Plant‐like cadinane sesquiterpenes from an actinobacterial mangrove endophyte

Cadinanes are typical plant sesquiterpenes with a broad range of biological functions. We report the isolation of three cadinanes ( 1–3 ) from a bacterial endophyte (Streptomyces sp.) of the mangrove plant Bruguiera gymnorrhiza. The structures of two new cadinenes, (+)‐11‐hydroxy‐epicubenol ( 1 ) and (+)‐12‐hydroxy‐epicubenol ( 2 ) were elucidated by nuclear magnetic resonance (NMR) and mass spectrometry. The bacterial product (+)‐11‐hydroxy‐epicubenol was elucidated to be an enantiomer of the plant product pubinernoid C. (+)‐12‐Hydroxy‐epicubenol was established as a diastereomer of the basidiomycete product trichapargin A. In addition, a crystal structure analysis corroborated the structure and configuration of 5,11‐epoxy‐10‐cadinanol ( 3 ), a cadinane cycloether initially described as a natural product from liverwort. The discovery of oxygenated cadinanes from a bacterial endophyte may set the basis for the production of cadinanes by bacterial fermentation.     

Multiconfigurational self-consistent field and multireference internally contracted configuration interaction studies on the excited states of weakly bonded NO2 dimer (N2O4)

In this paper, the vertical excitation energies of total of 32 states of N(2)O(4) including the lowest two singlet states and two triplet states of each of the A(g), B(3u), B(2u), B(1g), B(1u), B(2g), B(3g), and A(u) symmetries were calculated at multiconfigurational self-consistent field (MCSCF) and the multireference internally contracted configuration interaction (MRCI) levels of theory on the active space (15o,16e) with aug-cc-pVDZ basis set. The potential energy curves of the eight singlet states(1 (1)A(g), 1 (1)B(3u), 1 (1)B(2u), 1 (1)B(1g), 1 (1)B(1u), 1 (1)B(2g), 1 (1)B(3g), and 1 (1)A(u)) and eight triplet states (1 (3)A(g), 1 (3)B(3u), 1 (3)B(2u), 1 (3)B(1g), 1 (3)B(1u), 1 (3)B(2g), 1 (3)B(3g), and 1 (3)A(u)) were calculated at MCSCF and MRCI levels of theory on the active space (15o,16e) with aug-cc-pVDZ basis set along the N-N distance. The vertical excitation energies of 1 (1)B(3u), 1 (1)B(2u), and 1 (1)B(1u) states with nonzero transition moment are 4.60 eV (269.6 nm), 6.06 eV (204.6 nm), and 7.71 eV (160.8 nm), respectively, at MRCI level of theory. The photodissociation asymptotics were assigned as NO(2)(X (2)A(1))+NO(2)(X (2)A(1)) for ground state 1 (1)A(g) and the 1 (3)B(1u) state, NO(2)(X (2)A(1))+NO(2)(1 (2)A(2)) for the 1 (1)B(1g), 1 (3)B(1g), 1 (1)A(u), and 1 (3)A(u) states, NO(2)(X (2)A(1))+NO(2)(1 (2)B(1)) for the 1 (1)B(3u), 1 (3)B(3u), 1 (1)B(2g), and 1 (3)B(2g) states, and NO(2)(X (2)A(1))+NO(2)(1 (2)B(2)) for the 1 (1)B(2u), 1 (3)B(2u), 1 (1)B(3g), and 1 (3)B(3g) states.     

