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PubMed2003

Transdermal iontophoresis of insulin. V. Effect of terpenes.

To increase the skin permeation of large peptides like insulin, it is necessary to utilize a combination of enhancement strategies. In this regard, this study investigated the effect of terpenes/EtOH combination in comparison to EtOH and neat terpene on transdermal iontophoretic permeation of insulin. Ex-vivo experiments were conducted using full thickness rat skin after pre-treatment for 2 h with 5% of menthol, menthone, cineole and pulegone in EtOH; EtOH alone; neat menthone with and without iontophoresis (0.5 mA/cm(2); 6 h). FT-IR studies were carried out using rat epidermal sheets after pre-treatment with enhancer solution for 2 h and tritiated water permeation studies was used to investigate the alteration in skin barrier property after enhancer or current treatment. The lag time was significantly reduced (P<0.05) with terpene/EtOH pre-treatment in comparison to passive control and EtOH pre-treatment, although there was no significant difference (P>0.05) among the terpenes. Synergistic enhancement in flux was observed with terpene/EtOH, and menthone/EtOH showed highest enhancement among the terpene/EtOH combinations. On the other hand, enhancement with neat menthone was higher than with menthone/EtOH. FT-IR studies showed that terpene/EtOH, EtOH and neat terpene act at the intercellular lipids. The skin barrier property was significantly (P<0.05) compromised with neat menthone treatment. Iontophoresis had a lesser effect on skin barrier property compared to chemical enhancer pre-treatment. Terpene/EtOH caused synergistic enhancement of insulin permeation when combined with iontophoresis and was influenced by the type and concentration of terpene.

Administration, Cutaneous↗
PubMed1998

In vitro percutaneous absorption enhancement of a lipophilic drug tamoxifen by terpenes.

Tamoxifen is a highly lipophilic drug that is widely used in breast malignancies and also as a prophylactic therapy in women at high risk for the development of this disease. Recently, the terpenes have been reported to show an enhancement effect on percutaneous drug absorption. The effect of terpenes (e.g. carvone, 1,8-cineole, menthol, and thymol) was studied on the in vitro percutaneous absorption of tamoxifen through porcine epidermis. The above terpenes (5% w/v) in combination with 50% ethanol significantly (P < 0.01) increased the permeability coefficient of tamoxifen in comparison to the control (50% ethanol). The solubility of tamoxifen was determined in the control and enhancer solutions to correct the permeability enhancement by way of fractional solubility adjustment. Binding of tamoxifen to powdered stratum corneum from control and enhancer solutions was also determined. Binding studies reveal that the enhancement in the permeability coefficient of tamoxifen by menthol and thymol is due at least in part, to improvement in the partitioning of the drug to the stratum corneum. In conclusion, terpenes in combination with ethanol can be used to enhance the percutaneous absorption of the highly lipophilic drug tamoxifen.

Animals↗
PubMed1999

Induction of xenobiotic metabolising enzymes in the common brushtail possum, Trichosurus vulpecula, by Eucalyptus terpenes.

The mixed function oxidase (MFO) activity and content was studied in the liver of common brushtail possums fed for 10 days on a diet containing a mixture of terpenes found in Eucalyptus leaves on which possums commonly browse. The MFOs were compared to the MFOs in possums fed a control diet of fruits and cereals only. The terpenes chosen were 1,8-cineole, p-cymene, alpha-pinene and limonene. The selected terpenes caused induction of P450 enzymes, as shown by a 53% higher cytochrome P450 content and a 45% increase in aminopyrine demethylase activity in the test animals. Aniline hydroxylase activity was significantly increased, with levels of 2.95 and 1.43 nmol min(-1) mg(-1) microsomal protein in the test and control animals, respectively. There was also a significant increase in androstenedione 16alpha-hydroxylase activity in the test group, 0.85 as compared to 0.50 nmol mg(-1) min(-1) in the control group. Western blot studies using human CYP2E1 and rat CYP2C11 and CYP2C6 antibodies gave CYP2E, CYP2C11 and CYP2C6 immunoreactive bands of greater intensity in the test animals as compared to the control group. This study has shown experimentally that dietary terpenes cause enzyme induction in folivorous marsupials. It also confirms the importance of knowledge of diet when studying xenobiotic metabolising enzymes, particularly in wild animals such as the brushtail possum.

