NMR Spectra of the Camelliagenin A and A1-Barrigenol from the seed of Barringtonia asiatica

Barringtonia asiatica also known as “fish killer tree” is one of the mangrove plants that grows in tropical Asia and Pacific, including Northern Australia, the seeds of which are used as fish poison [1,2]. In previous paper, we reported that the triterpene moieties of saponins from the seeds of B. asiatica were camelliagenin A (1) [1] and A1-barrigenol (2). [2] Both camelliagenin A (1), C30H50O4 and A1-barrigenol (2), C30H50O5 have been isolated from B. asiatica, [3] Pittosporum undulatum, [4,5] and Harpullia cupaniodes[6,7]. Beside that, 1 has also been isolated from Maesa chisia, [8] while from Camellia species. The structures of 1 and 2 had earlier been deduced by H NMR spectroscopy to be 3,16,22,28-tetrahydroxyoelan-12-ene [6,9] and 3,15, 16,22,28-pentahydroxyolean-12-ene, [10] respectively. However, there has not been an extensive high-field NMR study on these compounds. In this paper, we wish to report complete assignments of the signals of the H and C NMR spectra 1 and 2, as well as their 2D data of homoand heteronuclear correlations including DQCOSY, TOCSY, HMQC, HMBC experiments. These assignments allowed us to determine the chemical shifts, positions, and configurations of hydroxyl groups of 1 and 2. The resulting proton and carbon assignments should serve as a basis for structural and spectral assignments of other members of the family of triterpenoidal sapogenins and for derivatives of these compounds.