Twenty years of nmrshiftdb2: A case study of an open database for analytical chemistry.

In October 2003, 20 years ago, the open-source and open-content database NMRshiftDB was announced. Since then, the database, renamed as nmrshiftdb2 later, has been continuously available and is one of the longer-running projects in the field of open data in chemistry. After 20 years, we evaluate the success of the project and present lessons learnt for similar projects.

Hirsutane-type sesquiterpenes with uncommon modifications from three basidiomycetes.

From three basidiomycetes, Xeromphalina sp., Stereum sp., and Pleurocybella porrigens, six triquinane sesquiterpenes with unprecendented modifications and a rearranged sesquiterpene related to coriolin C have been isolated. Their isolation, structure elucidation, and biological evaluation are described.

Xanthepinone, an antimicrobial polyketide from a soil fungus closely related to Phoma medicaginis.

The isolation, biological characterization, and structure elucidation of xanthepinone, a novel antifungal metabolite isolated from the broth of submerged cultures of a soil fungus, are described. Xanthepinone inhibits the conidial germination of Magnaporthe grisea (2 microg/mL), Phytophthora infestans (5 microg/mL), and Botrytis cinerea (10 microg/mL) while showing only weak antibacterial activity; cytotoxicity was not observed up to 50 microg/mL. Molecular taxonomy revealed that the producing strain is close to species in the genus Phoma as well as to uncultured soil fungi and endophytes.

New naphthoquinone derivatives from the ascomycete IBWF79B-90A.

Bioactivity-guided fractionation of extracts from the fungus IBWF79B-90A resulted in the isolation of three known naphthoquinones, herbarin, dehydroherbarin, and O-methylherbarin and the azaanthraquinone scorpinone as well as three structurally related derivatives, O-phenethylherbarin and herbaridines A and B. All seven compounds exhibited cytotoxic activities against several cell lines.

New caloporoside derivatives and their inhibition of fungal spore germination.

In our ongoing screening culture fluid extracts of Gloeoporus (Caloporus) dichrous strain 83065 inhibited the germination of Magnaporthe grisea and Fusarium graminearum spores. While isolating the active metabolites two new caloporosides, caloporoside G and caloporoside H, in addition to the known caloporoside derivatives F-16438G, caloporoside A, and 2-hydroxy-6-(16-hydroxyheptadecyl)benzoic acid were obtained.

Polyfunctional nitriles in organic syntheses: a novel route to aminopyrroles, pyridazines and pyrazolo[3,4-c]pyridazines.

Phenacylmalononitrile 1 reacts with dimethylformamide dimethyl acetal to yield an enaminone which could be readily converted into a pyrrole or an aminopyridazine by treating with ammonium acetate and hydrazine hydrate, respectively. Compound 1 reacted with hydrazine hydrate in ethanol at room temperature to yield the dihydropyridazine 9 as a single product. In refluxing ethanol this product further reacted with hydrazine hydrate to yield the novel dihydropyrazolopyridazinamine 10.

Ascomycones A-C, heptaketide metabolites from an unidentified ascomycete.

The ascomycones A-C (1-3), three novel heptaketide-derived secondary metabolites, have been isolated from cultures of an unknown ascomycete. While 1 and 2 are closely related pyranonaphthoquinones, 3 has a bicyclic dihydronaphthoquinone core. Compounds 2 and 3 exhibited significant activity against several phytopathogenic fungi.

Tetracyclic terpenoids from Dasyscyphus niveus, dasyscyphins D and E.

Cultures of the ascomycete Dasyscyphus niveus have yielded two new tetracyclic dasyscyphin-type terpenoids (1 and 2), and their structures were elucidated by NMR spectroscopy and X-ray crystallography. The absolute configuration of dasyscyphin D (1) was determined by synthesis and NMR spectroscopy of diastereomeric MTPA esters. Both compounds inhibited the germination of conidia of Magnaporthe grisea at 25 microg/mL.

