David Lontsi

Protective role of Anacardium occidentale extract against streptozotocin-induced diabetes in rats

The protective effect of Anacardium occidentale aqueous extract against streptozotocin-induced diabetes was evaluated in rats. The rats were treated with 175 mg/kg of the extract per os, twice daily; beginning 2 days before streptozotocin (STZ) injection. A total of 3 days after STZ administration, there was a 48% increase in blood glucose level in pretreated rats, compared with a 208% increase in diabetic control rats treated with STZ alone. Furthermore, these pretreated animals presented no glycosuria, a normal weight gain and a non significant increase in food and fluid intake at the end of the treatment compared with the normal control. Diabetic control animals showed a positive glycosuria, body weight loss, a real polyphagia and polydypsia. These results indicate the protective role of Anacardium occidentale extract against the diabetogenic action of STZ.

New isoflavones from Ceiba pentandra

Two new isoflavones, pentandrin (1) and pentandrin glucoside (2), were isolated from the stem barks of Ceiba pentandra along with beta-sitosterol and its 3-O-beta-D-glucopyranoside, which was isolated for the first time from this plant. The structures of these compounds were elucidated with the help of spectroscopic techniques, while the structure of 1 was unambiguously confirmed by single-crystal X-ray diffraction studies.

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).

Pachypophyllin and pachypostaudins A and B: three Bisnorlignans from Pachypodanthium staudtii

Abstract Three new bisnor lignans, pachypophyllin, pachypostaudin-A and pachypostaudin-B have been isolated from the bark of Pachypodanthium staudtii and their structures have been determined by 1 H and 13 CNMR spectroscopy and chemical correlations. 2,4,5-Trimethoxystyrene, probably a precursor of the bisnor lignans, was also isolated from the extracts. Furthermore, the potent antiviral flavonol, pachypodol, was obtained in significant amount.

Two saponins from Pteleopsis hylodendron

Abstract Two new saponins, 2α,3α,19α,23-tetrahydroxyolean-12-en-28-O-β- d -galactoside, and sitosterol α(1→3) diglucoside, were isolated from the stem barks of Pteleopsis hylodendron along with a known triterpenoid, 2α,3β,21β,23-tetrahydroxyolean-12-en-28-oic acid, which was isolated for the first time from this plant. The structures of these compounds were elucidated with the help of spectroscopic studies.

Seco-ring-A-triterpenoids from the rootwood of Musanga cecropioides

Abstract From the rootwood of the African tree Musanga cecropioides, three seco-triacidic triterpenes, cecropiacic acid, musangic acids A and B were isolated as their trimethyl esters. Their structures were determined on the basis of a spectral analysis.

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.

Musancropic acids A and B: A-ring contracted triterpenes from Musanga cecropioides

Abstract Two A-ring contracted triterpenes, musancropic acids A and B, having a new triterpene backbone, were isolated as their methyl esters from the rootwood of the African tree Musanga cecropioides . Their structures were determined by spectroscopic studies.

A pentacyclic triterpene diacid from Myrianthus arboreus

Abstract In addition to myrianthinic acid, arboreic acid, and the known tormentic and euscaphic acids, a new ursane derivative, myriaboric acid, has been isolated from the polar material of the stembark of Myrianthus arboreus , and its structure elucidated by spectroscopic methods.

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.