Camaldulensals A-C, the First Meroterpenoids Possessing Two Spatially Separated Formyl Phloroglucinols Conjugated to a Terpene Core from the Leaves of Eucalyptus camaldulensis Dehnh

J Nat Prod. 2023 Aug 25;86(8):1994-2005. doi: 10.1021/acs.jnatprod.3c00443. Epub 2023 Aug 14.

Abstract

Three new bis-formyl phloroglucinol-meroterpenoids (1-3), three new euglobal type formyl phloroglucinol-meroterpenoids (4-6), and one new dimeric formyl phloroglucinol (7) were isolated from the leaves of Eucalyptus camaldulensis. Camaldulensal A (1) is the first bis-isovaleryl-formyl-phloroglucinol-sesquiterpenoid. It features a novel 6/6/10/3/6/6 fused ring system and contains six stereogenic centers. Camaldulensals B (2) and C (3) are the first bis-isovaleryl-formyl-phloroglucinols, each conjugated to a monoterpene. Formyl phloroglucinol compounds (FPCs) containing two spatially separated formyl phloroglucinols conjugated to a terpene core such as 1-3 have not been reported previously. The structures of these compounds were elucidated by spectroscopic methods and computational analysis. Camaldulensals B (2) and C (3) exhibited significant antibacterial activity against methicillin-susceptible and methicillin-resistant Staphylococcus aureus. Structure activity relationships are discussed in relation to previously reported antibacterial activities of other molecules from the FPC structure class.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Eucalyptus* / chemistry
  • Methicillin-Resistant Staphylococcus aureus*
  • Molecular Structure
  • Phloroglucinol / chemistry
  • Phloroglucinol / pharmacology
  • Plant Leaves / chemistry
  • Terpenes / chemistry

Substances

  • Terpenes
  • Phloroglucinol