Theoretical study of photodetachment processes of anionic boron clusters. I. Structure

Photo-induced electron detachment spectroscopy of anionic boron clusters, B(4)(-) and B(5)(-), is theoretically investigated by performing electronic structure calculations and nuclear dynamics simulations. While the electronic potential energy surfaces (X(1)A(g), ?(3)B(2u), b(3)B(1u), ?(1)B(2u), c(3)B(2g), and B(1)B(2g) of neutral B(4) and X(2)B(2), ?(2)A(1), B(2)B(2), C(2)A(1), D(2)B(1), and E(2)A(1) of neutral B(5)) and their coupling surfaces are constructed in this paper, the details of the nuclear dynamics on these electronic states are presented in Paper II. Electronic structure calculations are carried out at the complete active space self-consistent field-multi-reference configuration interaction level of theory employing the correlation consistent polarized valance triple zeta basis set. Using the calculated electronic structure data suitable vibronic Hamiltonians are constructed utilizing a diabatic electronic basis and displacement coordinates of the normal vibrational modes. The theoretical results are discussed in relation to those recorded in recent experiments.     

Self-Inclusion Complexes Derived from Cyclodextrins: Synthesis and Characterization of 6(A),6(B)-Bis-O-[p-(allyloxy)phenyl]-Substituted beta-Cyclodextrins

The syntheses, structures, and spectroscopic properties of 6(A),6(B)-bis-O-[p-(allyloxy)phenyl]-substituted beta-cyclodextrins have been investigated. Selective activation of the 6(A),6(B)-hydroxy groups was carried out by treating heptakis(2,3-di-O-methyl)-beta-cyclodextrin (1) with 2,4-dimethoxybenzene-1,5-disulfonyl chloride to give 6(A),6(B)-bissulfonate ester 2 in a yield of only 3%. This material was treated with sodium p-(allyloxy)phenoxide in DMF to form 6(A),6(B)-bis-O-[p-(allyloxy)phenyl]-heptakis(2,3-di-O-methyl)-beta-cyclodextrin (3), which had two isomers. One (3A) has the two p-(allyloxy)phenyl arms directed away from the cyclodextrin cavity, and the other (3B) has one of the p-(allyloxy)phenyl groups through the cavity to form a self-inclusion complex. When either 3A or 3B was treated with methyl iodide and sodium hydride, the resulting permethylated 6(A),6(B)-bis-O-[p-(allyloxy)phenyl]heptakis(2,3-di-O-methyl)-6(C),6(D),6(E),6(F),6(G)-penta-O-methyl-beta-cyclodextrin (4) was composed of two isomers, in which 4B is a self-inclusion complex. 3A and 3B also can be converted into a mixture of 3A and 3B in strong base but not when melted in the absence of base. 4A and 4B do not isomerize. Detailed 1D and 2D NMR spectroscopic studies were carried out to characterize the structures of these new compounds, and molecular mechanics techniques were used to explain the experimental facts.     

3D-pharmacophore models for selective A2A and A2B adenosine receptor antagonists

Three-dimensional pharmacophore models were generated for A2A and A2B adenosine receptors (ARs) based on highly selective A2A and A2B antagonists using the Catalyst program. The best pharmacophore model for selective A2A antagonists (Hypo-A2A) was obtained through a careful validation process. Four features contained in Hypo-A2A (one ring aromatic feature (R), one positively ionizable feature (P), one hydrogen bond acceptor lipid feature (L), and one hydrophobic feature (H)) seem to be essential for antagonists in terms of binding activity and A2A AR selectivity. The best pharmacophore model for selective A2B antagonists (Hypo-A2B) was elaborated by modifying the Catalyst common features (HipHop) hypotheses generated from the selective A2B antagonists training set. Hypo-A2B also consists of four features: one ring aromatic feature (R), one hydrophobic aliphatic feature (Z), and two hydrogen bond acceptor lipid features (L). All features play an important role in A2B AR binding affinity and are essential for A2B selectivity. Both A2A and A2B pharmacophore models have been validated toward a wide set of test molecules containing structurally diverse selective antagonists of all AR subtypes. They are capable of identifying correspondingly high potent antagonists and differentiating antagonists between subtypes. The results of our study will act as a valuable tool for retrieving structurally diverse compounds with desired biological activities and designing novel selective adenosine receptor ligands.     

