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PubMedDate not supplied

O-[2-hydroxy-3-(dialkylamino)propyl]ethers of (+)-1,7,7-trimethyl bicyclo[2.2.1]heptan-2-one oxime (camphor oxime) with analgesic and antiarrhythmic activities.

A novel series of O-[2-hydroxy-3-(dialkylamino)propyl]ethers of (+)-camphor oxime was prepared and tested for its cardiovascular, analgesic and anti-inflammatory properties. No significant anti-inflammatory and hypotensive activities were displayed by any of the compounds, whereas several of them are reasonably active as antiarrhythmic and analgesic agents.

Acetates↗
PubMed2002

Studies of three genes encoding Cinnamomin (a type II RIP) isolated from the seeds of camphor tree and their expression patterns.

Cinnamomin, which has three isoforms, is a type II ribosome-inactivating protein (RIP) purified from the mature seeds of camphor tree (Cinnamomum camphora). In a previous study, an incomplete cDNA that encoded the A- and B-chain of Cinnamomin but lacked signal peptide sequence was cloned. In the present paper, its full-length cDNA was obtained by 5' rapid amplification of cDNA ends (5'RACE). Subsequently, polymerase chain reaction (PCR) amplification of its genomic DNA was performed. Unexpectedly, sequence analysis of the PCR products revealed three cinnamomin genes with >98.0% sequence identity. One of them corresponded to the published cDNA and was designated as cinnamomin I, whereas the other two genes were named as cinnamomin II and cinnamomin III, respectively. RT-PCR amplification of the cDNAs of cinnamomin II and III manifested that these two genes were functional. The three genes have no intron. Three Cinnamomin precursors that were inferred from the cDNA sequence of three cinnamomin genes exhibited relatively high sequence homology with other type II RIPs. Northern blot analysis demonstrated that the cinnamomin genes only expressed in cotyledons of C. camphora seeds and the acmes of expression emerged at 75-90 DAF when seeds were close to maturity. It is proposed that the three cinnamomin genes may encode three isoforms of Cinnamomin. The physiological function of Cinnamomin in C. camphora seeds is briefly discussed.

Algal Proteins↗
PubMed2003

Simultaneous existence of cinnamomin (a type II RIP) and small amount of its free A- and B-chain in mature seeds of camphor tree.

Cinnamomin, a type II ribosome-inactivating protein (RIP), was isolated from the mature seeds of camphor tree (Cinnamomum camphora). In this paper, small amount of free A- and B-chain of cinnamomin were found to be present in the mature seed cell of C. camphora besides the intact cinnamomin. Our results demonstrated that camphorin, a type I RIP previously reported to coexist with cinnamomin in the seeds of C. camphora, actually was the A-chain of cinnamomin. The percentage of free A- and B-chain in the total cinnamomin was 2.6-2.8% in the seed extract. Of these free A- and B-chain approximate 80% already existed in the seed cell, only about 20% were produced during the purification operation. As the enzymatic activity to reduce disulfide bond of cinnamomin in the seed extract of C. camphora was detected, we proposed that the free A- and B-chain were derived from the enzymatic reduction of the interchain disulfide bond of cinnamomin. It was demonstrated that the endogenous type II RIPs of several plant species, such as Cinnamomum porrectum, Cinnamomum bodinieri and Ricinus communis, could be enzymatically reduced into the free A- and B-chain in their respective seed cells. The function of the free A-chain in the seed cell and the possibility that metabolic enzymes might be involved in the reduction of the interchain disulfide bond of type II RIPs in vivo are discussed.

Algal Proteins↗
PubMed2006

Enantioselective synthesis of vinylcyclopropanes and vinylepoxides mediated by camphor-derived sulfur ylides: rationale of enantioselectivity, scope, and limitation.

By a sidearm approach, camphor-derived sulfur ylides 1 were designed and synthesized for the cyclopropanation of electron-deficient alkenes and epoxidation of aldehydes. Under the optimal conditions, the exo-type sulfonium salts 4a and 4b reacted with beta-aryl-alpha,beta-unsaturated esters, amides, ketones, and nitriles to give 1,3-disubstituted-2-vinylcyclopropanes with high diastereoselectivities and enantioselectivities. When the endo-type sulfonium salts 5a and 5b were used, the diastereoselectivities were not changed, whereas the absolute configurations of the products became the opposite to those of the reactions of 4a and 4b. An ylide cyclopropanation of chalcone derivatives with phenylvinyl bromide in the presence of catalytic amount of chiral sulfonium salts 4b and 5b has been developed. The sidearmed hydroxyl group was found to play a key role in the control of enantioselectivity and diastereoselectivity. The origins of the high diastereoselectivity and enantioselectivity were also studied by density functional theory calculations, which reveal the importance of the hydrogen-bonding between the sidearmed hydroxyl group and the substrate in determining the diastereoselectivity and enantioselectivity. The ylides 1 were also successfully applied for the epoxidation of aromatic aldehydes.

