minimal medium containing lovastatin. The silenced transformants showed a decrease in hmgR gene expression (up to a 8.4-fold, after 72h of incubation), together with an increase in the expression of erg7 (up to a 15.8-fold, after 72h of incubation), a gene involved in the biosynthesis of triterpenes. Finally, hmgR-silenced transformants showed a reduction in their antifungal activity against the plant-pathogen fungi Rhizoctonia solani and Fusarium oxysporum.

Antibiosis↗
PubMed2006

Limonene GP1/PG organogel as a vehicle in transdermal delivery of haloperidol.

Penetration enhancers are a classical means for improving transdermal drug delivery (TDD). Enhancers permeate into the skin and reversibly decrease the barrier resistance. Basically, our aim is to formulate a transdermal gel containing an appropriate enhancer for a controlled drug release. Terpenes, namely limonene, linalool and cineole, in propylene glycol (PG) were first investigated in vitro for their capacity to enhance the percutaneous release of an anti-psychotic drug, haloperidol (HP). Relative to oxygenated linalool and cineole, hydrocarbon limonene was more effective as a skin enhancer; it increased human skin permeability and decreased lag time. Limonene was thus incorporated in an organogel comprised of gelator GP1 and PG. This skin-friendly gel in a transdermal patch could act as a long-acting formulation that delivers HP at a sustained percutaneous rate. The microscopic framework of the organogel is a branched network of interlocking fibres. Varying the gelator content modulates the fibre density and gel stiffness, and presents different degrees of resistance to drug diffusion on the vehicle side. Rheological and permeation studies demonstrated that an increase in gelator concentration increased gel moduli and decreased drug flux simultaneously. The rheology of the gel matrix influenced drug release rate in a manner described by several experimentally-derived correlations.

Administration, Cutaneous↗
PubMed2004

The effect of penetration enhancers on drug delivery through skin: a QSAR study.

Skin penetration enhancers are used to allow formulation of transdermal delivery systems for drugs that are otherwise insufficiently skin-permeable. A full understanding of the mode of action could be beneficial for the design of potent enhancers and for the choice of the enhancer to be used in the topical formulation of a special drug. In this study, the structural requirements of penetration enhancers have been investigated using the Quantitative Structure-Activity Relationship (QSAR) technique. Activities of naturally occurring terpenes, pyrrolidinone and N-acetylprolinate derivatives on the skin penetration of 5-fluorouracil, diclofenac sodium (DFS), hydrocortisone (HC), estradiol and benazepril have been considered. The resulting QSARs indicated that for 5-fluorouracil and diclofenac sodium, less hydrophobic enhancers were the most active. More precisely, molecular descriptors in the corresponding QSARs indicated the possible involvement of intermolecular electron donor-acceptor interactions. This was in contrast to the skin permeation promotion of hydrocortisone, estradiol and benazepril by enhancers, where a linear relationship between enhancement activity and n-octanol/water partition coefficients of enhancers was evident. The possible mechanisms of penetration enhancement as suggested by the QSARs will be discussed.

Administration, Cutaneous↗
PubMed2004

The protozoan Tetrahymena as a bioindicator to screen bioactive substances.

Tetrahymena thermophila has been used as a "swimming receptor" to study its chemotaxis in the presence of various bioactive substances from herbal plants. Chemotaxis of this ciliated protozoan is, in part, controlled by a cyclic GMP-dependent protein kinase (PKG), which can adjust ciliary beating. In this paper, the effects of Ginkgo biloba extract (GBE) and its main functional constituents, terpene lactones, flavonol glycosides and aglycones, on the chemotaxis and PKG activity of ciliates, were systematically investigated. GBE and its constituents exerted significant inhibition of chemotaxis and PKG activity in cells of T. thermophila. The minimal concentrations to completely inhibit chemotaxis of T. thermophila were 12, 25, 50, 100, 300, 400, 400, 500 microM, 2 mg/ml for isorhamnetin, kaempferol, quercetin, myricetin, isoquercitrin, quercetin-3-beta-d-galactoside, rutin, quercitrin, and GBE, respectively. The IC(50) values for PKG were 14, 17, 20, 25, 186, 78 microM, 0.157 mg/ml for isorhamnetin, kaempferol, quercetin, myricetin, isoquercitrin, rutin and GBE, respectively. The results indicate that the chemotaxis inhibition by GBE and its constituents and their effects on PKG are similar. This suggests that T. thermophila may be a potential experimental organism for screening other bioactive substances.

