Paleic acid, a fatty acid from Paenibacillus sp.: taxonomy, fermentation, isolation, structure determination, and anti-Mannheimia and -Pasteurella activity.

Paleic acid (1), an antibiotic, was obtained from a fermentation broth of Paenibacillus sp. BMK771-AF3. The compound is a fatty acid (9Z,16R)-16-hydroxy-9-octadecenoic acid ((R)-16-hydroxyoleic acid), whose isolation required protection of its polar functional groups. Mosher esters of paleic acid yielded information on the absolute configuration of secondary alcohol, and well-resolved (1)H NMR peaks around the double bond suggested that olefin adopted a Z geometry. Paleic acid showed potent antibacterial activity and narrow spectrum against Mannheimia haemolytica with MIC values ranging between 0.78 and 1.56 microg ml(-1).

Caprazamycins, novel lipo-nucleoside antibiotics, from Streptomyces sp. II. Structure elucidation of caprazamycins.

Novel antibiotics, active against acid-fast bacteria, caprazamycins, were isolated from the culture broth of Streptomyces sp. MK730-62F2. The planar structures of the compounds were determined by 2D NMR spectroscopic study. Furthermore, the absolute structure of caprazamycin B (2) was established by NMR spectroscopy and X-ray crystallography of its degradation products and by total synthesis of the 5-amino-5-deoxy-D-ribose moiety. In the course of degradation studies of 2 under alkaline and acidic conditions, we obtained the two core components, caprazene (11) and caprazol (14), respectively, in high yield. Structurally, caprazamycins belong to a family of lipouridyl antibiotics, which have been discovered as specific inhibitors of a bacterial translocase.

Absolute configuration of kigamicins A, C and D.

The stereochemistry of kigamicins A (1), C (2) and D (3) were elucidated by a combination of X-ray crystallographic analysis and degradation studies. The absolute structures of kigamicins thus determined were depicted as shown in Fig. 2.

ICM0301s, new angiogenesis inhibitors from Aspergillus sp. F-1491. II. Physico-chemical properties and structure elucidation.

ICM0301A (1), B (2) and their congeners (3 approximately 8) were isolated from a culture broth of Aspergillus sp. F-1491 as new angiogenesis inhibitors. Their structures were elucidated by spectroscopic analyses. ICM0301A and B have a substituted decalin skeleton containing two oxirane rings.

Tripropeptins, novel antimicrobial agents produced by Lysobacter sp.

Planar structures of tripropeptins (TPPs) were elucidated by spectroscopic studies including various NMR measurements. Stereochemistry of constituent amino acids of tripropeptin C (TPPC) (3) was identified by marfey's method except hydroxyproline which was determined by studies of NMR and CD spectra. The absolute structure of 3 was determined by analyses of the fragments obtained by Birch reduction and LiBH4 reduction of 3. The configuration of the fatty acid, isolated from acid hydrolysate of 3, was determined to be (3R)-hydroxy-13-methyltetradecanoic acid from MS, NMR spectra and negative sign of the optical rotation.

Kigamicins, novel antitumor antibiotics. II. Structure determination.

Kigamicin A (1), B (2), C (3), D (4) and E (5) are novel antitumor antibiotics. Their structures were determined by spectroscopic analyses including various NMR measurements. Kigamicins have a unique aglycone of fused octacyclic ring system containing seven of six-membered rings and one oxazolidine. The aglycone links a sugar chain composed of one to four deoxysugars. These sugars were found to be amicetose and oleandrose.

Biosynthesis of the lipophilic side chain in the cyclic hexadepsipeptide antibiotic IC101.

Antibiotic IC101 is a cyclic hexadepsipeptide having a C(15) lipophilic side chain. The side chain was shown to be synthesized in Streptomyces from acetate, propionate, and 3-methylbutyrate derived from leucine. Thus, the terminal isopentyl structure came from leucine and not from the mevalonate pathway.

Panepophenanthrin, from a mushroom strain, a novel inhibitor of the ubiquitin-activating enzyme.

Screening for inhibitors of the ubiquitin-proteasome pathway, considered to regulate important cellular events and linked to serious diseases as well, led to isolation of a new compound, panepophenanthrin, from the fermented broth of a mushroom strain, Panus rudis Fr. IFO 8994. This is the first inhibitor of the ubiquitin-activating enzyme, which is indispensable for the ubiquitin-proteasome pathway. The structure of panepophenanthrin was determined by NMR and X-ray crystallographic analyses as 1,3a,10-trihydroxy-10c-(3-hydroxy-3-methylbut-1-enyl)-5,5-dimethyl-1,2,3,3a,5,5a,8,9,10,10a,10b,10c-dodecahydro-4-oxa-2,3,8,9-diepoxyacephenanthrylen-7-one.

