Two novel tricyclic spirolactones bearing long linear alkyl chains, yaoshanenolides A (1) and B (2), formed by Diels–Alder[4 + 2] cycloaddition of a molecule of each butenolide with β-phellandrene, were isolated from the bark of Machilus yaoshansis. Their structures and absolute configurations were determined by extensive spectroscopic methods, especially 2D NMR and ECD data analysis. The proposed biosynthetic pathway is discussed. Both compounds exhibited nonselective cytotoxic activities against several human cancer cell lines.

Nine new dammarane triterpene glycosides (1–3 and 8–13) and 12 known analogues have been isolated from an ethanol extract of the roots of Machilus yaoshansis. Compounds 1–7 have an uncommon 20,23-dihydroxydammar-24-en-21-oic acid-21,23-lactone moiety that was previously reported in compounds isolated from Gynostemma pentaphyllum. The configurations of the lactone moieties in 1–3 were determined by comparison of the experimental ECD spectra of 1–3 and the hydrolysates, 1a and 1b, with the corresponding calculated ECD spectra. On the basis of NMR and ECD data analysis of 1–7, the previously reported C-20 and C-23 configurations of 4–7 and related derivatives from Gynostemma pentaphyllum were revised. In addition, the application of NMR data and Cotton effects to the determination of the relative and absolute configurations of the γ-lactone moiety in 3β,20,23-trihydroxydammar-24-en-21-oic acid-21,23-lactone derivatives is discussed.

Seven new cucurbitane triterpene glucosides (1–5, 8, and 9) and five known analogues (6, 7, 10, cucurbitacin I 2-O-β-d-glucopyranoside, and khekadaengoside K) have been isolated from an ethanol extract of roots of Machilus yaoshansis. Compounds 1 and 2 have an unusual 16,23:22,25-diepoxy unit, 4 is an uncommon cucurbitane 25-carbamate with the carbamoyl amino group attached at C-24 to form an oxazolidinone ring in the side chain, and 8 is the first example of a trinorcucurbitane derivative. The configurations in several pairs of C-24 epimeric cucurbitacins with 24,25-dihydroxy-22-one side chains were assigned, and the validity of J23a,24 and J23b,24 values to differentiate the configuration at C-24 in these cucurbitane derivatives is discussed. Compounds 2–4 showed in vitro activity against protein tyrosine phosphatase 1B with IC50 values of 8.63, 2.81, and 4.26 μM, respectively. Cucurbitacin E 2-O-β-d-glucopyranoside (10) showed selective cytotoxicity against BGC-823 and A549 cancer cells with IC50 values of 4.98 and 3.20 μM, respectively.

A new ureido-substituted amino acid, conopsamide A (1), has been isolated from an ethanolic extract of the tubers of Gymnadenia conopsea. Its structure was elucidated by extensive spectroscopic analysis, and the absolute configuration was assigned by Marfey's method. The new compound was evaluated for in vitro assay for HDAC1 (Histone Deacetylase 1) inhibitory activity.A new ureido-substituted amino acid, conopsamide A (1), has been isolated from an ethanolic extract of the tubers of Gymnadenia conopsea. Its structure was elucidated by extensive spectroscopic analysis, and the absolute configuration was assigned by Marfey's method. The new compound was evaluated for in vitro assay for HDAC1 (Histone Deacetylase 1) inhibitory activity.