Sterelactones: new isolactarane type sesquiterpenoids with antifungal activity from Stereum sp. IBWF 01060.

Four members of a new family of tetracyclic sesquiterenoids possessing the isolactarane skeleton have been isolated from mycelial cultures of Stereum sp. IBWF 01060. Their structure elucidation and their antifungal activity against several plant pathogens as well as other microorganisms are reported.

Oxacyclododecindione, a novel inhibitor of IL-4 signaling from Exserohilum rostratum.

In a screening program for new metabolites from fungi inhibiting the IL-4 mediated signal transduction, a novel chlorinated macrocyclic lactone, designated as oxacyclododecindione, was isolated from fermentations of the imperfect fungus Exserohilum rostratum. The structure was determined by a combination of spectroscopic techniques. Oxacyclododecindione inhibits the IL-4 induced expression of the reporter gene secreted alkaline phosphatase (SEAP) in transiently transfected HepG2 cells with IC50 values of 20-25 ng/ml (54-67.5 nM). Studies on the mode of action of the compound revealed that the inhibition of the IL-4 dependent signaling pathway is caused by blocking the binding of the activated STAT6 transcription factors to the DNA binding site without inhibiting tyrosine phosphorylation. The compound has no antibacterial or antifungal activity.

Isolation and structure elucidation of a new indole alkaloid from Rauvolfia serpentina hairy root culture: the first naturally occurring alkaloid of the raumacline group.

A new monoterpenoid indole alkaloid, 10-hydroxy- N(alpha)-demethyl-19,20-dehydroraumacline ( 1), was isolated as a mixture of E- and Z-isomers from hairy root culture of Rauvolfia serpentina Benth. ex Kurz (Apocynaceae) and the structure was determined by 1D and 2D NMR analyses. The new indole alkaloid represents the first naturally occurring alkaloid of the raumacline group and its putative biosynthetical pathway is discussed.

New alkaloids of the sarpagine group from Rauvolfia serpentina hairy root culture.

Three new monoterpenoid indole alkaloids, 19(S),20(R)-dihydroperaksine (1), 19(S),20(R)-dihydroperaksine-17-al (2), and 10-hydroxy-19(S),20(R)-dihydroperaksine (3), along with 16 known alkaloids 4-19 were isolated from hairy root culture of Rauvolfia serpentina, and their structures were elucidated by 1D and 2D NMR analyses. Taking into account the stereochemistry of the new alkaloids and results of preliminary enzymatical studies, the putative biosynthetical relationships between the novel alkaloids are discussed.

Extension of conjugation leading to bathochromic or hypsochromic effects in OPV series.

Four OPV series 1-4 (a-d) with a terminal dialkylamino group as electron donor were prepared by Wittig-Horner reactions. To study the influence of the push-pull effect on the long-wavelength absorption, three of the four series contained terminal acceptor groups (CN, CHO, NO(2)). The length of the chromophores strongly affects the intramolecular charge transfer (ICT)-an effect which superimposes upon the extension of the conjugation. Increasing numbers n of repeat units cause an overall bathochromic shift for the purely donor-substituted series 1 a-4 a and the series 1 b-4 b with CN as weak acceptor. The two effects annihilate each other in the series 1 c-4 c with terminal CHO groups, so that the absorption maxima are almost independent of the length of the chromophore. A hypsochromic shift is observed for the series 1 d-4 d, which contains the strong acceptor group NO(2). This anomaly disappears on protonation of the dialkylamino group because the push-pull effect disappears in the ammonium salts. The results can be explained by semiempirical quantum mechanics (AM1, INDO/S). The HOMO-LUMO transition, which is mainly responsible for the ICT, becomes less important in the electron transitions S(0)-->S(1) when the distance between donor and acceptor is increased. The commonly used VB model, which contains an electroneutral and a zwitterionic resonance structure, is contrasted with a MO model with dipole segments at both ends of the OPV chains. The latter model turned out to be more appropriate-at least for donor-acceptor-substituted OPVs with n >/= 2.