Huanglongmycin A-C, Cytotoxic Polyketides Biosynthesized by a Putative Type II Polyketide Synthase From Streptomyces sp. CB09001

Abstract

Three natural products of nonaketide biosynthetic origin, probably biosynthesized from nine molecules of malonyl-CoA, have been isolated. Herein we described the isolation and structure elucidation of huanglongmycin (HLM) A-C and identification of the putative hlm biosynthetic gene cluster from Streptomyces sp. CB09001, isolated from a karstic cave in Xiangxi, China. Albeit previously isolated, HLM A was reported for the first time to exhibit moderate cytotoxicity against A549 lung cancer cell line (IC50 = 13.8 ± 1.5 μM) and weak antibacterial activity against gram-negative clinical isolates. A putative biosynthetic pathway for HLM A, featuring a nonaketide-specific type II polyketide synthase, was proposed. It would be consistent with the isolation of HLM B and C, which are two new natural products and likely shunt metabolites during HLM A biosynthesis.

Julichrome Monomers from Marine Gastropod Mollusk‐Associated Streptomyces and Stereochemical Revision of Julichromes Q3 ⋅ 5 and Q3 ⋅ 3

“…Biodiversity 2020, 17, e2000057 www.cb.wiley.com (2 of 9) e2000057 © 2020 Wiley-VHCA AG, Zurich, Switzerland compounds 1-11. Compounds 3 -11 were identified as julichromes Q 10 (3), [12] Q 3 · 5 (4), [4] Q 3 · 3 (5), [7] Q 6 · 6 (6), [7] Q 6 (7), [4] chrysophanol (8), [13] 4-acetylchrysophanol (9), [4] islandicin (10), [14] and huanglongmycin A (11) [15] on the basis of MS, 1 H-and 13 C-NMR spectroscopic analyses and subsequent comparisons to previously published datasets. Julichrome Q 11 (1) was obtained as yellowish oil.…”

Cave Actinobacteria as Producers of Bioactive Metabolites

“…Huanglongmycin B has weak antibacterial activity against S. aureus and multi-drug-resistant S. aureus (MRSA). Huanglongmycin C showed neither antibacterial nor anticancer activities (Jiang et al, 2018). Undecylprodigiosin was produced by Streptomyces sp.…”

Bioactive α-Pyrone Derivatives from the Endophytic Fungus Diaporthe sp. CB10100 as Inducible Nitric Oxide Synthase Inhibitors

“…To our knowledge, there are few reports of endophytes and their natural products from S. acutum. Since endophytes from medical plants are attractive sources of bioactive natural products, we initiated an endeavor to isolate natural products from endophytes colonized in the stem and root of S. acutum, in our continuous search for new bioactive metabolites of microorganisms from un-or underexplored niches (Jiang et al, 2018;Jiang et al, 2021a). In this study, we report that these accumulating efforts have resulted in the isolation of multiple endophytes from S. acutum, and bioactivity-guided natural product isolation have yielded eight compounds, including a new dibenzo-α-pyrone derivative, ellagic acid B (5) and four new α-pyrone diaporpyrone A-D (9-12), together with three known compounds (6-8).…”