Beibam L. Sondengam

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.

Spathodic acid: A triterpene acid from the stem bark of Spathodea campanulata

Abstract A new triterpene acid, spathodic acid and the sistosterol-3- O -β- d -glucopyranoside were isolated from the stem bark of Spathodea campanulata . The structure of the new compound was established by chemical and spectral analysis.

Hoslundin, hoslundal, and hoslunddiol: three new flavonoids from the twigs of Hoslundia opposita (Lamiaceae)

Abstract Three new flavonoids (hoslundin 1 , hoslundal 4 , and hoslunddiol 6 ) have been isolated from the twigs of Hoslundia opposita . The structure of hoslundin has been determined mainly by the use of 2D n.m.r. long-range δ C /δ H correlation in conjunction with the ID proton-coupled 13 C n.m.r. spectrum, while the structures of the rest were established using 1 H and 13 C n.m.r. spectroscopy. The manner in which 2D n.m.r. long-range δ C /δ H H correlation experiments are used for determining bond connectivity during the process of structural elucidation is discussed.

An ergostane derivative from the bark of Entandrophragma utile

Abstract A new ergostane derivative was isolated from the stem bark of Entandrophragma utile and identified as 3β,7α,20β-trihydroxy ergosta-5,24(24′) diene on the basis of spectroscopic data.

Pentacyclic triterpenes from Myrianthus liberecus

Abstract From the methylated trunk wood extracts of Myrianthus liberecus, six pentacyclic triterpenes have been isolated as their methyl esters. These included the known methyl benthamate, methyl euscaphate, methyl tormentate, methyl arjunolate, methyl 3-isoarjunolate and methyl 3β-O-(4″-O-methyl-E-coumaroyl)-arjunolate, a new triterpene derivative.

Oppositin and 5-O-methylhoslundin, pyrone-substituted flavonoids of Hoslundia opposita

The methanolic extract of the twigs of Hoslundia opposita afforded two new pyrone-substituted flavonoids oppositin and 5-O-methylhoslundin, in addition to the known flavonoids tectochrysin, hoslunddiol and hoslundin. Oppositin has its 6-C-pyrone substituent attached via a 6,6″-link in contrast to the 6,5″-link in hoslundin and is a likely biogenetic precursor of hoslundin.

Atomasins A and B, tetranortriterpenoids from the bark of Entandrophragma candollei

Abstract Two new tetranortriterpenoids, atomasins A and B, were isolated from the trunk bark of Entandrophragma candollei . The structures of the new compounds were established from their spectroscopic data.

The structure of veprisinium salt

Abstract The structure of a new quaternary dihydrofuroquinoline alkaloid, veprisinium salt, isolated from Vepris louisii and possessing antibacterial activity, has been determined from spectroscopic and chemical data and confirmed by partial synthesis.

Araliopdimerines A, B, and C, dimeric quinolone alkaloids from the bark of Araliopsis tabouensis

Abstract Araliopdimerines A, B, and C, three new dimeric 2-quinolone alkaloids have been isolated from the bark of Araliopsis tabouensis and their structures assigned on the basis of 1 H and 13 CNMR evidence and chemical correlation.