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Volatile constituents of ACHILLEA GRANDIFOLIA Friv. growing wild in Greece were studied by means of GC and GC-EIMS. Sixty constituents were identified. The main components were camphor, alpha- and beta-thujone, and 1,8-cineole. Twenty-six constituents have not been previously reported in the essential oils of the genus Achillea.
We present an implementation of the polarizable continuum model for the calculation of solvent effects on electronic circular dichroism spectra. The computational model used is density functional theory in the length-gauge formulation, and gauge-origin independence is ensured through the use of London atomic orbitals. Results of calculations carried out for methyloxirane and bicyclic ketones, camphor, norcamphor, norbornenone, and fenchone are presented, and the theoretically obtained solvent effects are compared with experimental observations.
GOAL, SCOPE AND BACKGROUND: Some anthropogenic pollutants posses the capacity to disrupt endogenous control of developmental and reproductive processes in aquatic biota by activating estrogen receptors. Many anthropogenic estrogen receptor agonists (ERAs) are hydrophobic and will therefore readily partition into the abiotic organic carbon phases present in natural waters. This partitioning process effectively reduces the proportion of ERAs readily available for bioconcentration by aquatic biota. Results from some studies have suggested that for many aquatic species, bioconcentration of the freely-dissolved fraction may be the principal route of uptake for hydrophobic pollutants with logarithm n-octanol/water partition coefficient (log Kow) values less than approximately 6.0, which includes the majority of known anthropogenic ERAs. The detection and identification of freely-dissolved readily bioconcentratable ERAs is therefore an important aspect of exposure and risk assessment. However, most studies use conventional techniques to sample total ERA concentrations and in doing so frequently fail to account for bioconcentration of the freely-dissolved fraction. The aim of the current study was to couple the biomimetic sampling properties of semipermeable membrane devices (SPMDs) to a bioassay-directed chemical analysis (BDCA) scheme for the detection and identification of readily bioconcentratable ERAs in surface waters. METHODS: SPMDs were constructed and deployed at a number of sites in Germany and the UK. Following the dialytic recovery of target compounds and size exclusion chromatographic cleanup, SPMD samples were fractionated using a reverse-phase HPLC method calibrated to provide an estimation of target analyte log Kow. A portion of each HPLC fraction was then subjected to the yeast estrogen screen (YES) to determine estrogenic potential. Results were plotted in the form of 'estrograms' which displayed profiles of estrogenic potential as a function of HPLC retention time (i.e. hydrophobicity) for each of the samples. Where significant activity was elicited in the YES, the remaining portion of the respective active fraction was subjected to GC-MS analysis in an attempt to identify the ERAs present. RESULTS AND DISCUSSION: Estrograms from each of the field samples showed that readily bioconcentratable ERAs were present at each of the sampling sites. Estimated log Kow values for the various active fractions ranged from 1.92 to 8.63. For some samples, estrogenic potential was associated with a relatively narrow range of log Kow values whilst in others estrogenic potential was more widely distributed across the respective estrograms. ERAs identified in active fractions included some benzophenones, various nonylphenol isomers, benzyl butyl phthalate, dehydroabietic acid, sitosterol, 3-(4-methylbenzylidine)camphor (4-MBC) and 6-acetyl-1,1,2,4,4,7-hexamethyltetralin (AHTN). Other tentatively identified compounds which may have contributed to the observed YES activity included various polycyclic aromatic hydrocarbons (PAHs) and their alkylated derivatives, methylated benzylphenols, various alkyl-phenols and dialkylphenols. However, potential ERAs present in some active fractions remain unidentified. CONCLUSIONS AND OUTLOOK: Our results show that SPMD-YES-based BDCA can be used to detect and identify readily bioconcentratable ERAs in surface waters. As such, this biomimetic approach can be employed as an alternative to conventional methodologies to provide investigators with a more environmentally relevant insight into the distribution and identity of ERAs in surface waters. The use of alternative bioassays also has the potential to expand SPMD-based BDCA to include a wide range of toxicological endpoints. Improvements to the analytical methodology used to identify ERAs or other target compounds in active fractions in the current study could greatly enhance the applicability of the methodology to risk assessment and monitoring programmes.
