NaBr-Induced Production of Brominated Azaphilones and Related Tricyclic Polyketides by the Marine-Derived Fungus Penicillium janthinellum HK1-6

J Nat Prod. 2019 Feb 22;82(2):368-374. doi: 10.1021/acs.jnatprod.8b00930. Epub 2019 Jan 29.

Abstract

Cultivation of the mangrove rhizosphere soil-derived fungus Penicillium janthinellum HK1-6 with NaBr led to the isolation of two new brominated azaphilones, penicilones G and H (5, 6), two new tricyclic polyketides, penijanthinones A and B (7, 8), and two known azaphilones, penicilones A and B (1, 2). The planar structures and relative configurations of the new compounds were elucidated using comprehensive spectroscopic methods including 1D and 2D NOE spectra. Their absolute configurations were determined by chemical conversions, TDDFT ECD calculations, and comparisons of their ECD spectra. Interestingly, the NaBr-induced brominated azaphilones (5, 6) had the opposite configuration at C-7 compared to the chloro analogues (3, 4) produced by this fungus cultivated with sea salt. Ester hydrolysis of penicilone B (2) afforded the carboxylic acid side chain 2,4-dimethyldec-2-enoic acid (9), with a 4 S configuration assigned by its specific rotation. Penicilone H (6) showed antibacterial activity with MIC values ranging from 3.13 to 12.5 μg/mL.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzopyrans / chemistry
  • Benzopyrans / metabolism*
  • Benzopyrans / pharmacology
  • Bromides / pharmacology
  • Cell Line, Tumor
  • Halogenation
  • Humans
  • Magnetic Resonance Spectroscopy
  • Penicillium / metabolism*
  • Polyketides / chemistry
  • Polyketides / metabolism*
  • Polyketides / pharmacology
  • Sodium Compounds / pharmacology
  • Soil Microbiology*

Substances

  • Benzopyrans
  • Bromides
  • Polyketides
  • Sodium Compounds
  • penicilone B
  • sodium bromide