Spirostan and spirosol saponin derivatives from Solanum muricatum Aiton and their cytotoxic activities: insights into bioactive compounds and molecular mechanisms

Solanum muricatum Aiton (Family: Solanaceae), commonly known as pepino, is a traditionally used edible plant with reported medicinal properties, though its bioactive compounds remain largely unexplored. This study aimed to isolate cytotoxic constituents from its aerial parts and investigate their anticancer mechanisms. Two new spirostan-type saponins (1-2), and one known spirosol saponin (3) were identified via spectroscopic analysis. Among them, the plant extract and compound 3 showed significant cytotoxicity against A549 and HepG2 human cancer cell lines. Computational studies suggested PI3K-alpha as a key molecular target, with compound 3 showing strong binding affinity and stable interactions as confirmed by molecular dynamics simulations. These findings highlight the potential of S. muricatum saponins, particularly compound 3, as promising anticancer agents targeting PI3K-alpha.