No abstract available.
Streptomyces*

Recently, we reported violapyrones B, C, H and I, unusual 3, 4, 6-trisubstituted alpha-pyrone derivatives, from the culture broth of the marine Streptomyces sp. 112CH148. In previous studies, violapyrones have been shown to have antibacterial and antitumor activities. However, the anti-inflammatory effect of violapyrones has not been reported yet. As part of our ongoing study for the discovery of bioactive metabolites from marine microorganisms, we found that violapyrones also have anti-inflammatory activity. In this study, we investigated the effect of violapyrones on LPS-induced inflammatory responses in vitro. Violapyrones B and C did not affect the viability of RAW 264.7 cells at concentrations up to 25 microM. However, violapyrones B and C inhibited the production of NO compared to the LPS-induced control. In addition, violapyrones B and C down-regulated the expression of iNOS protein in LPS-stimulated RAW 264.7 cells. To the best of our knowledge, this is the first report on the anti-inflammatory activity of violapyrones B and C.
Streptomyces*

Aim: A novel endophyte, Streptomyces kebangsaanensis was isolated from the stem of a Malaysian ethnomedicinal plant, Portulaca oleracea in 2013. Studies on S. kebangsaanensis crude extract showed that it had antifungal activities and further work led to isolation of a novel compound, phenazine-1-carboxylic acid (PCA). This study investigated the combinatorial effect of PCA isolated from S. kebangsaanensis with amphotericin B on the growth of four clinical Fusarium solani isolates. Methodology and results: Disk diffusion assay showed that the crude extract of S. kebangsaaneesis inhibited growth of all four F. solani isolates. Whereas, the compound PCA from this extract inhibited two of the tested F. solani isolates, UZ541/12, and UZ667/13 at minimum inhibitory concentration of 18.00 µg/mL Combinations of this compound with amphotericin B, reduced the minimum inhibitory concentration of amphotericin B for these two isolates from 8 to 0.13 µg/mL and 4 to 0.03 µg/mL respectively. Analysis of fractional inhibitory concentration index showed that a borderline synergism is present between the compound and amphotericin B. Conclusion, significance and impact of the study These results indicate PCA may be useful in improving actions of available drugs against antimicrobial resistant microorganisms.
Streptomyces

A new alpha-pyrone derivative, violapyrone J (1), and along with the two known violapyrones B (2) and C (3) were isolated from the fermentation broth of a marine actinomycete Streptomyces sp. SC0718. The structure of violapyrone J (1) was elucidated from 1D and 2D NMR spectroscopic analyses.
Actinobacteria* ; Fermentation ; Streptomyces*

No abstract available.
Staphylococcus aureus* ; Staphylococcus* ; Streptomyces*

Aims: The attention for new and effective anticancer drugs but less toxic is increasing over time. Streptomyces is the most important and well-known source of their bioactive compound production with useful bioactivities. This work aimed for evaluation of the anticancer potential of methanolic extract of Streptomyces sp. strain KSF 83 against non-cancerous cell lines (CCD-841-CoN), breast (MCF-7, MDA-MB-231) and colon cancer cell lines (HT-29, HCT-116). Methodology and results: The characteristic of the strain KSF 83 was identified by morphology and 16S rRNA sequencing and results confirmed that the strain belonged to the genus of Streptomyces. The crude substance was produced via submerged fermentation from the strain and methanol solvent was used to extract the culture filtrate. Methanolic extract possessed low toxicity against CCD-841-CoN with only 18% of inhibition activity at the 400 µg/mL. Among all tested cancer cells, the methanolic extract was able to inhibit the growth of all cancer cells tested with MCF-7 was the highest anticancer activity recorded. The methanolic extract also exhibited cytotoxicity in a range of EC50 of 65.79 μg/mL to 262.40 μg/mL. This study revealed the anticancer potential of Streptomyces sp. strain KSF 83, which could be sources of prospective anticancer drugs against breast and colon cancer. Conclusion, significance and impact of study The extract of KSF 83 was non-toxic toward normal cell lines and able to inhibit the growth of breast and cancer cell lines, thus it can be a potential source of the anticancer drug against breast and colon cancer.
Antineoplastic Agents--pharmacology ; Streptomyces

Angucyclines/angucyclinones are a large group of polycyclic aromatic polyketides and their producers are widely distributed in nature. This family of natural products attracts great attention because of their diverse biological activities and unique chemical structures. With the development of synthetic biology and the exploitation of the actinomycetes from previously unexplored environments, angucyclines/angucyclinones-like natural products with new skeletons were continuously discovered, thus enriching the structural diversity of this family. In this review we summarize the new angucyclines/angucyclinones analogues discovered in the last decade (2010-2020) by using different strategies, such as changing cultivation conditions, genetic modification, genome mining, bioactivity-guided compound isolation, and fermentation of actinomycetes from underexplored environments. We also discuss the role of synthetic biology in the discovery and development of new compounds of the angucycline/angucyclinone family.
Anthraquinones ; Biological Products ; Polyketides ; Streptomyces

Comprehensive chemical analysis of extracts and fractions of marine actinomycete strains led to the discovery of a new minor secondary metabolite, salternamide E (1), from a saltern-derived halophilic Streptomyces strain. The planar structure of salternamide E (1) was elucidated by a combinational analysis of spectroscopic data including NMR, MS, UV, and IR. The absolute configuration of salternamide E (1) was determined by circular dichroism spectroscopic analysis. Salternamide E displayed weak cytotoxicity against various human carcinoma cell lines.
Cell Line ; Circular Dichroism ; Humans ; Streptomyces*

Compared to their terrestrial and marine counterparts, little is known about the capacity of freshwater-derived actinomycete bacteria to produce novel secondary metabolites. In the current study, we highlight the disparities that exist between cultivation-independent and -dependent analyses of actinomycete communities from four locations in Lake Michigan sediment. Furthermore, through phylogenetic analysis of strains isolated from these locations, we identified a Streptomyces sp., strain B025, as being distinct from other Streptomyces spp. isolated from sediment. Upon fermentation this strain produced a rare class of eight-membered lactone secondary metabolites, which have been for their antitumor properties. We used spectroscopic and chemical derivitization techniques to characterize octalactin B (1) in addition to its corresponding novel, unnatural degradation product (2).
Bacteria ; Fermentation ; Fresh Water ; Lakes ; Michigan ; Streptomyces*

Natamycin is a polyene macrolide antibiotics with strong and broad spectrum antifungal activity. It not only effectively inhibits the growth and reproduction of fungi, but also prevents the formation of some mycotoxins. Consequently, it has been approved for use as an antifungal food preservative in most countries, and is also widely used in agriculture and healthcare. Streptomyces natalensis and Streptomyces chatanoogensis are the main producers of natamycin. This review summarizes the biosynthesis and regulatory mechanism of natamycin, as well as the strategies for improving natamycin production. Moreover, the future perspectives on natamycin research are discussed.
Antifungal Agents/pharmacology* ; Fungi ; Natamycin ; Streptomyces