A new trichostatin analog from Streptomyces sp. CPCC 203909

Ulleunganilines A-C, Trichostatin Analogues Bearing a Modified Side Chain from Streptomyces sp. 13F051

Three new trichostatin analogues, ulleunganilines A-C (1-3), and seven known trichostatins (4-10) were isolated from cultures of Streptomyces sp. 13F051. NMR, UV, and MS data indicated that the planar structures of 1-3 consisted of modified side chains in the trichostatic acid moiety. The absolute configuration of the 2,4-dimethyl-branched carbon chains in 1 and 2 was determined by the PGME method, while the amino acid group in 3 was identified by advanced Marfey's method. Based on the structure of the modified side chains, the origin of 1-3 is proposed. Further experiments indicated that 1 and 3 displayed moderate histone deacetylase inhibitory activity, suggesting that not only the hydroxamate group but also the N,N-dimethyl group were essential for the inhibitory activity.

Xanthanoltrimer A–C: three xanthanolide sesquiterpene trimers from the fruits of Xanthium italicum Moretti isolated by HPLC-MS-SPE-NMR

Xanthanoltrimer A–C, first three xanthanolide sesquiterpene trimers from the fruits of Xanthium italicum Moretti, were isolated by HPLC-MS-SPE-NMR. Xanthanoltrimer A–C had an unprecedented 5/7/6/5/7/6/5/7 polycyclic scaffold.

Exploration of Chemical Diversity and Antitrypanosomal Activity of Some Red Sea-Derived Actinomycetes Using the OSMAC Approach Supported by LC-MS-Based Metabolomics and Molecular Modelling

In the present study, we investigated the actinomycetes associated with the Red Sea-derived soft coral Sarcophyton glaucum in terms of biological and chemical diversity. Three strains were cultivated and identified to be members of genera Micromonospora, Streptomyces, and Nocardiopsis; out of them, Micromonospora sp. UR17 was putatively characterized as a new species. In order to explore the chemical diversity of these actinobacteria as far as possible, they were subjected to a series of fermentation experiments under altering conditions, that is, solid and liquid fermentation along with co-fermentation with a mycolic acid-containing strain, namely Nocardia sp. UR23. Each treatment was found to affect these actinomycetes differently in terms of biological activity (i.e., antitrypanosomal activity) and chemical profiles evidenced by LC-HRES-MS-based metabolomics and multivariate analysis. Thereafter, orthogonal projections to latent structures discriminant analysis (OPLS-DA) suggested a number of metabolites to be associated with the antitrypanosomal activity of the active extracts. The subsequent in silico screenings (neural networking-based and docking-based) further supported the OPLS-DA results and prioritized desferrioxamine B (3), bafilomycin D (10), and bafilomycin A1 (11) as possible antitrypanosomal agents. Our approach in this study can be applied as a primary step in the exploration of bioactive natural products, particularly those from actinomycetes.

Screening for tyrosinase inhibitors from actinomycetes; identification of trichostatin derivatives from Streptomyces sp. CA-129531 and scale up production in bioreactor

In the course of a primary screening of 614 microbial actinomycete extracts for the discovery of tyrosinase inhibitors, the EtOAc extract of the fermentation broth of the strain Streptomyces sp. CA-129531 isolated from a Martinique sample, exhibited in cell free and cell-based assays the most promising activity (IC₅₀ value of 63 μg/mL). Scaled-up production in a bioreactor led to the isolation of one new trichostatic acid analogue, namely trichostatic acid B (1), along with six known trichostatin derivatives (2-7), four diketopiperazines (8-11), two butyrolactones (12-13) and one hydroxamic acid siderophore (14). Among them, trichostatin A (4) showed a Ki value of 6.1 μM and six times stronger anti-tyrosinase activity (IC₅₀ 2.18 μΜ) than kojic acid (IC₅₀ 14.07 μΜ) used as a positive control. Deoxytrichostatin A (6) displayed also strong inhibitory activity against tyrosinase (IC₅₀ 19.18 μΜ). Trichostatin A production in bioreactor started together with the exponential phase of growth (day 4) and the maximum concentration was reached at day 9 (2.67 ± 0.13 μg/mL). Despite the cytotoxicity of some individual components, the EtOAc extract showed no cytotoxic effect on HepG2, A2058, A549, MCF-7 and MIA PaCa-2 cell lines, (IC₅₀ >2.84 mg/mL) and against BG fibroblasts at the concentrations where the whitening effect was exerted, reassuring its safety and great tyrosinase inhibitory potential.

Isocoumarindole A, a Chlorinated Isocoumarin and Indole Alkaloid Hybrid Metabolite from an Endolichenic Fungus Aspergillus sp

Isocoumarindole A (1), a novel polyketide synthetase-nonribosomal peptide synthetase (PKS-NRPS) hybrid metabolite, was isolated from the endolichenic fungus Aspergillus sp. CPCC 400810. The structure of isocoumarindole A (1) was featured by an unprecedented skeleton containing chlorinated isocoumarin and indole diketopiperazine alkaloid moieties linked by a carbon-carbon bond, which was determined by a combination of spectroscopic analyses, Marfey's method, and calculations of NMR chemical shifts, ECD spectra, and optical rotation values. Isocoumarindole A showed significant cytotoxicity and mild antifungal activities.

Ahmpatinin iBu, a new HIV-1 protease inhibitor, from Streptomyces sp. CPCC 202950

Ahmpatinin ⁱBu (1) and statinin ⁱBu (2), two new linear peptides, a novel pyrrolidine derivative, (−)-(S)-2-[3-(6-methylheptanamido)-2-oxopyrrolidin-1-yl] acetic acid (3), and three known pepstatin derivatives (4–6) along with their corresponding methanolysis artifacts (7–9) were isolated from Streptomyces sp. CPCC 202950. Their structures were elucidated on the basis of extensive spectroscopic data using Marfey's analysis, chiral-phase HPLC, and ECD and OR calculation to determine the absolute configurations. Compound 1 contains an unusual amino acid, 4-amino-3-hydroxy-5-(4-methoxyphenyl)pentanoic acid (Ahmppa), and 3 is the first natural product with a 2-(3-amino-2-oxopyrrolidin-1-yl)acetic acid system. Compounds 1, 2, and 4–9 are HIV-1 protease inhibitors. In particular, ahmpatinin ⁱBu (1) exhibits significant inhibitory activity against HIV-1 protease with an IC₅₀ value of 1.79 nM. A preliminary structure–activity relationship is discussed.

Ahmpatinin ⁱBu and statinin ⁱBu, two new linear peptides, were isolated from Streptomyces sp. CPCC 202950. Ahmpatinin ⁱBu exhibited significant inhibitory activity against HIV-1 protease with an IC₅₀ value of 1.79 nM.