A selective hybrid fluorescent sensor for fructose detection based on a phenylboronic acid and BODIPY-based hydrophobicity probe.

Fructose is widely used in the food industry. However, it may be involved in diseases by generating harmful advanced glycation end-products. We have designed and synthesized a novel fluorescent probe for fructose detection by combining a phenylboronic acid group with a BODIPY-based hydrophobicity probe. This probe showed a linear fluorescence response to d-fructose concentration in the range of 100-1000 µM, with a detection limit of 32 µM, which is advantageous for the simple and sensitive determination of fructose.

Elimination of Off-Target Effect by Chemical Modification of 5'-End of siRNA.

In this study, the efficiency of RNA interference of small interfering RNAs (siRNAs) bearing 5'-O-methyl-2'-deoxythymidine (X) and 5'-amino-2', 5'-dideoxythymidine (Z) at the 5'-end of the sense strand and the antisense strand of siRNA was investigated in HeLa cells stably expressing enhanced green fluorescent protein. The results indicated that when one strand of siRNA was modified with X or Z and the other was unmodified, the X or Z modification was predominant in the process of strand selection and the unmodified strand was selected as a guide strand. When both strands are modified with X or Z, the modified antisense strand with X or Z will be selected as a guide strand with a certain probability. The resulting mature RNA-induced silencing complex exerted reduced, but still moderate silencing activity remained. These results suggest that the modification of the sense strand with X or Z eliminates the off-target effects caused by the sense strand without affecting the silencing efficiency of the siRNA.

Immobilization of Baeyer-Villiger monooxygenase from acetone grown Fusarium sp.

OBJECTIVE: A novel biocatalyst for Baeyer-Villiger oxidations is necessary for pharmaceutical and chemical industries, so this study aims to find a Baeyer-Villiger monooxygenase (BVMO) and to improve its stability by immobilization. RESULTS: Acetone, the simplest ketone, was selected as the only carbon source for the screening of microorganisms with a BVMO. A eukaryote, Fusarium sp. NBRC 109816, with a BVMO (FBVMO), was isolated from a soil sample. FBVMO was overexpressed in E. coli and successfully immobilized by the organic-inorganic nanocrystal formation method. The immobilization improved the thermostability of FBVMO. Substrate specificity investigation revealed that both free and immobilized FBVMO were found to show catalytic activities not only for Baeyer-Villiger oxidation of ketones to esters but also for oxidation of sulfides to sulfoxides. Furthermore, a preparative scale reaction using immobilized FBVMO was successfully conducted. CONCLUSIONS: FBVMO was discovered from an environmental sample, overexpressed in E. coli, and immobilized by the organic-inorganic nanocrystal formation method. The immobilization successfully improved its thermostability.

Brønsted acid-induced transannulation of the phytochemical zerumbone.

The sesquiterpene zerumbone was treated with HCl in ethyl acetate under the light-protected condition, and the time-dependent conversions were analyzed by gas chromatography. Nine products were isolated, and their structures were revealed by several NMR measurements such as 1H NMR, 13C{1H} NMR, distortionless enhancement by polarization transfer (DEPT)-135, 1H-1H correlation spectroscopy (COSY), 1H-13C heteronuclear multiple quantum coherence (HMQC), and 1H-13C heteronuclear multiple bond coherence (HMBC). The X-ray crystallography determined the stereochemistries of the three products and the two derivatives. After all, this acidic reaction was found to provide the (2Z,6E,10E)-isomer, the two HCl adducts, the two 7,6-bicyclic compounds, the valence isomers cycloheptatriene and norcaradiene, and the two dihydronaphthalenes. Based on the product analyses of the reactions from the isolated intermediates as well as the mechanistic considerations, these products were arranged into two paths: one of the paths ended in the two dihydronaphthalenes the same as previously reported under the Lewis acid condition; the other ended in the 7,6-bicyclic compound, the epimer of which was known. In addition, density functional theory (DFT) calculations indicated that the (2Z,6E,10E)-isomer was more stable than the (2E,6E,10Z)-isomer as well as that the activation energy for the isomerization at the C2-C3 double bond decreased to half by protonation. The closely examined reaction mechanisms under the simple acidic condition were established upon the intensive characterization of the intermediates and products, and these findings would add to the attractive value of zerumbone and would help understand the unknown biosynthetic pathway around sesquiterpenoids.

