ANTIBACTERIAL, ANTIFUNGAL AND ANTIOXIDANT ACTIVITIES OF TUNISIAN OLEA EUROPAEA SSP. OLEASTER FRUIT PULP AND ITS ESSENTIAL FATTY ACIDS

Objective: This study was conceived to evaluate the essential fatty acids, secondary metabolite, antimicrobial and antioxidant activities of Olea europaea ssp. oleaster fruits pulp methanolic extract.Methods: Analysis of the lipid content from unexploited Olea europaea ssp. oleaster pulp was carried out using gas chromatography. The antioxidant activity was evaluated by DPPH radical scavenging. The antimicrobial activity was also tested against seven pathogenic bacteria, two fungal species and one yeast strain using two methods.Results: The obtained results showed that the major components of fatty acids were oleic acid (77.4%) and elaidic acid (17.58%). Moreover, the tested extract was rich in phenol (84.04±0.01 mg GAE/g DW) than in flavonoids (60.41±0.02 mg RE/g DW). In addition, it showed puissant antioxidant (IC50 = 28±0.01 µg/mL), antibacterial and antifungal activities. The inhibition zones diameters and the minimum inhibition concentration values for tested microorganisms were in the range of 13-18 mm and 3.125-25 mg/mL, respectively.Conclusion: This study shows that Olea europaea ssp. oleaster fruit pulp could be developed into ingredients for use in foods as the natural antioxidant and antimicrobial agent

Influence of the drought on antioxidant and enzymatic activities of two Pinus species in humid and sub-humid climate

Pinus genus is widespread in the Mediterranean region and the most common in Tunisia. The impact of high temperatures in the mid-summer period (July 2015 and July 2016) on phenols and biological properties were examined in vitro. The study was carried out in two arboreta, in humid and sub-humid climates, dry needles of Pinus pinea and Pinus pinaster were used for secondary metabolites, antioxidant activities, and enzymatic inhibitory activities. The amount of all measured parameters increased from 2015 to 2016 in the two pine species in the two arboreta. Pinus pinea produced more phenols and showed higher antioxidant activity and a-amylase and lipoxygenase inhibitory activities than Pinus pinaster. Besides, both species generally presented better biological activities and higher phenol amounts in 2016 than in 2015, being 2016 warmer and drier than 2015 in both harvest zones. It was evident that both species in every bioclimatic zones adapted to the new climate conditions producing more secondary metabolites that rendered better antioxidant and inhibitory enzymatic activities. These findings confirmed the impact of mid-summer water deficits on pine species in the context of climate change and help to select the most resistant species for future reforestation.info:eu-repo/semantics/publishedVersio

Fatty acids composition of Tunisian Ziziphus lotus L. (Desf.) fruits and variation in biological activities between leaf and fruit extracts

International audienceThis study was conceived to evaluate the essential fatty acids, secondary metabolites, antiradical and antimicrobial activities of unexploited Tunisian Ziziphus lotus L. The obtained results indicated that the major components of fatty acids were oleic acid (88.12%) and elaidic acid (7.88%). Leaves contained higher amount of total phenols, flavonoids and tannins than fruits, although both methanolic extracts had significant antioxidant activities. Significant correlations were observed between the total phenol or flavonoid contents in methanolic extracts and antioxidant activity estimated by using both 2,2-diphenyl-1-picrylhydrazyl and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic radical-scavenging methods. In addition, both methanolic extracts exhibited strong antibacterial and antifungal activities. The inhibition zone diameters and the minimal inhibition concentration values were in the range of 10-17mm and 3.1-50mg/mL, respectively

Phenolic content, antioxidant capacity and antimicrobial activity of leaf extracts from Pistacia atlantica

International audienceThe aim of this study was to investigate the secondary metabolites related to Pistacia atlantica Desf as well as their biological activities. Results show that using ethanol as a solvent exhibited the highest content of total phenolics and flavonoids (68.23 mg GAE g(-1) of DW and 44 mg RE g(-1) of DW), followed by aqueous one (20.07 mg GAE g(-1) of DW and 15 mg RE g(-1) of DW). Good correlation (Data not shown) was obtained between the DPPH radical-scavenging activities and total phenolics contents. Many similarities were observed between the results of the DPPH (IC50 = 32 and 200 mu g mL(-1)) and ABTS (IC50 = 42 and 300 mu g mL(-1)) assays. All tested extracts contained phenolic compounds exhibited an antimicrobial effect against Gram-positive and Gram-negative bacteria. Further, researches for identification and purification of phenolic compounds are required. [GRAPHICS]

Chemical Composition of Ruta chalepensis Leaves Essential Oil and Variation in Biological Activities between Leaves, Stems and Roots Methanolic Extracts

International audienceTo our knowledge, this study is the first to investigate the biological activities of the methanolic extracts of leaves, roots and stems of Ruta chalepensis L. (Rutaceae) in Tunisia. The chemical composition of the essential oil extracted from R. chalepensis leaves was determined by GC-MS. The antioxidant activities of tested essential oil and the methanolic extracts of leaves, stems and roots of R. chalepensis were evaluated using DPPH and ABTS radicals scavenging tests. Their antimicrobial activities were achieved by disc diffusion method and broth dilution assay. The main components of the selected essential oil were menthol (43.92 %) and linalool (42.10 %). Significant differences were found between the total phenol contents and biological activities of the different parts of R. chalepensis. In addition, significant correlations were observed between antioxidant activities and phenolic contents for methanol extracts. In fact, leaves extract presented higher total phenol content than stems and roots extracts. The tested oil showed better antioxidant activity than methanolic extracts. The highest antioxidant activity was recorded in leaves methanolic extract. The latter showed strong antibacterial activity against tested microorganisms, whereas the evaluated oil remained almost inactive. The inhibition zones diameters and minimal inhibitrice concentration values for tested bacteria, which were sensible to different methanolic extracts, were in the range of 8-35 mm and 0.78-25 mg/ml, respectively. This study demonstrated that the R. chalepensis extract can be regarded as promising candidate for natural plant source of antioxidant and antimicrobial agents

