Sesbagrandiflorain A and B: isolation of two new 2-arylbenzofurans from the stem bark of Sesbania grandiflora

Native to tropical Asia, Sesbania grandiflora (L.), Pers is a member of the Fabaceae family of flowering plants. All parts of S. grandiflora are used in traditional medicine and phytochemical investigations have been conducted on extracts of the leaves, seeds and roots of S. grandiflora to provide scientific validation of its properties. However, to date, no study has determined the phytochemical constituents of S. grandiflora stem bark. The stem bark powdered of S. grandiflora was extracted exhaustively with n-hexane, EtOAc and 90% aqueous MeOH sequentially. In this study, we successfully isolated two new 2-arylbenzofurans, sesbagrandiflorain A and B, from the EtOAc stem bark of S. grandiflora. The structure elucidation of these compounds was determined by using one- and two-dimensional nuclear magnetic resonance, ultraviolet and infrared spectroscopy and electrospray ionisation time-of-flight mass spectrometry. The finding expands the understanding of the natural constituents of the Fabaceae and, in particular, the Papilionoideae genera.