Preparation of S-acetylthioglycoloyl insulins based on separation by anion-exchange high-performance liquid chromatography.

A method for the preparation of insulin derivatives having protected sulfhydryl group(s) on definite site(s) on the molecule which uses anion-exchange high performance liquid chromatography on a TSKgel DEAE-2SW column for separation is described. Porcine insulin reacts with N-succinimidyl S-acetylthioacetate to afford four species of insulin derivatives that have S-acetylthioglycoloyl group(s) at: i) Gly(A1), ii) Gly(A1) and Phe(B1), iii) Gly(A1) and Lys(B29), and iv) Gly(A1), Phe(B1) and Lys(B29) positions. An insulin derivative which has a group at the Lys(B29)-position is prepared by the S-acetylthioglycoloylation of Gly(A1), Phe(B1)-dicitraconyl insulin followed by decitraconylation. The five derivatives are readily deacetylated with hydroxylamine to yield the corresponding sulfhydryl insulin derivatives.     

New triterpene constituents, foliasalacins A(1)-A(4), B(1)-B(3), and C, from the leaves of Salacia chinensis

Four dammarane-type, three lupane-type, and an oleanane-type triterpenes named foliasalacins A(1) (1), A(2) (2), A(3) (3), A(4) (4), B(1) (5), B(2) (6), B(3) (7), and C (8) were isolated from the leaves of Salacia chinensis LINN. collected in Thailand. The structures of new triterpene constituents (1-8) were characterized on the basis of chemical and physiochemical evidence.     

Novel dolabellane-type diterpene alkaloids with lipid metabolism promoting activities from the seeds of Nigella sativa

[structure: see text] Four new dolabellane-type diterpene alkaloids, nigellamines A(1) (1), A(2) (2), B(1) (3), and B(2) (4), were isolated from the seeds of Nigella sativa. Their absolute stereostructures were determined on the basis of chemical and physicochemical evidence. Nigellamines A(1) (1), B(1) (3), and B(2) (4) were found to show potent lipid metabolism promoting activity in primary cultured mouse hepatocytes, and their activities were equivalent to that of a PPAR-alpha agonist, clofibrate.     

Toward the observation of quartet states of the ozone radical cation: insights from coupled cluster theory

Since the discovery of ozone depletion, the doublet electronic states of the ozone radical cation have received much attention in experimental and theoretical investigations, while the low-lying quartet states have not. In the present research, viable pathways to the quartet states from the lowest three triplet states of ozone, (3)A(2), (3)B(2), and (3)B(1), and excitations from the (2)A(1) and (2)B(2) states of the ozone radical cation have been studied in detail. The potential energy surfaces, structural optimizations, and vibrational frequencies for several states of ozone and its radical cation have been thoroughly investigated using the complete active space self-consistent field, unrestricted coupled cluster theory from a restricted open-shell Hartree-Fock reference including all single and double excitations (UCCSD), UCCSD method with the effects of connected triple excitations included perturbatively, and unrestricted coupled cluster including all single, double, and triple excitations with the effects of connected quadruple excitations included perturbatively. These methods used Dunning's correlation-consistent polarized core-valence basis sets, cc-pCVXZ (X = D, T, Q, and 5). The most feasible pathways (symmetry and spin allowed transitions) to the quartet states are (4)A(1)<--(3)A(2), (4)A(2)<--(3)A(2), (4)A(1)<--(3)B(2), (4)A(2)<--(3)B(1), (4)B(2)<--(3)B(1), (4)A(2)<--(1)A(1), (4)B(2)<--(1)A(1), and (4)A(1)<--(1)A(1) with vertical ionization potentials of 12.46, 12.85, 12.82, 12.46, 12.65, 13.43, 13.93, and 14.90 eV, respectively.     