Animals↗
PubMed2003

Attracting friends to feast on foes: engineering terpene emission to make crop plants more attractive to herbivore enemies.

When attacked by herbivorous insects or mites, some plant species call on other arthropods for help. They emit mixtures of volatile compounds, dominated by terpenes, to attract carnivorous arthropods that prey on or parasitise herbivores and so reduce further damage. This fascinating defence strategy offers a new, environmentally friendly approach to crop protection. Using recent advances in the biochemistry and molecular genetics of terpene biosynthesis, it should now be possible to engineer crop plants that release terpenes for attracting herbivore enemies. By introducing or selectively altering the existing rate of terpene emission and composition, plant breeders could enable attacked plants to attract enemies and reduce additional herbivory, without compromising the effectiveness of other modes of defence.

Animals↗
PubMed2004

A method for extraction and quantification of Ginkgo terpene trilactones.

A method was developed for the extraction and quantification of pharmacologically active terpene trilactones (ginkgolides, bilobalide) from the tissues of Ginkgo biloba L. and pharmaceutical ginkgo products by RP-HPLC, based on the theory of terpene trilactones ionization. Four ginkgolides (GA, GB, GC, GJ) and bilobalide (BB) from both the ginkgo leaves and commercially available ginkgo extracts were quantitatively extracted by using this method. The recovery rate of the method was 97.5-100% with RSD of 1.2-2.8%. The detection limit was 0.05-0.1 microg, and the linear range was 0.1-12 microg. This detection limit represents a marked improvement over previously reported methods, suggesting the new method is a viable technique for routine analysis of ginkgo terpene trilactones in natural and commercial samples. The method reported by van Beek et al. in 1991 (van Beek, T. A.; Scheeren, H. A.; Rantio T.; Melger, W. C.; Lelyveld, G. P. J. Chromatogr. 1991, 543, 375-387.) was used as a reference method to monitor the accuracy of extraction and analysis in this study. SSI-MS technique was used to identify isolated target components. Carbohydrase treatment and solubility of terpene trilactones in various solvents were also discussed.

Chromatography, High Pressure Liquid↗
PubMed2003

Vanadium haloperoxidase-catalyzed bromination and cyclization of terpenes.

Marine red algae (Rhodophyta) are a rich source of bioactive halogenated natural products, including cyclic terpenes. The biogenesis of certain cyclic halogenated marine natural products is thought to involve marine haloperoxidase enzymes. Evidence is presented that vanadium bromoperoxidase (V-BrPO) isolated and cloned from marine red algae that produce halogenated compounds (e.g., Plocamium cartilagineum, Laurencia pacifica, Corallina officinalis) can catalyze the bromination and cyclization of terpenes and terpene analogues. The V-BrPO-catalyzed reaction with the monoterpene nerol in the presence of bromide ion and hydrogen peroxide produces a monobromo eight-membered cyclic ether similar to laurencin, a brominated C15 acetogenin, from Laurencia glandulifera, along with noncyclic bromohydrin, epoxide, and dibromoproducts; however, reaction of aqueous bromine with nerol produced only noncyclic bromohydrin, epoxide, and dibromoproducts. The V-BrPO-catalyzed reaction with geraniol in the presence of bromide ion and hydrogen peroxide produces two singly brominated six-membered cyclic products, analogous to the ring structures of alpha and beta snyderols, brominated sesquiterpenes from Laurencia, spp., along with noncyclic bromohydrin, epoxide, and dibromoproducts; again, reaction of geraniol with aqueous bromine produces only noncyclic bromohydrin, epoxide, and dibromoproducts. Thus, V-BrPO can direct the electrophilic bromination and cyclization of terpenes.

Catalysis↗
PubMed1998

Mechanism of transport enhancement of LHRH through porcine epidermis by terpenes and iontophoresis: permeability and lipid extraction studies.

