Chlorotonil A

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Chlorotonil A
Chlorotonil A.svg
IUPAC name
3D model (JSmol)
  • InChI=1S/C26H32Cl2O4/c1-14-12-16(3)21-19(13-14)10-11-20-15(2)8-6-7-9-17(4)32-25(31)18(5)23(29)26(27,28)24(30)22(20)21/h6-12,15-22H,13H2,1-5H3/b8-6-,9-7+/t15-,16-,17+,18+,19-,20+,21-,22-/m1/s1
  • C[C@@H]1/C=C\C=C\[C@@H](OC(=O)[C@H](C(=O)C(C(=O)[C@@H]2[C@H]1C=C[C@H]3[C@H]2[C@@H](C=C(C3)C)C)(Cl)Cl)C)C
Molar mass 479.436 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Chlorotonil A is a polyketide natural product produced by the myxobacterium Sorangium cellulosum So ce1525.[2] It displays antimalarial activity in an animal model,[3] and has in vitro antibacterial and antifungal activity.[citation needed] The activity of chlorotonil A has been attributed to the gem-dichloro-1,3-dione moiety, which is a unique functionality in polyketides. In addition to its unique halogenation, the structure of chlorotonil A has also garnered interest due to its similarity to anthracimycin, a polyketide natural product with antibiotic activity against Gram-positive bacteria.


Chlorotonil A is synthesized from a type I modular polyketide synthase (PKS). This gene cluster does not have any acyltransferase (AT) domains, indicating that it is a trans-AT PKS; in these systems, there is a tandem-AT domain that loads the extender subunits onto the acyl carrier protein (ACP) and checks the intermediates, rather than individual AT domains in each module. The gene cluster of chlorotonil A is organized so that the initiator, acetyl-CoA, is loaded onto the tandem-AT domain, then is iteratively elongated with malonyl-CoA units to construct the macrolactone backbone. At modules 3 and 7, a double bond shift occurs in the elongation module to allow for the β,γ-unsaturation and α-methylation. There is a spontaneous, non-enzymatic intramolecular Diels-Alder-like [4+2] cycloaddition at module 8 to furnish the decalin motif.

PKS architecture of chlorotonil A. Squares represent the enzymatic domains: KS, ketosynthase; DH, dehydratase; ACP, acyl carrier protein; KR, keto reductase; MT, methyl transferase; ER, enoyl reductase; TE, thioesterase. Inactive domains are shaded in grey.

Following macrolactonization by the thioesterase domain of module 10, the premature chlorotonil A core is chlorinated twice by CtoA, a flavin-dependent halogenase. The halogenated core is then methylated by the standalone SAM-dependent methyltransferase CtoF to yield chlorotonil A.[4]

Halogenation and methylation of the post-PKS macrolactonized core of chlorotonil A


  1. ^ "Chlorotonil A | Chemical Substance Information | J-GLOBAL".
  2. ^ Gerth, Klaus; Steinmetz, Heinrich; Höfle, Gerhard; Jansen, Rolf (2008). "Chlorotonil A, a Macrolide with a Unique gem-Dichloro-1,3-dione Functionality from Sorangium cellulosum, So ce1525". Angewandte Chemie International Edition. 47 (3): 600–602. doi:10.1002/anie.200703993. hdl:10033/23152. PMID 18058875.
  3. ^ Held, Jana; Gebru, Tamirat; Kalesse, Markus; Jansen, Rolf; Gerth, Klaus; Müller, Rolf; Mordmüller, Benjamin (2014). "Antimalarial Activity of the Myxobacterial Macrolide Chlorotonil A". Antimicrobial Agents and Chemotherapy. 58 (11): 6378–6384. doi:10.1128/AAC.03326-14. PMC 4249382. PMID 25114138.
  4. ^ Jungmann, Katrin; Jansen, Rolf; Gerth, Klaus; Huch, Volker; Krug, Daniel; Fenical, William; Müller, Rolf (2015). "Two of a Kind— The Biosynthetic Pathways of Chlorotonil and Anthracimycin". ACS Chemical Biology. 10 (11): 2480–2490. doi:10.1021/acschembio.5b00523. PMID 26348978.

See also[edit]