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 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.

Antifungal activity from polar and non-polar extracts of some Chenopodiaceae wild species growing in Tunisia.

Nine plants belonging to Chenopodiaceae family were collected around salt marshes near Monastir, located in the east Mediterranean coast of Tunisia. They were tested for their antifungal activities against six plant pathogenic fungi: Botrytis cinerea, Fusarium oxysporum f. sp. niveum, F. solani f. sp. cucurbitae, Phytophthora cactorum, Rhizoctonia solani and Nattrassia mangiferae. Data of this study showed that the highest inhibition of Botrytis cinerea growth was observed with the petroleum ether extract of Atriplex inflata fruits (F) (24.5 mm). The in vitro growth of F. oxysporum f. sp. niveum was reduced only with A. inflata whole plant (WP) petroleum ether extract (32.3 mm). The most important inhibition zones were obtained against F. solani f. sp. cucurbitae with Atriplex semibaccata methanol and acetone extracts (34.7 and 31.0 mm, respectively). This work revealed that fungitoxic compounds were probably present in the petroleum ether extract obtained from A. portulacoides (WP), since it has suppressed the growth of F. s. cucurbitae. Our investigation proved that many Chenopodiaceae species adapted to saline soils may contain phytochemical compounds with fungicidal properties.

Antiviral activity of some Tunisian medicinal plants against Herpes simplex virus type 1.

Fifteen species of Tunisian traditional medicinal plants, belonging to 10 families, were selected for this study. They were Inula viscosa (L.) Ait and Reichardia tingitana (L.) Roth ssp. discolor (Pom.) Batt. (Asteraceae), Mesembryanthemum cristallinum L. and M. nodiflorum L. (Aizoaceae), Arthrocnemum indicum (Willd.) Moq., Atriplex inflata Muell., A. parvifolia Lowe var. ifiniensis (Caball) Maire, and Salicornia fruticosa L. (Chenopodiaceae), Cistus monspeliensis L. (Cistaceae), Juniperus phoenicea L. (Cupressaceae), Erica multiflora L. (Ericaceae), Frankenia pulverulenta L. (Frankeniaceae), Hypericum crispum L. (Hypericaceae), Plantago coronopus L. ssp. eu-coronopus Pilger var. vulgaris G.G. (Plantaginaceae) and Zygophyllum album L. (Zygophyllaceae). Fifty extracts prepared from those plants were screened in order to assay their antiviral activity against Herpes simplex virus type 1 (HSV-1), using neutral red incorporation. Extracts from eight plants among these 15 showed some degree of antiviral activity, while the methanolic extract of E. multiflora was highly active with EC(50) of 132.6 microg mL(-1). These results corroborate that medicinal plants from Tunisia can be a rich source of potential antiviral compounds.

Responses of Spodoptera littoralis larvae to Tunisian plant extracts and to neo-clerodane diterpenoids isolated from Ajuga pseudoiva leaves.

Thirteen plants growing in Tunisia were tested against Spodoptera littoralis larvae. From the acetone extract of Ajuga pseudoiva leaves, showing interesting antifeedant activity, three new (1-3) and two known (4-5) active clerodane diterpenoids were isolated following a bioassay-guided chromatography.