Phytochemical analysis, biological activities of methanolic extracts and an isolated flavonoid from Tunisian Limoniastrum monopetalum (L.) Boiss: an in vitro and in silico investigations.

In recent years, due to the dramatic increase of the bacteria resistance to antibiotics and chemotherapeutic drugs, an increasing importance is given to the discovery of novel bioactive molecules, more potent than those in use. In this contest, methanol extracts of different parts of the medicinal plant Limoniastrum monopetalum (L.) Boiss. (Plumbaginaceae), widely occurring in Tunisia, were prepared to evaluate the antimicrobial and antiproliferative activities. The methanol extract of the roots showed the highest antibacterial activity against E. coli, S. aureus and E. faecalis, whereas the stem extract exhibited the highest antiproliferative effects towards a Hela cell line. Analysis of volatile fractions, using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detector (GC-FID) techniques, led to the identification of camphor as the most abundant constituent, which represented from 84.85 to 99.48% of the methanol extracts. Multiple chromatographic separation of the methanol leaf extract afforded the flavonoid maeopsin-6-O-glucoside (S1) and a few fractions that were subjected to biological activity assays. One fraction exhibited interesting antibacterial activity against E. coli and E. faecalis (MIC values of 62.5 and 78.12 µg/mL, respectively), and antiproliferative effects against Hela and A549 cells (IC50 = 226 and 242.52 µg/mL, respectively). In addition, in silico studies indicated that maesopsin-6-O-glucoside, which was moderately active against Staphylococcus aureus, strongly interacted with the active site of the accessory gene regulator protein A (AgrA) of Staphylococcus aureus.

Chemical composition, antioxidant and antimicrobial effects of Tunisian Limoniastrum guyonianum Durieu ex Boiss extracts.

In the present investigation, extracts obtained from L. guyonianum Durieu ex Boiss. aerial parts were used to evaluate total phenolic, flavonoid and tannin contents. A study of antioxidant activities of the prepared samples was carried out on the basis of 1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2-2'-azino-bis-(3-ethylbenz-thiazoline-6-sulfonic acid) (ABTS+.) and ferric reducing antioxidant power (FRAP) assays. Moreover, the efficiency of methanolic, chloroformic and petroleum ether extracts and the deriving fractions from the methanolic extract was tested against human bacterial and fungal pathogenic strains using micro dilution method in 96 multiwell microtiter plate. Furthermore, leaves and stems extracts were subjected to RP-HPLC for phenolic compounds identification. Results showed that polyphenolic contents and antioxidant activities varied considerably as function of solvent polarity. Moreover, antiradical capacities against DPPH, ABTS(+.) and reducing power were maxima in methanol aerial parts extract which showed the highest polyphenol contents (134mg CE/g DW). The antimicrobial activities showed that methanolic, chloroformic and petroleum ether extracts were found to be most potent against Pseudomonas aeruginosa and Staphylococcus aureus with MIC values of 23 and 46µ.mL(-1), respectively. The fractions F(13) and F(16) have a great antifungal potential against Candida glabrata, Candida krusei and Candida parapsilesis (MIC=39µ.mL(-1)). The RP-HPLC analysis lead the identification of gallic, procatechuic and trans-cinnamic acids, methyl-4-hydroxybenzoate, n-propyl-3,4,5-trihydroxybenzoate, epicatechin, naringin and myricetin in L. guyonianum Durieu ex Boiss. leaves and stems extracts.

Fluctuating asymmetry in grass goby Zosterisessor ophiocephalus Pallas, 1811 inhabiting polluted and unpolluted area in Tunisia.

Fluctuating asymmetry, a random deviation of bilateral traits, is assessed on grass goby Zosterisessor ophiocephalus Pallas, 1811 living in one disturbed site and in one unpolluted site Gulf of Gabes (Tunisia). Statistical analysis showed that assessed asymmetries are fluctuating. FA of orbital diameter, sub-orbital distance, pectoral fin and post-orbital length are higher in polluted site compared to control. Chemical pollution seems to be responsible for this high FA.