Correction to: Naturally occurring cell adhesion inhibitors.

The article Naturally occurring cell adhesion inhibitors, written by Satoshi Takamatsu, was originally published electronically on the publisher's internet portal.

Naturally occurring cell adhesion inhibitors.

This paper reviews naturally occurring cell adhesion inhibitors derived from a plant, microbial and marine origin. Plant-derived inhibitors are classified according to a type of structure. Microbially and marine-derived inhibitors were described according to age. In addition, effects of inhibitors on cell proliferation and that of standards on cell adhesion are listed as much as possible.

Corrigendum: Total synthesis and absolute configuration of avenolide, extracellular factor in Streptomyces avermitilis.

This corrects the article DOI: 10.1038/ja.2011.90.

Metabolome Analysis of Oryza sativa (Rice) Using Liquid Chromatography-Mass Spectrometry for Characterizing Organ Specificity of Flavonoids with Anti-inflammatory and Anti-oxidant Activity.

Oryza sativa L. (rice) is an important staple crop across the world. In the previous study, we identified 36 specialized (secondary) metabolites including 28 flavonoids. In the present study, a metabolome analysis using liquid chromatography-mass spectrometry was conducted on the leaf, bran, and brown and polished rice grains to better understand the distribution of these metabolites. Principal component analysis using the metabolome data clearly characterized the accumulation patterns of the metabolites. Flavonoids, e.g., tricin, tricin 7-O-rutinoside, and tricin 7-O-ß-D-glucopyranoside, were mainly present in the leaf and bran but not in the polished grain. In addition, anti-inflammatory and anti-oxidant activity of the metabolites were assayed in vitro. Tricin 4'-O-(erythro-ß-guaiacylglyceryl)ether and isoscoparin 2″-O-(6‴-(E)-feruloyl)-glucopyranoside showed the strongest activity for inhibiting nitric oxide (NO) production and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging, respectively.

Toward better annotation in plant metabolomics: isolation and structure elucidation of 36 specialized metabolites from Oryza sativa (rice) by using MS/MS and NMR analyses.

Metabolomics plays an important role in phytochemical genomics and crop breeding; however, metabolite annotation is a significant bottleneck in metabolomic studies. In particular, in liquid chromatography-mass spectrometry (MS)-based metabolomics, which has become a routine technology for the profiling of plant-specialized metabolites, a substantial number of metabolites detected as MS peaks are still not assigned properly to a single metabolite. Oryza sativa (rice) is one of the most important staple crops in the world. In the present study, we isolated and elucidated the structures of specialized metabolites from rice by using MS/MS and NMR. Thirty-six compounds, including five new flavonoids and eight rare flavonolignan isomers, were isolated from the rice leaves. The MS/MS spectral data of the isolated compounds, with a detailed interpretation of MS fragmentation data, will facilitate metabolite annotation of the related phytochemicals by enriching the public mass spectral data depositories, including the plant-specific MS/MS-based database, ReSpect.

Effects of the herbal medicine composition "Saiko-ka-ryukotsu-borei-To" on the function of endothelial progenitor cells in hypertensive rats.

Endothelial progenitor cells (EPCs) are known to repair vascular injuries. Recent studies suggest that Saiko-ka-ryukotsu-borei-To (SKRBT), a traditional herbal medicine that has been used to treat stress-related neuropsychiatric disorders, has protective effects on cardiovascular diseases such as hypertension and arteriosclerosis. Spontaneously hypertensive rats (SHRs) were fed diets containing lyophilized SKRBT extract for 6 weeks. Peripheral blood mononuclear cells (MNCs) were isolated and cultured to assay EPC colony formation. Oxidative stress in MNCs was evaluated by thiobarbituric acid reactive substance (TBARS) assay and flowcytometric analyses. Treatment with SKRBT increased EPC colony numbers significantly (p<0.05) with decrease in oxidative stress and without affecting blood pressure in SHRs. Treatment with SKRBT did not reduce the expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits in cardiovascular organs. Serum IL-6 level was significantly reduced. SKRBT is a feasible herbal medicine that protects against cardiovascular diseases through an increase in EPC function along with anti-oxidative effects, and may affect the link between chronic inflammation and cardiovascular disease.

