Sabrina Boutefnouchet

Antitumor Psoropermum Xanthones and Sarcomelicope Acridones: Privileged Structures Implied in DNA Alkylation†

Fused isopropylfuran and dimethylpyran units are privileged structures present in numerous bioactive natural products exemplified, in the field of anticancer drugs, by the furanoxanthone psorospermin and the pyranoacridone acronycine. Psorospermin binds to the N-7 position of the guanine units in the presence of topoisomerase II. In contrast, acronycine derivatives such as cis-1,2-diacetoxy-1,2-dihydrobenzo[b]acronycine alkylate the 2-amino group of DNA guanine residues in the minor groove. Hybrid compounds associating the acridone or benzo[b]acridone chromophore of acronycine derivatives and the epoxyfuran alkylating unit present in psorospermin also display very potent antiproliferative activities, alkylating DNA guanine units at position N-7 in the major groove, as natural xanthones belonging to the psorospermin series.

Triterpenoids with antimicrobial activity from Drypetes inaequalis

The air-dried stems and ripe fruit of Drypetes inaequalis Hutch. (Euphorbiaceae) were studied. Four triterpene derivatives, characterized as lup-20(29)-en-3beta,6alpha-diol, 3beta-acetoxylup-20(29)-en-6alpha-ol, 3beta-caffeoyloxylup-20(29)-en-6alpha-ol and 28-betad-glucopyranosyl-30-methyl 3beta-hydroxyolean-12-en-28,30-dioate along with 10 known compounds were isolated from the whole stems. One triterpene, characterized as 3alpha-hydroxyfriedelan-25-al along with six known compounds were isolated from the ripe fruit. Their structures were established on the basis of spectroscopic analysis and chemical evidence. The triterpenes were tested for antimicrobial activity against some Gram-positive and Gram-negative bacteria, and two of them appeared to be modestly active.

Large scale purification of the SERCA inhibitor thapsigargin from Thapsia garganica L. roots using centrifugal partition chromatography.

Thapsigargin (Tg) is a selective and irreversible inhibitor of the sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA)-dependent pump at subnanomolecular concentrations. As such, it has become a powerful tool in the study of Ca(2+) signaling pathway. Purification of Tg from Thapsia species requires repeated chromatographic steps with normal-phase alumina or silica and reverse phase chromatography. We thus developed an innovative procedure coupling high pressure automatized extraction with centrifugal partition chromatography allowing a fast and safe large-scale isolation of highly pure Tg, in two steps from Thapsia garganica L. roots. Comparison of influence of extraction procedures, storage conditions and harvesting areas on Tg content in different Algerian specimens of Thapsia garganica L. roots has been precised by mean of HPLC quantification procedure. Highest Tg content were found in the fresh material of the sample from Setif area.