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

Three new bis-formyl phloroglucinol-meroterpenoids (-), three new euglobal type formyl phloroglucinol-meroterpenoids (-), and one new dimeric formyl phloroglucinol () were isolated from the leaves of . Camaldulensal A () 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 () and C () 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 - have not been reported previously. The structures of these compounds were elucidated by spectroscopic methods and computational analysis. Camaldulensals B () and C () exhibited significant antibacterial activity against methicillin-susceptible and methicillin-resistant . Structure activity relationships are discussed in relation to previously reported antibacterial activities of other molecules from the FPC structure class.