Curvulamine, a new antibacterial alkaloid incorporating two undescribed units from a Curvularia species

The white croaker (Argyrosomus argentatus) derived Curvularia sp. IFB-Z10 produces curvulamine as a skeletally unprecedented alkaloid incorporating two undescribed extender units. Curvulamine is more selectively antibacterial than tinidazole and biosynthetically unique in the new extenders formed through a decarboxylative condensation between an oligoketide motif and alanine.

Fumigaclavines D-H, new ergot alkaloids from endophytic Aspergillus fumigatus

Ergot alkaloids are toxins which are produced biotechnologically on an industrial scale. The chemical investigation of endophytic Aspergillus fumigatus resulted in the isolation of five new ergot alkaloids named fumigaclavines D-H (2-6), along with three known analogues, fumigaclavine C (1), festuclavine (7), and fumigaclavine A (8). Their structures were unequivocally elucidated by extensive spectroscopic analyses in association with X-ray single-crystal diffraction. Fumigaclavines D-H are interesting clavine-type ergot alkaloids featuring a reverse prenyl moiety at C-2, with 1-4, 6, and 8 bearing additional substituents, e.g., an OH or OAc group at C-9. Compounds 2, 4, and 6-8 showed a broad spectrum of antimicrobial activity against a panel of anaerobic microorganisms, of which compounds 4 and 6 were the most active against Veillonella parvula with an MIC=16 µg/mL compared to that (0.12 µg/mL) of tinidazole, co-assayed as a positive reference.

An antibacterial metabolite from Lasiodiplodia pseudotheobromae F2

In searching for symbionts derived from bioactive natural products, six sulfureous diketopiperazines designated as lasiodiplines A-F (1-6) were characterized from the culture of Lasiodiplodia pseudotheobromae F2, previously residing in the apparently normal flower of Illigera rhodantha (Hernandiaceae). Identification of structures was accomplished by a combination of spectroscopic and computational approaches, in conjunction with the low-temperature (100K) single-crystal X-ray diffraction with Cu Kα radiation. Lasiodipline E (5) was demonstrated to be antibacterial against the clinical strains Streptococcus sp., Bacteroides vulgates, Peptostreptococcus sp. and Veillonella parvula, respectively, with an minimum inhibitory concentration (MIC) range of 0.12-0.25 μg/mL. In addition, compounds 4 and 6 exemplify two unusual architectures of natural cyclodipeptides, signifying the unique biochemical characteristics of the producing fungus.

Antibacterial epipolythiodioxopiperazine and unprecedented sesquiterpene from Pseudallescheria boydii, a beetle (coleoptera)-associated fungus

Pseudallescheria boydiiproduces four new epipolythiodioxopiperazine (ETP) boydines A–D and two novel sesquiterpene boydenes A and B.