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. 2017 Apr 19;12(4):e0176088.
doi: 10.1371/journal.pone.0176088. eCollection 2017.

Design, synthesis and structure-activity relationship study of wollamide B; a new potential anti TB agent

Henok Asfaw  1 , Katja Laqua  1 , Anna Maria Walkowska  1 , Fraser Cunningham  2 , Maria Santos Martinez-Martinez  2 , Juan Carlos Cuevas-Zurita  2 , Lluís Ballell-Pages  2 , Peter Imming  1
Affiliations

Design, synthesis and structure-activity relationship study of wollamide B; a new potential anti TB agent

Henok Asfaw et al. PLoS One. .

Abstract

Wollamide B is a cationic antimycobacterial cyclohexapeptide that exhibits activity against Mycobacterium bovis (M. bovis) (IC50 of 3.1 μM). Aiming to define its structural activity relationship (SAR), optimizing potency and pharmacokinetic properties, libraries of analogues were synthesized following a standard Fmoc-based solid phase peptide synthesis approach. The antimycobacterial activities of wollamide B and all the synthesized analogues were tested against Mycobacterium tuberculosis (Mtb) H37Rv. Parallely, in vitro drug metabolism and pharmacokinetic (ADME) profiling was done for the synthesized compounds to evaluate their drug likeness. Among the 25 synthesized wollamides five of them showed potent activities with MICs ≤ 3.1 μM and found to be nontoxic against human HepG2 cells up to 100 μM. The results of the in vitro ADME profiling revealed the remarkable plasma stability and very good aqueous solubility of the class in general while the metabolic stability was found to be moderate to low. Of particular note, compounds 7c (MIC = 1.1 μM) and 13c (0.6 μM) that exhibited good balance of antimycobacterial activity vs. optimal pharmacokinetic properties could be used as a new lead for further development.

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Conflict of interest statement

Competing Interests: The commercial affiliation - to GlaxoSmithKline, 28760 Tres Cantos, Madrid, Spain - of some of the authors does not alter our adherence to PLOS ONE policies on sharing data and materials. The authors affiliated commercially contributed to the paper as stated in the "author contributions" section.

Figures

Fig 1
Fig 1. Structure of wollamide B.
Fig 2
Fig 2. Scheme that shows the synthetic approach to wollamide B.
Fig 3
Fig 3. A synthetic scheme that shows the approach used to synthesize the linear precursor of wollamide B using SPPS.
Reagents and conditions: a) Fmoc-L-Leu-OH, DIPEA, DCM, 2 h; b) 20% piperidine/DMF, 10 min (2X); c) Fmoc-L-Trp (Boc)-OH, HATU, DIPEA, NMP, 1 h; d) Fmoc-D-Orn (Boc)-OH, HATU, DIPEA, NMP, 1 h; e) Fmoc-L-Asn (Trt)-OH, HATU, DIPEA, NMP, 1 h; f) Fmoc-L-Val-OH, HATU, DIPEA, NMP, 1 h; g) Fmoc-D-Leu-OH, HATU, DIPEA, NMP, 1 h; h) 20% HFIP/DC, 1 h.
Fig 4
Fig 4. Structures of the synthesized wollamide B analogues.
See this image and copyright information in PMC

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MeSH terms

Grants and funding

This work was supported by the Tres Cantos Open Lab Foundation, Milton Keynes, Buckinghamshire, MK9 1BP, United Kingdom. Award Number TC 152 to PI and the Deutscher Akademischer Austauschdienst (DAAD), 53175 Bonn, Germany, Personal Reference Number: 91540938 to HA. The funders provided support in the form of salaries for authors KL and HA, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.