Cytotoxic Acylphloroglucinol Derivatives from Callistemon salignus

Callisalignenes G–I (1–3), three new meroterpenoids of β-triketone and monoterpene, along with two known analogues (4 and 5), were isolated from Callistemon salignus. Their structures and absolute configurations were unambiguously established by a combination of NMR and MS analysis and electronic circular dichroism (ECD) evidence. Callisalignenes H (2) and I (3) have a rare sec-butyl moiety at C-7. Meroterpenoids 1–3 exhibited cytotoxicity...