Mulgravanols A and B, rare oxidized xanthenes and a new phloroglucinol isolated from the Australian rainforest plant Waterhousea mulgraveana (Myrtaceae)

Phytochemical investigation of the Australian rainforest plant leaves Waterhousia mulgraveana, yielded two rare oxidized xanthenes, mulgravanols A (1) and B (2) along with a new phloroglucinol, mulgravanol C (3). Mulgravanol A (1) is the first reported example of a complex xanthene flanked by a methine bridged phloroglucinol unit. All the compounds displayed moderate inhibitory effects on nitric oxide production and TNF-α release in RAW 264.7 macrophages (IC₅₀) 42–55 μM. The structures of the new compounds were assigned based on a detailed spectroscopic interpretation.