J. Foyere Ayafor

Quinolone and carbazole alkaloids from Clausena anisata

Abstract From the combined stem bark and root extracts of Clausena anisata we isolated two new alkaloids, 1-methyl-3,4-dimethoxy-2-quinolone and 3-formyl-1-hydroxycarbazole, and four known alkaloids identified as heptaphylline, girinimbine, ekeberginine and 3-methylcarbazole. The structure of the new alkaloids were assigned on the basis of 1H and 13CNMR evidence.

Erythrinasinate, an ester from three Erythrina species

Abstract The novel ester n -octacosanyl-3-hydroxy-4-methoxy cinnamate has been isolated from the stem bark of Erythrina senegalensis , E. glauca and E. mildbaedii and its structure determined by spectroscopic data and degradative studies. The known pterocarpan erythrabyssin-1 has also been isolated from . glauca .

Erythrisenegalone, a prenylated-flavanone from Erythrina senegalensis☆

Abstract The isolation of a new prenylated flavanone, erythrisenegalone, from the stem-bark of Erythrina senegalensis is described. Its structure was established by spectroscopic methods and a few chemical transformations.

The structures of vepridimerines A-D, four new dimeric prenylated quinolone alkaloids from Vepris lousii and Oricia renieri (Rutaceae)

Abstract Four new isomeric dimeric prenylated quinolone alkaloids, vepridimerines A-D, have been isolated from the bark of Vepris louisii and Oricia renieri (Rutaceae) and have been assigned structures (2)–(5) respectively on the basis of spectroscopic evidence, in particular 1 H and 13 C n.m.r. data.

The use of two-dimensional long-range δC/δH correlation in conjunction with the one-dimensional proton-coupled 13C NMR spectrum in the structural elucidation of ekeberginine, a new carbazole alkaloid from Ekebergia senegalensis (Meliaceae)

A new strategy involving the use of 2D long-range δC/δH correlation in conjunction with the 1D proton-coupled 13C NMR spectrum has been applied to the structural elucidation of ekeberginine, a new carbazole alkaloid from the stem bark of Ekebergia senegalensis (Meliaceae).

Erythrina studies. Part 1. Novel antibacterial flavanones from Erythrina sigmoidea

Two new flavanones, sigmoidin A and B have been isolated from the Cameroonian medicinal plant Erythrina sigmoidea. The two compounds exhibit significant antibacterial activity against Gram-positive bacteria.

Veprisine and N-methylpreskimmianine: Novel 2-quinolones from Vepris louisii

Abstract The structures of two new 2-quinolone alkaloids, N-methylpreskimmianine and veprisine (7,8-dimethoxy-N-methylflindersine) have been deduced from their spectra and confirmed by partial synthesis from known compounds.

KHAYALACTONE, A NOVEL LIMONOID FROM KHAYA GRANDIFOLIOLA

Abstract The isolation and structure elucidation by spectroscopic methods of khayalactone ( 1 ) from extracts of Khaya grandifoliola is described. Khayalactone is a novel hexacyclic A,B,D- seco limonoid with a highly oxidised carbon framework.

Cecropiacic acid, a new pentacyclic A-ring seco triterpenoid from Musanga cecropioides

Abstract From the methylated polar extract of stem bark of Musanga cecropioides (Cecropiaceae) a novel triterpenic A-ring seco derivative has been obtained and the structure elucidated by spectroscopic methods.

Oriciopsin, a new ring-D cleaved tetranortriterpenoid, and flindersiamine from Oriciopsis glaberrima

Abstract A novel ring-D cleaved tetranortriterpenoid, oriciopsin and flindersiamine have been isolated from the whole plant extracts of Oriciopsis glaberrima . The structure of the new limonoid was determined from its 1 H NMR and 13 C NMR spectra and by mass spectrometry.