Highly diverse endophytic fungi from Serra do Amolar-Pantanal (Brazil) producing bioactive secondary metabolites against phytopathogens.

Introduction: The exploration of new bioactive compounds for agricultural applications is critical for sustainable development. Endophytic fungi, particularly those from underexplored biomes in Brazil, represent a promising source of natural compounds. This study focused on isolation and bioprospecting endophytic fungi from the medicinal plant (Pohl), grown in Serra do Amolar (Brazilian Pantanal Biome), with an additional emphasis on conserving microbial biodiversity.

Diverse Combinatorial Biosynthesis Strategies for C-H Functionalization of Anthracyclinones.

spp. are "nature's antibiotic factories" that produce valuable bioactive metabolites, such as the cytotoxic anthracycline polyketides. While the anthracyclines have hundreds of natural and chemically synthesized analogues, much of the chemical diversity stems from enzymatic modifications to the saccharide chains and, to a lesser extent, from alterations to the core scaffold.

Biochemical and Structural Studies of the Carminomycin 4--Methyltransferase DnrK.

Structural and functional studies of the carminomycin 4--methyltransferase DnrK are described, with an emphasis on interrogating the acceptor substrate scope of DnrK. Specifically, the evaluation of 100 structurally and functionally diverse natural products and natural product mimetics revealed an array of pharmacophores as productive DnrK substrates. Representative newly identified DnrK substrates from this study included anthracyclines, angucyclines, anthraquinone-fused enediynes, flavonoids, pyranonaphthoquinones, and polyketides.

Bioactivity and Metabolomics Profiling of Endophytic Actinobacteria Isolated from Roots of the Medicinal Plants Dominant in South Asian Region.

Background: Plant-derived endophytic actinobacteria are the center of attention due to their capacity to produce diverse antimicrobial and anticancer compounds and their metabolites influence plant growth.

Methods: In this study, 40 endophytic actinobacteria strains were isolated from the roots of eight medicinal plants used as folk medicine in South Asian region. The isolates were characterized morphologically, biochemically and physiologically and the genus level identification of the selected strains was done by 16SrRNA gene sequencing.

Engineering BioBricks for Deoxysugar Biosynthesis and Generation of New Tetracenomycins.

Tetracenomycins and elloramycins are polyketide natural products produced by several actinomycetes that exhibit antibacterial and anticancer activities. They inhibit ribosomal translation by binding in the polypeptide exit channel of the large ribosomal subunit. The tetracenomycins and elloramycins are typified by a shared oxidatively modified linear decaketide core, yet they are distinguished by the extent of O-methylation and the presence of a 2',3',4'-tri-methyl-α-l-rhamnose appended at the 8-position of elloramycin.

Paecilins Q and R: Antifungal Chromanones Produced by the Endophytic Fungus Pseudofusicoccum stromaticum CMRP4328.

Chemical investigation of the endophyte CMRP4328 isolated from the medicinal plant yielded ten compounds, including two new dihydrochromones, paecilins Q (1: ) and R (2: ). The antifungal activity of the isolated metabolites was assessed against an important citrus pathogen, . Cytochalasin H (6: ) (78.

Bioprospecting of desert actinobacteria with special emphases on griseoviridin, mitomycin C and a new bacterial metabolite producing Streptomyces sp. PU-KB10-4.

Background: Bioprospecting of actinobacteria isolated from Kubuqi desert, China for antibacterial, antifungal and cytotoxic metabolites production and their structure elucidation.

Results: A total of 100 actinobacteria strains were selectively isolated from Kubuqi desert, Inner Mongolia, China. The taxonomic characterization revealed Streptomyces as the predominant genus comprising 37 different species, along with the rare actinobacterial genus Lentzea.

A BioBricks Metabolic Engineering Platform for the Biosynthesis of Anthracyclinones in .

Actinomycetes produce a variety of clinically indispensable molecules, such as antineoplastic anthracyclines. However, the actinomycetes are hindered in their further development as genetically engineered hosts for the synthesis of new anthracycline analogues due to their slow growth kinetics associated with their mycelial life cycle and the lack of a comprehensive genetic toolbox for combinatorial biosynthesis. In this report, we tackled both issues via the development of the BIOPOLYMER (BIOBricks POLYketide Metabolic EngineeRing) toolbox: a comprehensive synthetic biology toolbox consisting of engineered strains, promoters, vectors, and biosynthetic genes for the synthesis of anthracyclinones.

HDAC Inhibitor Titration of Transcription and Axolotl Tail Regeneration.

