Phytohabitols A-C, δ-Lactone-Terminated Polyketides from an Actinomycete of the Genus Phytohabitans

J Nat Prod. 2022 Jul 22;85(7):1697-1703. doi: 10.1021/acs.jnatprod.2c00137. Epub 2022 Jun 16.

Abstract

Phytohabitols A-C (1-3), new terminally δ-lactonized linear polyketides, were isolated from the culture extract of a rare actinomycete of the genus Phytohabitans. The structures of 1-3, substituted with multiple methyl and hydroxy groups on a conjugated and a skipped diene-containing backbone, were elucidated by NMR and MS spectroscopic analyses. The absolute configuration of 1 was determined by chemical derivatization and chiral anisotropic analysis, coupled with ROESY and J-based configuration analysis. In addition, closely similar 1H and 13C NMR data and optical rotations among 1-3 supported the same stereochemistry of these polyketides. The related streptomycetes metabolites lagunapyrones B, C, and D have α-pyrone rings on the linear part in place of the δ-lactone, but their chirality at the C19-C21 stereocenters were opposite from those described here, posing a question on the previous assignment made solely by comparison of the optical rotations of four possible diastereomers. Compounds 1-3 inhibited migration of cancer cells with IC50 values of 15, 11, and 8.3 μM, respectively, at noncytotoxic concentrations. In addition, 1-3 displayed potent antitrypanosomal activity against Trypanosoma cruzi with IC50 values of 12, 6.4, and 18 μM, comparable to a commonly used therapeutic drug, benznidazole (IC50 16 μM).

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Actinobacteria*
  • Lactones / pharmacology
  • Micromonosporaceae*
  • Molecular Structure
  • Polyketides* / chemistry
  • Polyketides* / pharmacology

Substances

  • Lactones
  • Polyketides