Bridged bicyclic sulfide 1 was originally found to provide high levels of asymmetric induction in sulfur ylide-mediated epoxidations. This sulfide possesses chirality in the [2.2.1] thioether moiety and the [2.2.1] camphor-derived carbocyclic moiety. To determine whether the optimal sulfide had been used, a diastereomer of sulfide 1 in which the stereochemistry of the [2.2.1] carbocycle was reversed (sulfide 5) was prepared and studied as an epoxidation catalyst. This diastereomer gave considerably lower levels of asymmetric induction than the original sulfide 1. From computational and x-ray studies it was found that sulfide 5 gave rise to a more hindered ylide, which reacted more reversibly with aldehydes leading to lower enantioselectivity. Conditions that reduced reversibility were also tested and high enantioselectivities were returned for sulfide 5 (similar to sulfide 1). The implications for the synthesis of chiral sulfides for asymmetric epoxidations are discussed.
High-resolution proton nuclear magnetic resonance spectra were studied in D(+)-camphor-saturated solutions of ferric and ferrous cytochrome P450(cam) from Pseudomonas putida, and of the cyanide complex of ferric P450(cam). In all these compounds several hyperfineshifted resonances of the heme group could be detected. In the ferrous protein, these resonance lines, which exhibit a Curie-type temperature dependence in the range of 5-28 degrees , indicate the presence of high-spin iron (II). It is suggested that the iron (II) in ferrous P450(cam) might be pentacoordinated, as in other hemoproteins that can reversibly bind molecular oxygen and carbon monoxide.
The enzymes responsible for the oxidation of n-octane to octanoic acid or beyond in Pseudomonas oleovorans are octane inducible and are coded by genes borne on a transmissible extrachromosomal element. The octane to octanoate enzymes induced by octane are repressed by octanol. The chromosome also carries genes coding octanol oxidation enzymes that, in contrast, are induced by octanol, not by octane. The octane plasmid has been transferred from P. oleovorans to several other fluorescent Pseudomonas species. In exconjugants, the presence of both octane and camphor plasmids enhances their segregation rate.
Methylene hydroxylation by cytochrome P-450(cam) (cytochrome m) can be resolved into four distinct steps: substrate addition, m(o) --> m(os); reduction, m(os) --> m(rs); dioxygen addition, m(rs) --> m(O2) (rs); followed by a second putidaredoxin (Pseudomonas putida ferredoxin)-mediated reduction and product formation. The isolated ferrous oxy-substrate complex exhibits first-order decay kinetics with the relatively slow rate constant of k [unk] 0.01 sec(-1), at 25 degrees , without product release. Putidaredoxin addition accelerates the decomposition with second-order kinetics, k [unk] 51,000 M(-1) sec(-1), and initiation of product formation. Cytochrome m forms a complex with putidaredoxin with dissociation constant of K(D) = 3 muM. In the complete three-protein hydroxylase system, consisting of cytochrome m, putidaredoxin, and the reductase (a DPNH-specific flavo-protein), camphor hydroxylation occurs with a stoichiometry of 1 mole each of DPNH and O(2) used per mole of product formed; the K(M) for putidaredoxin is about 4.2 muM.Putidaredoxin, on treatment with carboxypeptidase A, loses one molecule each of tryptophan and glutamine sequentially from the carboxy terminus to expose a terminal arginine. The tryptophan-free product has been separated from native putidaredoxin and other impurities, and retains the visible and electron paramagnetic resonance spectra and the redox potential of the active center of native putidaredoxin. This modified redoxin binds less tightly to cytochrome m, K(D) [unk] 150 muM, and is 50 times less effective in stimulation of the m(O2) (rs) decay rate. A similar decrease in specific activity is observed in the complete hydroxylase system.
Cytochromes P-450 and P-448 in microsomal suspensions have been shown to be spectrally distinct by magnetic circular dichroism spectroscopy. Furthermore, this technique can be used to measure induction of these two cytochromes by phenobarbital and 3-methyl-cholanthrene. Magnetic circular dichroism spectroscopy is thus at least as useful as difference spectroscopy for the investigation of P-450 and P-448 and more informative because the presence of cytochrome b(5) and hemoglobin can be detected concurrently. We have also shown that the molar magnetic ellipticity for reduced + CO treated cytochrome P-450 of Pseudomonas grown on camphor is of similar value to that of reduced + CO treated microsomal P-450 and P-448.
Using isotopic tracer methods, we have shown that dihydrolipoic acid (2,3-thioctic acid) acylates the distal oxygen of ferrous oxygenated Pseudomonas cytochrome P-450, forming a transient acyl peroxide intermediate that facilitates oxygen-oxygen bond cleavage. Single-turnover studies with 18O2 indicate one oxygen-18 atom incorporated into the carboxylate group of lipoic acid for each oxygen-18 inserted into the substrate, camphor, forming the product, exo-5-hydroxycamphor. Such a branching ratio for label indicates that water is initially released from an unlageled position and illustrates that the general P-450 mixed-function oxidase stoichiometry generates H218O from 18O2 only after multiple-turnover equilibration with the acylating carboxylate oxygen. Formation of an acyl peroxide state is a natural intermediate in peracid, "oxene", or radical mechanisms for methylene carbone oxygenation.
