Dihydromaltophilin; A Novel Fungicidal Tetramic Acid Containing Metabolite from Streptomyces sp.

Abstract

A new tetramic acid containing metabolite, A90931a has been isolated from Streptomyces sp., along with a second factor (A90931b) recently described and known as maltophilin. The structures were determined from spectroscopic data of the isolates and their acetylated products. A90931awas spectroscopically identical to the previously described antibiotic TAN-883bwhose structure was not reported. A90931a and A90931b exhibit fungicidal activity against the grape pathogen Plasmopara viticola. Due to its similarity to maltophilin, A90931a has been called dihydromaltophilin.

Common biosynthetic origins for polycyclic tetramate macrolactams from phylogenetically diverse bacteria

“…The frontalamides are closely related to a number of previously described polycyclic tetramate macrolactam antibiotics including dihydromaltophilin (12), maltophilin (10), cylindramide (13), ikarugamycin (11), alteramide (14), and discodermide (15). Of these, the frontalamides are distinguished by an unusual terminal olefin.…”

“…Of these, the frontalamides are distinguished by an unusual terminal olefin. Little is known about the biosyntheses of any of these compounds, which is surprising because they are produced by a wide range of phylogenetically diverse bacteria including γ-proteobacteria [Alteromonas (14), Stenotrophomonas (10), Lysobacter (8)], actinomycetes [Streptomyces (11,12)], and as-ofyet unidentified symbionts of marine sponges (13,15).…”

“…Each protein also contains the hybrid PKS-NRPS catalytic domain order (KS-AT-DH-KR-ACP-C-A-T-TE) noted during studies on the partial dihydromaltophilin cluster (8). Based on their structures, a number of researchers working on frontalamide-like polycyclic tetramate macrolactams postulated the biosynthetic incorporation of ornithine or β-hydroxyornithine (12,14,15). This idea was further supported after ornithine-selective residues were found in the amino acid adenylation domain of the dihydromaltophilin FtdB …”

Phenalinolactones A–D, terpenoglycoside antibiotics from Streptomyces sp. Tü 6071

“…6 Besides these compounds, a third unknown metabolite family was detected in the culture filtrate extract having characteristic UV-vis spectra, which were different from those of all reference compounds of the database. This report describes the fermentation, isolation and structure elucidation of four novel diterpenoid compounds, named phenalinolactones A-D (1)(2)(3)(4). Their structures are shown in Figure 1.…”

“…Tü 6071 was subjected to a closer scrutiny because of its production of chemically diverse metabolites. On the basis of their UV-visible spectra and retention times, the already known macrolactam antibiotics maltophilin 2 and dihydromaltophilin, 3 as well as the structurally related alteramide 4 were identified in the mycelium extract by our in-house developed HPLC-UV-vis database. 5 Furthermore, four new cyclic decapeptides, streptocidins A-D were isolated from the mycelium of strain Tü 6071.…”