New isofuranonaphthoquinones and isoindolequinones from Streptomyces sp. CB01883

Hericioic Acids A–G and Hericiofuranoic Acid; Neurotrophic Agents from Cultures of the European Mushroom Hericium flagellum

“…The 1 H– 1 H COSY and HSQC spectra of 8 (Table ) revealed three main spin systems as follows, namely, between two downfield aromatic protons at δ H 8.14 (H-1) and δ H 8.28 (H-6); between two aliphatic methylene groups at δ H 2.65 (dd, J = 6.8, 8.6 Hz, H 2 -1′) and at δ H 2.20 (t, J = 7.7 Hz, H 2 -2′); from an olefinic proton at δ H 5.27 (dd, J = 1.3, 7.1 Hz, H-4′) showing vicinal and allylic coupling to a methylene group at δ H 2.97 (d, J = 7.1 Hz, H 2 -5′) and a methyl peak at δ H 1.72 (d, J = 1.3 Hz, H 3 -7′), respectively. The HMBC spectrum of 8 showed key correlations (Figure ) from the two downfield protons at H-1 and H-6 to two carbonyl carbon atoms at δ C 182.8 (C-2) and δ C 177.7 (C-5) indicating the chemical structure of 8 (Figure ) to be containing an isobenzofuran-2,5-quinone moiety similar to the previously reported metabolites along with having an aliphatic side chain ending with a free carboxylic acid as in hericioic acids E–G ( 5 – 7 ). Further proofs for the position of the side chain were provided by HMBC spectrum that revealed key correlations from H 2 -1′ to C-2, C-3 (δ C 127.0) and C-4 (δ C 159.8) indicating its presence as a side chain at C-3.…”

“…Compound 8 was obtained as an off-white amorphous solid with a characteristic UV spectrum revealing absorption peaks (λ max ) at 201, 249 and 348 nm. The molecular formula of 8 was determined to be C 15 (Figure 1) to be containing an isobenzofuran-2,5-quinone moiety similar to the previously reported metabolites 24 along with having an aliphatic side chain ending with a free carboxylic acid as in hericioic acids E−G (5−7). Further proofs for the position of the side chain were provided by HMBC spectrum that revealed key correlations from H 2 -1′ to C-2, C-3 (δ C 127.0) and C-4 (δ C 159.8) indicating its presence as a side chain at C-3.…”

Herbicidins from Streptomyces sp. CB01388 Showing Anti-Cryptosporidium Activity

“…Natural products have an indisputable track record in drug discovery and remain a rich source of new drug leads and small-molecule probes . Biased on natural products of Actinomycetales origin, the Natural Products Library Initiative at The Scripps Research Institute (TSRI) aims to construct a library that occupies unique chemical space and complements the small-molecule collection at TSRI. − Also, natural products of bacterial origin are advantageous since the resupply of enough materials for follow-up studies will be guaranteed by large-scale fermentation once the interesting entities are identified. Three types of collections, including (i) crude extracts, (ii) medium-pressure liquid chromatography (MPLC)-generated fractions, and (iii) structurally assigned pure natural products, constitute the current natural products library (NPL) at TSRI.…”

Enceleamycins A–C, Furo-Naphthoquinones from Amycolatopsis sp. MCC0218: Isolation, Structure Elucidation, and Antimicrobial Activity

“…The presence of a furo-naphthoquinone substructure in several bioactive natural products isolated from terrestrial and marine organisms, − along with the potential biological activity of the secondary metabolites obtained from the Amycolatopsis genus, prompted us to screen the bioactive potentials of compounds 1 – 4 .…”