Sundarbanxylogranins A-E, five new limonoids from the Sundarban Mangrove, Xylocarpus granatum

Five new limonoids, named sundarbanxylogranins A-E (1-5), were isolated from the seeds of an Indian mangrove, Xylocarpus granatum, collected from mangrove swamps of the Sundarbans, India. The structures of these limonoids were established by HRESIMS and NMR spectroscopic data. Sundarbanxylogranin A (1) is a rare limonoid containing a bicyclo[5.2.1]dec-3-en-8-one scaffold as the ring A/B-fused core; whereas sundarbanxylogranin B (2) is a typical mexicanolide with an 8α, 30α-epoxy ring. Sundarbanxylogranins C-E (3-5), among which the former two possess a 29-OMe group with different orientation, belong to a small group of limonoids containing a C₁-O-C₂₉ oxygen bridge. Sundarbanxylogranin B exhibited moderate anti-HIV activity with an IC₅₀ value of 23.14±1.29μM and a CC₅₀ value of 78.45±1.69μM, respectively.