Total synthesis and absolute configuration of avenolide, extracellular factor in Streptomyces avermitilis.

The first total synthesis of extracellular factor, "Avenolide", in Streptomyces avermitilis has been achieved using a convergent approach. The stereogenic centers in two key segments were installed using Sharpless epoxidation and dihydroxylation. This synthetic study allowed the determination of the absolute configuration of avenolide as 4S,10R, and yielded important information on its structure-activity relationship.

Avenolide, a Streptomyces hormone controlling antibiotic production in Streptomyces avermitilis.

Gram-positive bacteria of the genus Streptomyces are industrially important microorganisms, producing >70% of commercially important antibiotics. The production of these compounds is often regulated by low-molecular-weight bacterial hormones called autoregulators. Although 60% of Streptomyces strains may use γ-butyrolactone-type molecules as autoregulators and some use furan-type molecules, little is known about the signaling molecules used to regulate antibiotic production in many other members of this genus. Here, we purified a signaling molecule (avenolide) from Streptomyces avermitilis--the producer of the important anthelmintic agent avermectin with annual world sales of $850 million--and determined its structure, including stereochemistry, by spectroscopic analysis and chemical synthesis as (4S,10R)-10-hydroxy-10-methyl-9-oxo-dodec-2-en-1,4-olide, a class of Streptomyces autoregulator. Avenolide is essential for eliciting avermectin production and is effective at nanomolar concentrations with a minimum effective concentration of 4 nM. The aco gene of S. avermitilis, which encodes an acyl-CoA oxidase, is required for avenolide biosynthesis, and homologs are also present in Streptomyces fradiae, Streptomyces ghanaensis, and Streptomyces griseoauranticus, suggesting that butenolide-type autoregulators may represent a widespread and another class of Streptomyces autoregulator involved in regulating antibiotic production.

Inhibitory effects of constituents from Morus alba var. multicaulis on differentiation of 3T3-L1 cells and nitric oxide production in RAW264.7 cells.

A new arylbenzofuran, 3',5'-dihydroxy-6-methoxy-7-prenyl-2-arylbenzofuran (1), and 25 known compounds, including moracin R (2), moracin C (3), moracin O (4), moracin P (5), artoindonesianin O (6), moracin D (7), alabafuran A (8), mulberrofuran L (9), mulberrofuran Y (10), kuwanon A (11), kuwanon C (12), kuwanon T (13), morusin (14), kuwanon E (15), sanggenon F (16), betulinic acid (17), uvaol (18), ursolic acid (19), ß-sitosterol (20), oxyresveratrol 2-O-ß-D-glucopyranoside (21), mulberroside A (22), mulberroside B (23), 5,7-dihydroxycoumarin 7-O-ß-D-glucopyranoside (24), 5,7-dihydroxycoumarin 7-O-ß-D-apiofuranosyl-(1→6)-O-ß-D-glucopyranoside (25) and adenosine (26), were isolated from Morus alba var. multicaulis Perro. (Moraceae). Their structures were determined by spectroscopic methods. The prenyl-flavonoids 11-14, 16, triterpenoids 17,18 and 20 showed significant inhibitory activity towards the differentiation of 3T3-L1 adipocytes. The arylbenzofurans 1-10 and prenyl-flavonoids 11-16 also showed significant nitric oxide (NO) production inhibitory effects in RAW264.7 cells.

Characterization of a silent sesquiterpenoid biosynthetic pathway in Streptomyces avermitilis controlling epi-isozizaene albaflavenone biosynthesis and isolation of a new oxidized epi-isozizaene metabolite.

