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PubMed1998

Floral Origin Markers of Chestnut and Lime Tree Honeys.

The apiculture industry is more and more interested in finding typical markers to authenticate floral origin of honeys. With this aim, some reliable volatile compounds were proposed to identify origin of lime tree and chestnut samples. A dichloromethane extraction followed by a Likens-Nickerson simultaneous steam distillation/solvent extraction led to representative honey extracts. About 400 volatile compounds were separated by gas chromatography, but only a few authenticated the floral origin of honeys. Chestnut honeys are distinguishable from other origins by high concentrations of acetophenone, 1-phenylethanol (>88 ppb), and 2-aminoacetophenone (>154 ppb). Lime tree honeys are characterized by enhanced amounts of shikimate pathway derivatives (ethylmethylphenol isomer (>31 ppb), 4-tert-butylphenol, estragole (>51 ppb), and p-methylacetophenone but also by high concentrations of monoterpene-derived compounds (menthol, thymol, 8-p-menthene-1,2-diol, and carvacrol (>76 ppb)) and methyl(1-methylethenyl)benzene.

Journal Article↗
PubMed2002

Stereocontrolled IMDA reaction of styrene derivatives. A way to enantiopure 3a,4,9,9a-tetrahydrobenz[f]isoindolines.

IMDA reactions on chiral perhydro-1,3-benzoxazines, derived from (-)-8-amino menthol, bearing a styrene substituent at C-2 acting as diene and an acryl amide acting as dienophile occur with high stereoselection and excellent chemical yields. After elimination of the chiral appendage, enantiopure 3a,4,9,9a-tetrahydrobenz[f]isoindolines are prepared in this way. The effect of the substituents at both diene and dienophile are studied, showing that a methyl group at C-1 in the diene inhibited the reaction, while the ene adduct, instead of the IMDA product, was obtained when a methyl group was at C-2.

Journal Article↗
PubMed2002

Photoinduced electron-transfer substitution reactions via unusual charge-transfer intermediates.

The photoinduced substitution reactions of halogenated alkanes (1-haloadamantanes, 1-haloronorbornanes, menthyl chloride) with a homologous series of amines or alcohols (methylamine, 2-methyl-2-aminopropane, methanol, or 2-methyl-2-propanol) to form the corresponding alkane-substituted amines or ethers and HCl were investigated. The geometry of the bridgehead carbons made S(N)2 reactions impossible. Nonpolar reaction conditions were employed which made classical and nonclassical carbocation S(N)1 reaction pathways unlikely. The reaction rates were measured. Trapping experiments indicated that free radical reactions were uninvolved in the substitution product formation. A novel, photoinduced electron-transfer reaction mechanism involving a charge-transfer intermediate is proposed to explain the observed production of secondary amines and ethers. The excitation wavelength dependence (action spectrum) was measured and found to be comparable to the ultraviolet absorption spectra of the charge-transfer complexes. The stereochemical implications of the reaction mechanism were investigated. The formation of the methyl ether of (1R,2S,5R)-menthol was the only organic reaction product observed in the photoreaction between (1R,2S,5R)-menthyl chloride and methanol.

Journal Article↗
PubMed2004

Origin of chiral induction in radical reactions with the diastereoisomers (5R)- and (5S)-5-l-menthyloxyfuran-2[5H]-one.

Acetalization of 5-hydroxyfuran-2[5H]-one with l-menthol yields (5R)- (1) and (5S)-5-l-menthyloxyfuran-2[5H]-one (2) in equal amounts. The diastereomer 1 crystallizes preferentially. For the first time, the isolation of pure diastereoisomer 2 is reported. Different diastereoselectivities were observed in the radical tandem reaction of 1 and 2 with N,N-dimethylaniline. The privileged conformations in solution of the substrates and the products of the radical reaction were then determined, and X-ray crystal structure analyses were carried out on the reaction products. The different stereoselectivities in both cases are explained by different orientations of the menthyloxy substituent.

Journal Article↗
PubMed2003

Synthesis of enantiopure 3-azabicyclo[3.2.0]heptanes by diastereoselective intramolecular [2+2] photocycloaddition reactions on chiral perhydro-1,3-benzoxazines.

[2+2] photocycloadditions involving chiral 3-acryloyl-2-vinylperhydro-1,3-benzoxazines derived from (-)-8-aminomenthol are highly diastereoselective reactions. The facial selectivity depends on the type of substitution at the vinyl double bond, and always leads to cis-fused bicyclic derivatives. The de is good for compounds with one substituent at the outer carbon of the double bond at C-2, but only one diastereomer is formed in cyclizations of compounds with two substituents at that position. The elimination of the menthol appendage gives enantiopure 3-azabicyclo[3.2.0]heptanes.

