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We discovered that the aluminosilicate-stabilized silyl cations, which were created from a solid-acid catalyst, the proton-exchanged montmorillonite, and Et3SiH, efficiently promoted the reductive benzylation of benzenes with aromatic carboxylic acid chlorides and Et3SiH in one pot.

Lascivol was identified as the bitter compound in two Tricholoma species, T. aestuans and T. virgatum, and was previously isolated from the European mushroom T. lascivum. The structure of lascivol was previously solved by X-ray crystallographical analysis but its stereochemistry at C3 remained ambiguous. We thus re-examined the absolute configuration of C3 bearing a hydroxy group using the modified Mosher's method.

A simple and high-throughput analytical method for determining clitidine in Paralepistopsis acromelalga using hydrophilic interaction liquid chromatography–tandem mass spectrometry (LC–MS/MS) was established. To determine clitidine in the mushrooms, a simple procedure including dilution with methanol solution and filtering by cartridge was employed just before quantification by LC–MS/MS for high-throughput analysis. In this report, concentrations of clitidine in mushrooms were determined by the standard addition method. The present established method was successfully applied to the analysis of fruit bodies of P. acromelalga, which were obtained from five different locations in Japan. Results on concentrations of clitidine in each stem and cap of P. acromelalga specimens tested showed that their concentrations were quite different, not only between stems and caps, but also among locations and strains; the concentrations of clitidine in stems and caps ranged from 1.41 to 9.30 mg/g and 3.17 to 14.4 mg/g, respectively. This is the first report to present a detailed quantitative analysis of clitidine by MS and the distribution of clitidine in stems and caps of P. acromelalga. This analytical method for clitidine was thought to be useful in P. acromelalga poisoning cases to identify the causative toxic mushroom.

A toxic mushroom, Russula subnigricans, causes fatal poisoning by mistaken ingestion. In spite of the potent bioactivity, the responsible toxin had not been identified for about 50 years since its first documentation. Recently, we isolated an unstable toxin and determined the structure. The slow elucidation was partly due to the instability of the toxin and also due to misidentification of R. subnigricans for similar mushrooms. To discriminate genuine Russula subnigricans from similar unidentified Russula species, we searched for a unique chemical marker contained in the mushroom. Cyclopropylacetyl-(R)-carnitine specific to R. subnigricans was identified as a novel compound whose (1)H-NMR signals appearing in the upfield region were easily recognizable among the complicated signals of the crude extract.

The tautomeric structures of hipposudoric and norhipposudoric acids were investigated using a computational method. The results indicated that the most appropriate canonical structures for these co...

A toxic mushroom, Russula subnigricans, causes fatal poisoning by mistaken ingestion. In spite of the potent bioactivity, the responsible toxin had not been identified for about 50 years since its first documentation. Recently, we isolated an unstable toxin and determined the structure. The slow elucidation was partly due to the instability of the toxin and also due to misidentification of R. subnigricans for similar mushrooms. To discriminate genuine Russula subnigricans from similar unidentified Russula species, we searched for a unique chemical marker contained in the mushroom. Cyclopropylacetyl-(R)-carnitine specific to R. subnigricans was identified as a novel compound whose (1)H-NMR signals appearing in the upfield region were easily recognizable among the complicated signals of the crude extract.

A toxic protein, dubbed molybdophyllysin, was isolated from the tropical toadstool Chlorophyllum molybdites by following its lethal effect in mice. Analysis of the protein using SDS-PAGE revealed a single 23-kDa band. Sequence analysis of molybdophyllysin tryptic fragments showed that this protein is highly homologous to metalloendopeptidases (MEPs) obtained from edible mushrooms, such as Grifola frondosa, Pleurotus ostreatus, and Armillaria mellea. These proteins include a HEXXH+D zinc-binding motif known as aspzincin. Accordingly, molybdophyllysin is a member of the deuterolysin family of zinc proteases. Molybdophyllysin retained its proteolytic activity at temperatures up to 60°C with an optimum pH of 7.0. The activity was inhibited by both 1,10-phenanthroline and N-bromosuccinimide, but molybdophyllysin exhibited strong resistance to SDS.

