Maximizing the sensitivity in 13C cross-polarization magic-angle-spinning solid-state NMR measurements with flip-back pulses.

The flip-back pulse combined with cross-polarization magic-angle spinning (CPMAS-FB) has been widely used to reduce the optimal repetition delay, resulting in enhancing sensitivity per unit time. Despite its common use in samples with long 1H T1 relaxation time, the experimental setup of the repetition delay in CPMAS-FB is not obvious. In this article, a simple model is used to derive the optimal repetition delay and expected sensitivity gain through the 1H T1 relaxation time and signal decay during 1H spinlock.

Improving the solubility of dexlansoprazole by cocrystallization with isonicotinamide.

Cocrystallization of an active pharmaceutical ingredient (API) with a cocrystal former (co-former) is widely used to tailor the physicochemical properties of parent APIs. For proton-pump inhibitors (PPIs), the isolation of cocrystals has not been widely investigated. Here, a 1:1 cocrystal of a PPI molecule, dexlansoprazole (DLS), was obtained by solvent crystallization with isonicotinamide (INM). The product was characterized by X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), solid-state and liquid NMR, as well as Fourier transform infrared spectroscopy (FTIR) techniques. A two-point R2(2)(9) hetero-synthon was proposed to exist in the cocrystal, where intermolecular hydrogen bonding occurs between NH, SO groups of DLS and amide of INM. The dissolution profiles of DLS and DLS-INM in water were also collected, and the results demonstrate the cocrystal exhibits superior apparent maximum solubility relative to the pure drug.

Structural elucidation and synthesis of vialinin C, a new inhibitor of TNF-α production.

A new inhibitor of TNF-α production (IC50=0.89 µM) named vialinin C (1) was isolated from dry fruiting bodies of an edible Chinese mushroom, Thelephora vialis. The structure of 1 was determined by high-resolution MS, NMR spectroscopic analysis, and confirmed by synthesis. Synthesis of ganbajunin B (5) obtained from the same origin was also described.

Rapid measurement of multidimensional 1H solid-state NMR spectra at ultra-fast MAS frequencies.

A novel method to realize rapid repetition of (1)H NMR experiments at ultra-fast MAS frequencies is demonstrated. The ultra-fast MAS at 110kHz slows the (1)H-(1)H spin diffusion, leading to variations of (1)H T1 relaxation times from atom to atom within a molecule. The different relaxation behavior is averaged by applying (1)H-(1)H recoupling during relaxation delay even at ultra-fast MAS, reducing the optimal relaxation delay to maximize the signal to noise ratio. The way to determine optimal relaxation delay for arbitrary relaxation curve is shown. The reduction of optimal relaxation delay by radio-frequency driven recoupling (RFDR) was demonstrated on powder samples of glycine and ethenzamide with one and multi-dimensional NMR measurements.

Ubiquitin-specific peptidase 5, a target molecule of vialinin A, is a key molecule of TNF-α production in RBL-2H3 cells.

Tumor necrosis factor alpha (TNF-α), a central mediator of the inflammatory response, is released from basophilic cells and other cells in response to a variety of proinflammatory stimuli. Vialinin A is a potent inhibitor of TNF-α production and is released from RBL-2H3 cells. Ubiquitin-specific peptidase 5 (USP5), a deubiquitinating enzyme, was identified as a target molecule of vialinin A and its enzymatic activity was inhibited by vialinin A. Here we report production of TNF-α is decreased in USP5 siRNA-knockdown RBL-2H3 cells, compared with control cells. The finding of the present study strongly suggests that USP5 is one of the essential molecules for the production of TNF-α in RBL-2H3.

Vialinin A is a ubiquitin-specific peptidase inhibitor.

Vialinin A, a small compound isolated from the Chinese mushroom Thelephora vialis, exhibits more effective anti-inflammatory activity than the widely used immunosuppressive drug tacrolimus (FK506). Here, we show that ubiquitin-specific peptidase 5/isopeptidase T (USP5/IsoT) is a target molecule of vialinin A, identified by using a beads-probe method. Vialinin A inhibited the peptidase activity of USP5/IsoT and also inhibited the enzymatic activities of USP4 among deubiquitinating enzymes tested. Although USPs are a member of thiol protease family, vialinin A exhibited no inhibitions for other thiol proteases, such as calpain and cathepsin.

Inhibitory effects of vialinin A and its analog on tumor necrosis factor-α release and production from RBL-2H3 cells.

Vialinin A is an extremely potent inhibitor of tumor necrosis factor (TNF)-α release from RBL-2H3 cells. The present study investigated in detail the inhibitory effects of vialinin A and its analog, 5',6'-dimethyl-1,1':4',1″-terphenyl-2',3',4,4″-tetraol (DMT), on TNF-α. Vialinin A and DMT inhibited the release of TNF-α from RBL-2H3 cells in a dose-dependent manner, but had no effect on ß-hexosaminidase activity. Also, vialinins had little effect on TNF-α mRNA levels. Intriguingly, vialinins inhibited TNF-α production at low concentrations, but not shown a dose-dependency. The potent inhibitory activities of vialinins against TNF-α production and release suggest promising new candidate pathways for anti-inflammatory agents.

Synthesis and biological activity of both enantiomers of kujigamberol isolated from 85-million-years-old Kuji amber.

The full-structure of a norlabdane terpenoid, kujigamberol (1) was determined by total synthesis. Key features of the total synthesis are (1) installation of isopentyl group through an o-lithiation of benzamide, (2) construction of tetralone by the RCM reaction, and (3) optical resolution of (±)-1 using chromatographical separation of the corresponding camphanates. X-ray crystallographical analysis of p-bromobenzoate obtained from the more polar camphanate that was identical with a natural derivative, revealed natural kujigamberol to have an S-configuration. Both the natural enantiomer and its (R)-antipode showed the same inhibitory activity toward the mutant yeast and HL-60 cells, while simple analogs without alkyl groups at the C-8 and 9 positions of (±)-1 had no such activity.