Remarkable Potential of Zerumbone to Generate a Library with Six Natural Product-like Skeletons by Natural Material-Related Diversity-Oriented Synthesis.

Diversity-oriented synthesis (DOS) is an effective strategy for the quick creation of diverse and high three-dimensional compounds from simple starting materials. The selection of a starting material is the key to constructing useful, chemically diverse compound libraries for the development of new drugs. Here, we report a novel, general, and facile strategy for the creation of diverse compounds with high structural diversity from readily available natural products, such as zerumbone, as the synthetic starting material. Zerumbone is the major component of the essential oil from wild ginger, Zingiber zerumbet Smith. It is noteworthy that zerumbone has a powerful latent reactivity, partly because of its three double bonds, two conjugated and one isolated, and a double conjugated carbonyl group in an 11-membered ring structure. In fact, zerumbone has been shown to be a successful example of natural material-related DOS (NMRDOS). We will report that zerumbone can be converted in one chemical step from four zerumbone derivatives into rare and markedly different scaffolds by transannulation.

Locomotor-Reducing Activity of Sesquiterpenes Related to Zingiber zerumbet Essential Oil and Hexahydrozerumbone Derivatives.

Zerumbone derivatives 1-4 are 11-membered cyclic compounds synthesised from a sesquiterpene zerumbone obtained from the rhizomes of Zingiber zerumbet SMITH (Zingiberaceae). In this study, we investigated the locomotor-reducing effects of hexahydrozerumbone derivatives 1-3 and zerumbol 4, and those of ß-caryophyllene 5 and caryophyllene oxide 6, which are present in Z. zerumbet essential oil. The absence of the double bond at C6 weakened the locomotor-reducing effects. ß-Caryophyllene 5 and caryophyllene oxide 6 showed locomotor-reducing effects in mice at 4.5×10(-3) mg/cage. Moreover, locomotor activity increased significantly at 0.45 mg/cage of caryophyllene oxide 6.

Regiospecific Distribution of trans-Octadecenoic Acid Positional Isomers in Triacylglycerols of Partially Hydrogenated Vegetable Oil and Ruminant Fat.

It is revealed that binding position of fatty acid in triacylglycerol (TAG) deeply relates to the expression of its function. Therefore, we investigated the binding positions of individual trans-octadecenoic acid (trans-C18:1) positional isomers, known as unhealthy fatty acids, on TAG in partially hydrogenated canola oil (PHCO), milk fat (MF), and beef tallow (BT). The analysis was carried out by the sn-1(3)-selective transesterification of Candida antarctica Lipase B and by using a highly polar ionic liquid capillary column for gas chromatography-flame ionization detection. Trans-9-C18:1, the major trans-C18:1 positional isomer, was selectively located at the sn-2 position of TAG in PHCO, although considerable amounts of trans-9-C18:1 were also esterified at the sn-1(3) position. Meanwhile, trans-11-C18:1, the major isomer in MF and BT, was preferentially located at the sn-1(3) position. These results revealed that the binding position of trans-C18:1 positional isomer varies between various fats and oils.

Locomotor-reducing effects and structural characteristics of inhaled zerumbone and tetrahydrozerumbone derivatives.

Zerumbone 1 is an 11-membered cyclic sesquiterpene obtained from the rhizomes of Zingiber zerumbet SMITH (Zingiberaceae). In this study, we investigated the structure-activity relationship of 1, α-humulene (2), tetrahydrozerumbone stereoisomers (3-5), and tetrahydrozerumbone derivatives (6-9). The oxygen-containing functional groups and the configurations at C1 and C2 contributed to the spontaneous locomotor activity reduction of zerumbone 1 and derivatives 2-9.

Sedative effects of inhaled benzylacetone and structural features contributing to its activity.

