Asterisulphoxide and asterisulphone: two new antibacterial and antifungal metabolites from the Tunisian Asteriscus maritimus (L.) Less.

Two new sulphur-containing metabolites, asterisulphoxide 1 and asterisulphone 2, together with six known compounds, coniferaldehyde 4, 4-hydroxy-2-methoxybenzaldehyde 3, methylcaffeate 5, isobutyrate 10-isobutyryloxy-8,9-epoxythymyle 6, 8,9-dihydroxy-10-isobutyryloxythymol 7 and 8-hydroxy-9,14-diisobutyryloxythymol 8, were isolated from Asteriscus maritimus roots. Their structures were elucidated on the basis of spectroscopic evidence and comparison with authentic samples. Compounds 1-8 were assessed for their in vitro antibacterial activity against Pseudomonas aureofasciens, Burkholderia glathei, Bacillus pumilus and their antifungal effects against Aspergillus flavus, Aspergillus niger, Penicillium digitatum, Botrytis cinerea and Fusarium oxysporum f. sp. lycopersici, using the disc diffusion method (20 µL/disc). A remarkable inhibition zone 10-15 mm of the growth of the bacterial and fungal agents was observed. The obtained results suggest that the isolated compounds could be promising abiotic antimicrobial agents.

Chemical composition, antibacterial and cytotoxic activities of the essential oil from the flowers of Tunisian Convolvulus althaeoides L.

This study describes the chemical composition and evaluates the antibacterial and the cytotoxic effects of the essential oil from the flowers of Convolvulus althaeoides. Its chemical composition, determined by GC and GC-MS, is reported for the first time. A total of 24 compounds, accounting for 95.5% of the total oil, have been identified. The oil was characterised by a high proportion of sesquiterpene hydrocarbons (36.3%), followed by oxygenated sesquiterpenes (34.7%) and oxygenated monoterpenes (24.5%). The main compounds were germacrene D (12.5%), T-cadinol (11.8%) and verbenone (6.9%). The essential oil was tested for its antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis and the clinical strain Acinetobacter sp. as well as facts cytotoxic activity towards the human breast cancer cells MCF-7. This oil did not exhibit significant antibacterial activity against the tested bacteria; however, it exerted a significant cytotoxic activity against the tested cell line (IC50 = 8.16 µg/mL).

Chemical composition of essential oils from leaves, stems, flower heads and roots of Conyza bonariensis L. from Tunisia.

The essential oils isolated at the flowering stage in spring, summer and autumn of the aerial and underground parts of Conyza bonariensis L. growing in Tunisia were analysed by GC and GC/MS; 143 constituents were identified, and among them 20 were major. The oils of C. bonariensis gathered in spring were rich in matricaria ester (1.2-67.3%), (Z)-nerolidol (0.3-19.9%) and caryophyllene oxide (0.8-14.3%). In the summer samples, the oils of C. bonariensis were rich in matricaria ester (1.6-76.4%), caryophyllene oxide (1.6-22.6%) and (E)-ß-farnesene (1.1-22.7%). The main constituents in the autumn samples were matricaria ester (trace to 63.5%), geranyl acetone (0.0-25.3%), trans-α-bergamotene (0.0-24.3%) and limonene (2.7-15.3%). The oils showed significant variation among the seasons. Remarkable differences were found between the constituent percentages of the different studied organs. The C. bonariensis sample from Tunisia was a matricaria ester chemotype and was quite different from the samples of other countries of origin.

Saoussanabiloïde, a novel antifungal alkaloid from Echiochilon fruticosum Desf. growing in Tunisia.

Bioactivity guided fractionation of Echiochilon fruticosum Desf. (Boraginaceae) butanolic extract biautography assay against fungi led to the isolation of a new bioactive alkaloid, named saoussanabiloïde (1). Its structure was established on the basis of spectroscopic measurements, IR, MS and 2D NMR using COSY, HMQC and HMBC experiments. The strongest inhibitory effect of the butanolic extract, from fractions derived from the crude extract and saoussanabiloïde (1), were observed against Fusarium oxysporum f. sp. niveum.

A new C9 nor-isoprenoid glucoside from Rantherium suaveolens.

The new C(9) nor-isoprenoid 3-methyl-octa-1,5-diene-7-one-3-O-beta-D-glucopyranoside, named as ranthenone glucoside (1), together with the previously known 9-hydoxylinaloyl glucoside (2), sitosterol-3beta-O-[6'-palmitoyl-beta-D-glucopyranoside] (3), scopoletin (4), fraxetin (5), and scopolin (6), were isolated from the aerial parts of Rantherium suaveolens. The structures of these compounds were elucidated by extensive spectroscopic analysis.

New ceramides from Rantherium suaveolens.

A mixture of five new ceramides was isolated from the aerial parts of Rantherium suaveolens and characterized by spectroscopic and chemical methods. Their structures were elucidated by spectroscopic and chemical methods as (2S,3S, 4R,2'R, 14E)-2-(2'-hydroxydocosanoylamino) - 14 - octadecene -1,3,4-triol (1), (2S,3S,4R,2'R, 14E)-2-(2'-hydroxytricosanoylamino)-14-octadecene-1,3,4-triol (2), (2S,3S,4R,2'R, 14E)-2-(2'-hydroxytetracosanoylamino)- 14 - octadecene - 1,3,4 - triol (3), (2S, 3S,4R,2'R, 14E) - 2 - (2'- hydroxypentacosanoylamino) - 14 - octadecene - 1,3,4-triol (4), and (2S,3S,4R,2'R,14E)-2-(2'-hydroxyhexacosanoylamino)-14-octadecene-1,3,4-triol (5).

Isolation and structure elucidation of a flavanone, a flavanone glycoside and vomifoliol from Echiochilon fruticosum growing in Tunisia.

A flavanone and a flavanone glycoside, together with vomifoliol, have been isolated for the first time from the aerial parts of the plant Echiochilon fruticosum and identified. Their structures were established on the basis of spectroscopic measurements, mainly 2D NMR using COSY, HMQC and HMBC experiments.