PURPOSE: The purpose of this study was to investigate the effect of 5% terpenes (i.e., limonene, carvone, thymol, and cineole)/ethanol (EtOH) and iontophoresis on the in vitro permeability of luteinizing hormone releasing hormone (LHRH) through the porcine epidermis and biophysical changes in the stratum comeum (SC) lipids by fourier transform infrared (FT-IR) spectroscopy. Methods. The porcine epidermis was pretreated with enhancer for 2 h. The permeability measurement system included Franz diffusion cells, Ag/AgCl electrodes, and SCEPTOR iontophoretic power source. FT-IR spectroscopy was performed to assess the possible contribution of lipid extraction to the transport enhancement of LHRH. RESULTS: Terpenes in combination with EtOH significantly (p < 0.05) increased the flux of LHRH in comparison with the control (epidermis which was not enhancer treated). Iontophoresis further enhanced (p < 0.05) the flux of LHRH through terpenes/EtOH treated epidermis in comparison with their passive permeability. Reversibility studies showed that the post-recovery passive flux of LHRH through 5% limonene in EtOH/iontophoresis treated epidermis was significantly (p < 0.05) decreased but did not significantly recover to the baseline flux (i.e., flux through control epidermis). The SC treated with terpenes/ EtOH showed a decrease in peak heights and areas for both asymmetric and symmetric C-H stretching absorbances in comparison to untreated SC. A greater percent decrease in peak heights and areas was obtained by limonene/EtOH. However, treatment of the SC with terpenes/EtOH followed by iontophoresis did not further decrease the percentage of peak height and area over and above terpene/EtOH suggesting that iontophoresis alone does not cause SC lipid extraction. CONCLUSIONS: Terpenes/EtOH increased LHRH permeability by enhancing the extraction of the SC lipids. Iontophoresis synergistically enhanced the permeability of LHRH through terpenes/EtOH treated epidermis. Thus, terpenes can be used as chemical enhancers in combination with iontophoresis to enhance the transdermal delivery of peptides such as LHRH.

Administration, Cutaneous↗
PubMedDate not supplied

Characterization and control of terpene emissions in Finnish sawmills.

This article describes an experimental study of terpene emission rates during fresh pine and spruce sawing and processing. Total terpene emission was determined by summing the product of the exhaust airflow rate and the mean concentration in the exhaust. Terpene concentrations were measured at fixed sampling points between the sawing lines. Terpene emission during pine sawing was found to be around 10 times greater than that during spruce sawing. The emission rates given here can be used to predict emission rates for various production rates. The predicted emission rates can be used in mass balance models to predict concentrations or required airflow rates to achieve the target concentration level.

Air Pollutants↗
PubMed1999

Influence of drug lipophilicity on terpenes as transdermal penetration enhancers.

Percutaneous absorption-enhancing effects on the skin of hairless mice of 11 monoterpenes [1, (+)-limonene; 2, (-)-menthone; 3, (+)-terpinen-4-ol; 4, alpha-terpineol; 5, 1,8-cineole; 6, (+)-carvone; 7, (-)-verbenone; 8, (-)-fenchone; 9, p-cymene; 10, (+)-neomenthol; and 11, geraniol] were investigated using three different model drugs (caffeine, hydrocortisone, triamcinolone acetonide [TA]) with varying lipophilicities. Terpenes were applied at 0.4 M in propylene glycol (PG) to mouse skin. The model drugs were applied as suspensions in PG 1 hr following enhancer pretreatment. The combination of terpenes in PG provided significant enhancement of the permeation of caffeine through mouse skin. The most active compounds 10 and 11 increased permeation by between 13-fold and 16-fold. The terpenes also enhanced the delivery of hydrocortisone, but not to as great an extent. The most active compounds 3 and 4 increased permeation between 3.9-fold and 5-fold. The compounds examined did not significantly increase the delivery of TA. The most active compound 4 only increased delivery 2.5-fold, while the next most active compound 6 only increased delivery 1.7-fold. Overall, these results indicate that the combination of terpenes with PG can significantly increase the transdermal penetration of the hydrophilic drug caffeine and the polar steroid hydrocortisone.

Animals↗
PubMed2004

Identification of syn-pimara-7,15-diene synthase reveals functional clustering of terpene synthases involved in rice phytoalexin/allelochemical biosynthesis.

