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A unique set of thiomethylated canthin-6-one derivatives was isolated from Boletus curtisii. The bright yellow color of this mushroom is caused by two optically active canthin-6-one sulfoxides for which the names curtisin and 9-deoxycurtisin are proposed. The structures of the new compounds were established by MS and NMR methods and the absolute configuration of the sulfoxides determined by quantum chemical calculations. This is the first occurrence of canthin-6-one alkaloids outside of higher plants. The chemotaxonomic implications of these findings are discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Three new disulfides, pentaporins A, B and C, with anthelmintic in vitro activity have been isolated from the mediterranean bryozoan Pentapora fascialis. The structures of these compounds were determined by 1D and 2D NMR spectroscopy, mass spectrometry and EDX-analysis. The pentaporins show activity against Trichinella spiralis.

The new antifungal strobilurins I (1) and K (19) are 3,4-dihydro-2H-benzo[b][1,4]dioxepin derivatives. Their structure and stereochemistry was determined by degradation to aldehyde 3. Both enantiomers of 3 were synthesised and the absolute configurations assigned by the high-field 1H NMR variant of Mosher's method. (S)- 3 is identical with the compound derived from the natural products. In the course of these investigations the epoxide structures 15, 16 and 17 previously assigned to strobilurin D, hydroxystrobilurin D and 9-methoxystrobilurin K have to be changed in 18, 21 and 20, respectively. All these compounds possess the same benzodioxepin core structure and (S)-configuration as strobilurin I (1).

The polyenoyltetramic acid physarorubinic acid (2) has been isolated from microplasmodia of the slime mold Physarum polycephalum. The structure was elucidated by means of 1D- and 2D-NMR, IR, and UV spectroscopy and mass spectrometry. The stereochemistry was proven by synthesis of the tetramic acid unit and application of circular dichroism. It was shown that plasmodia of a white mutant strain also contain yellow pigments.

The ascidian Dendrodoa grossularia , collected in the Baltic Sea, contains the new 1,3,5-oxadiazin-2-one alkaloid alboinon ( 1 ).

An orange pigment named echinotinctone was isolated from the wood-rotting polypores Echinodontium tinctorium and Pyrofomes albomarginatus. Its structure was elucidated as2, 6-dihydroxy-1, 8-dimethyl-3H-xanthen-3-one (1) on the basis of spectroscopic and chemical studies.1 represents the first naturally occurring pigment with a simple fluorone chromophore. Echinotinctone (1) constitutes the first simple fluorone pigment from fungi. Download : Download full-size image

The structures of two quinone methide pigments from fruiting bodies of Russula flavida have been elucidated. Russulaflavidin and its dihydro derivative contain the same chromophore as pristimerin and represent the first triterpenoids with a shionane (D:A friedo-18, 19-secolupane) skeleton isolated from fungi.

Novel Diterpenoids from the Toadstools Tricholoma aurantium and T. fracticum (Agaricales)1 Two novel diterpenoids trichaurantin (1) and its 6-O-acetyl derivative 2 have been isolated from Tricholoma species. Their structures were established by spectroscopic methods and an X-ray crystal analysis, 1 and 2 appear to be biosynthetically related to the neodolabellane and dolastane group of diterpenes and can be designated as 2,3-seconeodolastane derivatives.

The biosynthesis of shermilamine B is proposed which involves tryptophan, dopamine and cysteine.

A yellow optically-active pigment, chrysophysarin A ( 1 ), has been isolated from microplasmodia of the slime mould Physarum polycephalum . The structure was established by means of 1D and 2D NMR spectroscopy and mass spectrometry. The absolute configuration was assigned by the synthesis of N -(3,3-dimethylacryloyl) derivatives of ( S )- and ( R )-leucine and by comparison of the corresponding CD spectra. The biosynthesis of the compound was elucidated by feeding labeled acetate to the plasmodia.

The tunicate Clavelina lepadiformis, which was collected in the North Sea, contains the new decahydroquinoline alkaloid lepadin A (1), in addition to the pentachlorooctatriene 2. The structures have been determined on the basis of spectroscopic evidence and in comparison with published data for compound 2.

Lascivol, the Bitter Component of Tricholoma lascivum (Agaricales) The structure of lascivol (1), the bitter principle of the toadstool Tricholoma lascivum, has been elucidated by chemical and spectroscopic studies including a single crystal X-ray structure analysis. 1 is degraded to dimethyl L-glutamate (6) and 5-methoxy-2,4-dimethylindole (5) by acid methanolysis.

