Structural characterization of two new stereoisomeric furofuran lignans using modern spectroscopic methods and quantum chemical calculation

C. arborea Roxb stems yielded two newly isolated compounds callicarbonans A and B (1–2), optically active with specific rotations of [α] 25.0 D-14.0, and [α] 25.0 D+4.8, along with thirteen (3–15) reported compounds. Their structures were characterized by contemporary spectroscopic techniques, encompassing 1D (1H, 13C, DPET) and 2D (HSQC, HMBC, 1H–1H COSY, and ROESY) NMR, HR-ESI-MS, UV, IR, ECD. Their absolute configurations (AC) were confirmed through quantum chemical computations, and Diastereomeric Parameter 4 Plus (DP4+) analysis was utilized to identify their relative configurations. The cytotoxicity of all compounds was assessed against cancer cells. Specifically, diterpenoid 13 showed cytotoxic effects against MDA-MB-231, SW620, and HepG2 cancer cells with IC50 values of 20.34±0.89, 20.17±0.95, and 22.72±0.96 µM, respectively.