Rice (Oryza sativa) produces momilactone diterpenoids as both phytoalexins and allelochemicals. Accordingly, the committed step in biosynthesis of these natural products is catalyzed by the class I terpene synthase that converts syn-copalyl diphosphate to the corresponding polycyclic hydrocarbon intermediate syn-pimara-7,15-diene. Here, a functional genomics approach was utilized to identify a syn-copalyl diphosphate specific 9beta-pimara-7,15-diene synthase (OsDTS2). To our knowledge, this is the first identified terpene synthase with this particular substrate stereoselectivity and, by comparison with the previously described and closely related ent-copalyl diphosphate specific cassa-12,15-diene synthase (OsDTC1), provides a model system for investigating the enzymatic determinants underlying the observed difference in substrate specificity. Further, OsDTS2 mRNA in leaves is up-regulated by conditions that stimulate phytoalexin biosynthesis but is constitutively expressed in roots, where momilactones are constantly synthesized as allelochemicals. Therefore, transcription of OsDTS2 seems to be an important regulatory point for controlling production of these defensive compounds. Finally, the gene identified here as OsDTS2 has previously been mapped at 14.3 cM on chromosome 4. The class II terpene synthase producing syn-copalyl diphosphate from the universal diterpenoid precursor geranylgeranyl diphosphate was also mapped to this same region. These genes catalyze sequential cyclization steps in momilactone biosynthesis and seem to have been evolutionarily coupled by physical linkage and resulting cosegregation. Further, the observed correlation between physical proximity and common metabolic function indicates that other such class I and class II terpene synthase gene clusters may similarly catalyze consecutive reactions in shared biosynthetic pathways.

Alkyl and Aryl Transferases↗
PubMed1998

Enhancement by terpenes of 5-fluorouracil permeation through the stratum corneum: model solvent approach.

5-Fluorouracil permeates the stratum corneum through the intercellular pathway. 5-Fluorouracil is hydrophilic and, therefore, its partitioning from the aqueous region into the hydrocarbon interior of stratum corneum lipids is expected to be an important stage of its permeation and a target for some permeation enhancers. It has also been reported that complexation plays a role in the enhancement effect of some accelerants. These mechanisms have been investigated. For partitioning-permeation studies, isooctane was chosen as a model of the hydrocarbon interior of stratum corneum lipid bilayers and the effects of 26 different terpene enhancers on the solubility of 5-fluorouracil in isooctane were measured. Results were then compared with the effects of the same enhancers on the permeation of 5-fluorouracil through the epidermis in man. The stoichiometry of interaction of cineole and limonene with 5-fluorouracil were also studied to reveal possible complex formation. Solubility studies revealed good correlation between solubility and enhancement ratios for the majority of terpenes, indicating that one mechanism by which terpenes increase permeation of the stratum corneum by 5-fluorouracil is by improvement of partitioning. Stoichiometry studies showed that cineole can form 1:1 or higher complexes with 5-fluorouracil. With limonene, only a weak 1:1 complex was indicated. Data obtained using epidermis from man show that the enhancement effect of cineole toward 5-fluorouracil is much higher than that of limonene. These data reveal that terpenes might increase the permeation of 5-fluorouracil through the stratum corneum as a result of complex formation and a form of facilitated transport.

Antimetabolites↗
PubMed1973

Synthesis of glycols by microbial transformation of some monocyclic terpenes.

The transformation of three monocyclic terpenes by three soil microorganisms have been studied. The organisms were isolated on, and grew rapidly in, mineral salts medium containing the appropriate terpene substrates as sole carbon sources. These organisms belong to the class Fungi Imperfecti, and two of them have been tentatively identified as Cladosporium species. A Cladosporium species designated T(1) was isolated from terpene-soaked soil, using 1-menthene as the sole source of carbon. The major catabolic product isolated from the growth medium of this organism was found to be a cyclic 1,2-diol identified as trans-p-methane-1,2-diol. A similar but biochemically distinct Cladosporium sp. designated T(7) was isolated on D-limonene. After growth, the medium of this organism contained 1.5 g/liter of the analogous product, trans-limonene-1,2-diol. Minor quantities of the corresponding cis-1,2-diol were also isolated. The third organism, designated as laboratory culture T(8), was isolated on 3-menthene and yielded a diol identified as trans-p-menthane-3,4-diol. From these results it is concluded that the formation of diols is a common intermediate in the fungal metabolism of monocyclic terpenes.