The genome-sequenced, Gram-positive bacterium Streptomyces avermitilis harbours an orthologue (SAV_3032) of the previously identified epi-isozizaene synthase (SCO5222) in Streptomyces coelicolor A3(2). The sav3032 is translationally coupled with the downstream sav3031 gene encoding the cytochrome P450 CYP170A2 analogous to SCO5223 (CYP170A1) of S. coelicolor A3(2), which exhibits a similar translation coupling. Streptomyces avermitilis did not produce epi-isozizaene or any of its oxidized derivatives, albaflavenols and albaflavenone, under in any culture conditions examined. Nonetheless, recombinant SAV_3032 protein expressed in Escherichia coli catalysed the Mg²+-dependent cyclization of farnesyl diphosphate to epi-isozizaene. To effect the production of epi-isozizaene in S. avermitilis, the sav3032 gene was cloned and placed under control of a copy of the native S. avermitilis promoter rpsJp (sav4925). The derived expression construct was introduced by transformation into a large-deletion mutant of S. avermitilis SUKA16 and the resulting transformants accumulated epi-isozizaene. The previously characterized oxidized epi-isozizaene metabolites (4R)- and (4S)-albaflavenols and albaflavenone, as well as a previously undescribed doubly oxidized epi-isozizaene derivative were isolated from cultures of S. avermitilis SUKA16 transformants in which sav3032 was coexpressed with the P450-encoding sav3031. This new metabolite was identified as 4ß,5ß-epoxy-2-epi-zizaan-6ß-ol which is most likely formed by oxidation of (4S)-albaflavenol.

Pentalenic acid is a shunt metabolite in the biosynthesis of the pentalenolactone family of metabolites: hydroxylation of 1-deoxypentalenic acid mediated by CYP105D7 (SAV_7469) of Streptomyces avermitilis.

Pentalenic acid (1) has been isolated from many Streptomyces sp. as a co-metabolite of the sesquiterpenoid antibiotic pentalenolactone and related natural products. We have previously reported the identification of a 13.4-kb gene cluster in the genome of Streptomyces avermitilis implicated in the biosynthesis of the pentalenolactone family of metabolites consisting of 13 open reading frames. Detailed molecular genetic and biochemical studies have revealed that at least seven genes are involved in the biosynthesis of the newly discovered metabolites, neopentalenoketolactone, but no gene specifically dedicated to the formation of pentalenic acid (1) was evident in the same gene cluster. The wild-type strain of S. avermitilis, as well as its derivatives, mainly produce pentalenic acid (1), together with neopentalenoketolactone (9). Disruption of the sav7469 gene encoding a cytochrome P450 (CYP105D7), members of which class are associated with the hydroxylation of many structurally different compounds, abolished the production of pentalenic acid (1). The sav7469-deletion mutant derived from SUKA11 carrying pKU462∷ptl-clusterΔptlH accumulated 1-deoxypentalenic acid (5), but not pentalenic acid (1). Reintroduction of an extra-copy of the sav7469 gene to SUKA11 Δsav7469 carrying pKU462∷ptl-clusterΔptlH restored the production of pentalenic acid (1). Recombinant CYP105D7 prepared from Escherichia coli catalyzed the oxidative conversion of 1-deoxypentalenic acid (5) to pentalenic acid (1) in the presence of the electron-transport partners, ferredoxin (Fdx) and Fdx reductase, both in vivo and in vitro. These results unambiguously demonstrate that CYP105D7 is responsible for the conversion of 1-deoxypentalenic acid (5) to pentalenic acid (1), a shunt product in the biosynthesis of the pentalenolactone family of metabolites.

Regio- and stereospecificity of filipin hydroxylation sites revealed by crystal structures of cytochrome P450 105P1 and 105D6 from Streptomyces avermitilis.

The polyene macrolide antibiotic filipin is widely used as a probe for cholesterol and a diagnostic tool for type C Niemann-Pick disease. Two position-specific P450 enzymes are involved in the post-polyketide modification of filipin during its biosynthesis, thereby providing molecular diversity to the "filipin complex." CYP105P1 and CYP105D6 from Streptomyces avermitilis, despite their high sequence similarities, catalyze filipin hydroxylation at different positions, C26 and C1', respectively. Here, we determined the crystal structure of the CYP105P1-filipin I complex. The distal pocket of CYP105P1 has the second largest size among P450 hydroxylases that act on macrolide substrates. Compared with previously determined substrate-free structures, the FG helices showed significant closing motion on substrate binding. The long BC loop region adopts a unique extended conformation without a B' helix. The binding site is essentially hydrophobic, but numerous water molecules are involved in recognizing the polyol side of the substrate. Therefore, the distal pocket of CYP105P1 provides a specific environment for the large filipin substrate to bind with its pro-S side of position C26 directed toward the heme iron. The ligand-free CYP105D6 structure was also determined. A small sub-pocket accommodating the long alkyl side chain of filipin I was observed in the CYP105P1 structure but was absent in the CYP105D6 structure, indicating that filipin cannot bind to CYP105D6 with a similar orientation due to steric hindrance. This observation can explain the strict regiospecificity of these enzymes.

