Revision of the absolute configurations of chelocardin and amidochelocardin

Even with the aid of the available methods, the configurational assignment of natural products can be a challenging task that is prone to errors, and it sometimes needs to be corrected after total synthesis or single-crystal X-ray diffraction (XRD) analysis. Herein, the absolute configuration of amidochelocardin is revised using a combination of XRD, NMR spectroscopy, experimental ECD spectra, and time-dependent density-functional theory (TDDFT)-ECD calculations. As amidochelocardin was obtained via biosynthetic engineering of chelocardin, we propose the same absolute configuration for chelocardin based on the similar biosynthetic origins of the two compounds and result of TDDFT-ECD calculations. The evaluation of spectral data of two closely related analogues, 6-desmethyl-chelocardin and its semisynthetic derivative 1, also supports this conclusion

Development of biotechnological processes for systematic evaluation of biological activities from myxobacteria and characterization of corresponding metabolites

Naturstoffe erleben derzeit aus verschiedenen Gründen eine Renaissance in der pharmazeutischen Wirkstoffforschung. Aufgrund ihrer Anpassungsfähigkeit an verschiedenste Umweltbedingungen sind besonders Mikroorganismen vielversprechende Produzenten biologisch aktiver Substanzen. Schwierigkeiten, die mit der Kultvierung, Aufarbeitung und Wirkstoffidentifizierung assoziiert sind, erschweren jedoch häufig eine Charakterisierung neuer Moleküle aus diesen Produzenten. Den Schwerpunkt dieser Arbeit bildet die Entwicklung eines Screeningprozesses für eine möglichst umfassende Evaluierung des biosynthetischen Potenzials eines ausgewählten Myxobakteriums. Dies wurde mittels eines Ansatzes erreicht, der Wirkstoffscreening, produktion, -aufreinigung und -charakterisierung nicht als separate, sondern als miteinander verbundene und voneinander abhängige Bausteine betrachtet. Die Prozessentwicklung fand deshalb unter Berücksichtigung dieser übergeordneten Gesichtspunkte statt, da die Optimierung eines Einzelschrittes nicht zwangsläufig zur Verbesserung des Gesamtprozesses führt. Durch konsequente Aufzeichnung prozessrelevanter Daten während des Screening mit dem Myxobakterium SBCm007, konnten wichtige Faktoren zur beschleunigten Wirkstofffindung, produktion und -charakterisierung identifiziert werden. Durch gezielte Anwendung dieser Ergebnisse konnten neue Chondramid-Varianten mit verbesserter Spezifität für Krebszellen, sowie neue chemische Grundstrukturen charakterisiert werden.Natural products currently experience a renaissance in pharmaceutical research for several reasons. Due to their adaptability to various environmental conditions microorganisms are promising candidates for the production of bioactive substances. Difficulties associated with the cultivation, downstream processing, and the identification of bioactive molecules are frequent and complicate the characterization of new substances from these organisms. The aim of this study was the development of a screening process for the in-depth evaluation of the biosynthetic potential of a selected microorganism. Therefore bioactivity-guided screening, production, purification and characterization of biologically active substances were considered as intimately connected building blocks in contrary to their perception as independent steps in the process. Process engineering took place, considering these superior principles because optimization of a single step doesn’t necessarily improve the overall process. Consistent mapping of process-relevant data during the screening of the myxobacterium SBCm007 enabled the identification of important factors for an accelerated identification, production, and characterization of bioactive compounds. Following these established guidelines, new chondramide variants exhibiting increased cancer cell specificity as well as two new compound classes could be characterized, which indicates the applicability of this approach

Development of biotechnological processes for systematic evaluation of biological activities from myxobacteria and characterization of corresponding metabolites

