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PubMed1996

Aerobic biodegradation of selected monoterpenes.

Batch experiments were conducted to assess the biotransformation potential of four hydrocarbon monoterpenes (d-limonene, alpha-pinene, gamma-terpinene, and terpinolene) and four alcohols (arbanol, linalool, plinol, and alpha-terpineol) under aerobic conditions at 23 degrees C. Both forest-soil extract and enriched cultures were used as inocula for the biodegradation experiments conducted first without, then with prior microbial acclimation to the monoterpenes tested. All four hydrocarbons and two alcohols were readily degraded. The increase in biomass and headspace CO2 concentrations paralleled the depletion of monoterpenes, thus confirming that terpene disappearance was the result of biodegradation accompanied by microbial growth and mineralization. Plinol resisted degradation in assays using inocula from diverse sources, while arbanol degraded very slowly. A significant fraction of d-limonene-derived carbon was accounted for as non-extractable, dissolved organic carbon, whereas terpineol exhibited a much higher degree of utilization. The rate and extent of monoterpene biodegradation were not significantly affected by the presence of dissolved natural organic matter.

Acetates↗
PubMed2000

Volatile organic compounds associated with microbial growth in automobile air conditioning systems.

Volatile organic compounds from Penicillium viridicatum and Methylobacterium mesophilicum growing on laboratory media and on component materials of automobile air conditioners were analyzed with gas chromatography and mass spectrometry. P. viridicatum produced compounds such as 4-methyl thiazole, terpenes and alcohols, whereas M. mesophilicum produced dimethyl disulfide, dimethyl trisulfide, and chlorophenol with growth on laboratory media. In comparison with laboratory media, fewer volatiles were detected from colonized foam insulation materials. Biofilms of M. mesophilicum on aluminum evaporator components produced mainly dimethyl disulfide. These biofilms, after inoculation with P. viridicatum, produced offensive smelling alcohols and esters such as 2-methyl propanol, 3-penten-2-ol, and the ethyl ester of butanoic acid. The moisture and substrates innate to the automobile air conditioning systems provided an environment suitable for microbial biofilm development and odor production. Reduction of retained moisture in the air conditioning system coupled with use of less susceptible or antimicrobial substrates are advised for remediation of the noxious odors.

Air Conditioning↗
PubMed2003

Olfactory activation patterns in the antennal lobe of the sphinx moth, Manduca sexta.

The sphinx moth Manduca sexta is a well-studied insect with regard to central olfactory functions. Until now, the innervation patterns of olfactory receptor neurons into the array of olfactory glomeruli in the antennal lobe have, however, been unclear. Using optical imaging to visualize calcium dynamics within the antennal lobe we demonstrate specific patterns elicited by sex pheromone components and plant-derived odours. These patterns mainly reflect receptor neuron activity. Within the male-specific macroglomerular complex the two major pheromone components evoke stereotyped activity in either of two macroglomerular complex glomeruli. Based on previous knowledge of output neuron specificity, our results suggest a matching of information between input and output in the macroglomerular complex. Plant odours evoked activity in the sexually isomorphic glomeruli. Two major results were obtained: (1). terpenes and aromatic compounds activate different clusters of glomeruli with only minor overlapping, and (2). the position of certain key glomeruli is fixed in both males and females, which suggests that host-plant related odorants are processed in a similar way in both sexes.

Animals↗
PubMed2004

Changes in eye blink frequency as a measure of trigeminal stimulation by exposure to limonene oxidation products, isoprene oxidation products and nitrate radicals.

OBJECTIVES: To measure eye blink frequency as a measure of trigeminal stimulation of the eye. Human subjects were exposed to oxidation mixtures representative of reactive indoor pollutants and clean air, from which relative changes in blink frequencies were measured. METHOD: Male subjects ( n=8) were exposed for 20 min to limonene oxidation products (LOPs), isoprene oxidation products (IOPs), nitrate radicals (NO(3)), their residual reactants, and clean air at 20% relative humidity. A baseline blink frequency was measured prior to and following each exposure (2 x 8 min). The subjects were exposed locally in the non-dominant eye and single blind in random order. Blinking was video-recorded and evaluated for full sessions of 36 min while the subjects viewed an educational film. The initial terpene concentrations were one to two orders of magnitude higher than mean indoor concentrations. RESULTS: The mean blink frequency increased significantly during subjects' exposure to gas-phase oxidation products at lower part-per-billion (ppb) levels of LOPs, 42% ( P<0.0001) and NO(3), 21% ( P<0.022), compared with that at baseline. Neither the residual reactants nor clean air changed the blink frequency significantly. The findings coincided with qualitative reporting of weak eye irritation symptoms. CONCLUSIONS: Changes in blink frequency appear to be a promising measure of trigeminal stimulation from exposure to eye irritants in ppb levels. Gaseous products of limonene and ozone, and reactive radicals may cause eye irritation indoors.