Resonant two-photon ionization spectroscopy of BNB

Triatomic BNB has been produced by laser ablation of a boron nitride rod in a supersonic expansion of helium carrier gas and has been investigated using resonant two-photon ionization spectroscopy in the visible region. The B 2Pi(g)-X 2Sigma(u)+ band system has been recorded near 514 nm and is dominated by a strong origin band, which has been rotationally resolved and analyzed. Both the (11)B(14)N(11)B (64% natural abundance) and the (10)B(14)N(11)B (32% natural abundance) isotopic modifications have been analyzed, leading to the spectroscopic constants (and their 1sigma error limits) of B0"(X 2Sigma(u)+)=0.466 147(70), B0'(B 2Pi(g))=0.467 255(75), and A0'(B 2Pi(g))=6.1563(38) cm(-1) for (10)B(14)N(11)B, corresponding to r(B-N)"(X 2Sigma(u)+)=1.312 47(10) A and r(B-N)'(B 2Pi(g))=1.310 92(11) A. Very similar values are obtained for the more abundant isotopomer, (11)B(14)N(11)B: B0"(X 2Sigma(u)+)=0.444 493(69), B0'(B 2Pi(g))=0.445 606(70), A0'(B 2Pi(g))=6.1455(38) cm(-1), corresponding to r(B-N)"(X 2Sigma(u)+)=1.312 41(10) A and r(B-N)'(B 2Pi(g))=1.310 77(10) A. These results are discussed as they relate to Walsh's rules and are compared to results for related molecules.     

Methanol addition to dihapto-coordinated rhenium complexes of furan

The complexes [TpRe(CO)(L)(4,5-eta(2)-furan)], present as diastereomeric mixtures (L = (t)BuNC (1A, 1B), PMe(3) (2A, 2B), pyridine (3A, 3B), or 1-methylimidazole (4A, 4B)), undergo acid-catalyzed methanol addition in CH(2)Cl(2) at -40 degrees C, resulting in the syntheses of dihapto-coordinated 2-methoxy-2,3-dihydrofuran complexes. In all cases, two diastereomers resulted, one in which the oxygen of the dihydrofuran is oriented toward the L ligand (5A, 6A, 7A, and 8A), and one in which the oxygen is oriented away from the L ligand (5B, 6B, 7B, and 8B). In all cases, the methoxy group adds stereoselectively, anti to the metal fragment. In addition, the (t)BuNC complex 1 yields a dihapto-coordinated vinyl ether (5C) that results from ring opening of the protonated furan ligand. In no case does the diastereomeric ratio of products correlate with that of the starting material.     

Phenolic glycosides and pyrrolidine alkaloids from Codonopsis tangshen

Chemical examination of the n-butanol extract of the root of Codonopsis tangshen led to the isolation of four new compounds named codonosides A (1) and B (2) and codonopyrrolidiums A (3) and B (4), with seven known compounds [(Z)-2-(beta-glucopyranosyloxy)-3-phenylpropenoic acid (5), lobetyolin (6), lobetyol (7), luteolin (8), friedelin (9), 5,6,9-trihydroxy-octadec-7-enoic acid (10), and adenosine (11)]. Based on spectroscopic evidence, the structures of codonosides A (1) and B (2) were established as phenolic glycosides, and those of codonopyrrolidiums A (3) and B (4) as pyrrolidines. The relative configuration of 3 was determined by X-ray crystallographic analysis.     

Selective modification of beta-cyclodextrin: an unexpected tandem reaction enables the cross-linking of C2(A) and C2(B) via a sulfur atom

2(A),3(A)-Alloepithio-2(B)-sulfonyl-beta-cyclodextrin undergoes a tandem reaction to generate an unprecedented C2(A)-S-C2(B)-bridged glucosyl-3(A),6(A)-anhydroglucoside segment.     

