Jean-Claude Wallet

Scavenger and antioxidant properties of ten synthetic flavones

To study the effect of the hydroxyl groups on biological activities of flavones, we synthesized 10 polyhydroxyflavones with varied substitution patterns. The abilities of the 10 compounds to act as radical scavengers were investigated using chemiluminescence in two biological models: the xanthine/xanthine oxidase system and the oxidative burst of rat alveolar macrophages. Stable radical formation was observed by electron spin resonance (ESR) spectroscopy. We found that the presence of the pyrogallol moiety in the B component of flavones gave rise to radical scavenger activity and that C-6 substituted hydroxyl group may also provide the basis for biological activity. Furthermore, compounds with a hydroxyl at C-7 position appeared to be xanthine oxidase inhibitors. One particular compound exhibited radical scavenger activity and xanthine oxidase inhibition. This type of compound should prove to be useful in the treatment of ischemia, for which both properties were required.

Gas chromatography of some polymethoxylated flavones and their determination in orange peel oils

Abstract Separation of 27 polymethoxylated flavones (PMFs) was achieved using gas chromatography with a capillary column coated with OV - 1. The procedure was applied to the separation and determination of the most important PMFs contained in three samples of industrial orange peel oils. The relative contents of sinensetin, nobiletin and heptamethoxyflavone range from 19 to 30%, showing that these three PMFs are characteristic of orange peel oils. Tetra-O-methylscutellarein, tangeretin and 3,5,6,7,3′,4′-hexametoxyflavone are less abundant in all three samples.

The 1:1-adduct of chlorotriphenyltin with 2',6'-dimethoxyflavone : a potential fungicide

The 1∶1 adduct of chlorotriphenyltin with 2′,6′-dimethoxyflavone, (C35H29O4ClSn)Mr=667.78, crystallizes in the triclinic space groupP1 with the following data:a-9.094(2),b=12.369(3),c=14.674(3) Å, α=74.78(2), β=77.00(2), γ=73.06(3)°,V=1503.8(4) Å3,Z=2, Mo-Kα, μ=9, 8 cm−1,Dc=1.475 g cm−3, F(000)=676,T=293K. The structure was solved by direct-methods and has been refined to a finalR value (l>3σ(I)) of 0.0301. The flavone coordinates to the tin atom through the carbonyl oxygen atom. The metal center exhibits a trigonal bipyramidal configuration with the three phenyl groups in equatorial positions.

2′,6′-Dimethoxyflavone as an Aid to the Crystallization of Benzoic Acids and X-Ray Structure of the Inclusion Compound with 2,4,6-Trimethoxybenzoic Acid

The crystal structure of the inclusion compound formed between 2′-6′-dimethoxyflavone and 2,4,6-trimethoxybenzoic acid has been investigated by single-crystal X-ray analysis. The compound crystallizes in the triclinic system, space group P-1, as do inclusion compounds with acetic, propionic, and bromoacetic acids. However, the larger 2,4,6-trimethoxybenzoic acid molecule induces a layered structure.

7-Hydroxy-2-(2,3,4-trimethoxyphenyl)-4H-1-benzopyran-4-one: (7-hydroxy-2',3',4'-trimethoxyflavone)

Abstract7-Hydroxy-2′,3′,4′-trimethoxyflavone, (C18H16O6),Mr=328.32 crystallizes in the orthorhombic system, space groupPbna, with the following crystal data:a=8.853(2),b=12.870(2),c=26.293(3)Å,V=2996(1)Å3,Z=8, MoKα, μ=0.67 cm−1,Dc=1.454 g·cm−3,F(000)=1376,T=294K. The structure was solved by direct-methods and has been refined by full-matrix least-squares methods to a finalR value (F>σ(F)) of 0.0496. The molecule is not planar, the dihedral angle between the phenyl ring and the fused ring system is 27.3°. There are no intramolecular hydrogen bonds, but intermolecular short hydrogen contacts exist between hydroxyl hydrogen and carbonyl oxygen atoms.

A Practical Synthesis of Dibenzoylmethanes

Abstract Dibenzoylmethanes are easily prepared in two steps starting from acetophenones, phenol and benzoyl chlorides. The phenyl benzoate is obtained by condensation of benzoyl chloride with phenol in a classical way. Stirring of the phenyl benzoate and acetophenone in DMSO with powdered sodium hydroxide during a few minutes gave the dibenzoylmethanes in yields depending on substituents on the phenyl rings.

1-Phenyl-3-(3,4,5-trimethoxyphenyl)-1,3-propanedione

The crystal structure of 1-phenyl-3-(3,4,5-trimethoxyphenyl)-1,3-propanedione, C 18 H 18 O 5 , consists of discrete molecules separated by normal van der Waals interactions. The molecule exists in the enol form [i.e. 3-hydroxy-1-phenyl-3-(3,4,5-trimethoxyphenyl)propene-1-one] in the solid state, stabilized by a short intramolecular hydrogen bond

The crystal structure of the molecular complex of 2′,6′-dimethoxyflavone with picric acid: Alternating π-stacking and hydrogen-bonding interactions

The title complex is monoclinic with a = 15.100(5), b = 7.624(3), c = 39.997(15) Å, β = 99.49(4)°, Z = 8, and space group P21/c. There are two geometrically independent, hydrogen-bonded pairs of molecules in the asymmetric part of the structure. Picric acid and 2′,6′-dimethoxyflavone are held together by hydrogen bonding between the hydrogen of the phenol group and the oxygen of the carbonyl. Additionnally, this hydrogen forms an intramolecular hydrogen bond with the O atom of an ortho-nitro group. Moreover, a stacking interaction is observed between the γ-benzopyrone portion of the flavone and picric acid.

13C NMR studies of fluoroflavones

13C NMR chemical shifts were measured in DMSO‐d6 for fluorocarbonyl compounds. Sulfonic derivatives display 4J(C,F) coupling constants for carbonyl groups which are also obtained from non‐sulfonic derivatives when they are recorded in acidic solution.

2'-Hydroxy-3'-methoxy-5'-flavonesulfonic Acid Trihydrate: a New Zwitterion

The title compound, C16H12O7S.3H2O, displays an anionic part, the deprotonated sulfonic group and a cationic part, the protonated carbonyl group, indicative of a zwitterionic structure. These two parts in different molecules are linked by hydrogen bonding involving three water molecules.