Adult↗
PubMed2003

Natural products as antiparasitic drugs.

Natural products are not only the basis for traditional or ethnic medicine. Only recently, they have provided highly successful new drugs such as Artemisinin. Furthermore, screening natural products found in all sorts of environments such as the deep sea, rain forests and hot springs, and produced by all sorts of organisms ranging from bacteria, fungi and plants to protozoa, sponges and invertebrates, is a highly competitive field where all of the major pharmaceutical companies are encountered. Already, many new natural product groups have revealed antiparasitic properties of surprising efficacy and selectivity, as will be shown in this review for plant-derived alkaloids, terpenes and phenolics. Many novel lead structures, however, have severe chemico-physical drawbacks such as poor solubility. Here, innovative drug formulations and carrier systems might help, as discussed by the authors in another article of this series.

Alkaloids↗
PubMed1998

Cellular origin of chlorinated diketopiperazines in the dictyoceratid sponge Dysidea herbacea (Keller).

The tropical marine sponge Dysidea herbacea (Keller) contains the filamentous unicellular cyanobacterium Oscillatoria spongeliae (Schulze) Hauck as an endosymbiont, plus numerous bacteria, both intracellular and extracellular. Archaeocytes and choanocytes are the major sponge cell types present. Density gradient centrifugation of glutaraldehyde-fixed cells with Percoll as the support medium has been used to separate the cyanobacterial symbiont from the sponge cells on the basis of their differing densities. The protocol also has the advantage of separating broken from intact cells of O. spongeliae. The lighter cell preparations contain archaeocytes and choanocytes together with damaged cyanobacterial cells, whereas heavier cell preparations contain intact cyanobacterial cells, with less than 1% contamination by sponge cells. Gas chromatography/mass spectrometry analysis has revealed that the terpene spirodysin is concentrated in preparations containing archaeocytes and choanocytes, whereas nuclear magnetic resonance analysis of the symbiont cell preparations has shown that they usually contain the chlorinated diketopiperazines, dihydrodysamide C and didechlorodihydrodysamide C, which are the characteristic metabolites of the sponge/symbiont association. However, one symbiont preparation, partitioned by a second Percoll gradient, has been found to be devoid of chlorinated diketopiperazines. The capability to synthesize secondary metabolites may depend on the physiological state of the symbiont; alternatively, there may be two closely related cyanobacterial strains within the sponge tissue.

Animals↗
PubMed2006

Exogenous application of methyl jasmonate elicits defenses in Norway spruce (Picea abies) and reduces host colonization by the bark beetle Ips typographus.

The terpenoid and phenolic constituents of conifers have been implicated in protecting trees from infestation by bark beetles and phytopathogenic fungi, but it has been difficult to prove these defensive roles under natural conditions. We used methyl jasmonate, a well-known inducer of plant defense responses, to manipulate the biochemistry and anatomy of mature Picea abies (Norway spruce) trees and to test their resistance to attack by Ips typographus (the spruce bark beetle). Bark sections of P. abies treated with methyl jasmonate had significantly less I. typographus colonization than bark sections in the controls and exhibited shorter parental galleries and fewer eggs had been deposited. The numbers of beetles that emerged and mean dry weight per beetle were also significantly lower in methyl jasmonate-treated bark. In addition, fewer beetles were attracted to conspecifics tunneling in methyl jasmonate-treated bark. Stem sections of P. abies treated with methyl jasmonate had an increased number of traumatic resin ducts and a higher concentration of terpenes than untreated sections, whereas the concentration of soluble phenolics did not differ between treatments. The increased amount of terpenoid resin present in methyl jasmonate-treated bark could be directly responsible for the observed decrease in I. typographus colonization and reproduction.

