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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.

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