Zinc borate hollow nanospheres with diameter of 30 ± 2 nm have been fabricated by using polymeric micelles of poly(styrene-block-acrylic acid) (PS-b-PAA) as a template. The polymer forms spherical ...

The five practical segments for the total synthesis of siomycin A, that is, the dehydropiperidine segment A (5), the pentapeptide segment B (3), the dihydroquinoline segment C (6), and the beta-phenylselenoalanine dipeptide segments D (7) and E (4), were synthesized. Segment A (5) was constructed by the coupling of the azomethine ylide and the chiral sulfinimine, followed by the stereoselective reduction of the six-membered imine function. Segment B (3) was synthesized by the phenylselenylation of the beta-lactone, stereoselective vinylzinc addition to the chiral sulfinimine, and oxazoline-thioamide conversion. Segment C (6) was prepared by the one-pot olefination of the tetrahydroquinoline N-oxide using triflic anhydride and triethylamine, stereoselective reduction of the methyl ketone function, and regioselective Yb(OTf)(3)-catalyzed epoxide opening by the amino group. Segments D (7) and E (4) were synthesized by coupling of the properly protected beta-phenylselenoalanines.

Aims: Frequent onset of several mental disorders starts around undergraduate age for university students. Mental health check-ups of the new students might help provide them with useful supports for improving their mental health. However, few studies have examined the validity of the check-up methods. Methods: Whether the scores of a five-factor personality inventory (NEO-FFI) at matriculation predict the needs of mental care and treatment during the first year of the undergraduate course were examined in 8287 new students of a university in Tokyo. Results: Logistic regression showed that high neuroticism, low extraversion and high openness of NEO-FFI, majoring in literature/philosophy/ psychology and living out of home were associated with need for mental care/treatment, in addition to the previous use of mental care services. Conclusions: Personality inventory such as five-factor ones may be a useful supplemental tool for mental health check-up at matriculation to predict future needs of mental support in undergraduate university students. Students who smoke, live alone out of home and major in subjects such as philosophy might need to be more carefully supported than other students.

A toxic protein, called bolevenine, was isolated from the toxic mushroom Boletus venenatus based on its lethal effects on mice. On SDS-PAGE, in either the presence or absence of 2-mercaptoethanol, this protein showed a single band of approximately 12 kDa. In contrast, based on gel filtration and MALDI-TOFMS, its relative molecular mass was estimated to be approximately 30 kDa and approximately 33 kDa, respectively, indicating that the protein consists of three identical subunits. This toxin exhibited its lethal activity following injection at 10mg/kg into mice. The N-terminal amino acid sequence was determined up to 18, and found to be similar to the previously reported bolesatine, a toxic compound isolated from Boletus satanas.

We have succeeded in the total synthesis of siomycin A, a representative compound of the thiostrepton family of peptide antibiotics, featuring the one-pot cyclization–elongation of our strategic intermediates and the late-stage formations of the thiazoline and dehydroamino acid moieties.

The secretion from the hippopotamus' skin changes its color from colorless to red, and then brown by polymerization of its pigments. The responsible pigments for the coloring reaction were isolated and denoted as hipposudoric acid (the red pigment) and norhipposudoric acid (the orange pigment). The syntheses of these pigments and the related derivatives were performed, and the latter were of use to elucidate the structures of these pigments including their tautomeric structures in aprotic and protic solvents. These pigments were estimated to be medicines for the hippopotamus, having the effect of both protecting the skin from sunburn and preventing infection by some microbes.

Highly unstable pigments, hipposudoric acid and norhipposudoric acid, isolated from the red sweat of hippopotamus were synthesized using the Pschorr reaction for the construction of the fluorene nucleus as the key step and the careful oxidation in the last step.