Biotransformation↗
PubMedDate not supplied

Comparison of terpene composition in Engelmann spruce (Picea engelmannii) using hydrodistillation, SPME and PLE.

Terpenes emitted by conifer trees are generally determined by analysing plant extracts or essential oils, prepared from foliage and cones using steam distillation. The application of these procedures limits experiments to cut plant materials. Recently headspace techniques have been adopted to examine terpene emission by living plants. This paper deals with the application of solid-phase micro-extraction (SPME) for the analysis of terpenes emitted by conifers foliage of Engelmann spruce (Picea engelmannii), including its seedlings. The compositions of SPME extracts obtained for destroyed and non-destroyed old and juvenile spruce needles were compared with the compositions of essential oils and pressurised liquid extraction (PLE) extracts corresponding to the same plant materials. No substantial differences have been found in the qualitative terpene composition estimated by analysing essential oil and PLE and SPME extracts from non-destroyed old and juvenile foliage. The disintegration of spruce needles results in the formation of a significant amount of myrcene in the case of the old conifer foliage and non-terpenoic compounds in the case of juvenile conifer foliage. This phenomenon can be attributed to enzymatic reactions occurring in the destroyed plant cells.

Gas Chromatography-Mass Spectrometry↗
PubMed2000

Effect of individual terpenes on consumption of alfalfa pellets by sheep.

We examined effects of individual terpenes on alfalfa pellet intake of lambs in five experiments. Forty-five lambs (nine lambs/treatment) were individually fed alfalfa pellets sprayed with either p-cymene, alpha-humulene, 1,8-cineole, 3-carene, or sabinene at one of five concentrations (one terpene per experiment). Treatments (0, .5, 1, 2, and 10x) were multiples of the concentration (x) of a specific terpene in tarbush that was related to differential herbivory by livestock in previous studies. Terpenes were applied to alfalfa pellets (.64 kg x lamb(-1) x d(-1), DM basis), and consumption was measured during a 20-min interval for 5 d. Lambs were adapted to handling and pen feeding for 10 d and were maintained and fed alfalfa pellets in one group (except during 20-min tests) at a mean total daily intake of 4.7% of BW (DM basis). None of the five compounds decreased alfalfa pellet consumption during the 20-min interval. These five mono- and sesquiterpenes do not seem to be responsible for differential herbivory of individual tarbush plants by livestock.

Animals↗
PubMed1996

Terpene exposure and respiratory effects among sawmill workers.

OBJECTIVES: This study was performed to evaluate exposure to terpenes in sawmills and to study the acute effects on lung function and the respiratory tract of exposed laborers. METHODS: The relationships between personal exposure to sawing fumes, assessed by air sampling, and terpene metabolites in urine were studied. The association between exposure to terpenes and acute effects on lung function was studied for 48 workers. The reactivity to methacholine within the study population was investigated. Variation in acute subjective respiratory symptoms during a workshift was evaluated by interviewing the employees before and after work, following a standardized questionnaire. RESULTS: Personal exposure to terpenes in the sawmills was 11-158 mg. m-3. The correlation (correlation coefficient = 0.84) between exposure to alpha-pinene and the concentration of verbenols (metabolites from alpha-pinene) in urine was good. No acute effects on forced vital capacity or forced expiratory volume during 1 s were detected. A decrease in carbon monoxide lung diffusing capacity after a workshift was detected. Workers with > or = 5 years of sawmill employment showed a higher reactivity to methacholine than those with < 5 years. Eye irritation increased during a workday. CONCLUSIONS: Personal exposure to monoterpenes during a workshift sometimes exceeds the present Swedish limit value. The results show that verbenols in urine can be used as a biological exposure index of sawing fumes. Exposure in sawmills can cause an acute decrease in diffusing capacity. Workers with < or = 5 years of employment showed increased bronchial reactivity.

