Anti-Inflammatory Chemical Profiling of the Australian Rainforest Tree Alphitonia petriei (Rhamnaceae)

Chronic inflammation is an important pathological condition in many human diseases, and due to the side effects of the currently used non-steroidal anti-inflammatory drugs, discovery of novel anti-inflammatory drugs is of general interest. Anti-inflammatory activity guided compound isolation from the plant Alphitonia petriei led to the isolation of the known plant sterols emmolic acid (1), alphitolic acid (2), trans- and cis-coumaroyl esters of alphitolic acid (3 and 4) and betulinic acid (5). A detailed spectroscopic analysis led to the structure elucidation of the alphitolic acid derivatives (1–5), and the semi-synthetic emmolic acid acetate (6). When tested in LPS (Lipopolysaccharides) + IFN-γ (Interferon gamma) activated RAW 264.7 macrophages, all compounds except (1) exhibited potent anti-inflammatory activity (IC50 values as low as 1.7 μM) in terms of downregulation of NO and TNF-α production, but also demonstrated some considerable cytotoxicity.