Synthesis of the dihydroquinoline portion of thiostrepton, the siomycins, and the thiopeptins, members of the thiostrepton family of peptide antibiotics, has been achieved featuring the one-pot olefination via the Matsumura–Boekelheide rearrangement “using trifluoromethanesulfonic anhydride and triethylamine” and the stereoselective addition reaction controlled by the stereocenter of the peri-position.

The cyclic core portion containing the dehydropiperidine, dihydroquinoline, l -valine, and masked dehydroalanine (i.e., β-phenylselenoalanine) segments of the thiostrepton family of peptide antibiotics was synthesized via the consecutive coupling of these four segments followed by cyclization at the amide bond between the dehydropiperidine and masked dehydroalanine segments.

Steroidal saponins are widely distributed in many plant species. Their diverse structures have resulted in a wide range of applications, including drug and medicine production. It has been suggested that the nature of the non-saccharide and oligosaccharide portions of the saponin molecule both contribute to the properties of individual saponins. Despite numerous studies on the occurrence, chemical structure, and varying pharmaceutical activities of steroidal saponins, their biosynthesis pathway is poorly understood. Glycosylation is thought to be the final step in steroidal saponin biosynthesis and it is thought to be involved in regulating the biological activities of saponins. Isolation of the glycosyltransferases that catalyze the transfer of sugar molecules to steroidal compounds will help to clarify the mechanisms that produce diverse saponins and control their activities in plants. In this study, we obtained three cDNAs encoding putative glycosyltransferases from Solanum aculeatissimum. One of the three, SaGT4A showed UDP-glucosyltransferase activity. This is the first cloned glucosyltransferase involved in steroidal saponin biosynthesis. SaGT4A catalyzes the 3-O-glucosylation of steroidal sapogenins, such as diosgenin, nuatigenin, and tigogenin. This enzyme also glucosylates steroidal alkaloids, such as solanidine, solasodine, and tomatidine. Gene expression analysis revealed that the accumulation of SaGT4A transcripts showed a unique response to wounding stress indicating the involvement of SaGT4A in plant defense system.

The Pummerer rearrangement of 1-deoxy-5-thioglucopyranose derivatives carrying acetonides at the C3,4-positions proceeded regioselectively at the C1 position by treating with TFAA in the presence of pyridine. Studies employing deuterium-labelled derivatives revealed that the reaction was induced by E2 1,2-elimination of trifluoroacetic acid of the trifluoroacetoxy sulfonium intermediate. This methodology was applied to the synthesis of an isomaltotriose derivative consisting of 5-thioglucopyranoside units.

Chiral sulfinimines were prepared from chiral sulfinamides and aldehydes in CH 2 Cl 2 in the presence of cesium carbonate as an amine-activating and dehydrating reagent.

The Pummerer rearrangement of 3,4-O-isopropylidene-1-deoxy-5-thiopyranose oxide derivatives took place at the C1 position regioselectively to give the corresponding 5-thiopyranoses. The reaction mechanism of this reaction is also discussed.

Bioassay-directed fractionation of an extract prepared from the dried leaves and stem barks of Ficus fistulosa Reinw. ex Blume (Moraceae) led to the isolation of verrucarin L acetate (1), together with 3alpha-hydroxyisohop-22(29)-en-24-oic acid, 3beta-gluco-sitosterol, 3,4-dihydro-6,7-dimethoxyisocarbostyril, 3,4,5-trimethoxybenzyl alcohol, alpha-methyl-3,4,5-trimethoxybenzyl alcohol, indole-3-carboxaldehyde, palmanine, and aurantiamide acetate. Roridin E (2) was identified in a subfraction from the dried leaves and stems of Rhaphidophora decursiva Schott (Araceae). Verrucarin L acetate and roridin E were characterized as macrocyclic trichothecene sesquiterpenoids and found to inhibit the growth of Plasmodium falciparum with IC 50 values below 1 ng/ml.

