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The structures of five linear lipopeptides, thaxteramides A1, A2, B1, B2, and C isolated from the myxobacterium Jahnella thaxteri, were elucidated. They have a C-terminal common tetrapeptidic Tyr-Gly-β-Ala-Tyr core but differ in the stereochemistry of the tyrosine units, methylations, the remaining amino acids, and the N-terminal polyketide. In silico analysis of the genome sequence complemented with feeding experiments revealed two distinct hybrid PKS/NRPS gene clusters. Three semisynthesized cyclic analogues were found to inhibit the growth of Gram-positive bacteria.

The structures of five linear lipopeptides, thaxteramides A1, A2, B1, B2, and C isolated from the myxobacterium

Three new siderophores, termed hyalachelins A-C (1-3), were isolated from the terrestrial myxobacterium Hyalangium minutum. Their structures were determined by 2D NMR and HR-MS/MS experiments, and their stereochemical configuration was established by a combination of NMR data, quantum mechanical calculations, and circular dichroism experiments. Hyalachelins are unusual catecholate-type siderophores that bear a 3,7,8-trihydroxy-1-oxo-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid. Their iron chelating activities were evaluated in a CAS assay showing EC50 values of ∼30 μM.

Cystomanamides A-D were isolated as novel natural product scaffolds from Cystobacter fuscus MCy9118, and their structures were established by spectroscopic techniques including 2D NMR, LC-SPE-NMR/-MS, and HR-MS. The cystomanamides contain β-hydroxy amino acids along with 3-amino-9-methyldecanoic acid that is N-glycosylated in cystomanamide C and D. The gene cluster for cystomanamide biosynthesis was identified by gene disruption as PKS/NRPS hybrid incorporating an iso-fatty acid as starter unit and including a reductive amination step at the interface of the PKS and NRPS modules.

A new linear polyketide, juniperolide A (1), was produced by the terrestrial actinomycete (Lv1-48) isolated from the rhizosphere of the plant Juniperus excelsa. The juniperolide A (1) structure contains a THP unit and a 3-amino-2,3,6-trideoxyhexose as the glycosidic moiety. Mosher's analysis was used for absolute stereochemistry determinations at C-2, C-8, C-20, and C-4', while the relative stereochemistry assignments of the remaining stereocenters were based on ROESY correlations and J-based coupling.

Two new cyclic peptides, termed jahnellamides A and B, were isolated from the myxobacterium Jahnella sp. Their structures were solved by NMR, ESIMS, and chemical derivatizations. Jahnellamides are a new class of α-ketoamide-containing peptides comprised of nonproteinogenic amino acids, including α-keto-β-methionine and 4-hydroxyglutamic acid. Moreover, in silico analysis of the genome sequence along with feeding experiments allowed us to identify and annotate a candidate nonribosomal peptide synthetase biosynthetic gene cluster containing a polyketide synthase module involved in the formation of the α-ketoamide moiety.

Aetheramides are structurally distinctive cyclic peptides isolated from a novel myxobacterial genus proposed to be termed "Aetherobacter". The structures were solved by a combination of NMR analyses, quantum mechanical calculations, and chemical derivatizations. Aetheramides which contain a unique polyketide moiety and two amino acid residues potently inhibited HIV-1 infection with IC(50) values of ~0.015 μM. Furthermore aetheramides showed cytostatic activity against human colon carcinoma (HCT-116) cells with IC(50) values of 0.11 μM.

Seven new antibacterials, motualevic acids A-F (1-6) and (4E)-(R)-antazirine (7), have been isolated from the marine sponge Siliquariaspongia sp. and their structures elucidated by spectroscopic methods. Motualevic acids A-D are the first glycyl conjugates of the omega-brominated lipid (E)-14,14-dibromotetradeca-2,13-dienoic acid, and motualevic acid F is the first long-chain 2H-azirine 2-carboxylic acid to be found in nature. Carboxylic acid-containing compounds 1 and 6 inhibit the growth of Staphylococcus aureus and methicillin-resistant S. aureus at 1.2-10.9 microg/mL.