Naturstoffe erleben derzeit aus verschiedenen Gründen eine Renaissance in der pharmazeutischen Wirkstoffforschung. Aufgrund ihrer Anpassungsfähigkeit an verschiedenste Umweltbedingungen sind besonders Mikroorganismen vielversprechende Produzenten biologisch aktiver Substanzen. Schwierigkeiten, die mit der Kultvierung, Aufarbeitung und Wirkstoffidentifizierung assoziiert sind, erschweren jedoch häufig eine Charakterisierung neuer Moleküle aus diesen Produzenten. Den Schwerpunkt dieser Arbeit bildet die Entwicklung eines Screeningprozesses für eine möglichst umfassende Evaluierung des biosynthetischen Potenzials eines ausgewählten Myxobakteriums. Dies wurde mittels eines Ansatzes erreicht, der Wirkstoffscreening, produktion, -aufreinigung und -charakterisierung nicht als separate, sondern als miteinander verbundene und voneinander abhängige Bausteine betrachtet. Die Prozessentwicklung fand deshalb unter Berücksichtigung dieser übergeordneten Gesichtspunkte statt, da die Optimierung eines Einzelschrittes nicht zwangsläufig zur Verbesserung des Gesamtprozesses führt. Durch konsequente Aufzeichnung prozessrelevanter Daten während des Screening mit dem Myxobakterium SBCm007, konnten wichtige Faktoren zur beschleunigten Wirkstofffindung, produktion und -charakterisierung identifiziert werden. Durch gezielte Anwendung dieser Ergebnisse konnten neue Chondramid-Varianten mit verbesserter Spezifität für Krebszellen, sowie neue chemische Grundstrukturen charakterisiert werden.Natural products currently experience a renaissance in pharmaceutical research for several reasons. Due to their adaptability to various environmental conditions microorganisms are promising candidates for the production of bioactive substances. Difficulties associated with the cultivation, downstream processing, and the identification of bioactive molecules are frequent and complicate the characterization of new substances from these organisms. The aim of this study was the development of a screening process for the in-depth evaluation of the biosynthetic potential of a selected microorganism. Therefore bioactivity-guided screening, production, purification and characterization of biologically active substances were considered as intimately connected building blocks in contrary to their perception as independent steps in the process. Process engineering took place, considering these superior principles because optimization of a single step doesn’t necessarily improve the overall process. Consistent mapping of process-relevant data during the screening of the myxobacterium SBCm007 enabled the identification of important factors for an accelerated identification, production, and characterization of bioactive compounds. Following these established guidelines, new chondramide variants exhibiting increased cancer cell specificity as well as two new compound classes could be characterized, which indicates the applicability of this approach

Optimization of the production process for the anticancer lead compound illudin M: process development in stirred tank bioreactors

Abstract Background The fungal natural products illudin S and M have been investigated as precursors for the development of semisynthetic anticancer agents such as Irofulven (illudin S derivative) which is currently in phase II clinical trials. Recently, illudin M derivatives have shown improved in vitro selectivity towards cancer cells encouraging further investigation. This requires a stable supply of the precursor which is produced by Basidiomycota of the genus Omphalotus. We have recently reported a robust shake flask process for the production of gram quantities of illudin M from Omphalotus nidiformis aiming to transfer that process into stirred tank bioreactors, which can be used in a commercial production set-up. However, process transfer across different systems is not straightforward and particularly challenging when the producer is morphologically complex. There are only a few reports that address the development of bioprocesses for the production of compounds from Basidiomycota as these organisms have not been extensively studied because of their complex life cycles and often are difficult to cultivate under laboratory conditions. Results The recently developed shake flask process delivering stable titers of ~ 940 mg L−1 of illudin M was investigated using off-gas analysis to identify critical parameters which facilitated the transfer from shaken into stirred tank bioreactors. Comparable titers to the shake flask process were achieved in 2 L stirred tank bioreactors (1.5 L working volume) by controlling growth of biomass with a carefully timed pH-shift combined with an improved precursor-feeding strategy. A scale-up experiment in a 15 L bioreactor (10 L working volume), resembling the process at 1.5 L resulted in 523 mg L−1 and is the starting point for optimization of the identified parameters at that scale. Conclusion By identifying and controlling key process parameters, the production process for illudin M was transferred from shake flasks into 2 L stirred tank bioreactors reaching a comparable titer (> 900 mg L−1), which is significantly higher than any previously reported. The insights obtained from 10 L scale pave the way towards further scale-up studies that will enable a sustainable supply of illudin M to support preclinical and clinical development programs

Optimization of the biotechnological production of a novel class of anti-MRSA antibiotics from Chitinophaga sancti.

