1. Isolation and Structure Identification of Novel Brominated Diketopiperazines from Nocardia ignorata-A Lichen-Associated Actinobacterium
Jean-Pierre Hurvois, Solenn Ferron, Alba Noël, Nicolas Gouault, Isabelle Rouaud, Sophie Tomasi Molecules . 2017 Feb 28;22(3):371. doi: 10.3390/molecules22030371.
Actinobacteria are well known for their potential in biotechnology and their production of metabolites of interest. Lichens are a promising source of new bacterial strains, especially Actinobacteria, which afford a broad chemical diversity. In this context, the culture medium of the actinobacteriumNocardia ignorata,isolated from the terrestrial lichenCollema auriforme, was studied. The strain was cultivated in a BioFlo 115 bioreactor, and the culture medium was extracted using an XAD7HP resin. Five known diketopiperazines: cyclo (l-Pro-l-OMet) (1), cyclo (l-Pro-l-Tyr) (2), cyclo (d-Pro-l-Tyr) (3), cyclo (l-Pro-l-Val) (4), cyclo (l-Pro-l-Leu) (5), and one auxin derivative: indole-carboxaldehyde (8) were isolated, along with two new brominated diketopiperazines: cyclo (d-Pro-l-Br-Tyr) (6) and cyclo (l-Pro-l-Br-Tyr) (7). Structure elucidation was performed using HRMS and 1D and 2D NMR analysis, and the synthesis of compounds6and7was carried out in order to confirm their structure.
2. 2, 5-diketopiperazines (cyclic dipeptides) in beef: identification, synthesis, and sensory evaluation
L Trinnaman, K Kraut, N C Da Costa, D Merritt, L Reiber, M L Dewis, M Z Chen J Food Sci . 2009 Mar;74(2):C100-5. doi: 10.1111/j.1750-3841.2009.01062.x.
Stewed beef and grilled dry aged beef were analyzed as part of an in-depth analytical program, with the aim of creating new flavors incorporating only compounds identified in the target foods and identifying new synthesis targets. In-house GC-MS analyses of several types of cooked beef have identified over 1000 volatile and semivolatile components; many for the 1st time. Among the semivolatiles detected were ten 2, 5-diketopiperazines (cyclic dipeptides) previously unreported in beef. These cyclic dipeptides are cis-cyclo(L-Ile-L-Pro), cis-cyclo(L-Leu-L-Pro), cis-cyclo(L-Pro-L-Pro), cis-cyclo(L-Pro-L-Val), cis-cyclo(L-Ala-L-Pro), cyclo(Gly-L-Pro), cyclo(Gly-L-Leu), cis-cyclo(L-Met-L-Pro), cis-cyclo(L-Phe-L-Pro), and cis-cyclo(L-Phe-L-Val). All 10 cyclic dipeptides were synthesized and evaluated organoleptically. Among them cis-cyclo(L-Leu-L-Pro), cis-cyclo(L-Met-L-Pro), and cis-cyclo(L-Phe-L-Pro) were found to be of particular organoleptic interest.
3. New cytotoxic furan from the marine sediment-derived fungi Aspergillus niger
Ludwig H Pfenning, Barbara S F Rodrigues, Antonia T A Pimenta, Diego V Wilke, Paula Karina S Uchoa, Katharine G D Florêncio, Natália N Saraiva, Mary Anne S Lima, Raimundo Braz-Filho, Maria da Conceição F de Oliveira, Lucas M Abreu Nat Prod Res . 2017 Nov;31(22):2599-2603. doi: 10.1080/14786419.2017.1283499.
A fungal strain of Aspergillus niger was recovered from sediments collected in the Northeast coast of Brazil (Pecém's offshore port terminal). Cultivation in different growth media yielded a new ester furan derivative, 1, along with malformin A1, malformin C, cyclo (trans-4-hydroxy-L-Pro-L-Leu), cyclo (trans-4-hydroxy-L-Pro-L-Phe), cyclo (L-Pro-L-Leu), cyclo (L-Pro-L-Phe), pseurotin D, pseurotin A, chlovalicin, cyclo (L-Pro-L-Tyr) and cyclo (L-Pro-L-Val). Compound 1 was cytotoxic against HCT-116 cell line, showing IC50= 2.9 μg/mL (CI 95% from 1.8 to 4.7 μg/mL).