Journal Article↗
PubMed2003

Enantioselective Synthesis of L-CCG-I.

Introduction of natural menthol as the chiral auxiliary in a gamma-Br-alpha,beta-unsaturated ester leads to enantioselective generation of three chiral centers in a single step on reaction with a glycine anion equivalent to provide L-CCG-I in 94% ee.

Amino Acids, Dicarboxylic↗
PubMed2005

Diastereoselective yang photocyclization reactions in solution. synthesis of enantiopure azetidin-3-ol derivatives.

[reaction: see text] Chiral 2-acyl-3-allyl- or 2-acyl-3-benzyl-substituted perhydro-1,3-benzoxazines readily cyclized under irradiation to azetidin-3-ol derivatives. The diastereoselectivity of the cyclization is dependent on the nature of the substituents at the nitrogen atom. N-allyl-substituted derivatives yielded only two of the four possible diastereomers in moderate to good diastereomeric excess. The cyclization of N-benzyl derivatives was totally diastereoselective leading to a single diastereomer. The elimination of the menthol appendage lead to enantiopure 2,3-disubstituted azetidin-3-ol derivatives.

Journal Article↗
PubMed2005

Synthesis and characterization of fluorescent poly(aromatic amide) dendrimers.

The synthesis of a series of poly(aromatic amide) dendrimers up to the second generation is described herein. The AB(2) building block used throughout the synthesis of the dendrimers was the allyl ester of 3,5-diaminocinnamic acid, which has been synthesized from 3,5-dinitrobenzoic acid in good yield with use of a four-step procedure. Dendron synthesis was achieved via a convergent approach with use of a sequence of deprotection/coupling steps. Two commercially available alcohols, L-menthol and citronellol, were coupled to the AB(2) monomer by using an alkyl diacid spacer and two core units; 1,7-diaminoheptane and tris(2-aminoethyl)amine have been used to produce the final dendrimers. Characterization was carried out by NMR and IR spectroscopies, MALDI-TOF mass spectrometry, GPC, and DSC. The novel monomer and dendritic derivatives exhibited a strong fluorescence emission in the visible region (lambda approximately 500 nm) of the spectrum and a weak emission in the near-infrared (lambda approximately 850 nm) upon excitation in the near-UV region. The fluorescence emission characteristics were found to be solvent and dendrimer generation dependent.

Journal Article↗
PubMed2006

IB-01212, a new cytotoxic cyclodepsipeptide isolated from the marine fungus Clonostachys sp. ESNA-A009.

IB-01212, a new cytotoxic cyclodepsipeptide featuring C2 symmetry, was isolated from the mycelium extract of Clonostachys sp. ESNA-A009. The amino acid sequence of the compound was determined by spectroscopy techniques. The absolute configuration of the amino acids was determined by a combination of the Marfey and menthol methods. The structure, which was confirmed by comparison of the analytical data for the natural product with a sample obtained by solid-phase peptide synthesis, was revealed to be a cyclic dimer formed by two chains of L-N,N-Me2Leu-L-Ser-L-N-MeLeu-L-N-MePhe bound by the two esters formed between the carboxylic acid of the L-N-MePhe and the hydroxyl function of the L-Ser. IB-01212 is highly cytotoxic to different tumor cell lines.

Antibiotics, Antineoplastic↗
PubMed2006

Efficient asymmetric synthesis of novel gastrin receptor antagonist AG-041R via highly stereoselective alkylation of oxindole enolates.

An efficient method for asymmetric synthesis of the potent Gastrin/CCK-B receptor antagonist AG-041R was developed. Core oxindole stereochemistry was established by asymmetric alkylation of oxindole enolates with bromoacetic acid esters, using l-menthol as a chiral auxiliary. The key alkylation reaction of the oxindole enolates generated tetrasubstituted chiral intermediates with high diastereoselectivity. The stereoselective alkylation reactions are described in detail.

Alkylation↗
PubMed1996

Superbase-Promoted Acylation of Hindered Alcohols.

The commercially available nonionic superbase P(MeNCH(2)CH(2))(3)N (1a) is very useful for the acylation of unreactive hindered alcohols as well as acid-sensitive alcohols. The reactions proceed in high yields using an acid anhydride, and 1a can be regenerated in a single step. The relative rates for benzoylation of (+/-)-menthol in C(6)D(6) using conventional acylation reagents and strong nonionic bases are compared. In general, acetylation with 1a is accelerated in the polar solvent CH(3)CN whereas benzoylation is faster in the nonpolar solvent C(6)H(6). The benzoylation intermediate RC(O)P(MeNCH(2)CH(2))(3)N(+) was found to be in equilibrium with 1a, with lower temperatures favoring the intermediate. The relative stabilities of several known acylating intermediates are compared.