Journal Article↗
PubMed2000

Camphor-based alpha-bromo ketones for the asymmetric darzens reaction

(1R)-2-endo-Bromoacetyl-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol (endo-2-bromoacetylisoborneol) 4 and its trimethylsilyl ether 3 are presented as efficient reagents for the asymmetric Darzens reaction. From the alpha,beta-epoxy ketone adducts the chiral inductor camphor is removed, by treatment with ceric(IV) ammonium nitrate, to yield the corresponding epoxy acids which are isolated as their dicyclohexylammonium salts.

Journal Article↗
PubMed2001

A facile and highly diastereoselective aziridination of chiral camphor n-enoylpyrazolidinones with n-aminophthalimide.

Reaction of various chiral camphor N-enoylpyrazolidinones 2a-g with N-aminophthalimide in the presence of lead tetraacetate in CH(2)Cl(2) proceed smoothly afford the corresponding N-phthalimidoaziridines (3a-e, 4f-g) with excellent material yields (86-95%) at room temperature in 5 min. High levels of diastereoselectivities (up to >95:5 dr) were obtained. The solvent effect was investigated, and the auxiliary can be easily recovered in high yields under mild reaction conditions.

Journal Article↗
PubMed2001

Asymmetric Pauson-Khand reactions using camphor-derived chelating thiols as chiral controllers.

A convenient procedure for the preparation of enantiopure 10-(R-thio)-2-exo-bornanethiols from (1S)-camphor-10-thiol has been developed. The ethynyl derivatives of these thiols gave excellent diastereoselectivities (up to 98:2) in Pauson-Khand reactions with norbornene and norbornadiene through the intermediacy of a chelated dicobalt pentacarbonyl complex. Thermal reaction conditions starting from the preformed chelated complex gave better results than N-oxide-promoted runs with in situ generation of the chelated intermediate. The corresponding adducts have been elaborated through a protocol consisting of conjugate addition, samarium iodide-promoted cleavage of the chiral auxiliary, and retro-Diels-Alder reaction to afford 4-substituted 2-cyclopentenones in high enantiomeric purity.

Journal Article↗
PubMed2005

A short synthesis of 10-hydroxy 7-spirocyclopropanated camphor.

[Chemical reaction: see text] A short alternative synthesis of the title 10-hydroxy 7-spirocyclopropanated camphor (4) en route to 10-hydroxycamphor (5) was achieved from cyclopentadiene-derived 4-benzyloxymethylspiro[2.4]hepta-4,6-diene (6a) by a facile regioselective Diels-Alder cycloaddition with 2-chloroacrylonitrile in an overall yield of 20%.

Journal Article↗
PubMed1996

Preparation of Enantiomerically Enriched (2R,3R)- or (2S,3S)-trans-2,3-Diaryloxiranes via Camphor-Derived Sulfonium Ylides.

Easily available D-(+)-camphor-derived sulfides 3, 4, 6, and 7 were employed for enantioselective epoxidation via an ylide route. When benzylated or methylated sulfides were used as reagents or mediators for benzylidene transfer, stoichiometric and catalytic epoxidations were realized, respectively. Opposite asymmetric induction was achieved only when sulfides containing exo- (3 and 4) and endo- (6 and 7) alkylthio groups were used. That is, both (+)- and (-)-trans-diaryloxiranes could be obtained in excellent yields and moderate to good ee values under extremely mild conditions from the same chiral pool-derived reagents. A nonbonded interaction between the free OH in the ylides from sulfides (3, 6, and 7) and the carbonyl group of aldehydes controls the approach of the substrates to the ylidic carbon preferentially at one specified face and therefore leads to a more efficient asymmetric induction than that in the case of the ylide from methyl-protected hydroxylated sulfides 4, which cannot cause such an interaction. The same opposite asymmetric induction was also observed in the catalytic reaction with methyl-protected hydroxylated sulfide 4b and unprotected hydroxylated sulfide 3b.

Journal Article↗
PubMed2004

CamTHP*OH: a camphor-derived delta-lactol auxiliary for the effective desymmetrization of attached glycinamide residues. Asymmetric synthesis of alpha-amino carbonyl compounds.

Stereoselective allylation of camphor and subsequent terminal hydroformylation affords a new delta-lactol auxiliary (camTHP*OH) on multigram scale. Stereoselective condensation with glycine dimethylamide and Cbz protection affords a camTHP*-desymmetrized glycinamide building block which undergoes efficient and highly diastereoselective metal enolate alkylation reactions. Acid-mediated deprotection affords the N-Cbz-protected alpha-amino amide products which may be converted directly to alpha-amino ketones on treatment with Grignard or organolithium reagents without loss of stereochemical integrity. [reaction: see text]

Journal Article↗
PubMed2002

Cinnamomin, a type II ribosome-inactivating protein, is a storage protein in the seed of the camphor tree (Cinnamomum camphora).