Acetates↗
PubMed2004

Genomic hardwiring and phenotypic plasticity of terpenoid-based defenses in conifers.

Over evolutionary history, conifers have faced a myriad of threats from phloem- and xylem-feeding insects, defoliating insects, and fungal pathogens. Among the trees' defenses, terpenoids appear to play a major role by harming, disabling, deterring, repelling, or otherwise reducing the fitness of potential invaders. Each of the three classes of terpenoids in conifers, monoterpenes, sesquiterpenes, and diterpenes, are composed of a large number of representative compounds. In most cases, the presence of a particular terpenoid compound in the oleoresin or volatile emissions from a specific conifer can be accounted for by the expression of one of many committed terpene synthase (TPS) genes. However, while each TPS may produce one or a few major products, many produce a variety of minor products with relatively constant component ratios in the product blends. TPS genes exist in conifers in large and functionally diverse, yet monophyletic, gene families. Within these gene families, new biochemical functions of TPS appear to have evolved by gene duplication and changes in the amino acid sequence of the enzyme's active site. In addition, TPS genes may be differentially expressed prior to, during, and following attack by insects or pathogens. Thus, while the production of any particular terpenoid is hardwired into a conifer's genome, these trees have the capacity to change the mixture of terpenoids in oleoresin secretions and volatile emissions. Anatomical changes may also accompany induced terpenoid production, supplementing the plasticity of the molecular and biochemical events.

Alkyl and Aryl Transferases↗
PubMed2005

Feeding response to host and nonhost compounds by males and females of the spruce bark beetle Ips typographus in a tunneling microassay.

Research on host selection by bark and wood boring insects has concentrated on flight orientation behavior. Less is known of the factors that govern the steps successive to host landing. Here, we discuss chemical factors involved in host acceptance by bark beetles and a new microassay. Adult males and females of Ips typographus were offered an artificial diet treated with various concentrations of different plant-derived compounds (host terpenes and nonhost compounds) in a no-choice mode. Beetles were tested individually in a glass tube for 4 hr, and the length of feeding was measured and compared to a control (diet with only solvent). The first effect was diet rejection, especially when nonhost compounds were tested at high concentrations. Most compounds reduced feeding, in proportion to concentration. Females fed more readily than males after addition of both host and nonhost compounds. Diet removal was significantly affected by all the tested factors (sex, compound, dose) as well as by their interactions. With increased concentrations, males were more responsive than females to antifeedants, as all compounds (except juglone) showed clear sex differences of diet consumption. 3-Octanol, 1-hexanol, and a Green Leaf Volatile (GLV)-blend (three C6 alcohols) showed the strongest antifeedant effects, which started at a low dose (0.1%) and had a low Effective Dose 50 (ED50, 0.3-1%). In contrast, host monoterpenes, limonene and alpha-pinene, inhibited feeding at high doses (10-30%) only, with ED50 > 10%. The highest Antifeedant Indexes were shown by verbenone, carvone, and 1-hexanol (AFI = 0.90-1.00). Both host and nonhost compounds inhibited feeding at some concentration. No significant stimulation of feeding by any host compound at concentrations reported in the literature as optimal were found, with the possible exception of alpha-pinene at low concentrations in females.

Animals↗
PubMed2006

Volatile emissions from an odorous plant in response to herbivory and methyl jasmonate exposure.