Genome mining in Streptomyces avermitilis: A biochemical Baeyer-Villiger reaction and discovery of a new branch of the pentalenolactone family tree.

Incubation of 1-deoxy-11-oxopentalenic acid (12) with recombinant PtlE protein from Streptomyces avermitilis in the presence of NADPH and catalytic FAD gave the Baeyer-Villiger oxidation product, the previously unknown compound neopentalenolactone D (13), representing a new branch of the pentalenolactone biosynthetic pathway. The structure and stereochemistry of the derived neopentalenolactone D methyl ester (13-Me) were fully assigned by a combination of GC-MS and NMR analysis and confirmed by X-ray crystallography. Neopentalenolactone D (13) was also isolated from engineered cultures of S. avermitilis from which the ptlD gene within the 13.4-kb (neo)-ptl biosynthetic gene cluster had been deleted. The DeltaptlEDeltaptlD double deletion mutant accumulated 12, the substrate for the ptlE gene product, while the corresponding single DeltaptlE mutant produced 12 as well as the related oxidation products 14 and 15. Engineered strains of S. avermitilis, SUKA5 and pKU462::ermRp-ptl cluster, harboring the complete (neo)ptl cluster produced the oxidized lactone 18 and the closely related seco acid hydrolysis products 16 and 17.

Effects of chemically induced contraction of a coordination polyhedron on the dynamical magnetism of bis(phthalocyaninato)disprosium, a single-4f-ionic single-molecule magnet with a Kramers ground state.

Chemically induced longitudinal contraction of the square-antiprism coordination polyhedron of a peripherically substituted bis(phthalocyaninato)dysprosiumate(III), a dysprosium-based single-4f-ionic single-molecule magnet having a J z = +/- (13)/ 2 Kramers doublet ground state, resulted in drastic changes in dynamical magnetism including a doubling of the energy barrier, a 2-order-of-magnitude decrease of the spin reversal rate, a significant rise of the blocking temperature, and the first observation of the emergence of a large remanent magnetization.

Screening for free radical scavenging and cell aggregation inhibitory activities by secondary metabolites from Turkish Verbascum species.

Free radical scavenging and cell aggregation inhibitory activities of 36 secondary metabolites isolated from the methanolic extracts of Verbascum cilicicum Boiss., V. lasianthum Boiss. ex Bentham, V pterocalycinum var. mutense Hub.-Mor., and V. salviifolium Boiss. (Scrophulariaceae) were investigated. The isolated compounds, 6-O-vaniloyl ajugol (1), ilwensisaponin A (2), ilwensisaponin C (3), verbascoside (4), beta-hydroxyacteoside (5), martynoside (6), poliumoside (7), forsythoside B (8), angoroside A (9), dehydrodiconiferyl alcohol-9-O-beta-D-glucopyranoside (10), dehydrodiconiferyl alcohol-9'-O-beta-D-glucopyranoside (11), apigenin 7-O-beta-glucopyranoside (12), luteolin 7-O-beta-glucopyranoside (13), luteolin 3'-O-beta-glucopyranoside (14) and chrysoeriol 7-O-beta-glucopyranoside (15), exhibited a dose-dependent inhibition of bioautographic and spectrophotometric DPPH activities. Verbascoside (4) was the most active (IC50 4.0 microg/ml) comparing it to vitamin C (IC50 4.4 microg/ml) to inhibit phorbol 12-myristate 13-acetate (PMA)-induced peroxide-catalyzed oxidation of 2',7'-dichlorofluorescein (DCFH) by reactive oxygen species (ROS) within human promyelocytic HL-60 cells. Ilwensisaponin A (2) (MIC 6.9 microg/ml) showed moderate in vitro activity on lymphocyte-associated antigen-1 (LFA-1)/intercellular adhesion molecule-1 (ICAM-1)-mediated aggregation using the HL-60 cell line [positive control was cytochalasin B (MIC 2.3 microg/ml)]. None of the other compounds showed free radical scavenging and cell aggregation inhibitory activities.

