title: New diketopiperazine derivatives from a deep-sea-derived Nocardiopsis alba SCSIO 03039.
abstract: The strain SCSIO 03039 was isolated from a sediment sample in the Indian Ocean and was characterized as a Nocardiopsis alba species on the basis of its 16S rRNA gene sequence. Seven diketopiperazines (DKPs), including two new DKPs nocazines D (2a) and E (2b), and five known DKPs (1, 3-6), were isolated from N. alba SCSIO 03039, along with two known compounds 2-methoxy-1,4-naphthoquinone (7) and 1-hydroxy-4-methoxy-2-naphthoic acid (8). Their structures were elucidated by mass and NMR spectroscopic analyses. The structure of methoxyneihumicin (1), previously proposed in a conference poster lacking publicly available experimental data, was validated for the first time by detailed NMR analyses and X-ray diffraction study. The two enantiomers nocazines D (2a) and E (2b) were isolated as a mixture. Compounds 3 and 4 were only known as synthetic compounds before. Methoxyneihumicin (1) exhibited in vitro cytotoxicities against MCF-7 and SF-268 with IC₅₀ values of 4.6 and 12.7 μM, respectively, better than those of 6 (22.0 and 20.6 μM). The other compounds showed less pronounced cytotoxities against three tested human cancer cell lines and no compounds displayed antibacterial activities toward four indicator strains.
authors.affiliation: CAS Key Laboratory of Marine Bio-resources Sustainable Utilization, RNAM Center for Marine Microbiology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.
authors.forename: Qingbo
authors.initials: Q
authors.lastname: Zhang
authors.forename: Sumei
authors.initials: S
authors.lastname: Li
authors.forename: Yuchan
authors.initials: Y
authors.lastname: Chen
authors.forename: Xinpeng
authors.initials: X
authors.lastname: Tian
authors.forename: Haibo
authors.initials: H
authors.lastname: Zhang
authors.forename: Guangtao
authors.initials: G
authors.lastname: Zhang
authors.forename: Yiguang
authors.initials: Y
authors.lastname: Zhu
authors.forename: Si
authors.initials: S
authors.lastname: Zhang
authors.forename: Weimin
authors.initials: W
authors.lastname: Zhang
authors.forename: Changsheng
authors.initials: C
authors.lastname: Zhang
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D045744:Cell Line, Tumor; D054659:Diketopiperazines / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D004354:Drug Screening Assays, Antitumor; D005285:Fermentation; D006094:Gram-Positive Bacteria / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D020128:Inhibitory Concentration 50; D009682:Magnetic Resonance Spectroscopy; D008386:Marine Biology; D008958:Models, Molecular; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D014961:X-Ray Diffraction
chemical_list: D000900:Anti-Bacterial Agents; D054659:Diketopiperazines; D012336:RNA, Ribosomal, 16S