Animals↗
PubMed2005

A geraniol-synthase gene from Cinnamomum tenuipilum.

Geraniol may accumulate up to 86-98% of the leaf essential oils in geraniol chemotypes of the evergreen camphor tree Cinnamomum tenuipilum. A similarity-based cloning strategy yielded a cDNA clone that appeared to encode a terpene synthase and which could be phylogenetically grouped within the angiosperm monoterpene synthase/subfamily. After its expression in Escherichia coli and enzyme assay with prenyl diphosphates as substrates, the enzyme encoded by the putative C. tenuipilum monoterpene synthase gene was shown to specifically convert geranyl diphosphate to geraniol as a single product by GC-MS analysis. Biochemical characterization of the partially purified recombinant protein revealed a strong dependency for Mg2+ and Mn2+, and an apparent Michaelis constant of 55.8 microM for geranyl diphosphate. Thus, a new member of the monoterpene synthase family was identified and designated as CtGES. The genome contains a single copy of CtGES gene. Expression of CtGES was exclusively observed in the geraniol chemotype of C. tenuipilum. Furthermore, in situ hybridization analysis demonstrated that CtGES mRNA was localized in the oil cells of the leaves.

Acyclic Monoterpenes↗
PubMed2006

Terpenoids and phenol derivatives from Malva silvestris.

A sesquiterpene and a tetrahydroxylated acyclic diterpene as well as two known monoterpenes, 6 C(13)nor-terpenes and 11 aromatic compounds were isolated from the water extract of Malva silvestris. The structures of the compounds were determined by spectroscopic NMR and MS analysis. Effects of these compounds on germination and growth of dicotyledon Lactuca sativa L. (lettuce) were studied in the 10(-4)-10(-7)M concentration range.

Lactuca↗
PubMed2026

Biochemical analysis of the TPS-b subfamily reveals a cineole-centered monoterpene biosynthetic module in Medicago truncatula.

Terpenoids constitute one of the largest and most structurally diverse classes of plant specialized metabolites, with diversity generated by terpene synthases (TPSs) and downstream tailoring enzymes. In Medicago truncatula, the TPS-b subfamily comprises five putative synthases, two of which are embedded within a previously uncharacterized genomic locus containing a cytochrome P450 (CYP) and a BAHD-type acyltransferase. Here, we present a comprehensive biochemical analysis of the M. truncatula TPS-b subfamily and define a cineole-centered monoterpene biosynthetic module. Heterologous expression and in vitro assays with multiple prenyl diphosphate substrates revealed three catalytically active TPS-b enzymes with distinct substrate preferences and product profiles. MtTPS4 functions as a dedicated (E)-β-ocimene synthase, whereas MtTPS15 exhibits substrate-dependent bifunctionality, producing (E)-β-ocimene from geranyl diphosphate and α-farnesene from farnesyl diphosphate. MtTPS36 generates 1,8-cineole as the predominant product alongside α-terpineol from geranyl and neryl diphosphate. Genome analysis revealed that MtTPS36 is colocalized with a cytochrome P450 belonging to the CYP736 family. Biochemical characterization of this CYP identified a previously undescribed plant cineole hydroxylase that catalyzes oxidation of 1,8-cineole to yield 2α-hydroxy-1,8-cineole (also known as 2-exo-hydroxy-1,8-cineole), establishing a TPS-CYP biosynthetic module. These results define the gene-to-metabolite relationships within the TPS-b subfamily in M. truncatula and expand the known enzymatic biosynthetic capacity underlying oxygenated monoterpene biosynthesis in plants.

