Studies on julimycins—VII

Isolation and anticancer activity evaluation of rare Bisaryl anthraquinone antibiotics from novel Streptomyces sp. strain of NW Himalayan region

Biosynthesis of bisaryl preanthraquinone antibiotics by various microorganisms differs in monomeric subunits as well as their dimerization positions leading to different configurations. The present study relates to the production of rare bisaryl anthraquinone antibiotics by a new Streptomyces strain isolated from Shivalik region of NW Himalayas. In vitro anticancer and anti-migratory effects of Setomimycin (9,9' bisanthraquinone antibiotic) was seen with a significant reduction in the expression of both MEK as well as ERK pathways in a dose dependent manner at 6.5 μM & 8 μM concentration in HCT-116 and 5.5 μM & 7 μM concentration in MCF-7 cells. In vivo studies in aggressive orthotopic mouse mammary carcinoma model (4T1) demonstrated about 76% reduction of primary tumor weight and 90.5% reduction in the tumor volume within two weeks. In vivo pharmacokinetics study of setomimycin revealed that it can be rapidly absorbed with an adequate plasma exposure and half-life which can be linked to its in vivo efficacy.

Dimeric Tetrahydroanthracene Regioisomers and Their Monomeric Precursor Produced by Streptomyces fumigatiscleroticus HDN10255

Four new tetrahydroanthracene derivatives (1, 3-5) and a known antibiotic, A-39183A (2), were discovered from the marine-sponge-derived actinomycete Streptomyces fumigatiscleroticus HDN10255. Their structures including absolute configurations were elucidated based upon MS and NMR spectroscopic data, ECD calculations, and biogenetic considerations. Compounds 2 and 4 showed considerable cytotoxicity with the best IC₅₀ value of 1.8 μM against HeLa cells.

Julichrome derivatives and gliotoxin from a soil derived Streptomyces sp

Six julichrome derivatives including a new monomeric julichrome named as julichrome Q₁₀ (1), and previous reported julichrome Q₆ (2), julichrome Q_6.6 (4), julichrome Q_3.5 (5), julichrome Q_5.6 (6), julichrome Q_2.3 (7), along with a diketopiperazine gliotoxin (3) were isolated from a soil derived strain Streptomyces sp. The structures of these compounds were identified by HR-ESI-MS, UV, IR and NMR methods. The isolated compounds were tested for their in vitro cytotoxicity against human hepatocarcinoma HepG-2 and SMMC-7721 cell lines, human breast cancer MCF-7 and MDA-MB-231 cell lines, and human normal heptical LO2 cell line. Gliotoxin (3) showed the most cytotoxic activity against the tested tumor cell lines, with IC₅₀ values ranging from 0.11 to 1.45 μM. Julichrome Q_6.6 (4) displayed selective cytotoxic activity against SMMC-7721, MCF-7 and MDA-MB-231 cell lines.

Effective Production of Aromatic Polyketides in Streptomyces using a Combined-Culture Method

Combined-culture is a fermentation method which efficiently induces secondary metabolite production in Streptomyces by co-culturing them with mycolic acid-containing bacteria. As a result of combined-culture screening of our terrestrial Streptomyces collection using UV-HPLC, one of the tested strains, Streptomyces sp. TAKO-2, produced two known aromatic polyketides, julichrome Q6 (1) and julichrome Q8·8 (2), when co-cultured with the mycolic acid-containing bacterium Tsukamurella pulmonis TP-B0596. The structures of 1 and 2 were confirmed by spectroscopic analysis and literature data.

Julichrome Q6 glucuronide, a monomeric subunit of the julimycin B-I complex from a terrestrial Streptomyces sp

The terrestrial Streptomyces sp. isolate GW6225 afforded julichrome Q 6 glucuronide ( 9), the first monomeric member of the julimycin-B complex, and additionally the julichromes Q 1.2 ( 7a), Q 1.5 ( 7b), and Q 3.5 ( 8), which were fully characterized by 2D NMR spectra. Additional new microbial compounds were 4-acetylchrysophanol ( 6a) and N-phenyl-beta-naphthylamine ( 10). The isomeric N-phenyl-alpha-naphthylamine ( 11) was found in the marine Streptomyces sp. B8335 and was also characterized. The high antibiotic activity of Streptomyces sp. GW6225 extracts was probably due to the thiazolyl cyclopeptide nosiheptide.