Chemical Composition and in vitro Antimicrobial Activities of Mentha pulegium Leaves Extracts against Foodborne Pathogens

International audienceThe replacement of synthetic additives by natural active compounds fosters research on the screening of medicinal plants as sources of new antioxidants. Moreover, such compounds can be used for extension of product shelf life by inhibiting the growth of foodborne spoilage bacteria. This study focused on the evaluation of biological activities of M. pulegium EO because of its application in food industries as a reasonably safe agent.Thus, this species might be a good candidate for further investigation in devel-oping new antioxidants, as well as preservatives in food against the well-known causal agents of foodborne diseases and food spoilage, particularly E. coli, S. typhimirium, L. monocytogenes, P. aeruginosa and S. aureu

Effect of environmental conditions on chemical polymorphism and biological activities among Artemisia absinthium L. essential oil provenances grown in Tunisia

International audienceVariation on yields, chemical composition and biological activities of essential oils of Artemisia absinthium L. collected from four different bioclimatic areas ranging from Humid to Arid stage of Tunisia was investigated. The observed yields of essential oils increase significantly from arid to humid climate. A significant qualitative and quantitative variation of the chemical composition according to the studied localities was revealed. Plants collected from the Inferior Arid bioclimatic region (Gafsa) presented chamazulene, a-thujone and camphor as the main components of their essential oils. However, for Superior Arid (Kasserine) and Semi Arid (El Kef) bioclimatic regions, camphor and chamazulene are the dominant constituents followed by linalool for Kasserine and bornyl acetate for El Kef originated oils. The Humid bioclimatic zone (Ghar Dimaou) showed different chemotype and presented camphor, (Z)-sabinene hydrate and 1-terpinen-4-ol as the major compounds. Based on the two DPPH and ABTS tests, the investigated oils highlighted important in vitro antioxidant capacities which increase significantly from the humid (Ghar Dimaou) to the Inferior Arid bioclimatic zone (Gasfa). Even the investigated essential oils displayed an antimicrobial activity against all the tested bacterial and fungal strains with variable degrees, our findings did not reveal a clear correlation between the antimicrobial properties and the studied bioclimatic zones. (C) 2014 Elsevier B.V. All rights reserved

Ecotype effects on photosynthesis performance using A/PFFD among Pinus nigra Arn.

International audienceThis study aimed to provide insights on intraspecific variability of photosynthesis performance of 19 provenances of black pine planted in a common garden. The experiment was conducted in an experimental trial located at Souiniet (the southern limit of its range) Photosynthetic capacity characterized by lightsaturated net photosynthetic rates, associated light compensation points and apparent quantum yield was monitored by measuring the response of leaf gas exchange to light levels. Amax was the highest in provenancesPuget Theniers (nigra ssp), Saint-Guilhem (salzmanni ssp), Marghese and les barres (laricio ssp). The lowest value was recorded in Olette of the subspecies salzmanni. Needles from two provenances Crimea (pallasiana ssp) and Les Barres (ssp laricio) revealed the highest apparent quantum yield (ɸ), followed by Brougatlès Ales (salzmanni ssp), Trenta Coste (ssp laricio), Les barres and Puget Theniers (nigra ssp). The lowest apparent quantum Yield was recorded in Laricio subspecies (Cosenza; Les barres and Bois frerot). The highest value ofdark respiration (Rd) was shown in provenance Les barres (laricio ssp), while Grancia and Tavola of the laricio subspecies reported the lowest one. Provenances Tavola (laricio ssp) and Puget Theniers (nigra ssp) exhibited the highest LCP. The provenance Crimée (pallasiana ssp) and Aspromonto (laricio ssp) recorded the lowest values. The maximum values of photosynthesis are positively correlated with the total chlorophyll contentsand Leaf Mass area. Our study illustrates that Photosynthesis performance showed a difference between 19 provenances of black pine; it seems that black pine photosynthetic performance is eco-typical independent

Chemical Composition, Antioxidant Potential, and Antibacterial Activity of Essential Oil Cones of Tunisian Cupressus sempervirens

The extraction yield of the essential oil (EO) extracted by hydrodistillation from the cones of Tunisian Cupressus sempervirens L. was of 0.518%. The chemical composition was analyzed by GC-MS. Results showed that this essential oil was mainly composed of monoterpene hydrocarbons (65%) with α-pinene as the major constituent (47.51%). Its antioxidant activity was ascertained by evaluating the total antioxidant capacity and also by evaluating its inhibitory effect against DPPH and ABTS radicals. In addition, it showed a strong antioxidant power against the DPPH (IC50 = 151 µg/mL) and ABTS (IC50 = 176.454 µg/mL) radicals scavenging. Moreover, its antibacterial activity was tested against different species of pathogenic bacteria (three Gram-positive and eight Gram-negative bacteria). The bacterial strains susceptible to the evaluated oil were Bacillus subtilis, Escherichia coli, Klebsiella oxytoca, Morganella morganii, Shigella, and Vibrio cholerae