We determined the coding nucleotide sequence of the mRNA for a 3-methylcholanthrene-inducible cytochrome P-450, P-450d, of rat liver by sequence analysis of cloned cDNAs. The predicted amino acid sequence of the cytochrome is composed of 513 amino acids, and its NH2-terminal sequence of 30 amino acids completely coincides with that reported from analysis of the purified cytochrome P-450d. The amino acid composition of the deduced sequence also agrees well with that determined from the purified protein. Computer-aided analysis was carried out to compare the complete primary structures of five species of cytochrome P-450, two molecular species of phenobarbital-inducible rat liver cytochrome P-450 (P-450b and P-450e), phenobarbital-inducible rabbit liver cytochrome P-450LM2, 3-methylcholanthrene-inducible rat liver cytochrome P-450d, and camphor-hydroxylating P-450 of Pseudomonas putida (P-450CAM). It is concluded therefrom that the time of divergence between cytochrome P-450b (P-450e) and P-450d is much earlier than that of branching between phenobarbital-inducible cytochromes P-450 of rat and rabbit. One highly conserved cysteine-containing region that is close to the COOH terminus is found in all of these cytochrome P-450 sequences, indicating that the heme-binding site is the cysteine residue in this region.
The plant acyl-acyl carrier protein (ACP) thioesterases (TEs) are of biochemical interest because of their roles in fatty acid synthesis and their utilities in the bioengineering of plant seed oils. When the FatB1 cDNA encoding a 12:0-ACP TE (Uc FatB1) from California bay, Umbellularia californica (Uc) was expressed in Escherichia coli and in developing oilseeds of the plants Arabidopsis thaliana and Brassica napus, large amounts of laurate (12:0) and small amounts of myristate (14:0) were accumulated. We have isolated a TE cDNA from camphor (Cinnamomum camphorum) (Cc) seeds that shares 92% amino acid identity with Uc FatB1. This TE, Cc FatB1, mainly hydrolyzes 14:0-ACP as shown by E. coli expression. We have investigated the roles of the N- and C-terminal regions in determining substrate specificity by constructing two chimeric enzymes, in which the N-terminal portion of one protein is fused to the C-terminal portion of the other. Our results show that the C-terminal two-thirds of the protein is critical for the specificity. By site-directed mutagenesis, we have replaced several amino acids in Uc FatB1 by using the Cc FatB1 sequence as a guide. A double mutant, which changes Met-197 to an Arg and Arg-199 to a His (M197R/R199H), turns Uc FatB1 into a 12:0/14:0 TE with equal preference for both substrates. Another mutation, T231K, by itself does not effect the specificity. However, when it is combined with the double mutant to generate a triple mutant (M197R/R199H/T231K), Uc FatB1 is converted to a 14:0-ACP TE. Expression of the double-mutant cDNA in E. coli K27, a strain deficient in fatty acid degradation, results in accumulation of similar amounts of 12:0 and 14:0. Meanwhile the E. coli expressing the triple-mutant cDNA produces predominantly 14:0 with very small amounts of 12:0. Kinetic studies indicate that both wild-type Uc FatB1 and the triple mutant have similar values of Km,app with respect to 14:0-ACP. Inhibitory studies also show that 12:0-ACP is a good competitive inhibitor with respect to 14:0-ACP in both the wild type and the triple mutant. These results imply that both 12:0- and 14:0-ACP can bind to the two proteins equally well, but in the case of the triple mutant, the hydrolysis of 12:0-ACP is severely impaired. The ability to modify TE specificity should allow the production of additional "designer oils" in genetically engineered plants.