Kujigamberol, a new dinorlabdane diterpenoid isolated from 85million years old Kuji amber using a biotechnological assay.

A new compound, 15,20-dinor-5,7,9-labdatriene-18-ol (1), named kujigamberol, was isolated from amber, fossilized tree resin from the Kuji area in Japan, has been dated as being 85 million years old (late Cretaceous). Kujigamberol was identified using the hypersensitive mutant yeast (zds1∆ erg3∆ pdr1∆ pdr3∆) with respect to Ca(2+)-signal transduction. The structure was elucidated on the basis of spectroscopic analysis including 1D NMR, 2D NMR and HR-EI-MS. It was different from known diterpenoids with a similar activity isolated from Baltic amber (agathic acid 15-monomethyl ester (2), dehydroabietic acid (3) and pimaric acid (4)). Kujigamberol showed glycogen synthase kinase-3ß (GSK-3ß) inhibition activity involving the growth restored activity against the mutant yeast and was cytotoxic to HL60 cells (IC(50)=19.6 µM).

Design and synthesis of a vialinin A analog with a potent inhibitory activity of TNF-α production and its transformation into a couple of bioprobes.

Vialinin A (1) is an extremely potent inhibitor against tumor necrosis factor (TNF)-α production in rat basophilic leukemia (RBL-2H3) cells. This Letter describes the design and synthesis of its advanced analog, 5',6'-dimethyl-1,1':4'1″-terphenyl-2',3',4,4″-tetraol (2) with a comparable inhibitory activity (IC(50)=0.02 nM) to that of 1. The synthesis involved double Suzuki-Miyaura coupling as a key step, and required only five steps from commercially available 3,4-dimethylphenol. For identification of the target molecule, fluorescent and biotinylated derivatives of 2 were prepared through a 'click' coupling process.

Synthesis of atromentin and its O-alkylated natural products.

The structure of a long-known natural pigment, atromentin, was established by a total synthesis based on double Suzuki-Miyaura coupling and by a single-crystal X-ray analysis of the synthetic sample thereby obtained. A similar strategy including ceric ammonium nitrate (CAN) oxidation was applied to prepare 2-O-methoxyatromentin and thelephantin I.

Studies on natural p-terphenyls: total syntheses of vialinin A and terrestrin B.

A powerful inhibitor of TNF-alpha production, vialinin A, was synthesized from sesamol through a series of reactions involving double Suzuki-Miyaura coupling, 2,3-dichloro-5,6-dicyano-1,4-benzoquino (DDQ) mediated de-methoxymethylation and oxidative removal of methylene acetal by lead tetraacetate. The synthetic method also made it possible to prepare a related compound, terrestrin B.

Expeditious synthesis of vialinin B, an extremely potent inhibitor of TNF-alpha production.

A first total synthesis of vialinin B, a powerful inhibitor (IC(50) 20 pM) of TNF-alpha production, is described. The key reactions include a double Suzuki-Miyaura coupling of electron-rich aryl bromide with a couple of phenylboronic acids, a Cu-mediated Ullmann reaction, and a LHMDS-promoted phenylacetylation. This synthesis proceeded in 11 steps with 18% overall yield from a known sesamol derivative.

Structural revision of thelephantin G by total synthesis and the inhibitory activity against TNF-alpha production.

This paper describes the total synthesis of thelephantin G, thus revising the proposed structure 1 to 2. The key steps involved a double Suzuki-Miyaura coupling and an esterification reaction. By a similar strategy, ganbajunins D and E (3 and 4) were also prepared. Compound 2 strongly inhibited TNF (tumor necrosis factor)-alpha production in rat basophilic leukemia (RBL-2H3) cells: IC(50) = 3.5 nM, while a mixture of 1 and its regioisomer 15 showed no such activity.

Vialinin A, a novel potent inhibitor of TNF-alpha production from RBL-2H3 cells.

Thelephora vialis is a mushroom that grows in symbiosis with pine trees in Yunnan, China, a place known to have some of the richest and most diverse bioresources in the world. This is one of the most favored edible mushrooms, due to its flavor. Our screening for bioactive compounds from these mushrooms isolated a novel potent antioxidant, vialinin A, together with known compounds, from the dry fruiting bodies of T. vialis. Vialinin A is a terphenyl derivative and was elucidated by spectroscopic and chemical methods. Vialinin A showed anti-allergic activities, inhibition of beta-hexosaminidase, tumor necrosis factor (TNF)-alpha, interleukin 4 and monocyte chemotactic protein 1 release from RBL-2H3 cells, whereas atromentin and an inseparable mixture of ganbajunins D and E showed no such effects. Vialinin A displayed potent inhibition of TNF-alpha production from RBL-2H3 cells (IC50, 0.09+/-0.01 nM), indicating stronger inhibition than tacrolimus for organ transplantation (IC50, 0.25+/-0.03 nM). The potent inhibitory activities of these compounds against TNF-alpha production indicate promising new candidates for anti-allergic agents.

First total synthesis of vialinin A, a novel and extremely potent inhibitor of TNF-alpha production.

Vialinin A, a powerful inhibitor (IC50 90 pM) of TNF-alpha production, was synthesized from sesamol in 11 steps with 28% overall yield. The key reactions include a double Suzuki coupling of electron-rich aryl triflate with phenylboronic acid and an oxidative deprotection of bis-MOM ether. In addition, the related synthetic studies also suggest the necessity for structural revision of ganbajunin C, a positional isomer of vialinin A.