Benzylacetone is released by heated agarwood, when inhaled it has a potent effect on reducing the locomotor activity of mice. This study investigated the relationships between the sedative activities of benzylacetone and its derivatives as well as the chemical structures of these compounds by comparing their activities in mice treated with a series of compounds. It was demonstrated that benzylacetone-like compounds had sedative activities and their intensities varied depending on the functional group in the carbon chain, the substituent in the benzene ring, and their combinations. A quantitative structure-activity relationship study was carried out using a series of 17 benzylacetone derivatives to determine the structural features with significant for the sedative activity.

Catalytic enantioselective synthesis of ß-trifluoromethyl pyrrolines.

Enantioselective synthesis of ß-trifluoromethylated pyrrolines has been developed by the organocatalyzed-conjugated addition of nitromethane to ß-trifluoromethylated enones, followed by a nitro-reduction/cyclization/dehydration sequence in a one-pot procedure with 97-98% ees.

Attractive reactivity of a natural product, zerumbone.

Zerumbone is a cyclic seaquiterpene and, a potential resource for natural materials-related diversity-oriented synthesis (NMRDOS). Zerumbone, the main component of the essential oil of a wild ginger, Zingiber zerumbet Smith, showed strong reactivity with good chemo-, regio-, and stereoselectivity. To build the foundations for the industrial use of zerumbone, we examined conjugate addition, transannular reactions, ring cleavage, ring expansion, and asymmetric induction. The biological activity of zerumbone derivatives was also studied.

Concise synthesis of Valerena-4,7(11)-diene, a highly active sedative, from valerenic acid.

A concise synthesis of valerena-4,7(11)-diene with potent sedative activity was achieved in three steps involving, reduction of carboxylic acid, bromination of the resulting alcohol, and reduction of the bromide from valerenic acid in a 63% total yield. This synthetic method makes it possible to provide further materials for biological testing to realize comprehensive SAR studies.

Synthesis of a novel inhibitor against MRSA and VRE: preparation from zerumbone ring opening material showing histidine-kinase inhibition.

Zerumbone ring-opening derivative 2 inhibited autophosphorylation of the essential histidine protein kinase (HPK), YycG, existing in Bacillus subtilis constituting a two-component system (TCS). However, it did not inhibit drug-resistant bacterium such as MRSA and VRE. Tryptophan derivative 34 also could be regulated by a TCS system like 2. In addition, 34 showed good inhibition against MRSA and VRE.

Targeting protein homodimerization: a novel drug discovery system.

To identify a novel class of antibiotics, we have developed a high-throughput genetic system for targeting the homodimerization (HD system) of histidine kinase (HK), which is essential for a bacterial signal transduction system (two-component system, TCS). By using the HD system, we screened a chemical library and identified a compound, I-8-15 (1-dodecyl-2-isopropylimidazole), that specifically inhibited the dimerization of HK encoded by the YycG gene of Staphylococcus aureus and induced concomitant bacterial cell death. I-8-15 also showed antibacterial activity against MRSA (methicillin-resistant S. aureus) and VRE (vancomycin-resistant Enterococcus faecalis) with MICs at 25 and 50 microg/ml, respectively.

Unprecedented olefin-dependent histidine-kinase inhibitory of zerumbone ring-opening material.

Zerumbone ring-opening derivative, 4 (10E/10Z=3/2), inhibited autophosphorylation of the essential histidine-kinase YycG existing in Bacillus subtilis constituting a two-component system (TCS). Generation of 4E-form could be regulated chemically using the difference from the ring-opening reactivity of the precursor forming of 4 and pure 4E was isolated. The stereoisomer, 4E, showed main inhibition activity of autophosphorylation of YycG (IC(50)=63.5 microM).

Inhibitory actions of several natural products on proliferation of rat vascular smooth muscle cells induced by Hsp60 from Chlamydia pneumoniae J138.