Acute Disease↗
PubMedDate not supplied

Fluorophotometric thin-layer chromatography of ginkgo terpenes by postchromatographic thermochemical derivatization and quality survey of commercial ginkgo products.

Terpenoid lactones in Ginkgo biloba leaves are the main active constituents and the content of these terpenes is therefore the key factor for evaluating the quality of the leaves, the extract, and its preparations distributed on the market. The precleanup sample solutions were applied onto the silica gel plate modified with sodium acetate solution and developed with a solvent system of toluene-ethyl acetate-acetone-methanol, and a fluorescence chromatogram was generated by means of postchromatographic thermal chemical reaction. Fluorescence scanning was conducted quantitatively. The methodology validation confirmed that it is a practical alternative for routine quality control for ginkgo terpenes and the results are comparable with those obtained by high-performance liquid chromatography (HPLC). On the basis of the method established, a quality survey of the various commercial ginkgo products from different sources was undertaken. The obtained data demonstrated that the fluctuation of the content of individual terpene and/or the total terpenes among replicate samples is so significant as to cast doubts on the consistency of their pharmacological and clinical efficacy.

Chromatography, Thin Layer↗
PubMed1973

Terpene Biosynthesis in Cell-free Extracts and Excised Shoots from Wedgwood Iris.

Excised shoots and cell-free extracts prepared from Wedgwood iris (Iris hollandica Hoog. "Wedgwood") shoots metabolized (14)C-labeled mevalonic acid (MVA). By using cell-free extracts, the (14)C from MVA-1-(14)C was recovered as (14)CO(2), while that from MVA-2-(14)C was recovered as neutral terpenes, acid-hydrolyzable terpenes, or (14)CO(2). Also, under optimal incubation conditions, 12.8 nanomoles R-MVA-2-(14)C was incorporated into neutral terpenes per milligram fresh weight per hour. In contrast, excised shoots incorporated only 0.58 nanomoles R-MVA-2-(14)C per mg fresh weight per hour. Labeled products identified from the cell-free system were squalene, farnesol, geranylgeraniol, and compounds that are converted to farnesol and geranylgeraniol after alkaline hydrolysis. Squalene and a 4,4-dimethylsterol were identified as products from excised shoots but not the terpene alcohols or the alkaline-hydrolyzable compounds.

Journal Article↗
PubMed1998

Sensory properties of selected terpenes. Thresholds for odor, nasal pungency, nasal localization, and eye irritation.

We tested four normosmics and four anosmics in detection thresholds for six terpenes commonly found indoors: cumene, p-cymene, delta-3-carene, linalool, 1,8-cineole and geraniol. Normosmics provided odor thresholds and anosmics provided nasal pungency thresholds. All subjects provided nasal localization (i.e., right/left nostril) and eye irritation thresholds. Each type of threshold was measured eight times per subject-stimulus combination. Stimuli were presented from squeeze bottles in a two-alternative forced-choice procedure via an ascending method of limits. Odor thresholds ranged between 0.1 and 1.0 parts per million (ppm, by volume). Nasal pungency thresholds lay about three orders of magnitude above odor thresholds. Nasal localization and eye irritation thresholds did not differ between normosmics and anosmics, and fell close to nasal pungency thresholds. Olfactory thresholds could be obtained for all stimuli in all repetitions using the criterion of five correct choices in a row. Trigeminal thresholds (i.e., pungency, localization and eye irritation) could be obtained on all repetitions only for some terpenes using that same criterion. Carene and cineol produced nasal pungency and eye irritation on all repetitions. None of the terpenes could be localized on all repetitions, but cineol was localized a higher percentage of instances than were the other stimuli. At the other extreme, geraniol failed to evoke any of the three trigeminal responses in most instances. Overall, the results indicate that the three trigeminal thresholds produce a uniform view of the potency of these terpenes, with nasal pungency and eye irritation being slightly more sensitive than nasal localization. Furthermore, application of a previously derived linear solvation energy relationship to the results reinforced the view that physicochemical properties can predict the chemesthetic impact of volatile organic compounds.

Eye↗