An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

In our previous studies (Refs. 1 and 2), it was shown that protein tyrosine kinase (PTK) inhibitors, radicicol and herbimycin A, inhibit the expression of the mitogen-inducible cyclooxygenase (COX-2) and proinflammatory cytokines. Radicicol and herbimycin A possess polarized double bonds which can conjugate sulphydryl groups of proteins. Parthenolide, the predominant sesquiterpene lactone in European feverfew (Tanacetum parthenium), contains α-methylene-gamma-lactone (MGL) and an epoxide in its structure. These moieties can interact with biological nucleophiles such as a sulfhydryl group. Parthenolide inhibited the expression of COX-2 and proinflammatory cytokines (TNFα and IL-1) in lipopolysaccharide (LPS)-stimulated macrophages. The structure-function relationship indicates that the MGL moiety confers the inhibitory effect. Parthenolide suppressed LPS-stimulated protein tyrosine phosphorylation in the murine macrophage cell line (RAW 264.7). This suppression was correlated with its inhibitory effect on the expression of COX-2 and the cytokines. Among tyrosine phosphorylated proteins, mitogen-activated protein kinases (MAPKs) exhibited the most dramatic inhibition.

Two melampolide-type sesquiterpene lactones, enhydrin and 2,' 3'-dehydromelnerin A, were isolated from a Louisiana population of Polymnia uvedalia. Their C-13 NMR spectra were assigned using C-13-H-1 correlation, DEPT and COLOC experiments. The molecular structure of enhydrin was established by single crystal X-ray diffraction.

Aerial parts of Erigeron annuus and E. strigosus afforded 3-hydroxy-4-pyrone, the molecular structure of which was determined by single crystal X-ray diffraction.

The title compound, 3-phenyl-1-(2,4,5-trihydroxy-3,5-dimethyl-6-oxo- 1,5-cyclohexadienyl)-1-propanone, was confirmed to be a dihydrochalcone containing a fully substituted cyclohexadienone ring. This ring has a flattened half-chair conformation, with the dione C atom 0.203 (1) Angstrom out of the diene plane and the tetrahedral C atom 0.184(1) Angstrom to the opposite side of the plane. The hydroxy substituent on the tetrahedral C atom forms an intramolecular hydrogen bond to the carbonyl O atom of the cyclohexadienone, having an O...O distance of 2.658 (1) Angstrom and an angle at H of 116(2)degrees. One of the other hydroxy substituents forms an intramolecular hydrogen bond with the carbonyl O atom of the beta-phenylpropionyl group, having an O...O distance of 2.414 (2) A and an angle at H of 160 (2)degrees.