Mushrooms of the genus Retiboletus contain the retipolides A–D (1, 6–8), unusual 14-membered spiromacrolides with a biphenyl ether linkage. The structures of these metabolites suggested a biogenetic sequence starting from retipolide E (16), which could furnish the unique 2(3H)-oxepinone unit of retipolide C (7) via an oxidative enlargement of the 4-hydroxyphenyl ring. A subsequent O/C-acyl shift would then lead to the cyclopenta[c]pyran system of retipolide A (1). The proposed precursor 16 was synthesized and subsequently detected in the fungal extract in addition to the probable biosynthetic intermediates butyrolactone II (13), tyrosol (14), and secoretipolide E (15). The structural elucidation of retipolide A (1) was accomplished after transformation into a methoxyfulvene derivative 2a, and the absolute (R) configuration of 1 was assigned by a single-crystal X-ray analysis of the corresponding (S)-sec-butoxyfulvene analogue 2b. Some samples of R. retipes/ornatipes contained isoretipolide A (9), an isomer of 1 with a highly strained 12-membered lactone ring incorporating two C,C-coupled 4-hydroxyphenyl units. A comparison of the CD spectrum of retipolide A (1) with those of the other retipolides and isoretipolide A (9) indicates that all of these macrolides possess R configuration. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

The absolute configuration of polycephalin C ( 1 ) isolated from plasmodia of the slime mold Physarum polycephalum is supposed to be 3″R,4″R as found by comparison of CD spectra of the natural product polycephalin C (1) and CD spectra of synthetic bis-benzoates (−)-4 and (+)-4 . An X-ray structure of the corresponding bis-camphanate (+)-3 shows that the exciton chirality method may not be applied on these 1,4-diols in the usual manner.

Prostaglandin E1 is currently marketed as a freeze-dried injectable inclusion complex with alpha-cyclodextrin for the treatment of peripheral arterial diseases. alpha-Cyclodextrin is used as a stabilizing agent and to improve the dissolution characteristics of prostaglandin E1. Upon dilution with the infusion medium, the inclusion complex dissociates almost completely as shown by NMR chemical shift measurements of the complexed and uncomplexed prostaglandin E1. Nuclear Overhauser effect (NOE) measurements of the interacting atoms of alpha-cyclodextrin and prostaglandin E1 provide insight into the structure of the complex.

It covers all classes of natural products: -amino acids -peptides and proteins -carbohydrates -antibiotics -alkaloids -steroids -terpenoids -porphyrins -vitamins -aroma/flavour compounds -chinons -pigments -lipids -toxins -medicinal herbs -substances of moss and ferns -fungi -marine organism -lichen substances -plant protection products and other unusual natural product

Xylaral, a Hydroxyphthalide Derivative from Fruiting Bodies of Xylaria polymorpha (Ascomycetes) Fruiting bodies of Dead Man's Fingers, Xylaria polymorpha, contain a hydroxyphthalide derivative, xylaral (1), which exhibits a violet colour reaction with aqueous ammonia. 1 is a homologue of cyclopaldic acid (5) with a C14-side chain containing an enone moiety.

Fruit bodies of the myxomycete Lycogala epidendrum contain the title compounds 1a–c and 2, staurosporinone (3) and traces of bisindolylmaleimides. Lycogalic acid A dimethyl ester (1a) has been synthesized from methyl 3-(indol-3-yl)pyruvate in a one-pot reaction.

Aus Kulturen des Mycosymbionten der tropischen Rindenflechte Trypethelium eluteriae Sprengel wurden die antibiotisch aktiven 1,2-Naphthochinone Trypethelon (2), Trypethelon-methylether (3), 8-Methoxytrypethelon-methylether (5) und 4′-Hydroxy-8-methoxytrypethelon-methylether (6) isoliert. Es handelt sich um Derivate des (+)-Dunnions (1), deren Substituentenanordnung mit einer Polyketidbiogenese des Chinonsystems im Einklang ist. 1,2-Naphthochinon-Derivate from Cultures of the Mycosymbiont from the Lichen Trypethelium eluteriae (Trypetheliaceae) From cultures of the mycosymbiont of the tropical cortical lichen Trypethelium eluteriae Sprengel the antibiotically active 1,2-naphthoquinones trypethelone (2), trypethelone methyl ether (3), 8-methoxytrypethelone methyl ether (5), and 4′-hydroxy-8-methoxytrypethelone methyl ether (6) have been isolated. The substitution pattern of these new derivatives of (+)-dunnione (1) is in accord with a polyketide biogenesis of the quinone system.

