Isolation and structure elucidation of five new asterriquinones from Aspergillus, Humicola and Botryotrichum species.

Five new quinone pigments have been discovered from the fermentation broth of Aspergillus, Humicola and Botryotrichum species isolated from different soil samples. These compounds inhibit serine proteases of the coagulation pathway. Their structures which differ in the identity and position of a 5-carbon side chain on the indole moiety have been elucidated based on NMR and FAB-MS experiments.

Biosynthesis of pyrrolnitrin. Incorporation of 13C, 15N double-labelled D- and L-tryptophan.

Experiments on the incorporation of D- and L-[alanine-3-13C,2-15N]tryptophan into the antibiotic pyrrolnitrin in Pseudomonas aureofaciens confirmed earlier conclusions about the conversion of L-tryptophan into pyrrolnitrin. They also demonstrated that a fraction of the D isomer is incorporated without breakage of the 15N-carbon bond, consistent with the operation of a second pathway from D-tryptophan to pyrrolnitrin. Cell-free experiments confirmed the conversion of 3-(o-aminophenyl)pyrrole into aminopyrrolnitrin but failed to detect enzymatic oxidation of the latter to pyrrolnitrin.

Omphalone, an antibiotically active benzoquinone derivative from fermentations of Lentinellus omphalodes.

Omphalone, a new antibiotic, cytotoxic, and phytotoxic pigment has been isolated from fermentations of a Canadian strain of Lentinellus omphalodes. Its structure has been established as 2-(4-methylfuran-2-yl)-1,4-benzoquinone (1) by spectroscopic investigations and conversion into leuco-acetate 2.

Antibiotics from basidiomycetes. XXXVII. New inhibitors of cholesterol biosynthesis from cultures of Xerula melanotricha Dörfelt.

Three new inhibitors of cholesterol biosynthesis have been isolated from cultures of Xerula melanotricha and their structures elucidated by spectroscopic methods. Dihydroxerulin (1) in admixture with xerulin (2) strongly inhibits the incorporation of 14C- acetate into cholesterol in HeLa cells while the incorporation of 14C-mevalonate is not affected. Xerulinic acid (3) shows similar biological activities but a higher cytotoxicity.

1H and 13C NMR assignments of the thiopeptide antibiotic nosiheptide.

The 1H and 13C NMR spectra of nosiheptide have been assigned by use of 2D NMR techniques on unlabeled samples and biosynthetically multiple-labeled samples from stable isotope feeding experiments.

Reexamination of the 1H and 13C NMR spectral assignments of thiostrepton.

The use of 2D NMR techniques on unlabeled and biosynthetically multiple 13C-labeled samples enabled us to refine the 1H and 13C NMR spectral assignments for thiostrepton.

Antibiotics from basidiomycetes. XXIX: Pilatin, a new antibiotically active marasmane derivative from cultures of Flagelloscypha pilatii agerer.

Pilatin, a new marasmane derivative, was isolated from fermentations of the cyphelloid fungus Flagelloscypha pilatii. Its structure was determined by chemical and physical methods. Pilatin inhibits the growth of bacteria and fungi at concentrations of 5-50 micrograms/ml. The compound is highly cytotoxic. The incorporation of thymidine and uridine into DNA and RNA in Ehrlich carcinoma ascitic cells is strongly inhibited by pilatin. Like marasmic acid pilatin causes frameshift mutations in Salmonella typhimurium TA98.

Lentinellic acid, a biologically active protoilludane derivative from Lentinellus species (Basidiomycetes).

A new antimicrobial and cytotoxic sesquiterpenoid, lentinellic acid, has been isolated from submerged cultures of Lentinellus ursinus and L. omphalodes. The structure of the antibiotic was elucidated by spectroscopic methods and a single crystal X-ray analysis. 1 may be formed biogenetically by condensation of a protoilludane aldehyde 4 with a malonate unit.

Antibiotics from basidiomycetes. XVIII. Strobilurin C and oudemansin B, two new antifungal metabolites from Xerula species (Agaricales).

Two new antifungal (E)-beta-methoxyacrylates, strobilurin C and oudemansin B, were isolated from cultures of Xerula longipes and Xerula melanotricha. Their structures were elucidated by spectroscopic methods. Both antibiotics inhibit the growth of a wide variety of saprophytic and phytopathogenic fungi at very low concentrations. Like strobilurins A, B, and oudemansin A the new metabolites are potent inhibitors of respiration.