New phytoconstituents, anti-microbial and cytotoxic activities of Acacia etbaica Schweinf.

Acacia etbaica is wild plant growing in the desert of Egypt, and it has folkloric medicinal uses. Phytochemical investigation of Acacia etbaica extracts led to the isolation and identification of seven compounds. Among these compounds are three new simple phenolics: Resacetophenone-6-methyl [1], Resorcinol [2], Resorcinol-O- ß -Glucoside [3]; phenolic ester; and other four known compounds: Methylparaben [4]; two chromones, Noreugenin [5], Eugenin [6]; and one cyclitol: pinitol [7]. Compounds [1-3] isolated and identified for the first time from natural origin. In contrast, compounds [4-6] isolated for the first time from the family Fabaceae. The biological investigation was conducted on plant extracts and showed that the methylene chloride extract had a strong efficacy against Bacillus subtilis and good activity against Candida albicans. In contrast, the n-butanol extract showed extreme cytotoxic activity against Mammary gland breast cancer (MCF-7), and strong activity against Hepatocellular carcinoma (HEPG-2), and Colorectal carcinoma (HCT-116) cell lines.

Functional expression of an ajmaline pathway-specific esterase from Rauvolfia in a novel plant-virus expression system.

Acetylajmalan esterase (AAE) plays an essential role in the late stage of ajmaline biosynthesis. Based on the partial peptide sequences of AAE isolated and purified from Rauvolfia cell suspensions, a full-length AAE cDNA clone was isolated. The amino acid sequence of AAE has the highest level of identity of 40% to putative lipases known from the Arabidopsis thaliana genome project. Based on the primary structure AAE is a new member of the GDSL lipase superfamily. The expression in Escherichia coli failed although a wide range of conditions were tested. With a novel virus-based plant expression system, it was possible to express AAE functionally in leaves of Nicotiana benthamiana Domin. An extraordinarily high enzyme activity was detected in the Nicotiana tissue, which exceeded that in Rauvolfia serpentina (L.) Benth. ex Kurz cell suspension cultures about 20-fold. This expression allowed molecular analysis of AAE for the first time and increased the number of functionally expressed alkaloid genes from Rauvolfia now to eight, and the number of ajmaline pathway-specific cDNAs to a total of six.