Cinnamomin is a novel type II ribosome-inactivating protein (RIP) isolated in our laboratory from the seed of the camphor tree (Cinnamomum camphora). In this paper the physiological role it plays in the plant cell was studied. Northern and Western blotting revealed that cinnamomin was expressed specifically in cotyledons. It accumulated in large amounts simultaneously with other proteins at the post-stages of seed development. Cinnamomin degraded rapidly during the early stages of seed germination. Endopeptidase was proved to play an important role in the degradation of cinnamomin. Western blotting of total proteins from the protein body with antibodies against cinnamomin demonstrated that it only existed in this specific cellular organelle as a storage protein. The similar properties of cinnamomin and other seed storage proteins of dicotyledons were compared. We conclude that cinnamomin is a special storage protein in the seed of C. camphora.

Algal Proteins↗
PubMed2004

Photoelectron circular dichroism in core level ionization of randomly oriented pure enantiomers of the chiral molecule camphor.

The inner-shell photoionization of unoriented camphor molecules by circularly polarized light has been investigated from threshold to a photoelectron kinetic energy of approximately 65 eV. Photoelectron spectra of the carbonyl C 1s orbital, recorded at the magic angle of 54.7 degrees with respect to the light propagation direction, show an asymmetry of up to 6% on change of either the photon helicity or molecular enantiomer. These observations reveal a circular dichroism in the angle resolved emission with an asymmetry between forward and backward scattering (i.e., 0 degrees and 180 degrees to the light beam) which can exceed 12%. Since the initial state is an atomiclike spherically symmetric orbital, this strongly suggests that the asymmetry is caused by final-state effects dependent on the chiral geometry of the molecule. These findings are confirmed by electron multiple scattering calculations of the photoionization dynamics in the electric-dipole approximation.

Journal Article↗
PubMed2006

Determination of chiral asymmetries in the valence photoionization of camphor enantiomers by photoelectron imaging using tunable circularly polarized light.

An electron imaging technique has been used to study the full angular distribution of valence photoelectrons produced from enantiomerically pure molecular beams of camphor when these are photoionized with circularly polarized light. In addition to the familiar beta parameter, this provides a new chiral term, taking the form of an additional cosine function in the angular distribution which consequently displays a forward-backward electron ejection asymmetry. Several ionization channels have been studied using synchrotron radiation in the 8.85-26 eV photon energy range. With alternating left and right circularly polarized radiations the photoelectron circular dichroism (PECD) in the angular distribution can be measured and shows some strong dynamical variations with the photon energy, depending in sign and intensity on the ionized orbital. For all orbitals the measured PECD has a quite perfect antisymmetry when switching between R and S enantiomers, as expected from theory. In the HOMO(-1) channel the PECD chiral asymmetry curves show a double maxima reaching nearly 10% close to threshold, and peaking again at approximately 20% some 11 eV above threshold. This is attributed to a resonance that is also visible in the beta parameter curve. Newly optimized CMS-Xalpha photoionization dynamics calculations are also presented. They are in reasonably good agreement with the experimental data, including in the very challenging threshold regions. These calculations show that PECD in such randomly oriented samples can be understood in the electric dipole approximation and that, unlike the case pertaining in core-shell ionization-where a highly localized achiral initial orbital means that the dichroism arises purely as a final state scattering effect-in valence shell ionization there is a significant additional influence contributed by the initial orbital density.

Journal Article↗
PubMed2000

The low-temperature study of D- and DL-camphoric anhydride.

The low-temperature crystal stuctures of D- and DL-camphoric anhydride, C(10)H(14)O(3), have been determined by X-ray diffraction methods. Although the two enantiomers crystallize in different space groups, the cell volumes and densities are essentially the same. The six-membered rings deviate significantly from planarity, both exhibiting half-boat conformations. The dihedral angle between the six- and five-membered rings is 80.3 (1) degrees in both cases. The main difference in the molecular stuctures can be described by two torsion angles associated with the H atoms of the methyl substituents. The packing of the racemic and chiral structures are essentially the same.

Journal Article↗
PubMed2004

Systemic absorption of the sunscreens benzophenone-3, octyl-methoxycinnamate, and 3-(4-methyl-benzylidene) camphor after whole-body topical application and reproductive hormone levels in humans.

Recent in vitro and animal studies have reported estrogen-like activity of chemicals used in sunscreen preparations. We investigated whether the three sunscreens benzophenone-3 (BP-3), octyl-methoxycinnamate (OMC), and 3-(4-methylbenzylidene) camphor (4-MBC) were absorbed and influenced endogenous reproductive hormone levels in humans after topical application. In this 2-wk single-blinded study 32 healthy volunteers, 15 young males and 17 postmenopausal females, were assigned to daily whole-body topical application of 2 mg per cm(2) of basic cream formulation without (week 1) and with (week 2) the three sunscreens at 10% (wt/wt) of each. Maximum plasma concentrations were 200 ng per mL BP-3, 20 ng per mL 4-MBC, and 10 ng per mL OMC for females and 300 ng per mL BP-3, 20 ng per mL 4-MBC, and 20 ng per mL OMC for men. All three sunscreens were detectable in urine. The reproductive hormones FSH, LH were unchanged but minor differences in testosterone levels were observed between the 2 wk. A minor difference in serum estradiol and inhibin B levels were observed in men only. These differences in hormone levels were not related to sunscreen exposure.

Administration, Topical↗