Journal Article↗
PubMed1997

Asymmetric Synthesis and Properties of Sulfinimines (Thiooxime S-Oxides).

Enantiomerically pure sulfinimines (thiooxime S-oxides 10), important building blocks in the asymmetric synthesis of amine derivatives, are prepared in good to excellent yields in one step from aromatic, heteroaromatic, and aliphatic aldehydes. This protocol involves treating commercially available (R)- or (S)-menthyl p-toluenesufinate (Andersen reagent 4) with LiHMDS, followed by the aldehyde, affording (E)-10 exclusively. The sulfinimines 10 are formed via a Peterson-type olefination reaction of silylsulfinamide anion 13 with the aldehyde. Anion 13 is generated by reaction of lithium menthoxide (12a) with bis(trimethylsilyl)sulfinamide 11, which is formed in the reaction of 4 with LiHMDS. The other product formed is O-(trimethylsilyl)menthol (12c), which is isolated in >80% yield for recycling. Two other less efficient methods for the asymmetric synthesis of 10 are discussed: (i) the asymmetric oxidation of sulfenimines 6 with chiral nonracemic oxaziridines and (ii) the reaction of metal aldimines, prepared from nitriles, with 4. All of these protocols fail with ketones.

Journal Article↗
PubMed1999

Molecular Recognition Study on Supramolecular Systems. 20. Molecular Recognition and Enantioselectivity of Aliphatic Alcohols by L-Tryptophan-Modified beta-Cyclodextrin.

L-Tryptophan-modified beta-cyclodextrin (L-Trp-beta-CD) has been synthesized and its molecular recognition behavior investigated through fluorescence and circular dichroism spectrometry, as well as fluorescence lifetime measurement in the presence and absence of various alcohols as guest molecules. Employing the indolyl group as a spectral probe, spectrofluorometric and spectropolarimetric titrations have been performed in aqueous phosphate buffer solution at pH 7.20 to calculate the complex stability constants for 1:1 inclusion complexation of L-Trp-beta-CD with several series of alcohols at 25 degrees C. The results obtained indicate that L-Trp-beta-CD can recognize not only size/shape and hydrophobicity but also the enantiomeric and geometrical isomers of the guest alcohols, showing a 230-fold molecular selectivity (13.5 kJ mol(-)(1)) for 2-adamantanol over cyclopentanol among the cyclic alcohols examined. Moderate enantiomeric selectivities of 1.2 and 1.9 for (-)-isomers of borneol and menthol, respectively, and geometrical selectivity of 2.0 for geraniol over nerol have also been observed.

Journal Article↗
PubMed2001

A new colorimetric assay for studying and rapid screening of membrane penetration enhancers.

PURPOSE: This work aims to demonstrate a novel chemical assay for rapid screening and analysis of the mode of action of membrane interaction by penetration enhancers. METHODS: The new bio-mimetic membrane assembly, consisting of supramolecular aggregates of lipids and conjugated polydiacetylene, undergoes visible and quantifiable blue-red color transitions upon interaction with penetration enhancers. RESULTS: The new colorimetric model has been employed to examine various classes of penetration enhancers, including 1-dodecylhexahydro-2H-azepin-2-one (Azone), oleic acid, propylene-glycol, menthol, ethoxyglycol-diethyleneglycol-monoethyl-ether (Transcutol), polysorbate-polyethylenesorbitan-monolaurate (Tween-20), and the drug 7-chloro-1-methyl-5-phenyl-3H-1,4-benzodiazepin-2-one (Diazepam). The assay enables to evaluate the validity of various observations and hypotheses proposed in previous studies regarding permeation enhancement activities. Our results suggest, for example. that propylene glycol (PG) by itself does not interfere with membranes, but rather exhibits synergistic effect in combination with other penetration enhancers. Similarly, our data demonstrate that Transcutol does not independently interact with membranes. The colorimetric system also indicates that interaction of penetration enhancers with membranes depend upon the lipid phase, as well as the self-assembly properties of the enhancer molecules. CONCLUSIONS: The new biomimetic model membrane system can be applied for rapid screening of the activities of penetration enhancers, and provides insight into the mechanisms of permeability of membrane-active compounds.

Acetylene↗
PubMed2002

Reported cessation advice given to African Americans by health care providers in a community health clinic.

