Actinomycetes and filamentous fungi produce a wide range of bioactive compounds, with applications as antimicrobials, anticancer agents or agrochemicals. Their genomes contain a far larger number of gene clusters for natural products than originally anticipated, and novel approaches are required to exploit this potential reservoir of new drugs. Here, we show that co-cultivation of the filamentous model microbes Streptomyces coelicolor and Aspergillus niger has a major impact on their secondary metabolism. NMR-based metabolomics combined with multivariate data analysis revealed several compounds that correlated specifically to co-cultures, including the cyclic dipeptide cyclo(Phe-Phe) and 2-hydroxyphenylacetic acid, both of which were produced by A. niger in response to S. coelicolor. Furthermore, biotransformation studies with o-coumaric acid and caffeic acid resulted in the production of the novel compounds (E)-2-(3-hydroxyprop-1-en-1-yl)-phenol and (2E,4E)-3-(2-carboxy-1-hydroxyethyl)-2,4-hexadienedioxic acid, respectively. This highlights the utility of microbial co-cultivation combined with NMR-based metabolomics as an efficient pipeline for the discovery of novel natural products.

https://scholarlypublications.universiteitleiden.nl/access/item%3A3145990/view

Expanding the chemical space for natural products by Aspergillus-Streptomyces co-cultivation and biotransformation

Antimicrobial peptides (AMPs) are an essential part of innate immunity. These compounds have been considered as potential therapeutics because of their broad-spectrum activities and proven ability to avoid antimicrobial resistance, but their clinical and commercial developments have some limitations, such as susceptibility to proteases and a high cost of peptide production. To overcome these problems, many researchers have tried to develop short active peptides, their modifications and mimics with better properties while retaining their basic features of natural AMPs such as cationic charge and the amphipathic structure.

/pdf/antimicrobial-peptides-and-their-analogs-searching-for-new-34r0kaqx3c.pdf

Antimicrobial Peptides and Their Analogs: Searching for New Potential Therapeutics:

Pseudomonas aeruginosa is an opportunistic pathogen of plants and animals, which produces virulence factors in order to infect or colonize its eukaryotic hosts. Cyclodipeptides (CDPs) produced by P. aeruginosa exhibit cytotoxic properties toward human tumor cells. In this study, we evaluated the effect of a CDP mix, comprised of cyclo(L-Pro-L-Tyr), cyclo(L-Pro-L-Val), and cyclo(L-Pro-L-Phe) that were isolated from P. aeruginosa, on two human cancer cell lines. Our results demonstrated that the CDP mix promoted cell death in cultures of the HeLa cervical adenocarcinoma and Caco-2 colorectal adenocarcinoma cell lines in a dose-dependent manner, with a 50% inhibitory concentration (IC50) of 0.53 and 0.66 mg/mL, for HeLa and Caco-2 cells, respectively. Flow cytometric analysis, using annexin V and propidium iodide as apoptosis and necrosis indicators, respectively, clearly showed that HeLa and Caco-2 cells exhibited apoptotic characteristics when treated with the CDP mix at a concentration <0.001 mg/mL. IC50 values for apoptotic cells in HeLa and Caco-2 cells were 6.5 × 10−5 and 1.8 × 10−4 mg/mL, respectively. Our results indicate that an apoptotic pathway is involved in the inhibition of cell proliferation caused by the P. aeruginosa CDP mix.

/pdf/cytotoxicity-of-cyclodipeptides-from-pseudomonas-aeruginosa-32fysnyi1l.pdf

Cytotoxicity of Cyclodipeptides from Pseudomonas aeruginosa PAO1 Leads to Apoptosis in Human Cancer Cell Lines