Significant increase of the barrier energy for magnetization reversal of a single-4f-ionic single-molecule magnet by a longitudinal contraction of the coordination space.

Two-electron oxidation of [{Pc(OEt)8}2TbIII]- [Pc(OEt)8=dianion of 2,3,9,10,16,17,23,24-octaethoxyphthalocyanine], which leads to a longitudinal contraction of the coordination space of the single-4f-ionic single-molecule magnet (SMM), resulted in a significant increase of the magnetization-reversal barrier energy and a remarkable upward temperature shift of chi'' peaks and chi'T drops. This is the first evidence that the dynamic magnetism of 4f SMMs can be controlled by a redox reaction on the ligand side without introducing any additional magnetic site or spin system.

A gene cluster for biosynthesis of the sesquiterpenoid antibiotic pentalenolactone in Streptomyces avermitilis.

Streptomyces avermitilis, an industrial organism responsible for the production of the anthelminthic avermectins, harbors a 13.4 kb gene cluster containing 13 unidirectionally transcribed open reading frames corresponding to the apparent biosynthetic operon for the sesquiterpene antibiotic pentalenolactone. The advanced intermediate pentalenolactone F, along with the shunt metabolite pentalenic acid, could be isolated from cultures of S. avermitilis, thereby establishing that the pentalenolactone biosynthetic pathway is functional in S. avermitilis. Deletion of the entire 13.4 kb cluster from S. avermitilis abolished formation of pentalenolactone metabolites, while transfer of the intact cluster to the pentalenolactone nonproducer Streptomyces lividans 1326 resulted in production of pentalenic acid. Direct evidence for the biochemical function of the individual biosynthetic genes came from expression of the ptlA gene (SAV2998) in Escherichia coli. Assay of the resultant protein established that PtlA is a pentalenene synthase, catalyzing the cyclization of farnesyl diphosphate to pentalenene, the parent hydrocarbon of the pentalenolactone family of metabolites. The most upstream gene in the cluster, gap1 (SAV2990), was shown to correspond to the pentalenolactone resistance gene, based on expression in E. coli and demonstration that the resulting glyceraldehyde-3-phosphate dehydrogenase, the normal target of pentalenolactone, was insensitive to the antibiotic. Furthermore, a second GAPDH isozyme (gap2, SAV6296) has been expressed in E. coli and shown to be inactivated by pentalenolactone.

Schisandrene, a dibenzocyclooctadiene lignan from Schisandra chinensis: structure-antioxidant activity relationships of dibenzocyclooctadiene lignans.

Phytochemical investigation of the fruits of Schisandra chinensis led to the isolation of 13 lignans including schisandrene (13), a new lignan based on a dibenzocyclooctadiene backbone with an exocyclic double bond. Its structure and absolute configuration were established using NMR, MS, and CD data. Antioxidant activity of the lignans was evaluated using a DCFH-DA cellular-based assay. The structure-activity relationships of the dibenzocyclooctadiene lignans showed that the exocyclic methylene functionality was essential for antioxidant activity, with the benzoyloxy group probably enhancing such effects.

Synthesis of fluorinated nucleosides.

Two practical synthetic approaches to the production of lodenosine [FddA, 9-(2,3-dideoxy-2-fluoro-beta-D-threo-pentofuranosyl)adenine] via 6-chloropurine riboside or 6-chloropurine 3'-deoxyriboside are described. The reaction sequence contains new fluorination methods and new applications of radical reduction. The reagents and reaction conditions of each step have been carefully selected to ensure robustness and safety.

Isolation of lignans and biological activity studies of Ephedra viridis.

Phytochemical investigation of Ephedra viridis (whole plant) led to the isolation of four lignans including (+)-9-acetoxyisolariciresinol, which is a new lignan, lariciresinol, 9-acetoxylariciresinol and isolariciresinol. All the isolates were tested for their antioxidant activity and cytotoxicity against a panel of solid tumor and human leukemia cells. They were also screened for estrogenic activity using a recombinant yeast estrogen screening (YES) assay. Most of the lignans exhibited moderate antioxidant activity without any cytotoxicity. None of them were estrogenic in the YES assay.