We discovered new structural diversity to a prevalent, yet medicinally underappreciated, cyanobacterial protease inhibitor scaffold and undertook comprehensive protease profiling to reveal potent and selective elastase inhibition. Structure-activity relationship (SAR) studies and X-ray cocrystal structure analysis allowed a detailed assessment of critical and tunable structural elements. To realize the therapeutic potential of these cyclodepsipeptides, we probed the cellular effects of a novel and representative family member, symplostatin 5 (1), which attenuated the downstream cellular effects of elastase in an epithelial lung airway model system, alleviating clinical hallmarks of chronic pulmonary diseases such as cell death, cell detachment, and inflammation.
View Article and Find Full Text PDFWe compared the full-length capsid maturational protease (pPR, pUL80a) of human cytomegalovirus with its proteolytic domain (assemblin) for the ability to cleave two biological substrates, and we found that pPR is more efficient with both. Affinity-purified, refolded enzymes and substrates were combined under defined reaction conditions, and cleavage was monitored and quantified following staining of the resulting electrophoretically separated fragments. The enzymes were stabilized against self-cleavage by a single point mutation in each cleavage site (ICRMT-pPR and IC-assemblin).
View Article and Find Full Text PDFInvestigation of an extract from the marine cyanobacterium Lyngbya semiplena, collected in Tumon Bay, Guam, led to the identification of three new cyclodepsipeptides, lyngbyastatins 8-10 (1-3). The structures of 1-3 were determined by NMR, MS, ESIMS fragmentation and chemical degradation. Compounds 1-3 are closely related to lyngbyastatins 4-7.
View Article and Find Full Text PDFCombinatorial biosynthesis meets combinatorial pharmacology, cyanobacterial style: A new antimitotic natural product with features of both dolastatins 10 and 15 was isolated from the same Floridian Symploca sp. sample that produced the histone deacetylase inhibitor largazole. Both agents in combination are more effective in inhibiting cancer cell proliferation than either agent alone.
View Article and Find Full Text PDFTwo cyclodepsipeptides named kempopeptins A (1) and B (2) were isolated from a collection of a Floridian marine cyanobacterium, Lyngbya sp., that had previously afforded the structurally related potent elastase inhibitors lyngbyastatin 7 and somamide B. The structures of 1 and 2 were elucidated mainly by 1D and 2D NMR spectroscopy, and the absolute configuration was established by chiral HPLC and Marfey's analysis of the degradation products.
View Article and Find Full Text PDFFull details of the concise and convergent synthesis (eight steps, 19% overall yield), its extension to the preparation of a series of key analogues, and the molecular target and pharmacophore of largazole are described. Central to the synthesis of largazole is a macrocyclization reaction for formation of the strained 16-membered depsipeptide core followed by an olefin cross-metathesis reaction for installation of the thioester. The biological evaluation of largazole and its key analogues, including an acetyl analogue, a thiol analogue, and a hydroxyl analogue, suggested that histone deacetylases (HDACs) are molecular targets of largazole and largazole is a class I HDAC inhibitor.
View Article and Find Full Text PDFThree new analogues of dolastatin 13, termed lyngbyastatins 5-7 ( 1- 3), were isolated from two different collections of marine cyanobacteria, Lyngbya spp., from South Florida. Their planar structures were deduced by a combination of NMR techniques, and the absolute configurations were established by modified Marfey's analysis of the acid hydrolyzates.
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