Limonoids from the aerial parts of Munronia pinnata

Abstract Six new limonoids, munropins A−F (1–6), were isolated from the aerial parts of a Chinese medicinal plant, Munronia pinnata (Meliaceae). The structures of 1–6 were assigned by detailed analyses of their spectroscopic data. Munropins A (1) and B (2) are limonoids possessing a prieurianin skeleton with α,β-unsaturated γ-lactam moieties at C-17. Munropins C (3), D (4), and E (5) are also prieurianin type limonoids with an α,β-unsaturated γ-lactone moiety, an acetyl group, and an acetoxyacetyl group at C-17, respectively. Munropin F (6) was assigned as a nimbolinin type limonoid with a γ-hydroxy-α,β-unsaturated γ-lactone moiety.