Induced volatile terpenes have been commonly reported among diverse agricultural plant species, but less commonly investigated in odorous plant species. Odorous plants synthesize and constitutively store relatively large amounts of volatiles, and these may play a role in defense against herbivores. We examined the effect of herbivory and methyl jasmonate (MeJA) exposure on the release of volatile organic compounds (VOCs) in the marsh elder, Iva frutescens, which contains numerous constitutive VOCs, mainly mono- and sesquiterpenes. Our specific goal was to test for the presence of inducible VOCs in a naturally occurring plant already armed with VOCs. The abundant, native specialist leaf beetle Paria aterrima was used in herbivore induction trials. VOCs were sampled from herbivore wounded and unwounded, and from MeJA treated and untreated I. frutescens. Total VOC emissions were significantly greater in response to herbivory and MeJA treatment compared to unwounded controls. Herbivore wounding caused a substantial shift in the emission profile (42 VOCs from wounded, compared to 8 VOCs from unwounded I. frutescens), and MeJA had a similar yet less substantial influence on the emission pattern (28 VOCs from MeJA treated compared to 8 VOCs from untreated I. frutescens). Constitutive VOC emissions predominated, but some VOCs were detected only in response to herbivory and MeJA treatment, suggesting de novo synthesis. Several VOCs exhibited a delayed emission profile in contrast to the rapid release of constitutive VOCs, and principal components analysis revealed they were not associated with constitutive emissions. While I. frutescens contains many constitutive VOCs that are released immediately in response to herbivory, it also produces novel VOCs in response to feeding by the specialist P. aterrima and MeJA treatment.

Acetates↗
PubMed2006

Caterpillar herbivory and salivary enzymes decrease transcript levels of Medicago truncatula genes encoding early enzymes in terpenoid biosynthesis.

In response to caterpillar herbivory, alfalfa and related plant species defend themselves through the induction of saponin and volatile terpenoid biosynthesis. Both these types of defensive compounds are derived from the metabolic intermediate, isopentenyl diphosphate (IPP). In plants, two distinct biosynthetic pathways can generate IPP; the cytosolic mevalonate pathway and the plastid-associated 2C-methyl erythritol 4-phosphate (MEP) pathway. In Medicago truncatula, transcript levels of key regulatory genes active in the early steps of these biosynthetic pathways were measured in response to larval herbivory by the beet army worm, Spodoptera exigua. Transcripts encoding enzymes at early steps of both terpenoid pathways were lower in caterpillar-damaged leaves. Higher degrees of herbivore damage accentuated the decrease in transcript levels; however, transcript amounts were not affected by insect larval stage. Insect larvae, manipulated to reduce labial gland salivary secretions, were used to examine the role of the salivary elicitors in modulating gene expression. Results suggest that an insect salivary factor, possibly glucose oxidase (GOX), may be involved in reduction of transcript levels following herbivory. Addition of GOX or hydrogen peroxide to mechanically wounded leaves confirm these findings. In comparison, transcript levels of a gene encoding a putative terpene synthase are induced in mechanically- or insect-damaged leaves. These data show that insect salivary factors can act to suppress transcript levels of genes involved in plant defense pathways. Findings also suggest that in response to stress such as insect herbivory, regulation occurs at the early steps of the MEP pathway.

Animals↗
PubMed1985

Heterogeneity of hepatic microsomal UDP-glucuronosyltransferase activities. Conjugations of phenolic and monoterpenoid aglycones in control and induced rats and guinea pigs.

In this report we present evidence that the heterogeneity of hepatic microsomal UDP-glucuronosyltransferase(s) (UDPGT) activities depends on the chemical structures of the aglycones as well as their biophysical constants. Three animal models were used: Wistar rats, which have active UDPGTs; Gunn rats, in which some of the UDPGT activities are reduced, but which can be induced by phenobarbital; and guinea pigs. In Wistar rats, we found that some coumarins were poor substrates of UDPGT (GT1) and that twenty monoterpenoid alcohol activities showed typical phenobarbital-inducible behavior. In Gunn rats, we showed that substitution of the phenolic aglycone by bulky (alkyl- or methoxy-) groups in the 2-position of the phenolic ring decreased UDPGT (GT1) activity, whereas substitution in the 4-position resulted in an increase in this activity. We also showed that, in this particular strain, activities toward terpenes were less affected than activities toward flat (aromatic) aglycones. Induction by phenobarbital in Gunn rats increased the activity and limited the deficiency for monoterpenoid alcohols. In guinea pigs, we confirmed that phenobarbital selectively increased the activities of UDPGT towards twenty monoterpenoid alcohols without affecting other typical phenobarbital-induced activities such as those for conjugation of morphine. Finally, we showed that orientation of the aglycone molecule in the active site was apparently related to its dipole moment and that the distance between "acceptor-oxygen" (hydroxyl) and the carbons out of the general plane of the molecule was an important factor. These studies clearly suggest that rat and guinea pig contain a UDPGT(monoterpenoid alcohols) with restricted specificities and also that UDPGT(GT1) comprises at least two or three different isoenzymes, each with a slightly different restricted specificity towards flat aromatic aglycones.