alpha-TEPHOS: a cyclodextrin-derived tetraphosphine for multiple metal binding

The tetraphosphine 6(A),6(B),6(D),6(E)-tetradeoxy-6(A),6(B),6(D),6(E)-tetra(diphenylphosphinyl)-2(A),2(B),2(C),2(D),2(E),2(F),3(A),3(B),3(C),3(D),3(E),3(F),6(C),6(F)-tetradeca-O-methyl-alpha-cyclodextrin (alpha-TEPHOS) has been prepared in high yield by reacting 6(A),6(B),6(D),6(E)-tetra-O-methylsulfonyl-2(A),2(B),2(C),2(D), 2(E),2(F),3(A),3(B),3(C),3(D),3(E),3(F),6(C),6(F)-tetradeca-O-methyl-alpha-cyclodextrin with excess PPh(2)Li. The product was purified in its BH(3)-protected form. alpha-TEPHOS is the first optically active tetraphosphine in which the four phosphine units are tethered to a cavity-shaped scaffold. When reacted with [AuCl(tetrahydrothiophene)], alpha-TEPHOS led to the corresponding tetragold complex [(alpha-TEPHOS)(AuCl)(4)] in which the four gold atoms are all located close to the primary face of the cyclodextrin. Reaction with [PdCl(o-C(6)H(4)CH(2)NMe(2))](2) gave the C(2)-symmetrical complex [(alpha-TEPHOS){PdCl(o-C(6)H(4)CH(2)NMe(2))}(4)]. Treatment of the ligand with two equiv. of [Rh(norbornadiene)(tetrahydrofuran)(2)]BF(4) afforded selectively the bimetallic complex [(alpha-TEPHOS){Rh(norbornadiene)}(2)](BF(4))(2) in which each metal centre is coordinated to two phosphorus atoms belonging to adjacent glucose units.     

The 1 (2)A(1), 1 (2)B(2), and 1 (2)A(2) states of the SO(2) (+) ion studied using multiconfiguration second-order perturbation theory

The 1 (2)A(1), 1 (2)B(2), and 1 (2)A(2) electronic states of the SO(2) (+) ion have been studied using multiconfiguration second-order perturbation theory (CASPT2) and two contracted atomic natural orbital basis sets, S[6s4p3d1f]/O[5s3p2d1f] (ANO-L) and S[4s3p2d]/O[3s2p1d] (ANO-S), and the three states were considered to correspond to the observed X, B, and A states, respectively, in the previous experimental and theoretical studies. Based on the CASPT2/ANO-L adiabatic excitation energy calculations, the X, A, and B states of SO(2) (+) are assigned to 1 (2)A(1), 1 (2)B(2), and 1 (2)A(2), respectively, and our assignments of the A and B states are contrary to the previous assignments (A to (2)A(2) and B to (2)B(2)). The CASPT2/ANO-L energetic calculations also indicate that the 1 (2)A(1), 1 (2)B(2), and 1 (2)A(2) states are, respectively, the ground, first excited, and second excited states at the ground-state (1 (2)A(1)) geometry of the ion and at the geometry of the ground-state SO(2) molecule. Based on the CASPT2/ANO-L results for the geometries, we realize that the experimental geometries (determined by assuming the bond lengths to be the same as the neutral ground state of SO(2)) were not accurate. The CASPT2/ANO-S calculations for the potential energy curves as functions of the OSO angle confirm that the 1 (2)B(2) and 1 (2)A(2) states are the results of the Renner-Teller effect in the degenerate (2)Pi(g) state at the linear geometry, and it is clearly shown that the 1 (2)B(2) curve, as the lower component of the Renner splitting, lies below the 1 (2)A(2) curve. The UB3LYP/cc-pVTZ adiabatic excitation energy calculations support the assignments (A to (2)B(2) and B to (2)A(2)) based on the CASPT2/ANO-L calculations.     

