A new seco-norlignan and a rare ring B aromatic 1(10→6)abeo-ergostane-type steroid from Tarlmounia elliptica

The first phytochemical investigation of Tarlmounia elliptica (the sole species of its genus) led to the isolation of eight compounds from its aerial parts, including a previously undescribed seco-norlignan, tarlelliptin A (1), and a rare ring B aromatic 1(10→6)abeo-ergostane-type steroid, tarlelliptin B (2). Their structures were fully characterised by comprehensive spectroscopic analysis (HRESIMS, 1D/2D NMR) and corroborated by quantum chemical calculations (including ECD and NMR computations). Biological evaluation for cytotoxic, anti-inflammatory, and antibacterial activities indicated that only the known compound 7-oxo-β-sitosterol (8) exhibited weak antibacterial activity (MIC = 64.0 μg/mL) against methicillin-resistant Staphylococcus aureus (MRSA) strain 252.