Biosynthesis of the cyclitol moiety of pyralomicin 1a in Nonomuraea spiralis MI178-34F18.

The biosynthetic pathway leading to the cyclitol moiety of pyralomicin 1a (1) in Nonomuraea spiralis MI178-34F18 has been studied using a series of 2H-labeled potential precursors. The results demonstrate that 2-epi-5-epi-valiolone (7), a common precursor for acarbose (4) and validamycin A (5) biosynthesis, is an immediate precursor of pyralomicin 1a. 5-epi-Valiolone (8) was also incorporated into 1, albeit less efficiently than 7. Other potential intermediates, such as valiolone (9), valienone (10), valienol (11), 1-epi-valienol (12), 5-epi-valiolol (13), and 1-epi-5-epi-valiolol (14) were not incorporated into pyralomicin 1a. To explain this surprising observation, it is proposed that either 2-epi-5-epi-valiolone (7) is specifically activated (e.g., to its phosphate) and that the further transformations take place on activated intermediates (which can not be generated directly from their unactivated counterparts), or that the transformation of 7 into 1 involves a substrate-channeling mechanism in which enzyme-bound intermediates are directly transferred from one enzyme active site to the next in a multi-enzyme complex.

Bacilysocin, a novel phospholipid antibiotic produced by Bacillus subtilis 168.

We have found a novel phospholipid antibiotic (named bacilysocin) which accumulates within (or associates with) the cells of Bacillus subtilis 168 and determined the structure by nuclear magnetic resonance and mass spectrometry analyses. The structure of bacilysocin elucidated was 1-(12-methyltetradecanoyl)-3-phosphoglyceroglycerol. Bacilysocin demonstrated antimicrobial activity, especially against certain fungi. Production of bacilysocin commenced immediately after growth ceased and before the formation of heat-resistant spores. The production of bacilysocin was completely blocked when the ytpA gene, which encodes a protein homologous to lysophospholipase, was disrupted, but blockage of the ytpA gene did not significantly affect growth. Sporulation was also impaired, with a 10-fold reduction in heat-resistant spore titers being detected. Since the ytpA disruptant actually lacked phospholipase activity, we propose that the YtpA protein functions as an enzyme for the biosynthesis of bacilysocin.

Polyoxypeptins A and B Produced by Streptomyces: Apoptosis-Inducing Cyclic Depsipeptides Containing the Novel Amino Acid (2S,3R)-3-Hydroxy-3-methylproline.

Potent apoptosis-inducing peptides, polyoxypeptins A (1) and B (2) were isolated from the culture broth of Streptomyces sp. by solvent extraction and column chromatography. Structural elucidation of 1 by MS and NMR analyses revealed that it is a cyclic hexadepsipeptide having a novel amino acid and a previously unrecognized N-acyl side chain. The depsipeptide consisted of 3-hydroxyleucine, N-hydroxyvaline, N-hydroxyalanine, piperazic acid, 5-hydroxyhexahydropiperazine-3-carboxylic acid, and an unusual and hitherto unreported amino acid, 3-hydroxy-3-methylproline. Alanine and valine obtained from the hydrolyzate of 1 were both in the L-configuration as concluded from chiral TLC analysis. Then, the absolute structure of 1 was determined with the relative structure obtained from X-ray crystallographic analysis, and the new amino acid was isolated and confirmed to be (2S,3R)-3-hydroxy-3-methylproline (3). MS and NMR of 2 exhibited that it is a monodeoxy compound of 1. Stereochemistry of 2 was determined by degradation studies. Both 1 and 2 at a concentration of about 0.1 &mgr;g/mL induced early cell death, nuclear fragmentation, and internucleosomal DNA scission, all of which are characteristic of apoptosis, in human pancreatic carcinoma AsPC-1 cells.

Pholipeptin, a Novel Cyclic Lipoundecapeptide fromPseudomonas fluorescens.

An inhibitor of phosphatidylinositol-specific phospholipase C (PI-PLC), pholipeptin (1), was purified from the culture broth of Pseudomonas sp. by solvent extraction and column chromatography. Acid hydrolysis of 1 gave Leu, Ile, Ser, Thr, and Asp moieties. Although 1 was a peptide compound, fragmentation by mild hydrolysis was not accomplished under any conditions. So, we performed the structure elucidation using various 2D NMR techniques. In the NMR studies, the addition of a small amount of trifluoroacetic acid gave relatively sharp and resolved signals, such that the structure of this novel cyclic lipodepsipeptide consisting of 11 amino acids and a 3-hydroxydecanoic acid moiety could be determined. Chirality of the constituent amino acids was analyzed by chiral HPLC, but two Asp residues could not be distinguished because they were contained as a racemic mixture. Finally, their chiralities were determined by NMR analysis of (13)C-labeled 1 into which [L-(13)C]Asp had been biosynthetically incorporated.