A new bicyclic azepinoindole alkaloid from the seed cotyledon of <i>Chrysophyllum albidum</i> G. Don-Holl. (Sapotaceae)

Background: Previous investigation in our laboratory revealed the presence of beta carbolines in the seed cotyledon of Chrysophyllum albidum (G. Don), Sapotaceae. Recent developments underscore the utility of repurposing antifungal compounds for anticancer activities. As a continuation of our search for antcancer compounds from Nigerian medicinal plants, the seed cotyledons of Chrysophyllum albidum (G. Don), Sapotaceae was re-investigated for the expression of anti-tumour compounds. Methods: The seed cotyledons of C albidum were air-dried under shade for two weeks after which they were powdered using Hammer mill. The powdered seed cotyledons was extracted with methanol (100 %). The methanol (MeOH) extract was defatted and subjected to solid phase extraction using Strata C-18-E cartridge (Phenomenex, USA) (20 g), to obtain four fractions (CA1-CA4). Further purification of CA1 on silica gel (mesh 200-400) gave pure compounds 1 and 2. Both compounds were subjected to extensive spectroscopic analysis using NMR (1H- and 13C-NMR, 1H–1H COSY, DEPT, HMQC, HMBC) and ESI-MS spectra. Cell viability assay was carried out on the identified compounds using MTT assay. Results: Compounds 1 and 2 were named (provisionally) as albidumine, a new azepinoindole alkaloid, and bamindolinol, a new fused beta carboline, respectively. The compounds did not show any significant effect against human cervical adenocarcinoma (HeLa) cell line in the cytotoxicity assay. Conclusion: Two new beta carbolines were identified from the seed cotyledon of C albidum for the first time.