Retraction Note to: Rhodozepinone, a new antitrypanosomal azepino-diindole alkaloid from the marine sponge-derived bacterium Rhodococcus sp. UA13

New Cytotoxic Cyclic Peptide from the Marine Sponge-Associated Nocardiopsis sp. UR67

“…White amorphous powder; (1 mg; R t = 17.1 min) 1 H NMR (CD3OD, 600 MHz): δ 7.01 (1H, s, H-3), 8.26 (1H, ddd, J = 8.5, 1.4, 0.6 Hz, H-5), 7.47 (1H, td, J = 7.7, 1.4 Hz, H-6), 7.78 (1H, td, J = 7.7, 1.0 Hz, H-7), 7.88 (1H, ddd, J = 8.5, 1.0, 0.6 Hz, H-8); 13 C NMR (CD3OD, 150 MHz): δ 143.3 (C, C-2), 110.3 (CH, C-3), 181.1 (C, C-4), 126.0 (CH, C-5), 126.0 (CH, C-6), 134.3 (CH, C-7), 120.4 (CH, C-8), 141.3 (C, C-9), 126.5 (C, C-10), 164.8 (C, C-11). The physical and spectral data were in accordance with those reported in the literature [ 43 ]. This is the first isolation of this compound from microbial origins.…”

“…Additionally, three known compounds—tryptophan ( 2 ), kynurenic acid ( 3 ), and 4-amino-3-methoxy benzoic acid ( 4 ) ( Figure 1 )—were also separated and could be identified by comparing their 1 D and 2 D NMR spectral analysis ( Figures S12–S26 ) with the published data [ 42 , 43 ]. It is worth mentioning that kynurenic acid ( 3 ) was isolated for the first time from microbial origins.…”

Metabolomic profiling and biological investigation of the marine sponge‐derived bacterium Rhodococcus sp. UA13

“…To date, a growing number of natural products have been identified from marine actinomycetes, of which those associated with sponges are markedly rich in ubiquitous bioactive metabolites, particularly species of Streptomyces , Nocardia , Salinispora , Micromonospora , and Rhodococcus . These microorganisms have also contributed to the discovery of a number of clinically important anti‐infective agents .…”

“…Eight different media were used for isolation of the actinobacteria, including M1, ISP medium 2, Oligotrophic medium (OLIGO), M1 plus, Actinomycete Isolation Agar, Marine Agar, Glycerol Asparagine Agar, and R2A Agar. All media were supplemented with 0.2 μm pore size filtered nalidixic acid (25 μg/mL), nystatin (25 μg/mL), and cycloheximide (100 μg/mL) to assist the isolation of slow‐growing actinobacteria, where cycloheximide and nystatin prevent fungal growth and nalidixic acid inhibits many of the fast‐growing Gram‐negative bacteria . After incubating the inoculated plates at 30°C for six to eight weeks, the distinct colony morphotypes were picked and re‐streaked until visually free from contaminants.…”

“…Actinomycetes are a diverse group of aerobic Gram‐positive microorganisms and represent an unlimited source of novel bioactive compounds . A large body of evidence has stated the capacity of these bacteria to biosynthesise potent antibiotic, antimicrobial, antioxidant, cytotoxic, and antitumour metabolites, including peptides, alkaloids, polyketides, terpenoids, and fatty acids . Different microbial secondary metabolites identified from actinomycetes have largely contributed to the development of a wide array of therapeutic agents .…”