Recently, the discovery of the elansolids, a group of macrolides, was reported. The molecules show activity against methicillin-resistant Staphylococcus aureus as well as other gram-positive organisms. This fact renders those substances a promising starting point for future chemical development. The active atropisomers A1/A2 are formed by macrolactonization of the biosynthesis product A3 but are prone to ring opening and subsequent formation of several unwanted side products. Recently it could be shown that addition of different nucleophiles to culture extracts of Chitinophaga sancti enable the formation of new stable elansolid derivatives. Furthermore, addition of such a nucleophile directly into the culture led exclusively to formation of a single active elansolid derivative. Due to low product yields, methods for production of gram amounts of these molecules have to be established to enable further development of this promising compound class

Large Scale Production and Downstream Processing of Labyrinthopeptins from the Actinobacterium Actinomadura namibiensis

A method was established for the production of 1.2-fold and 4.2-fold increased amounts of the antiviral and central nervous system-active lantipeptides, labyrinthopeptins A1 and A2, respectively, isolated from the actinobacterium Actinomadura namibiensis, to enable production in gram scale. We then performed in vivo characterization of this promising compound class. The labyrinthopeptins A1 and A2 have similar chemical structures and physical properties but differ drastically in their bioactivities. Therefore, large quantities of highly pure material are required for pharmacological studies. An effective methodology was established for the first time for their production in bioreactors, their separation involving gel permeation chromatography on LH20 material, followed by reversed phase-high performance liquid chromatography. With an optimized methodology, 580 mg of labyrinthopeptin A1 and 510 mg of labyrinthopeptin A2 were quantitatively isolated with recovery rates of 72.5% and 42.3% from 7.5 L of culture broth, respectively. However, the fermentation that had already resulted in maximum yields of over 100 mg/L of both target molecules after 300 h in a 10-L scale bioreactor, still requires further optimisation

Furanones and Anthranilic Acid Derivatives from the Endophytic Fungus Dendrothyrium variisporum.

Extracts from an endophytic fungus isolated from the roots of the Algerian plant Globularia alypum showed prominent antimicrobial activity in a screening for novel antibiotics. The producer organism was identified as Dendrothyrium variisporum by means of morphological studies and molecular phylogenetic methods. Studies on the secondary metabolite production of this strain in various culture media revealed that the major components from shake flasks were massarilactones D (1) and H (2) as well as two new furanone derivatives for which we propose the trivial names (5S)-cis-gregatin B (3) and graminin D (4). Scale-up of the fermentation in a 10 L bioreactor yielded massarilactone D and several further metabolites. Among those were three new anthranilic acid derivatives (5-7), two known anthranilic acid analogues (8 and 9) and three cyclopeptides (10-12). Their structures were elucidated on the basis of extensive spectroscopic analysis (1D- and 2D-NMR), high-resolution mass spectrometry (HRESIMS), and the application of the modified Mosher's method. The isolated metabolites were tested for antimicrobial and cytotoxic activities against various bacteria, fungi, and two mammalian cell lines. The new Metabolite 5 and Compound 9 exhibited antimicrobial activity while Compound 9 showed cytotoxicity activity against KB3.1 cells

Biological and chemical diversity go hand in hand: Basidiomycota as source of new pharmaceuticals and agrochemicals.

The Basidiomycota constitutes the second largest higher taxonomic group of the Fungi after the Ascomycota and comprises over 30.000 species. Mycelial cultures of Basidiomycota have already been studied since the 1950s for production of antibiotics and other beneficial secondary metabolites. Despite the fact that unique and selective compounds like pleuromutilin were obtained early on, it took several decades more until they were subjected to a systematic screening for antimicrobial and anticancer activities. These efforts led to the discovery of the strobilurins and several hundreds of further compounds that mainly constitute terpenoids. In parallel the traditional medicinal mushrooms of Asia were also studied intensively for metabolite production, aimed at finding new therapeutic agents for treatment of various diseases including metabolic disorders and the central nervous system. While the evaluation of this organism group has in general been more tedious as compared to the Ascomycota, the chances to discover new metabolites and to develop them further to candidates for drugs, agrochemicals and other products for the Life Science industry have substantially increased over the past decade. This is owing to the revolutionary developments in -OMICS techniques, bioinformatics, analytical chemistry and biotechnological process technology, which are steadily being developed further. On the other hand, the new developments in polythetic fungal taxonomy now also allow a more concise selection of previously untapped organisms. The current review is dedicated to summarize the state of the art and to give an outlook to further developments

Aetheramides A and B, Potent HIV-Inhibitory Depsipeptides from a Myxobacterium of the New Genus “Aetherobacter”

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

Cystobactamids 920-1 and 920-2: Assignment of the Constitution and Relative Configuration by Total Synthesis.

Total synthesis of cystobactamid 920-1 and its epimer has allowed an unambiguous assignment of the relative and absolute configuration of the natural product. A careful structural analysis of each isomer using both NMR and computational techniques also prompted a constitutional revision of the structures originally reported for cystobactamids 920-1 and 920-2, and has provided further insight into the unique conformational preferences of the cystobactamid famil