A new synthetic method for an acromelic acid analog, MFPA, was developed. The key step is the photoinduced benzyl radical cyclization with excellent stereoselectivity.

The tetrasubstituted dehydropiperidine and piperidine cores of the thiostrepton family of peptide antibiotics were synthesized which featured the coupling between the azomethine ylide and the enantiopure sulfinimine, and the subsequent stereoselective reduction of the six-membered imine.

From the culture broth of a poisonous mushroom Podostroma cornu-damae , roridin E, verrucarin J, and satratoxin H were isolated. From the fruit bodies of the same fungus, satratoxin H, satratoxin H 12′,13′-diacetate, satratoxin H 12′-acetate, and satratoxin H 13′-acetate were isolated. All these macrocyclic trichothecenes except for verrucarin J had a lethal effect on mice by at least 0.5 mg per capita.

The S absolute configuration of both chiral centers of xylindein was assigned using X-ray crystallographic heavy atom analysis after its conversion to a synthetic derivative. Crystallographic analysis of xylindein crystallized with phenols revealed that the proposed structure is the proper tautomer in the crystals.

Fluorescent nonnatural amino acids were incorporated into specific positions of streptavidin. The positions of the nonnatural amino acids were directed by a CGGG/CCCG four-base codon/anticodon pair. The nonnatural mutants with a single 2-anthrylalanine at the 22nd, 43rd, 54th, and 120th positions, respectively, were found to bind biotin, indicating that the mutants retained active conformation. The fluorescence intensities of the anthryl groups were relatively insensitive to the positions and the biotin binding when excited at 265 nm. When the anthryl group at the 120th position was excited through energy transfer from tryptophan units, the fluorescence intensity markedly decreased with biotin binding, because of a suppression of the energy transfer. Amino acids carrying 7-methoxycoumarine fluorophore were also incorporated at the 120th position. Their fluorescence quantum yields were very sensitive to the biotin binding. The high sensitivity of the coumarine-labeled streptavidin exemplifies potential applications of fluorescent nonnatural mutants for detecting specific molecules at very low concentrations.

We have isolated the small, highly strained carboxylic acid cycloprop-2-ene carboxylic acid from the Asian toxic mushroom Russula subnigricans. This compound is responsible for fatal rhabdomyolysis, a new type of mushroom poisoning that is indicated by an increase in serum creatine phosphokinase activity in mice. We found that polymerization of the compound at high concentrations via ene reaction abolishes its toxicity.

(±)-A80915G, a member of the napyradiomycin family of antibiotics, has been synthesized from 1-amino-2,5-dimethoxy-4-nitrobenzene via the sequential palladium-catalyzed cross-coupling reactions (the Stille reaction) of aryl halides with allyltins and the Diels-Alder reaction of the chloroquinone with the Danishefsky-Brassard diene.

ヒドロキシインドール類における重水素置換位置を簡便な計算化学的方法を用いて定性的に予測できることを報告する。その方法は、分子構造を半経験的分子軌道法で最適化し、その構造と最小基底を用いた非経験的分子軌道法を用いて、骨格原子上の電荷を計算することが基本となっている。５つのモデル分子の計算結果は、水酸基に隣接する炭素原子の電荷が大きく、実験的にはその原子に結合している水素がラベル化される傾向がある。しかし立体障害がある場合はこの限りではない。立体障害などを考慮する必要がある場合もあるが、簡便な分子軌道計算により基本骨格分子の電荷分布を予め算出することで、ヒドロキシインドール類の重水素によるラベル化位置の予測を定性的に行うことが可能である。

W493 A and B, which showed strong antifungal activity, were isolated from a culture broth of Fusarium sp. The structure of W493 B was determined to be that of a cyclodepsipeptide, cyclo(3S,4R-HMTA-D-allo-Thr-L-Ala-D-Ala-L-Gln-D-Tyr-L-Ile) (1) by MS and NMR data, an amino acid analysis, and synthesis of the component. HMTA represents 3-hydroxy-4-methyltetradecanoic acid. W493 A (2) had a similar structure, except that L-Ile in 1 was replaced by L-Val. The absolute configuration of each amino acid was determined by chiral HPLC, and the sequence of the components was determined by HMBC experiments. The sequence of the two alanines was determined to be a L-Ala-D-Ala by a chiral HPLC analysis of the peptide fragment containing only one Ala residue. The absolute configuration of HMTA obtained from the hydrolysis of W493 B was determined to be 3S and 4R by comparing with four isomers prepared by enantioselective synthesis via Sharpless asymmetric epoxidation.