Kondensation von Zimtaldehyd (5) mit 2-Oxobuttersaure (6) liefert die (E,E)-Ketosaure 7, die nach Uberfuhrung in den Methylester 9 und Wittig-Reaktion mit (Methoxymethylen)triphenylphosphoran (9E)-Strobilurin A (1a) ergibt. Inversion der 9-Doppelbindung durch Belichten fuhrt zu Strobilurin A (1b), das mit dem Naturprodukt identisch ist. Danach besitzen alle naturlichen Strobilurine 1b–4b im Gegensatz zu fruheren Angaben die (9Z)-Konfiguration. Diese Zuordnung wird durch den spektroskopischen Vergleich von 1a und 1b sowie durch thermische Cyclisierung von 1b zum Biphenyl-Derivat 11 gesichert. 11 kann auch durch Reaktion von 2-(Methoxymethylen)acetessigsaure-methylester (13) mit Cinnamylidentriphenylphosphoran (12) erhalten werden. Kondensation von 13 unter basischen Bedingungen liefert 4-Hydroxyisophthalsaure-dimethylester (14). Antibiotics from Basidiomycetes, XX. – Synthesis of Strobilurin A and Revision of the Stereochemistry of Natural Strobilurins Condensation of cinnamaldehyde (5) with 2-oxobutyric acid (6) leads to the (E,E)-keto acid 7 which is converted into (9E)-strobilurin (1a) via methyl ester 9 and Wittig reaction of the latter with (methoxymethylene)triphenylphosphorane. On irradiation 1a undergoes inversion at the double bond in position 9 and yields strobilurin A (1b) which is identical with the natural product. Due to this result the (9Z) stereochemistry has to be assigned to all natural strobilurins 1b–4b, contrary to former formulations. This assignment is further supported by spectral comparison of 1a and 1b as well as by thermal cyclization of 1b to the biphenyl derivative 11. The latter can also be obtained by condensation of methyl 2-(methoxymethylene)acetoacetate (13) with cinnamylidenetriphenylphosphorane (12). Base-catalyzed condensation of 13 yields dimethyl 4-hydroxyisophthalate (14).

The structure of merulidial (1a), a sesquiterpenoid antibiotic produced by cultures of Merulius tremellosus has been elucidated by spectral investigations and conversion into several derivatives.

Necatorone, an alkaloid possessing an unusual 5,10-dihydroxydibenzo [de,h] [1,6] naphthyridin-6-one structure has been isolated from fruit-bodies of the toadstool Lactarius necator .

The reaction of indolyl magnesium bromide with 2,3-dibromo-N-methylmaleimide (3) in toluene leads to bisindolylmaleimides 6. In THF a monosubstitution product 5 is obtained which after protection of the indole NH-group with the Boc residue can be used to prepare unsymmetrically substituted bisindolylmaleimides, arcyriarubin B given as an example.

Two pungent 2 H -azepines, chalciporone (1) and norchalciporyl propionate (2), were isolated from ethyl acetate extracts of fruit-bodies of the fungus Chalciporus piperatus , together with the related but nonpungent 3 H -azepines isochalciporone (3) and dehydroisochalciporone (4).

The structures of the antibiotically active sesquiterpenoids hypnophilin, pleurotellic acid and pleurotellol have been elucidated by spectral investigations. Pleurotellic acid and pleurotellol contain a rearranged hirsutane skeleton which may be derived biosynthetically from hypnophilin by a Wagner-Meerwein type rearrangement.

From plasmodia of the slime mould Physarum polycephalum a yellow pigment physarochrome A (1) has been obtained. lts structure has been established as all- trans N -[11-(2-acetylamino-3-hydroxyphenyl)-2,4,6,8,10-undecapentaenoyl]- S -glutamine (1) on the basis of spectroscopic evidence and hydrogenation to a decahydro derivative.

Die Isolierung, Strukturaufklarung und biologische Aktivitat von Naematolin (1) und Naematolon (9), zweier Sesquiterpenoide vom Caryophyllan-Typ aus Kulturen verschiedener Hypholoma-Arten, werden beschrieben. Antibiotics from Basidiomycetes, XIX. - Naematolin and Naematolone, Two Caryophyllane Derivatives from Cultures of Hypholoma Species (Agaricales) The isolation, structural elucidation, and biological activity of naematolin (1) and naematolone (9), two sesquiterpenoids with caryophyllane skeleton from cultures of several Hypholoma species, is described.