Common sage (Salvia officinalis) produces an extremely broad range of cyclic monoterpenes bearing diverse carbon skeletons, including members of the p-menthane (1,8-cineole), pinane (alpha- and beta-pinene), thujane (isothujone), camphane (camphene), and bornane (camphor) families. An homology-based polymerase chain reaction cloning strategy was developed and used to isolate the cDNAs encoding three multiproduct monoterpene synthases from this species that were functionally expressed in Escherichia coli. The heterologously expressed synthases produce (+)-bornyl diphosphate, 1, 8-cineole, and (+)-sabinene, respectively, as their major products from geranyl diphosphate. The bornyl diphosphate synthase also produces significant amounts of (+)-alpha-pinene, (+)-camphene, and (+/-)-limonene. The 1,8-cineole synthase produces significant amounts of (+)- and (-)-alpha-pinene, (+)- and (-)-beta-pinene, myrcene and (+)-sabinene, and the (+)-sabinene synthase produces significant quantities of gamma-terpinene and terpinolene. All three enzymes appear to be translated as preproteins bearing an amino-terminal plastid targeting sequence, consistent with the plastidial origin of monoterpenes in plants. Deduced sequence analysis and size exclusion chromatography indicate that the recombinant bornyl diphosphate synthase is a homodimer, whereas the other two recombinant enzymes are monomeric, consistent with the size and subunit architecture of their native enzyme counterparts. The distribution and stereochemistry of the products generated by the recombinant (+)-bornyl diphosphate synthase suggest that this enzyme might represent both (+)-bornyl diphosphate synthase and (+)-pinene synthase which were previously assumed to be distinct enzymes.
Cinnamon (Cinnamomum zeylanicum, Nees in Wall) is one of the world's oldest spices. Sri Lanka is the main provider of cinnamon, mainly exported as "cinnamon quills." From a phytochemical viewpoint, cinnamon is q uniquely interesting plant. The volatile oils obtained from the bark, leaf, and root bark vary significantly in chemical composition. Each oil has a different primary constituent: cinnamaldehyde (in the bark oil), eugenol (in the leaf oil), and camphor (in the root-bark oil). Recent studies based on techniques such as gas-liquid chromatography and infrared spectrometry have revealed that the three oils possess the same array of monoterpene hydrocarbons in different proportions. Both gas-liquid chromatography and quantitative infrared spectrometry have recently been used to study changes in the chemical composition in the volatiles of cultivated and wild-growing cinnamons. As a result, some interesting biosynthetic speculations have evolved, and reliable methods of analytical assessment of quality have been developed. The technology of production of cinnamon oils has varied little from the methods introduced by the early Dutch settlers. They are based on variations on the general theme of steam distillation. Recently, new still designs have greatly enhanced the technological capability in Sri Lanka. Cinnamon bark and leaf oils form the basis of a variety of synthetically derived chemicals used in the food and cosmetic industries.
Isolation of volatile concentrate from the dried leaves of Artemisia arborescens and of Helichrysum splendidum has been obtained by supercritical extraction with carbon dioxide. To obtain a pure volatile extract devoid of cuticular waxes, the extraction products were fractionated in two separators operating in series. A good extraction process was obtained operating at 90 bar and 50 degrees C in the extraction vessel, at 90 bar and at -5 degrees C in the first separator and at a pressure between 20 and 15 bar and temperatures in the range 10-20 degrees C in the second one. The composition of the volatile concentrate has been analyzed by GC/MS. The volatile concentrate of A. arborescens was found to contain: trans-thujone (13.96%), camphor (6.15%) and chamazulene (5.95%). The main constituents in the extract of H. splendidum were: germacrene D-4-ol (17.08%), germacrene D (9.04%), bicyclogermacrene (8.79%) and delta-cadinene (8.43%). A comparison with the oils obtained by hydrodistillation is also given. The differences observed between the composition of the SFE volatile concentrates and of the hydrodistilled (HD) oils were relevant. Indeed, the HD oils had a blue color whereas the volatile concentrates were pale yellow. The HD oil of H. splendidum had a blue color due to the presence of guaiazulene (0.42% vs 0%), whereas the coloration of HD oil of A. arborecens was due to the high concentration of chamazulene (26.64% vs 3.37%).
Variations in the essential oil composition of Achillea millefolium L. growing in Estonia and in other European countries, were determined. The oils were obtained in yields of 0.9-9.5 mL kg-1. A total of 102 components were identified. The quantitatively most important components of yarrow were sabinene, beta-pinene, 1,8-cineole, artemisia ketone, linalool, alpha-thujone, beta-thujone, camphor, borneol, fenchyl acetate, bornyl acetate, (E)-beta-caryophyllene, germacrene D, caryophyllene oxide, beta-bisabolol, delta-cadinol, chamazulene etc. Samples from Estonia contained high amounts of monoterpenes and chamazulene. High amounts of monoterpenes and chamazulene were also found in samples from Hungary, Greek, Moldavia, Latvia, Lithuania and Germany. The oils from France, Belgium, Russia, Armenia, Spain and Italy were rich in oxygenated monoterpenes and contained a little amount of chamazulene. The drugs from Greece, Estonia, Moldavia and Scotland were rich in sesquiterpenes. The Millefolii herba grown in Estonia conforms to the European Pharmacopoeia (EP) standards in the aspect of the essential oil contents.
