Estudo químico de Ouratea hexasperma St. Hill (Ochnaceae)

Abstract

The specimen of Ouratea hexasperma (St. Hill.) Barl (Ochnaceae) was collected in Amapá state Brazil and was identified by botanist Benedito Vitor Rabelo. A voucher specimen (Nº 01519) is deposited at the herbario amapaense HAMAB of the museum Angelo Moreira da Costa Lima, IEPA, Macapá, Brazil. The solvent partition and chromatographic column and prep-TLC fractions of the root, bark and leaves extracts afforded four new biflavonoids and a known isoflavone. The hexanic extract of root afforded 5-hidroxy-4',7-dimethoxy- 2,3- trans-isofl avone-(2®2")-5 "-hidroxy-4"',7"-dimethoxy-2", 3"-trans-isoflavanone (hexaspermone-A), the CH2Cl2 extract of bark afforded 5-hidroxy -4',7 - dimethoxy- 2,3- trans-isoflavone- (2®2"')-4'"-hidroxy-5",7"-dimethoxy- 2",3"-trans-isoflavanone (hexaspermone-B), 5-hidroxy-4',7-dimethoxy-2,3- trans-isofavone-(2®2'')-4''',5''-dihidroxy-7''-methoxy-2'',3''-trans-isoflavanone (hexaspermone-C) together with 5,7,4'-trimetoxy isoflavone the methanolic extract of leaves afforded the biflavone 5,7,4'-trihidroxy-flavone- (6®8")5",4"'-dihidroxy-7"-methoxy-flavone (7"-metyl-agathisfavone), a mixture of aliphatic alkenes, a mixture of aliphatic esters and a mixture of pentacyclic triterpenes (a-amirin, b-amirin, lupeol and germanicol). The biflavone was found much more potent inhibit the tumors cells growth than quercetin. The structures of the products were determined on the basis of chemical and spectral data including 2D NMR experiments and MSFAB besides UV, IV and MSIE ofthe natural products and methyl ethers and acetyl ester derivatives.