1. Relative and absolute configuration of antitumor agent SW-163D
Mino Nakaya, Hiroki Oguri, Kosaku Takahashi, Eri Fukushi, Kenji Watanabe, Hideaki Oikawa Biosci Biotechnol Biochem. 2007 Dec;71(12):2969-76. doi: 10.1271/bbb.70371. Epub 2007 Dec 7.
Our interest on engineering non-ribosomal synthetase responsible for SW-163 biosynthesis prompted us to determine the relative and absolute configuration of antitumor cyclic depsipeptide SW-163s. We first isolated and identified SW-163 homologs D, F and G as known compounds UK-63598, UK-65662 and UK-63052, respectively. Both enantiomers of the unusual constitutive amino acid, N-methylnorcoromic acid, were synthesized in chiral forms starting from (R)- and (S)-1,2-propanediol. The hydrolyzate of SW-163D, a major constituent of this family, was converted with Marfey's reagent, 1-fluoro-2,4-dinitrophenyl-5-L-alanine-amide (L-FDAA), and the resulting mixture of amino acid derivatives was subjected to an LC/MS analysis. Compared with authentic samples, the analytical data unambiguously show that SW-163D consisted of L-Ala, D-Ser and (1S, 2S)-N-methylnorcoronamic acid. The remaining stereochemistry of the N-methylcysteine moieties was determined from NOE data.
2. Identification of diverse microbial metabolites as potent inhibitors of HIV-1 Tat transactivation
Hiranthi Jayasuriya, Deborah L Zink, Jon D Polishook, Gerald F Bills, Anne W Dombrowski, Olga Genilloud, Fernando F Pelaez, Lucia Herranz, Donette Quamina, Russell B Lingham, Renee Danzeizen, Pia L Graham, Joanne E Tomassini, Sheo B Singh Chem Biodivers. 2005 Jan;2(1):112-22. doi: 10.1002/cbdv.200490162.
HIV-1 Tat is one of six regulatory proteins that are required for viral replication and is an attractive target for the development of new anti-HIV agents. Screening of microbial extracts using a whole cell Tat-dependent transactivation assay, which guided the separation of the active broths, led to the identification of five structurally diverse classes (M(R) range 232-1126) of natural products. These include i) three sesquiterpenoids, namely, sporogen-AO1, petasol, and 6-dehydropetasol, ii) two resorcylic 14-membered lactones, namely monorden and monocillin IV, iii) a ten-membered lactone, iv) a quinoline and quinoxiline bicyclic octadepsipeptides, namely echinomycin and UK-63598, and v) a cyclic heptapeptide, ternatin. These compounds displayed varying degrees of potencies with IC50 values ranging from 0.0002 to 100 microM. The most active compound was the quinoxiline bicyclic octadepsipeptides, UK-63598, which inhibited Tat-dependent transactivation with an IC50 value of 0.2 nM and exhibited a 100-fold therapeutic window with respect to toxicity. In a single-cycle antiviral assay, UK-6358 inhibited viral replication with an IC50 value of 0.5 nM; however, it appeared to be equally toxic at that concentration. Monocillin IV was significantly less active (Tat transactivation inhibitory IC50 of 5 microM) but was not toxic at 100 microM in an equivalent cytotoxicity assay. The compound exhibited antiviral activity with an IC50 value of 6.2 microM in the single-cycle antiviral assay and a sixfold therapeutic window. Details of the isolation, fermentation, and biological activities of these structurally diverse natural products are described.
3. RK-1355A and B, novel quinomycin derivatives isolated from a microbial metabolites fraction library based on NPPlot screening
Chung Liang Lim, Toshihiko Nogawa, Masakazu Uramoto, Akiko Okano, Yayoi Hongo, Takemichi Nakamura, Hiroyuki Koshino, Shunji Takahashi, Darah Ibrahim, Hiroyuki Osada J Antibiot (Tokyo). 2014 Apr;67(4):323-9. doi: 10.1038/ja.2013.144. Epub 2014 Feb 5.
Two novel quinomycin derivatives, RK-1355A (1) and B (2), and one known quinomycin derivative, UK-63,598 (3), were isolated from a microbial metabolites fraction library of Streptomyces sp. RK88-1355 based on Natural Products Plot screening. The structural elucidation of 1 and 2 was established through two-dimensional NMR and mass spectrometric measurements. They belong to a class of quinomycin antibiotics family having 3-hydroxyquinaldic acid and a sulfoxide moiety. They are the first examples for natural products as a quinoline type quinomycin having a sulfoxide on the intramolecular cross-linkage. They showed potent antiproliferative activities against various cancer cell lines and they were also found to exhibit moderate antibacterial activity.