Antiobesity and lipid lowering effects of Glycyrrhiza chalcones: experimental and computational studies.

Simultaneous extraction and separation of flavonoids and alkaloids from Crotalaria sessiliflora L. by microwave-assisted cloud-point extraction

Microwave-assisted aqueous two-phase extraction coupled with high performance liquid chromatography for simultaneous extraction and determination of four flavonoids in Crotalaria sessiliflora L.

Two new isopropenyl-dihydrofuranoisoflavones exhibiting antimicrobial properties have been isolated along with eight known compounds from the Cameroonian medicinal plant Crotalaria lachnophora. The structures of the new compounds were elucidated by 1D and 2D NMR spectroscopy and high-resolution mass spectrometry as 7,2′,4′-trihydroxy-5′′-isopropenyl-4′′,5′′-dihydrofurano[2′′,3′′:5,6]isoflavone (1) and 4,8-dihydroxy-2-isopropenyl-2,3-dihydro-5H-[1]benzofuro[2,3-b]furo[3,2-g]chromen-5-one (2). The CH2Cl2/MeOH (1:1) extract and the compounds isolated were subjected to in vitro antimicrobial assays against a panel of pathogenic microorganisms, including Gram-positive and Gram-negative bacteria and fungi. The new compounds, named lachnoisoflavones A (1) and B (2), showed moderate inhibitory activities against Escherichia coli and Klebsiella pneumoniae.

Antimicrobial Isopropenyl-dihydrofuranoisoflavones from Crotalaria lachnophora

Fermentation of 3-hydroxyflavone (1) with Beauveria bassiana (ATCC 13144) yielded 3,4'-dihdroxyflavone (3), flavone 3-O-beta-D-4-O-methylglucopyranoside (4) and two minor metabolites. 7-Hydroxyflavone (2) was transformed by Nocardia species (NRRL 5646) to 7-methoxyflavone (5) whilst Aspergillus alliaceus (ATCC 10060) converted it to 4',7-dihydroxyflavone (6). Flavone 7-O-beta-D-4-O-metylglucopyranoside (7) and 4'-hydroxyflavone 7-O-beta-D-4-O-methylglucopyranoside (8) were the metabolic products of 7-hydroxyflavone (2) when fermented with Beauveria bassiana (ATCC 7159). One of the minor metabolites of 3-hydroxyflavone (1) was tentatively assigned a beta'-chalcanol structure (9). Compounds 4, 7 and 8 are reported as new compounds. Structure elucidation of the metabolites was based on spectroscopic data.

Microbial metabolism. Part 6. Metabolites of 3- and 7-hydroxyflavones.

Phytochemical investigation of the whole plants of Crotalaria sessiliflora L. led to the isolation of four flavonoids. The structures of these compounds were identified as 2′,4′,5,7-tetrahydroxyisoflavone (1), 2′,4′,7-trihydroxyisoflavone (2), 4′,7-dihydroxyflavone (3), and isovitexin (4) using spectroscopic analysis. Among these, compounds2, and3 have not been reported from.Crotalaria species, whereas compounds1, and4 were reported from this plant for the first time.

Hun Sung Yoo

Papers

Flavonoids of Crotalaria sessiliflora.