Four stereoisomers of the β-benzylglutamic acids were synthesized by the Michael addition of benzylphenylsulfide to protected (4 S )- and (4 R )- 4 -amino-2-penten-5-olide and to protected (2 S )- and (2 R )-3-dehydro-2-hydroxymethyl-5-pyrrolidone. The β-methallyl- and β-isobutylglutamic acids were also synthesized in a similar manner. The depolarizing activities of these synthesized compounds were observed.

Conformationally restricted analogs of kainic acid, which have an azabicyclo[3.3.0]octane system, were synthesized through the intramolecular addition reaction of trimethylenemethane to the α,β-unsaturated ester. Every synthesized isomer showed very weak depolarizing activity. These results indicate that the plane of the isopropenyl group of kainic acid should be diagonal to the pyrrolidine ring to show potent activity.

Four stereoisomers of PRDAs 1∼4 , a novel aspartate analogue incorporating a pyrrolidine ring, were synthesized in an enantiomerically pure form starting from a chiral synthon, 5-amino-5,6-dihydropyrone. Electrophysiological experiments of 1∼4 in newborn rat spinal cords showed a variety of depolarizing activities. The conformational studies of PRDAs and their activity profile suggested that the gauche and the anti conformers about two carboxylic acid groups of Asp could be active forms to NMDA and non-NMDA receptors, respectively

New gymnopilins (with m = 3, n = 5 and 6) were isolated from Gymnopilus spectabilis and their structures were deduced from spectral data an

(−)-Acromelic acid B(2) was synthesized from 2-cyano-3-(2-hydroxyethyl)pyridine(4) in 21% overall yield. Acromelic acid E(3) was also prepared on the way of above synthesis.

Four stereoisomers of PRDAs 1∼4 , a novel aspartate analogue incorporating a pyrrolidine ring, were synthesized in an enantiomerically pure form starting from a chiral synthon, 5-amino-5,6-dihydropyrone. Electrophysiological experiments of 1∼4 in newborn rat spinal cords showed a variety of depolarizing activities. The conformational studies of PRDAs and their activity profile suggested that the gauche and the anti conformers about two carboxylic acid groups of Asp could be active forms to NMDA and non-NMDA receptors, respectively

Alternariolide (AM-toxin) is synthesized in 44% overall yield from L-2-amino-5-(4-methoxyphenyl)pentanoic acid; D-β-phenylselenoalanine is used as the dehydroalanine precursor.

The kainoid amino acids are biologically important compounds because they show remarkable neuroexcitatory and excitotoxic activities. For exhibiting potent activity, the stereochemical relationship of the substituents on the pyrrolidine ring is crucial. We found simple methods for determining the relative stereochemistry of these compounds on the basis of the 1H NMR chemical shifts of H-2 and H-4 in D2O solution. The signals of H-2 appear at fields higher than 4.2 ppm when the compounds have 2,3-trans stereochemistry whereas, in the 2,3-cis compounds, they appear lower than 4.2 ppm, irrespective of the C-4 substituent. This criterion holds when the solution is in the range of pD 3−8. Moreover, when an epimeric pair at C-2 is available and the spectra are recorded at the same or nearly equal pD, the H-2 chemical shift of the 2,3-trans isomer is higher than that of the corresponding 2,3-cis isomer. Similarly, the relative stereochemistry between C-3 and C-4 can be determined from the chemical shift of H-4. ...