Molecular networking-assisted isolation, structural elucidation, and bioactivity evaluation of new diterpenoids from...

A new ent-isopimarane, castanocarpinone (1), and a new ent-beyerane, castanocarpin (2), together with 12 known compounds (3-14), were isolated from the twigs of Chaetocarpus castanocarpus. Feature-based molecular networking with NPClassifier-assisted annotation was used to profile the ethyl acetate fractions. Besides fatty acids, most features were assigned to triterpenoid and shikimate/phenylpropanoid pathways, dominated by diterpenes and by coumarins and flavonoids, respectively. These two phytochemical groups were therefore prioritised for isolation, and the resulting compounds were mapped and re-annotated within their molecular families. Structural elucidation was accomplished using comprehensive spectroscopic techniques. Compound 7 showed the strongest DPPH radical scavenging activity (IC₅₀ = 4.431 ± 0.024 µM), while compound 14 exhibited the most potent α-glucosidase inhibition (IC₅₀ = 28.034 ± 2.965 µM). Overall, this integrated study provides a comprehensive chemical and biological profile of Chaetocarpus castanocarpus, highlighting its potential as a source of bioactive drug leads.