Antiplasmodial Triterpenoids from Ekebergia capensis

Abstract

From the stem bark of Ekebergia capensis, 10 new triterpenoid compounds, ekeberins A (1), B (2), C1 (3), C2 (4), C3 (5), D1 (6), D2 (7), D3 (8), D4 (9), and D5 (10), were isolated together with 17 known compounds. The structures of these new compounds were elucidated on the basis of the results of spectroscopic analysis, and the absolute configuration of compounds 6-10 were determined by partial synthesis from known compounds and using the Mosher ester method. Several of these compounds were screened in vitro against both chloroquine (CQ)-sensitive and -resistant Plasmodium falciparum isolates and were found to exhibit moderate antiplasmodial activity, with compounds 20 (7-deacetoxy-7-oxogedunin) and 27 (2-hydroxymethyl-2,3,22,23-tetrahydroxy-2,6,10,15,19,23-hexamethyl-6,10,14,18-tetracosatetraene) showing IC50 values of 6 and 7 microM, respectively. Compound 27 at a dose of 500 mg/kg showed moderate parasitemia suppression of 52.9% against P. berghei NK 65 in a mouse model.

Isolation of farnesylhydroquinones from the basidiomycete Ganoderma pfeifferi

“…These observed shifts correspond well to those of a dihydroxy isoprene moiety observed in other natural products. [14][15][16] The identified hydroquinoneisoprenelactone and dihydroxy isoprene moieties could be connected based on several HMBC correlations as indicated in Table 1 to give the planar structure of 2. The absolute configuration at C-1 was established using the circular dichroic method described for the determination of the absolute configuration of 5-substituted 2-(5H)-furanones, where it is known that the sign of the Cotton effect due to the n-π* and π-π* transitions is directly correlated with the absolute configuration of the stereogenic center at the γ-carbon of the butenolide moiety.…”

In vitroantileishmanial, antiplasmodial and cytotoxic activities of a new ventiloquinone and five known triterpenes fromParinari excelsa

“…However, these medicines are not orally active, requiring long-term parenteral administration, not to mention that they lead to serious side effects (Rocha et al 2005). Nature remains an ever evolving source for compounds of medicinal importance among which triterpenes (Murata et al 2008;Camacho et al 2000) and quinines (Eyong et al 2008;Laurent et al 2006). Parinari excelsa Sabine (Chrysobalanaceae) is a woody species commonly found in forest of West Africa and Eastern Africa.…”

2,3,22,23-Tetrahydroxyl-2,6,10,15,19,23-hexamethyl-6,10,14,18-tetracosatetraene, an Acyclic Triterpenoid Isolated from the Seeds of <i>Alpinia katsumadai</i>, Inhibits Acyl-CoA : Cholesterol Acyltransferase Activity

“…The characteristics of the NMR data and other physicochemical data of the isolated compound were in concurrence with the chemical structure from previous reports. 24,25) Thus, compound 1 was identified as 2,3,22,23-tetra hydroxyl-2,6,10,15,19,23-hexamethyl-6,10,14,18-tetracosatetraene, an acyclic triterpenoid (Fig. 1) previously reported in the stem bark of Ekebergia capensis.…”