New patterns of gene expression are enacted and regulated during tissue regeneration. Histone deacetylases (HDACs) regulate gene expression by removing acetylated lysine residues from histones and proteins that function directly or indirectly in transcriptional regulation. Previously we showed that romidepsin, an FDA-approved HDAC inhibitor, potently blocks axolotl embryo tail regeneration by altering initial transcriptional responses to injury.

Taxonomic and Metabolomics Profiling of Actinobacteria Strains from Himalayan Collection Sites in Pakistan.

Actinobacteria have proven themselves as the major producers of bioactive compounds with wide applications. In this study, 35 actinobacteria strains were isolated from soil samples collected from the Himalayan mountains region in Pakistan. The isolated strains were identified by polyphasic taxonomy and were prioritized based on biological and chemical screening to identify the strains with ability to produce inimitable metabolites.

RF-3192C and other polyketides from the marine endophytic ASSB4: structure assignment and bioactivity investigation.

Chemical investigation of the methanolic extract of endophytic SB4, isolated from the marine alga , afforded the pentacyclic polyketide, RF-3192C (), the dimeric coumarin orlandin (), fonsecin B (), TMC-256A1 (), cyclo-(Leu-Ala) (), and cerebroside A ().The chemical structure of RF-3192C () is assigned herein for the first time using 1D/2D NMR and HRESI-MS. Additionally, the revision of the NMR assignments of orlandin () was reported herein as well.

Chemical genetics of regeneration: Contrasting temporal effects of CoCl on axolotl tail regeneration.

Background: Histone deacetylases (HDACs) regulate transcriptional responses to injury stimuli that are critical for successful tissue regeneration. Previously we showed that HDAC inhibitor romidepsin potently inhibits axolotl tail regeneration when applied for only 1-minute postamputation (MPA).

Results: Here we tested CoCl a chemical that induces hypoxia and cellular stress, for potential to reverse romidepsin inhibition of tail regeneration.

Metal-free domino amination-Knoevenagel condensation approach to access new coumarins as potent nanomolar inhibitors of VEGFR-2 and EGFR.

A metal-free, atom-economy and simple work-up domino amination-Knoevenagel condensation approach to construct new coumarin analogous ( and ) was described. Further, new formyl () and nitro () coumarin derivatives were synthesized via C-N coupling reaction of various cyclic secondary amines and 4-chloro-3-(formyl-/nitro)coumarins (), respectively. The confirmed compounds were screened for their anti-proliferative activity against KB-3-1, A549 and PC3 human cancer cell lines using resazurin cellular-based assay.

Mithramycin 2'-Oximes with Improved Selectivity, Pharmacokinetics, and Ewing Sarcoma Antitumor Efficacy.

Mithramycin A (MTM) inhibits the oncogenic transcription factor EWS-FLI1 in Ewing sarcoma, but poor pharmacokinetics (PK) and toxicity limit its clinical use. To address this limitation, we report an efficient MTM 2'-oxime (MTM) conjugation strategy for rapid MTM diversification. Comparative cytotoxicity assays of 41 MTM analogues using E-twenty-six (ETS) fusion-dependent and ETS fusion-independent cancer cell lines revealed improved ETS fusion-independent/dependent selectivity indices for select 2'-conjugated analogues as compared to MTM.

Sugar-Pirating as an Enabling Platform for the Synthesis of 4,6-Dideoxyhexoses.

An efficient divergent synthetic strategy that leverages the natural product spectinomycin to access uniquely functionalized monosaccharides is described. Stereoselective 2'- and 3'-reduction of key spectinomycin-derived intermediates enabled facile access to all eight possible 2,3-stereoisomers of 4,6-dideoxyhexoses as well as representative 3,4,6-trideoxysugars and 3,4,6-trideoxy-3-aminohexoses. In addition, the method was applied to the synthesis of two functionalized sugars commonly associated with macrolide antibiotics-the 3--alkyl-4,6-dideoxysugar d-chalcose and the 3--alkyl-3,4,6-trideoxysugar d-desosamine.

Structure Determination, Functional Characterization, and Biosynthetic Implications of Nybomycin Metabolites from a Mining Reclamation Site-Associated .

We report the isolation and characterization of three new nybomycins (nybomycins B-D, -) and six known compounds (nybomycin, ; deoxynyboquinone, ; α-rubromycin, ; β-rubromycin, ; γ-rubromycin, ; and [2α(1,3),4β]-2-(1,3-pentadienyl)-4-piperidinol, ) from the Rock Creek (McCreary County, KY) underground coal mine acid reclamation site isolate sp. AD-3-6. Nybomycin D () and deoxynyboquinone () displayed moderate () to potent () cancer cell line cytotoxicity and displayed weak to moderate anti-Gram-(+) bacterial activity, whereas rubromycins - displayed little to no cancer cell line cytotoxicity but moderate to potent anti-Gram-(+) bacterial and antifungal activity.

