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Shaaban KA, Saunders MA, Zhang Y, Tran T, Elshahawi SI, Ponomareva LV, Wang X, Zhang J, Copley GC, Sunkara M, Kharel MK, Morris AJ, Hower JC, Tremblay MS, Prendergast MA, Thorson JS. Spoxazomicin D and Oxachelin C, Potent Neuroprotective Carboxamides from the Appalachian Coal Fire-Associated Isolate Streptomyces sp. RM-14-6. JOURNAL OF NATURAL PRODUCTS 2017; 80:2-11. [PMID: 28029795 PMCID: PMC5337259 DOI: 10.1021/acs.jnatprod.6b00948] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The isolation and structure elucidation of six new bacterial metabolites [spoxazomicin D (2), oxachelins B and C (4, 5), and carboxamides 6-8] and 11 previously reported bacterial metabolites (1, 3, 9-12a, and 14-18) from Streptomyces sp. RM-14-6 is reported. Structures were elucidated on the basis of comprehensive 1D and 2D NMR and mass spectrometry data analysis, along with direct comparison to synthetic standards for 2, 11, and 12a,b. Complete 2D NMR assignments for the known metabolites lenoremycin (9) and lenoremycin sodium salt (10) were also provided for the first time. Comparative analysis also provided the basis for structural revision of several previously reported putative aziridine-containing compounds [exemplified by madurastatins A1, B1, C1 (also known as MBJ-0034), and MBJ-0035] as phenol-dihydrooxazoles. Bioactivity analysis [including antibacterial, antifungal, cancer cell line cytotoxicity, unfolded protein response (UPR) modulation, and EtOH damage neuroprotection] revealed 2 and 5 as potent neuroprotectives and lenoremycin (9) and its sodium salt (10) as potent UPR modulators, highlighting new functions for phenol-oxazolines/salicylates and polyether pharmacophores.
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Affiliation(s)
- Khaled A. Shaaban
- Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
- Corresponding Authors: ,
| | - Meredith A. Saunders
- Department of Psychology and Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky 40536, United States
| | - Yinan Zhang
- Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
| | - Tuan Tran
- California Institute for Biomedical Research (Calibr), La Jolla, California 92037, United States
| | - Sherif I. Elshahawi
- Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
| | - Larissa V. Ponomareva
- Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
| | - Xiachang Wang
- Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
| | - Jianjun Zhang
- Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
| | - Gregory C. Copley
- Center for Applied Energy Research, University of Kentucky, Lexington, Kentucky 40511, United States
| | - Manjula Sunkara
- Division of Cardiovascular Medicine, University of Kentucky, Lexington, Kentucky 40536, United States
| | - Madan K. Kharel
- School of Pharmacy, University of Maryland Eastern Shore, Princess Anne, Maryland 21853, United States
| | - Andrew J. Morris
- Division of Cardiovascular Medicine, University of Kentucky, Lexington, Kentucky 40536, United States
| | - James C. Hower
- Center for Applied Energy Research, University of Kentucky, Lexington, Kentucky 40511, United States
| | - Matthew S. Tremblay
- California Institute for Biomedical Research (Calibr), La Jolla, California 92037, United States
| | - Mark A. Prendergast
- Department of Psychology and Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky 40536, United States
| | - Jon S. Thorson
- Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, United States
- Corresponding Authors: ,
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