Anastasie E. Tih

Tetraflavonoids of Lophira alata

Abstract A new tetraflavonoid, lophiroflavan A, was isolated from the stem bark of Lophira alata along with lophirochalcone. Both compounds were obtained as their permethyl ether derivatives and their structures determined from spectroscopic and chemical evidence.

Lophiroflavans B and C, tetraflavonoids of Lophira alata

Abstract Two new tetraflavonoids, lophiroflavans B and C, were isolated from the stem bark of Lophira alata along with lophirochalcone and lophiroflavan A and their structures determined from spectroscopic and chemical evidences.

A new chalcone dimer from Lophira alata.

Abstract A new biflavonoid, mbamichalcone, has been isolated from Lophira alata stem bark and structure determined from spectroscopic and chemical evidences.

New flavonoid C-O-C dimers and other chemical constituents from Garcinia brevipedicellata stem heartwood.

Abstract The methanol extract of the stem heartwood of Garcinia brevipedicellata has furnished three new flavonoid C–O–C dimers, brevipedicilones A (6), B (8) and C (10), along with five previously reported flavonoid dimers, viz. amentoflavone (1), 4″′-O-methylamentoflavone (2), robustaflavone (3), 4′-O-methyl robustaflavone (4) and tetrahinokiflavone (5). The new structures, which are composed of flavanone–flavanonol or flavanonol–flavanonol sub-units, were established based on spectroscopic analysis including 1D and 2D NMR (1H-1H COSY, HSQC, HMBC, and NOESY) spectroscopy, and by comparing their spectral data with those reported for related compounds.

Chemical constituents of the leaves of Campylospermum elongatum.

Abstract The leaves of Campylospermum elongatum have furnished the cyano-glycoside (lithospermoside), nine isomeric biflavonoid derivatives among which five are I3–II6 linked (robustaflavone; 4′-O-methyl robustaflavone; 4′,4″′-di-O-methyl robustaflavone; 7,4′,4″-tri-O-methyl robustaflavone; 4′,7″-di-O-methyl robustaflavone) and four I3–II8 linked (amentoflavone; 7-O-methyl amentoflavone; 7,7″-di-O-methyl amentoflavone; 7, 4′,7″-tri-O-methyl amentoflavone) and a flavone glycoside, 4″-O-methyl-7-O-β-d-galactosylapigenin. All structures were established from a complete spectroscopic analysis (MS, IR, 1D, and 2D NMR, including HSQC, HMBC, and NOESY) as well as by comparing the obtained spectroscopic data with literature. This is the first report on the characterization of 4′-O-methyl-7-O-β-d-galactosylapigenin from the genus campylospermum and thus has important chemotaxonomic implications.

Flavonoid glycosides and their p-coumaroyl esters from Campylospermum calanthum leaves.

Six new compounds, comprising three flavonoid glycosides and their respective coumaroyl esters, have been isolated and characterized from the methanol extract of the leaves of Campylospermum calanthum, along with three known flavonoid aglycones, 7-O-methyl apigenin (1), 7-O-methyl luteolin (2), and 7-O-methyl quercetin (3). Their structures were elucidated based on chemical evidence as well as spectroscopic analysis including 1D and 2D NMR (1H-1H COSY, HSQC, HMBC, and NOESY) spectroscopy and by comparing their spectral data with those reported for related compounds