Atherosclerosis is a vascular disorder involving inflammation, a narrowed vascular lumen in the entire tunica intima, and reduced elasticity of the arterial wall. It has been found that Hsp60 from Chlamydia pneumoniae, an obligate bacterial pathogen associated with atheroma lesions, mimics human Hsp60, thereby causing attacks by immune cells on stressed endothelial cells expressing endogenous Hsp60 on their surface. Furthermore, Hsp60 from C. pneumoniae has been shown to promote the growth of vascular smooth muscle cells (VSMCs). To explore probes that can be used for studying signal transduction elicited by the chlamydial Hsp60, we have tested several natural products for their inhibitory actions on the Hsp60-induced proliferation of rat arterial smooth muscle cells. Sesamol, vanillyl alcohol, and trans-ferulic acid exhibited moderate inhibitory actions on the Hsp60-induced cell proliferation; zerumbone, humulene, and caryophylene effectively inhibited it at low concentrations with IC(50) values of 529, 122, and 110 nM, respectively. The results indicated that the 11-membered alicyclic ring is favorable for interactions with receptors involved in the Hsp60-induced VSMC proliferation.

P-glycoprotein mediates resistance to histidine kinase inhibitors.

Histidine kinase inhibitors are being developed as a new class of antimicrobial drugs. We recently demonstrated the activity of a class of histidine kinase inhibitors against a mammalian enzyme, elongation factor-2 kinase (eEF-2K), and the effect of these compounds on cancer cell viability (Arora et al., 2003). To further characterize these compounds, we studied their interaction with ATP-binding cassette transporters, which are known to mediate resistance to a variety of chemotherapeutic agents. The 24 compounds studied belong to three structural series of derivatives of 2-methylimidazolium iodide. We focused this work on a representative compound (NH125) because we found it to be most potent against both histidine kinase and eEF-2K among the series. Cell lines that expressed P-glycoprotein (P-gp) were 2- to 5-fold resistant to NH125. NH125 increased accumulation of P-gp substrates such as paclitaxel and doxorubicin but had no effect on the accumulation of non-P-gp substrates. P-gp modulators verapamil and trans-flupenthixol and MDR1-targeted siRNA increased sensitivity of multidrug-resistant cell lines to NH125. The presence of a benzyl group on the N-3 position of the 2-methylimidazolium iodide was important for the interaction with P-gp. C6-NH, an NH125-resistant cell line, markedly overexpressed P-gp compared with the parental cell line. In animal models, we found that NH125 increased by 129% the survival of sensitive P388 cells bearing mice but had no effect on mice harboring the resistant cell line. These observations indicate that certain histidine kinase inhibitors are substrates for P-gp and hence an important consideration in development of these agents as potential antimicrobial and anticancer agents.

Identification and characterization of an inhibitor of eukaryotic elongation factor 2 kinase against human cancer cell lines.

Recent evidence suggests that the machinery of protein synthesis may provide novel targets for anticancer drugs. For example, aberrations in protein synthesis are commonly encountered in established cancers, and disruption by mutation or overexpression of translation factors can cause cellular transformation. We previously demonstrated that the activity of eukaryotic elongation factor 2 (eEF-2) kinase was markedly increased in several forms of malignancy and that nonspecific inhibitors of this enzyme promoted cell death. On the basis of the predicted amino acid sequence of eEF-2 kinase deduced from the cloned cDNA, we hypothesized that inhibitors of prokaryotic histidine kinases might also inhibit the activity of eEF-2 kinase. We describe herein the screening of a series of imidazolium histidine kinase inhibitors and the identification of an active lead compound, NH125. NH125 inhibited eEF-2 kinase activity (IC(50) = 60 nM) in vitro, blocked the phosphorylation of eEF-2 in intact cells, and showed relative selectivity over other protein kinases: protein kinase C (IC(50) = 7.5 microM), protein kinase A (IC(50) = 80 microM), and calmodulin-dependent kinase II (IC(50) > 100 microM). NH125 decreased the viability of 10 cancer cell lines with IC(50)s ranging from 0.7 to 4.7 microM. Forced overexpression of eEF-2 kinase in a glioma cell line produced 10-fold resistance to NH125. In conclusion, these results suggest that identification of potent inhibitors of eEF-2 kinase may lead to the development of new types of anticancer drugs.