Ten new structurally diverse quassinoids (1-10) and 14 known compounds were isolated from the stems of Eurycoma longifolia. The new compounds were two eurycomanone-type C(20) quassinoids (1, 2), one klaineanone-type C(20) quassinoid (3), one C(19) quassinoid (4) with a 1,2-seco-1-nor-6(5-->10)-abeo-picrasan-2,5-olide skeleton, and six eurycomalactone-type C(19) quassinoids (5-10). Compounds 5 and 6 both possessed a 3,4-epoxy group observed for the first time in eurycomalactones. Compound 1 had an alpha-oriented OH group at C-14 that had not been reported previously in eurycomanone-type quassinoids. All of the isolates were evaluated for cytotoxicity toward the highly metastatic HT-1080 human fibrosarcoma cell line, and compounds 11, 23, and 24 showed potent cytotoxicity (IC(50) values 0.93-1.1 microM).

Seven new [acronyculatins I–O (1–7)] and four known acetophenone monomers were isolated from a CH3OH/CH2Cl2 (1:1) extract (N089419) of Acronychia trifoliolata provided by the U.S. National Cancer Institute (NCI, Frederick, MD, USA). Their structures were characterized by using various NMR and HRMS techniques. Among the known compounds, the structure of acronyculatin B (8) was revised. Some of the isolated compounds were evaluated for antiproliferative activity against human cancer cell lines. While most of the tested compounds were not cytotoxic, acronyculatins I (1) and J (2) showed moderate antiproliferative activity.

Six novel lactone derivatives, cryptolaevilactones A-F (1-6), were isolated from Cryptocarya laevigata. Their unique spiro[3.5]nonane moiety by hetero [2 + 2] cyclization with monoterpene and polyketide was found for the first time in nature. Structural elucidation using various nuclear magnetic resonance (NMR) techniques revealed that 1-3 and 4-6 are diastereomers and partially established the absolute configurations.

A bioactive CH3OH–CH2Cl2 (1:1) extract of the bark of Laetia corymbulosa provided five new clerodane diterpenes with an isozuelanin skeleton, designated as corymbulosins D–H (1–5), as well as the known corymbulosins B (6) and C (7), for which the relative configurations were not previously determined. The structures of 1–5 were characterized on the basis of 1D and 2D NMR spectroscopic and HRMS analysis. The absolute configurations of all isolated compounds 1–7 were verified through chemical methods, including modified Mosher esterifications or oxidation of the hydroxy group at C-2, ECD experiments, and spectroscopic data comparison. The isolated compounds were evaluated for antiproliferative activity against a small panel of human cancer cell lines.

A CH3OH–CH2Cl2 (1:1) extract (N025439) of the leaves and twigs of Cryptocarya laevigata furnished eight new compounds, 1–8. Based on extensive 1D and 2D NMR spectroscopic data examination, the new δ-lactone derivatives 1–6 are monoterpene–polyketide hybrids containing a unique spiro[3.5]­nonenyl moiety. Their trivial names, cryptolaevilactones G–L, follow those of the related known meroterpenoids cryptolaevilactones A–F. Cryptolaevilactone L (6) contains 11,12-cis-oriented substituents, while the other cryptolaevilactones contain trans-oriented groups. The structure of the linear δ-lactone 7, cryptolaevilactone M, was characterized from various spectroscopic data analysis, and the absolute configuration was determined by total synthesis through stereoselective allylation and Grubbs olefin metathesis. Compound 8 was elucidated to be an ionone derivative with a 3,4-syn-diol functionality.