Sesquiterpenes and butenolides, natural anti-HIV constituents from Litsea verticillata

In a continuing investigation, six sesquiterpenes, as well as five butenolides were isolated from the leaves and twigs of Litsea verticillata Hance (Lauraceae). Among the isolates, three were determined to be new sesquiterpenes: isolitseanes A (1), B (2) and C (3); three known sesquiterpenes were identified as oxyphyllenodiol B (4), 1,2,3,4-tetrahydro-2,5-dimethyl-8-(1- methyl-ethyl)-1,2-naphthalenediol (5), and chromolaevanedione (6). The butenolides include the novel litseabutenolide (9) and four known compounds: 3-epi-litsenolide D₂ (7), cis-listenolide D₁ (8), 4-hydroxy-2-methylbut-2-enolide (10), and hydroxydihydrobovolide (11). Isolates 2,4,5,7,9,10 and 11 were found to inhibit HIV-1 replication in a green fluorescent protein (GFP)-based reporter cell line (HOG.R5) with IC₅₀ values of 38.1, 54.6, 91.0, 9.9, 40.3, 129.8, and 122.7 μM, respectively. Structure elucidation and identification were based on spectroscopic means including 1D and 2D NMR analyses.