1,8-Cineole↗
PubMed1975

Trace analysis of organic volatiles in water by gas chromatography-mass spectrometry with glass capillary columns.

Traces of volatile organic materials in water have been concentrated by gas phase stripping and adsorption onto a porous polymer. A simple all-glass sampling device is proposed which allows efficient concentration at elevated temperatures. Sample transfer from absorbent into a gas chromatographic column is effected by a simple one-step procedure involving heat desorption. The capacity of the absorbent has been determined for a number of model substances which are found in water. Under the sampling conditions used, compounds being less volatile than benzene are usually quantitatively retained, with some exceptions. Separations were effected with highly efficient glass capillary columns. Water samples, collected from a small number of locations, included both tap water and untreated waters. A number of volatiles have been determined by gas chromatography-mass spectrometry in drinking water and in a river which flows through an industrialized area. The drinking water examined contains a large number of chlorinated and brominated compounds whereas the river water is largely free from this class of substances. Derivatives of camphor and terpenes have been identified in this particular river.

Absorption↗
PubMed1988

Applications of gas chromatography to the study of terpenoid metabolism.

Studies on the enzymology and mechanism of biosynthesis of the essential oil terpenes are often hampered by the need to resolve and detect trace levels of these metabolites, an analytical requirement for which gas chromatography is ideally suited. Essential principles in the application of gas chromatography to terpenoid metabolism are described, with particular emphasis on experimental strategies employing flame ionization, mass spectrometric and thermal conductivity-radiochemical detection methods. The general approaches described can be readily adapted to studies on the origin of other volatile natural products.

Chromatography, Gas↗
PubMed2000

Cavernolide: a new inhibitor of human sPLA2 sharing unusual chemical features.

The inhibitory effect of cavernolide, a novel C2, terpene lactone isolated from the sponge Fasciospongia cavernosa, on PLA2 and other enzyme activities involved in the inflammatory process was studied. Cavernolide inhibited human synovial sPLA2 in a concentration-dependent manner with an IC50 value of 8.8 microM. Besides, this compound decreased in the nanomolar range the myeloperoxidase degranulation process using different stimuli. Cavernolide also inhibited TNFalpha, NO and PGE2 production in intact cell experiments. NO and PGE2 reduction was the consequence of the inhibition on iNOS and COX-2 expression because it did not affect inducible nitric oxide synthase and cyclooxygenase-2 activities in intact cells.

Animals↗
PubMed2000

Volatile constituents of wood-rotting basidiomycetes.

Phytochemical investigation of the hydrodistillation products of the basidiomycetes Fomitopsis pinicola, Piptoporus betulinus, Gloeophyllum odoratum and Trametes suaveolens led to the identification of numerous mono- and sesquiterpenes as well as many aliphatic alcohols, aldehydes and ketones and some aromatic compounds. In addition, some diterpenes were identified as constituents of Fomitopsis pinicola. The absolute configuration of some terpenes was determined

Basidiomycota↗
PubMed2001

Terpenoids from Guarea rhophalocarpa.

Four new terpenes including, two sandaracopimaradiene diterpenoids, ent-8(14),15-sandaracopimaradiene-2alpha,18-diol, and ent8(14),15-sandaracopimaradiene-2beta,18-diol, and two lanostane triterpenoids, 23-hydroxy-5alpha-lanosta 7,9(11),24-triene-3-one, and 5alpha-lanosta-7,9(11),24-triene-3alpha,23-diol, were isolated from the methanolic extract prepared from the leaves of G. rhopalocarpa together with the known steroid stigmasterol and the coumarin, scopoletin. The isolates showed weak antiprotozoal activity against Leishmania donovani promastigotes, and Trypanosoma brucei brucei blood stream trypomastigotes, and were devoid of interesting activity towards Plasmodium falciparum. The isolates did not show significant cytotoxic activity against KB cells.

Animals↗