Dukunolide G: A New Limonoid from the Root of Lansium domesticum Corr. (Meliaceae)

The Lansium genus belongs to the Meliaceae which is well known for limonoids. Limonoid is triterpenoid derivatives that have various structures due to rearrangements and degree oxidation. Lansium domesticum is a trunked tree growing more than 20 m in hight and it has antifeedant and antimalarial activities. Phytochemical investigations have been conducted toward fruits, leaves, and bark of this plant, except for the root. Methanol root extract of L. domesticum was fractionated by chromatography techniques including C₁₈-HPLC to isolate pure compounds. Exploration of secondary metabolites from the root of L. domesticum has resulted a new limonoid attached with an isopropyl moeity, dukunolide G (1) together with four known constituents, dukunolides A-C (2–4) and langsatide B (5). The chemical structures were characterized by 1D and 2D NMR (COSY, HSQC, HMBC), [α]_D values including DART-HRMS, and comparing with literature. Antimalarial activity of isolated compounds against Plasmodium falciparum strain 3D7 were evaluated and the results revealed that compounds 1 and 4 has strong and medium activities with IC₅₀ values 0.48 and 2.74 mg/mL, respectively. Graphical Abstract: [Figure not available: see fulltext.]