All substances are capable of producing toxicity, so nothing is completely non-toxic. Minimally toxic substances are those which produce little toxicity, minor self-limited toxicity, or clinically insignificant effects at most doses. Examples include silica gel, A&D ointment, chalk, lipstick, and non-camphor lip balms, watercolors, hand dishwashing detergents, non-salicylate antacids (excluding magnesium or sodium bicarbonate containing products), calamine lotion, clay, crayons, diaper rash creams and ointments, fabric softeners/sheets, glow products, glue (white, arts, and crafts type), household plant food, oral contraceptives, pen ink, pencils, starch/sizing, throat lozenges without local anesthetics, topical antibiotics, topical antifungals, topical steroids, topical steroids with antibiotics, and water-based paints. Minimally toxic exposures have the following characteristics: (1) The information specialist has confidence in the accuracy of the history obtained and the ability to communicate effectively with the caller. (2) The information specialist has confidence in the identity of the product(s) or substance(s) and a reasonable estimation of the maximum amount involved in the exposure. (3) The risks of adverse reactions or expected effects are acceptable to both the information specialist and the caller based on available medical literature and clinical experience. (4) The exposure does not require a healthcare referral since the potential effects are benign and self-limited. However, decisions regarding patient disposition should take into account the patient's intent, symptoms, and social environment. In addition, individual patient circumstances (e.g., pregnancy, pre-existing medical conditions, therapeutic interventions) need to be considered. Minimally toxic exposures may vary in route (dermal, inhalation, ingestion, ocular), chronicity (acute, chronic), and substance composition (single or multi-ingredient, single or multiple product). Future categorization of substances as "minimally toxic" should be based on a process involving review of current knowledge, a thorough analysis of poisoning experience, and prospective validation.
BACKGROUND: Many substances deemed too dangerous for commercial use are still available to the general public. The purchase of these substances may potentially place members of the general public at risk for serious poisonings. This study was designed to document the large variety of dangerous poisons readily available on a popular online auction Web site. Methods. Over a 10-month period, the online auction Web site eBays was searched daily using the terms "poison" and "contents." Product name, active ingredients, what form the product is in, amount in container, and relative toxicity rating (Clinical Toxicology of Commercial Products, Gosselin, et al.) were recorded. If available, pictures of the products were saved. RESULTS: One hundred twenty-one individual products were identified. Fifty-five were in solid/tablet form, 37 were powders, and 29 were liquids. Product containers were full for 56 items and partially full for 65. Twenty-four products contained ingredients rated as "supertoxic" and included strychnine (10), arsenic trioxide (8), cyanide (2) and nicotine, pilocarpine, phosphorus, powdered conium maculatum (1 each). Sixty-three products contained "extremely toxic" ingredients including thallium, picrotoxin, soluble barium, antimony, mercury, arsenates, podophyllin, fluoride, zinc phosphide, atropine, scopolamine, and plant extracts of gelsemium, aconite, larkspur, and croton. Twenty-one products contained "very toxic" ingredients including lead, copper, camphor, caffeine, theobromine, creosote, pyrogallic acid, sparteine, quinine, lindane, warfarin, phenol, and digitalis. The remaining 13 were "moderately-slightly toxic." CONCLUSION: While the viability of the labeled ingredients could not be verified, the transportation, handling, and potential utilization of these dangerous poisons by the general public could result in serious poisonings.
The P450 cytochromes represent a universal class of heme-monooxygenases. The detailed mechanistic understanding of their oxidative prowess is a critical theme in the studies of metabolism of a wide range of organic compounds including xenobiotics. Integral to the O2 bond cleavage mechanism by P450 is the enzyme's concerted use of protein and solvent-mediated proton transfer events to transform reduced dioxygen to a species capable of oxidative chemistry. To this end, a wide range of kinetic, structural, and mutagenesis data has been accrued. A critical role of conserved acid-alcohol residues in the P450 distal pocket, as well as stabilized waters, enables the enzyme to catalyze effective monooxygenation chemistry. In this review, we discuss the detailed mechanism of P450 dioxygen scission utilizing the CYP101 hydroxylation of camphor as a model system. The application of low-temperature radiolytic techniques has enabled a structural and spectroscopic analysis of the nature of critical intermediate states in the reaction.