Seven new limonoids, namely, xylorumphiins E-J (1-2 and 4-7) and 2-hydroxyxylorumphiin F (3), along with three known derivatives (8-10), were isolated from the seeds of Xylocarpus rumphii. 2-Hydroxyxylorumphiin F (3) and xylorumphiin I (6) displayed moderate inhibitory activity against nitric oxide production from lipopolysaccharide-activated macrophages with IC50 values of 24.5 and 31.3 μM, respectively.

Four new mexicanolide limonoids, named xylorumphiins A-D (1-4), were isolated from the seed kernels of Xylocarpus rumphii, together with three known limonoids. Their structures and configurations were established on the basis of spectroscopic data.

The title compound (also known as phragmalin triacetate), C35H42O14, is a phragmalin-type limonoid extracted from X. rumphii. The mol­ecule consists of eight rings with the orthoacetate group bridged at positions 1, 8 and 9. The two five-carbocyclic rings (A 1 and A 2) and the dioxolane ring (G) adopt a distorted envelope conformation. The 1,3-dioxane ring (E) exists in a chair conformation. The six-carbocyclic rings (B and C) exhibit a twisted-boat conformation. The lactone ring has a half-chair conformation and the furan ring is planar (r.m.s. deviation = 0.002 Å). Rings A 1/B, A 2/B, B/C, C/D and C/G are all cis-fused. The two acet­oxy groups attached to ring B and the furan ring attached to the lactone ring are in equatorial positions. The porous crystal packing exhibits voids of 688 Å3 and weak inter­molecular C—H⋯O inter­actions. The absolute configuration was assigned on the basis of literature data.

In this study, limonoids isolated from Xylocarpus plants were tested for their in vitro anti-inflammatory effects. The results demonstrated that only 7-deacetylgedunin (1), a gedunin-type limonoid, significantly inhibited lipopolysaccharide- and interferon-γ-stimulated production of nitric oxide in murine macrophage RAW 264.7 cells. The suppression of nitric oxide production by 1 was correlated with the downregulation of mRNA and protein expression of inducible nitric oxide synthase. Mechanistic studies revealed that the transcriptional activity of nuclear factor-κB, IκBα degradation, and the activation of mitogen-activated protein kinases, stimulated with lipopolysaccharide and interferon-γ, were suppressed by 1.