Total Synthesis of Siomycin A: Completion of the Total Synthesis

The total synthesis of siomycin A ( 1 ), a representative compound of the thiostrepton family of peptide antibiotics, was achieved by incorporating the five synthetic segments A ( 2 ), B ( 3 ), C ( 4 ), D ( 5 ), and E ( 6 ). The dehydropiperidine segment A ( 2 ) was esterified with the dihydroquinoline segment C ( 4 ), and the subsequent coupling with the β‐phenylselenoalanine dipeptide segment D ( 5 ) at the segment C portion followed by lactamization between the segments A and D gave segment A‐C‐D ( 27 ). This was amidated with the pentapeptide segment B ( 3 ) at the segment A portion followed by one‐pot cyclization (between segments A and B) and elongation (with the β‐phenylselenoalanine dipeptide segment E ( 6 ) at the segment A portion), thus furnishing siomycin A ( 1 ).     

Preparation of acetylmercapto-3-carboxypropanoyl insulins using preparative high-performance liquid chromatography on an anion-exchange column.

A method for the preparation of insulin derivatives which have protected sulfhydryl group(s) at definite site(s) on the molecule is described. Porcine insulin reacts with S-acetylmercaptosuccinic anhydride to afford four species of insulin derivatives that have 2 (or 3)-acetylmercapto-3-carboxypropanoyl group(s) at i) Gly(A1), ii) Gly(A1) and Phe(B1), iii) Gly(A1) and Lys(B29), and iv) Gly(A1), Phe(B1) and Lys(B29) positions. The derivatives are efficiently separated in a preparative scale by anion-exchange high-performance liquid chromatography on a TSKgel DEAE-2SW column. The four derivatives are all readily deacetylated with hydroxylamine to give the corresponding sulfhydryl insulin derivatives.     

Penicillenols from Penicillium sp. GQ-7, an endophytic fungus associated with Aegiceras corniculatum

Six new tetramic acids derivatives, penicillenols A(1), A(2), B(1), B(2), C(1), and C(2) (1-6), together with citrinin, phenol A acid, phenol A, and dihydrocitrinin, were identified from Penicillium sp. GQ-7, an endophytic fungus associated with Aegiceras corniculatum. Their structures were elucidated on the basis of comprehensive spectral analysis. All the new compounds were evaluated for their cytotoxic effects on four cell lines by the MTT method. Penicillenols A(1) and B(1) showed cytotoxicities against HL-60 cell line with IC(50) values of 0.76 microM and 3.20 microM, respectively.     

New meroterpenoids from the marine sponge Aka coralliphaga

Three new sulfated meroterpenoids containing sesquiterpene and hydroquinone moieties, namely siphonodictyal A sulfate (1), akadisulfate A (2) and akadisulfate B (3), along with the known siphonodictyal B3 and bis(sulfato)-cyclosiphonodictyol A were isolated from the sponge Aka coralliphaga. Their structures were elucidated on the basis of spectroscopic data. Akadisulfate B and siphonodictyal B3 showed a radical-scavenging activity comparable with that of the known lipophylic antioxidant BHT.     

Structures of novel epipolythiodioxopiperazines, emethallicins B, C, and D, potent inhibitors of histamine release, from Emericella heterothallica

Novel compounds designated emethallicins B (1), C (2), and D (3), along with emethallicin A (4), were isolated from the mycelium of the heterothallic fungus, Emericella heterothallica (mating type a). The structures of emethallicins B (1), C (2), and D (3) were determined on the basis of spectroscopic and chemical investigations. Emethallicins B (1) and C (2) are epitetrathiodioxopiperazines, which have the same basic carbon skeleton as apoaranotin (19) and acetylaranotin (17), respectively, whereas emethallicin D (3) is an epitrithiodioxopiperazine derivative, which has the same carbon skeleton as apoaranotin (19). It is very interesting that a large amount of the disulfide, emethallicin A (4), was isolated from the strain of mating type A and that the corresponding tetrasulfide, emethallicin B (1), and trisulfide, emethallicin D (3), were isolated from the other mating type strain, along with a small amount of the disulfide (4). Emethallicins B (1), C (2), and D (3) have potent inhibitory activity against compound 48/80-induced histamine release from mast cells, like emethallicin A (4).