Lepidotrichilins A and B, new protolimonoids with cytotoxic activity from Trichilia lepidota (Meliaceae)

Two novel protolimonoids, named lepidotrichilins A (1) and B (2), four known protolimonoids, 21,23-epoxy-7α-21α-dihydroxyapotirucalla-14,24-dien-3-one (3), 21,23-epoxy-7α-21β-dihydroxyapotiru-calla-14,24-dien-3-one (4), dysorone D (5), deoxy-flindissone (6), and the two steroids β-sitosterol (7) and stigmasterol (8) were identified in leaves of Trichilia lepidota subsp. schumanniana (Harms) T.D. Pennington. From wood the coumarin scopoletin (9) was isolated. The structures were established by NMR (1D (1)H and (13)C-NMR and 2D (1)H-(1)H COSY, HMQC and HMBC), mass spectroscopy and infrared (IR) spectral data. The hexane and methanol extracts of the leaves, the protolimonoids lepidotrichilins A (1) and B (2) (IC₅₀ 42.7 µg mL(-1)) and the protolimonoid deoxy-flindissone (6; IC₅₀ 9.3 µgmL(-1)) exhibited significant cytotoxic activity against the MOLT-4 and U937 leukemic cell lines.