Animals↗
PubMed1994

Structure-activity relationships among monoterpene inhibitors of protein isoprenylation and cell proliferation.

The monoterpene d-limonene inhibits the post-translational isoprenylation of p21ras and other small G proteins, a mechanism that may contribute to its efficacy in the chemoprevention and therapy of chemically induced rodent cancers. In the present study, the relative abilities of 26 limonene-like monoterpenes to inhibit protein isoprenylation and cell proliferation were determined. Many monoterpenes were found to be more potent than limonene as inhibitors of small G protein isoprenylation and cell proliferation. The relative potency of limonene-derived monoterpenes was found to be: monohydroxyl = ester = aldehyde > thiol > acid = diol = epoxide > triol = unsubstituted. All monoterpenes that inhibited protein isoprenylation did so in a selective manner, such that 21-26 kDa proteins were preferentially affected. Perillyl alcohol, one of the most potent terpenes, reduced 21-26 kDa protein isoprenylation to 50% of the control level at a concentration of 1 mM, but had no effect on the isoprenylation of 67, 47 or 17 kDa proteins. In particular, p21ras farnesylation was inhibited 40% by 1 mM perillyl alcohol. At the same concentration, perillyl alcohol completely inhibited the proliferation of human HT-29 colon carcinoma cells. The structure-activity relationships observed among the monoterpene isoprenylation inhibitors support a role for small G proteins in cell proliferation, and suggest that many limonene-derived monoterpenes warrant further investigation as antitumor agents.

3T3 Cells↗
PubMed1980

Elevation of serum high density lipoprotein cholesterol by rowachol, a proprietary mixture of six pure monoterpenes.

Rowachol, a proprietary choleretic containing 6 pure monoterpenes markedly elevates serum HDL cholesterol (SHDL-C) concentrations in man. The concentration of SHDL-C showed a progressive increase in 16 patients treated with 6-9 capsules of Rowachol daily for periods of 2-28 weeks. There was no accompanying significant change in the concentrations of serum total cholesterol or triglyceride. In view of the significant inverse relationship between SHDL-C concentration and the risk of developing ischaemic heart disease, it is suggested that Rowachol and possibly other terpenes merit further investigation as possible therapeutic agents in the prevention and treatment of atheroma.

Adolescent↗
PubMed1992

Analytical methods for monoterpene glycosides in grape and wine. II. Qualitative and quantitative determination of monoterpene glycosides in grape.

Free and glycosidically bound terpenes of five Vitis vinifera grape cultivars (muscat of Alexandria, muscat of Frontignan, muscat of Hamburg, muscat Ottonel and Gewürztraminer) were investigated. The free and bound fractions were separated by selective retention on Amberlite XAD-2 resin. The glycosidic fractions were analysed by gas chromatography and gas chromatography-mass spectrometry using either enzymic hydrolysis and subsequent analysis of the released aglycones or trimethylsilyl (TMS) and trifluoroacetyl derivatives. The known monoterpenyl, benzyl and 2-phenylethyl beta-D-glucopyranosides, beta-rutinosides, 6-O-alpha-L-arabinofuranosyl-beta-D-glucopyranosides and 6-O-beta-D-apiofuranosyl-beta-D-glucopyranosides were determined. A number of other glycosides were detected and the structures of some of them, mainly apiosylglucosides and glucosides with aglycones in higher oxidation state than linalol, were tentatively identified using the mass spectra of their TMS and TFA derivatives and the results obtained from the analysis of their aglycones.

Chromatography, Gas↗
PubMed1992

Biochemical basis for mouse resistance to hyaline droplet nephropathy: lack of relevance of the alpha 2u-globulin protein superfamily in this male rat-specific syndrome.