Physician smoking cessation advice has been shown to be effective in encouraging patients to attempt cessation. Few studies have examined factors associated with patient-reported physician advice in an inner city community health clinic. Smokers identified via chart review and provider referral met with a study "smoking specialist." Eligible participants self-identified as African American, smoked at least 1 cigarette per day in the prior 7 days, were 18 or older, had access to a telephone, and agreed to consider blood testing for genetic susceptibility to lung cancer. Of the 869 smokers identified, 487 were eligible and completed a brief in-person and a more extensive follow-up telephone survey within one week after their visit. Patient reports of smoking cessation advice by providers were regressed on patient demographic, smoking, health, and social support variables. Seventy percent of participants reported that they had been advised to quit smoking. Smokers who were older, did not smoke menthol cigarettes, were in poorer health, and who had a regular health care provider were most likely to report having received advice. Patients in this community health setting reported high rates of provider advice to quit smoking. Yet, even in this optimal condition, young healthy smokers did not report receiving advice, even when they were ready to quit smoking. Providers may need additional training and prompting to counsel young healthy smokers about the importance of cessation.

Adolescent↗
PubMed2003

[Pruritus without skin manifestation--what kind of state of the art nursing intervention?].

The search for evidence based information and its evaluation for planning the care of a woman with pruritus without visible signs on her skin is exemplified and described in this article. Literature was sought with the key words "itch", "pruritus", and "elderly" in medline, Cinahl and the Cochrane library. Retrieved studies were appraised by the criteria for valid information of evidence based nursing. Most pruritus studies were about pruritus with skin rash or about pruritus connected to liver or renal failure. Randomised controlled trials about the treatment of pruritus were characterised by small sample sizes or were done with only men or women. The little knowledge found in these studies did not help resolve the complex individual situation of the patient. Treatment suggestions from the studies: to assess the causes and exacerbating factors of pruritus; to wash the skin with water only, e.g. without soap; to emulsify the skin with Vaseline or oil at least once daily; to prevent too much heat by covering the patient just enough for him or her to feel no cold; prescribing Atarax, a histamin inhibitor of the first generation at night time; to try the antidepressant drug Doxepin; and emulsification with alcohol, menthol and cool water. There is no evidence to predict results of any one of these suggested interventions. Further research regarding the pathophysiology and the effectiveness of interventions against pruritus is needed.

Aged↗
PubMed2003

Erythema multiforme due to contact with weeds: a recurrence after patch testing.

Erythema multiforme (EM) as a complication of patch testing (PT) is rare. A 52-year-old woman with a 13-year history of episodes of EM, after contact with weeds during home gardening, had had no recent history of herpes simplex, other infection, drug ingestion or vaccination. On examination, EM lesions were distributed on the exposed skin. 5 weeks after complete resolution, PT and photopatch testing (PPT) were done with fresh plants she brought in. She was PT with a standard series and the Hermal-Trolab plants, woods, tars, balsams and flavors series. Intradermal testing, with a 3 + reaction to mixed weed pollens, was done 3 weeks later. Specific IgE to weed pollens class 1 (CAP-Pharmacia) was detected. Eczematous PT reactions were obtained with fresh leaves: common chickweed (Stellaria media Caryophyllaceae), dandelion (Taraxacum officinale Compositae), field-milk thistle (Sonchus arvensis Compositae) and white clover (Trifolium repens Leguminosae). Photoaggravation was seen to common chickweed and dandelion. Positive PT was also seen with alantolactone. By the 4-day reading, a typical EM had commenced, coming up to quite the same extent as seen on admission. There was no photosensitivity (UV skin tester, K. Waldmann). In the essential oil obtained from common chickweed, thin layer chromatography (TLC) revealed the well-known contact allergens borneol, menthol, linalool, 1,8-cineole, and other terpenes such as epoxy-dehydro-caryophyllene, monoterpene alcohol-ester and caryophyllene. Up to now, no data on essential oil in Stellaria media (common chickweed) have been reported. It can be concluded that EM developed due to contact with weeds, and recurred after patch testing. Neither blistering nor eczematous lesions have been seen on her skin, making this case very unusual. As far as the world literature is concerned, this is only the 4th report of EM developing in association with patch testing.

Dermatitis, Occupational↗
PubMed2001

Enantioselectivity of odor perception in honeybees (Apis mellifera carnica).

The authors tested the ability of 60 free-flying honeybees (Apis mellifera carnica) to discriminate a conditioning odor from an array of 26 simultaneously presented substances. The stimuli included 10 pairs of enantiomers and 6 essential oils. The bees (a) significantly distinguished between 98% of the 540 odor pairs tested, thus showing an excellent overall discrimination performance, and (b) were able to discriminate between the optical isomers of limonene, alpha-pinene, beta-citronellol, menthol, and carvone but failed to distinguish between the (+)- and (-)-forms of alpha-terpineol, camphor, rose oxide, fenchone, and 2-butanol. The findings support the assumptions that enantioselective molecular odor receptors may exist only for some volatile enantiomers and that insects and mammals may share common principles of odor quality perception, irrespective of their completely differing repertoires of olfactory receptors.

Animals↗