A freshwater algicidal bacterial strain, Lzh-5, isolated from Lake Taihu, with strong algicidal activity against Microcystis aeruginosa, was identified as Bacillus sp. based on its phenotypic characteristics and 16S ribosomal RNA (rRNA) gene sequence. The algicidal mode of Bacillus sp. Lzh-5 was indirect, attacking M. aeruginosa cells by releasing algicidal compounds. Two algicidal compounds (S-5A and S-5B) produced by Bacillus sp. Lzh-5 were purified with ethyl acetate extraction, column chromatography, and high-performance liquid chromatography and identified as hexahydropyrrolo[1,2-a]pyrazine-1,4-dione and 3-isopropyl-hexahydropyrrolo[1,2-a]pyrazine-1,4-dione based on liquid chromatography-mass spectrometry, gas chromatography-mass spectrometry, and nuclear magnetic resonance analyses. The active algicidal compounds S-5A (hexahydropyrrolo[1,2-a]pyrazine-1,4-dione) and S-5B (3-isopropyl-hexahydropyrrolo[1,2-a]pyrazine-1,4-dione) displayed high levels of algicidal activity against M. aeruginosa 9110, with LD50 values of 5.7 and 19.4 μg/ml, respectively. This is the first report of 3-isopropyl-hexahydropyrrolo[1,2-a]pyrazine-1,4-dione as an algicidal compound. Compounds S-5A and S-5B also induced obvious morphological changes in M. aeruginosa 9110. In cocultures of M. aeruginosa 9110 and Bacillus sp. Lzh-5, the cell density of Bacillus sp. Lzh-5 and the concentrations of S-5A and S-5B correlated positively with the algicidal activity. Our results indicate that strain Lzh-5 and its two algicidal compounds are potentially useful for controlling cyanobacterial blooms in Lake Taihu.

Algicidal activity of Bacillus sp. Lzh-5 and its algicidal compounds against Microcystis aeruginosa

Bacillaceae-derived peptide antibiotics since 2000.

A new microbial cyclic dipeptide (diketopiperazine), cyclo(d-Tyr-d-Phe) was isolated for the first time from the ethyl acetate extract of fermented modified nutrient broth of Bacillus sp. N strain associated with rhabditid Entomopathogenic nematode. Antibacterial activity of the compound was determined by minimum inhibitory concentration and agar disc diffusion method against medically important bacteria and the compound recorded significant antibacterial against test bacteria. Highest activity was recorded against Staphylococcus epidermis (1 µg/ml) followed by Proteus mirabilis (2 µg/ml). The activity of cyclo(d-Tyr-d-Phe) against S. epidermis is better than chloramphenicol, the standard antibiotics. Cyclo(d-Tyr-d-Phe) recorded significant antitumor activity against A549 cells (IC50 value: 10 μM) and this compound recorded no cytotoxicity against factor signaling normal fibroblast cells up to 100 μM. Cyclo(d-Tyr-d-Phe) induced significant morphological changes and DNA fragmentation associated with apoptosis in A549 cells. Acridine orange/ethidium bromide stained cells indicated apoptosis induction by cyclo(d-Tyr-d-Phe). Flow cytometry analysis showed that the cyclo(d-Tyr-d-Phe) did not induce cell cycle arrest. Effector molecule of apoptosis such as caspase-3 was found activated in treated cells, suggesting apoptosis as the main mode of cell death. Antioxidant activity was evaluated by free radical scavenging and reducing power activity, and the compound recorded significant antioxidant activity. The free radical scavenging activity of cyclo(d-Tyr-d-Phe) is almost equal to that of butylated hydroxyanisole, the standard antioxidant agent. We also compared the biological activity of natural cyclo(d-Tyr-d-Phe) with synthetic cyclo(d-Tyr-d-Phe) and cyclo(l-Tyr-l-Phe). Natural and synthetic cyclo(d-Tyr-d-Phe) recorded similar pattern of activity. Although synthetic cyclo(l-Tyr-l-Phe) recorded lower activity. But in the case of reducing power activity, synthetic cyclo(l-Tyr-l-Phe) recorded significant activity than natural and synthetic cyclo(d-Tyr-d-Phe). The results of the present study reveals that cyclo(d-Tyr-d-Phe) is more bioactive than cyclo(l-Tyr-l-Phe). To the best of our knowledge, this is the first time that cyclo(d-Tyr-d-Phe) has been isolated from microbial natural source and also the antibacterial, anticancer, and antioxidant activity of cyclo(d-Tyr-d-Phe) is also reported for the first time. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.

Cyclo(D-Tyr-D-Phe): a new antibacterial, anticancer, and antioxidant cyclic dipeptide from Bacillus sp. N strain associated with a rhabditid entomopathogenic nematode.

Jayaprakas Ca

Papers

Cyclo(D-Tyr-D-Phe): a new antibacterial, anticancer, and antioxidant cyclic dipeptide from Bacillus sp. N strain associated with a rhabditid entomopathogenic nematode.