OleD Loki as a Catalyst for Hydroxamate Glycosylation.

Herein we describe the ability of the permissive glycosyltransferase (GT) OleD Loki to convert a diverse set of >15 histone deacetylase (HDAC) inhibitors (HDACis) into their corresponding hydroxamate glycosyl esters. Representative glycosyl esters were subsequently evaluated in assays for cancer cell line cytotoxicity, chemical and enzymatic stability, and axolotl embryo tail regeneration. Computational substrate docking models were predictive of enzyme-catalyzed turnover and suggest certain HDACis may form unproductive, potentially inhibitory, complexes with GTs.

Total synthesis of griseusins and elucidation of the griseusin mechanism of action.

A divergent modular strategy for the enantioselective total synthesis of 12 naturally-occurring griseusin type pyranonaphthoquinones and 8 structurally-similar analogues is described. Key synthetic highlights include Cu-catalyzed enantioselective boration-hydroxylation and hydroxyl-directed C-H olefination to afford the central pharmacophore followed by epoxidation-cyclization and maturation diastereoselective reduction and regioselective acetylation. Structural revision of griseusin D and absolute structural assignment of 2,8-epoxy--4'-deacetyl griseusin B are also reported.

Dihydroisocoumarins produced by Diaporthe cf. heveae LGMF1631 inhibiting citrus pathogens.

Citrus black spot (CBS) and post-bloom fruit drop (PFD), caused by Phyllosticta citricarpa and Colletotrichum abscissum, respectively, are two important citrus diseases worldwide. CBS depreciates the market value and prevents exportation of citrus fruits to Europe. PFD under favorable climatic conditions can cause the abscission of flowers, thereby reducing citrus production by 80%.

Vochysiamides A and B: Two new bioactive carboxamides produced by the new species Diaporthe vochysiae.

Endophytic fungi have been considered a rich source for bioactive secondary metabolites with novel chemical structures. A high diverse group of endophytes, isolated from different medicinal plants, belongs to the genus Diaporthe. In a previously study performed by our group the crude extract of strain LGMF1583 showed considerable antibacterial activity mainly against Gram-negative bacteria.

Baraphenazines A-G, Divergent Fused Phenazine-Based Metabolites from a Himalayan Streptomyces.

The structures and bioactivities of three unprecedented fused 5-hydroxyquinoxaline/alpha-keto acid amino acid metabolites (baraphenazines A-C, 1-3), two unique diastaphenazine-type metabolites (baraphenazines D and E, 4 and 5) and two new phenazinolin-type (baraphenazines F and G, 6 and 7) metabolites from the Himalayan isolate Streptomyces sp. PU-10A are reported. This study highlights the first reported bacterial strain capable of producing diastaphenazine-type, phenazinolin-type, and izumiphenazine A-type metabolites and presents a unique opportunity for the future biosynthetic interrogation of late-stage phenazine-based metabolite maturation.

HDAC Regulates Transcription at the Outset of Axolotl Tail Regeneration.

Tissue regeneration is associated with complex changes in gene expression and post-translational modifications of proteins, including transcription factors and histones that comprise chromatin. We tested 172 compounds designed to target epigenetic mechanisms in an axolotl (Ambystoma mexicanum) embryo tail regeneration assay. A relatively large number of compounds (N = 55) inhibited tail regeneration, including 18 histone deacetylase inhibitors (HDACi).

Secondary metabolites produced by the citrus phytopathogen Phyllosticta citricarpa.

The isolation and structure elucidation of one new fungal metabolite, phenguignardic acid butyl ester (1a), and four previously reported metabolites (1b, 2a, 3-4) from the citrus phytopathogen Phyllosticta citricarpa LGMF06 are described. The new dioxolanone phenguignardic acid butyl ester (1a) had low phytotoxic activity in citrus leaves and fruits (at dose of 100 µg), and its importance as virulence factor in citrus black spot disease needs to be further addressed. Beside the phytotoxic analysis, we also evaluated the antibacterial (against methicillin sensitive and resistant Staphylococcus aureus) and cytotoxic (A549 non-small cell lung cancer, PC3 prostate cancer and HEL 299 normal epithelial lung) activities of the isolated compounds, which revealed that compounds 1a, 1b and 2a were responsible for the antibacterial activity of this strain.