It is well-established that binding of a chemical to alpha 2u-globulin is the rate-limiting step in the development of male rat-specific hyaline droplet nephropathy. Mice synthesize mouse urinary protein (MUP), a protein which is very similar to alpha 2u-globulin, but this protein does not render the mouse sensitive to a similar renal toxicity. Therefore, the purpose of the present study was to determine the biochemical basis for mouse resistance to hyaline droplet nephropathy. Male Fischer 344 rats and B6C3F1 mice excreted 12.24 +/- 0.60 and 14.88 +/- 0.99 mg of alpha 2u-globulin and MUP daily, indicating that quantitative differences in protein excretion were not involved in the species specificity of the nephropathy. With d-limonene as a model hyaline droplet inducing agent, both rat and mouse liver microsomes oxidized the terpene to its 1,2-epoxide (the metabolite that binds reversibly to alpha 2u-globulin in vivo), demonstrating that metabolic differences do not determine the mouse resistance to this lesion. In spite of the formation of the epoxide intermediate, no binding of [14C]d-limonene equivalents to mouse kidney proteins was observed. In contrast, about 40% of the d-limonene equivalents in male rat kidney was reversibly bound to renal proteins. The renal reabsorption of alpha 2u-globulin and MUP was markedly different, as rats reabsorbed about 60% of the total filtered load of alpha 2u-globulin, but MUP was not reabsorbed by the mouse kidney. Given the absence of MUP in mouse kidney, in vitro equilibrium saturation binding studies were also conducted to determine whether MUP could bind the epoxide metabolite. alpha 2u-Globulin bound [14C]d-limonene-1,2-oxide with an apparent Kd of 4 x 10(-7) M. However, under identical experimental conditions, MUP failed to bind the epoxide. These data indicate that two major biochemical differences between alpha 2u-globulin and MUP contribute to mouse resistance to hyaline droplet nephropathy. Under both in vivo and in vitro conditions, MUP does not bind d-limonene-1,2-oxide, the rate-limiting step in the development of the nephropathy. However, even if MUP did bind the epoxide, the fact that it is not reabsorbed into the mouse kidney precludes its involvement in a syndrome involving renal protein overload. Finally, the absence of an interaction between d-limonene, a model hyaline droplet inducer, and the protein most similar to alpha 2u-globulin suggests that no other protein in the alpha 2u-globulin superfamily is likely to cause hyaline droplet nephropathy in other species.

Alpha-Globulins↗
PubMed1993

Peri- and postnatal developmental toxicity of beta-myrcene in the rat.

beta-Myrcene (MYR) and essential oils containing this monoterpene have been widely used as scenting agents in cosmetics, detergents, soaps, and as flavouring additives in food and beverages. Recently, MYR was reported to be an analgesic substance and the active principle of lemongrass tea. Despite the importance of human exposure to MYR, its toxicological profile has not been comprehensively studied. The aim of this study was to provide data on the peri- and postnatal developmental toxicity of this terpene. MYR (0.25, 0.5, 1.0 and 1.5 g/kg) in corn oil was given by gavage to female Wistar rats from day 15 of pregnancy, parturition and throughout the period of lactation up to weaning (postnatal day 21). The progeny were examined at birth and subsequently to weaning. Mortality, weight gain and physical signs of postnatal development (ear unfolding, incisor eruption, fur development and eye opening) were evaluated. When the exposed offspring reached maturity (120 days) their reproductive capacity was assessed. No adverse effects on the offspring were seen with the lowest dose tested, but 0.5 g/kg and higher doses decreased birth weight, increased perinatal mortality and delayed the day of appearance of landmarks of postnatal development. Moreover, fertility was impaired in female offspring exposed to the two highest doses of MYR. From the data presented in this paper the no-observed-adverse-effect level for peri- and postnatal developmental toxicity could be set at 0.25 g beta-myrcene/kg body weight.

Acyclic Monoterpenes↗
PubMed1993

Characterization of a lysine-to-glutamic acid mutation in a conservative sequence of farnesyl diphosphate synthase from Saccharomyces cerevisiae.

The mutant gene erg20-2 was isolated from a yeast strain defective in farnesyl diphosphate synthase (FPPS). This strain had the unusual property of excreting prenyl alcohols such as geraniol. The nucleotide (nt) sequence, compared with that of the wild-type gene, showed a single nt change, resulting in a Lys197-->Glu substitution in FPPS which is directly involved in terpenic alcohol formation. In addition, disruption of ERG20 revealed that in yeast no other prenyl transferase is able to synthesize the FPP molecules required for essential non-sterol metabolites.

Acyclic Monoterpenes↗