•Milk contamination can cause health problems and economic losses.•Gram-positive bacteria are involved in milk contamination.•Thymus capitatus essential oil inhibit the growth of milk contaminating ...bacteria.•Nanoencapsulation enhance Thymus capitatus essential oil antibacterial activity.
The objective of this study is to evaluate the effect of either a solution of Thymus capitatus essential oil or its nanoemulsion on the quality of milk contaminated by bacteria. After 24h of S. aureus inoculation, bacterial growth reached 202×103CFU/ml in the presence of the essential oil while it was limited to 132×103CFU/ml when treated with nanoemulsion. The reduction of antioxidant capacity of milk treated with essential oil was higher when treated with nanoemulsion. Moreover, free essential oil was more efficient in protecting proteins from degradation than the nanoemulsion. For instance, after 24h of E. hirae contamination, 26% of the total proteins were consumed in the presence of nano-encapsulated essential oil, while only 14% of the initial content was consumed when free essential oil was added. Concerning milk acidity increase and the inhibition of peroxide production, no statistical differences have been recorded between the use of free essential oil or its nano-emulsion. In conclusion, bulk or nano-encapsulated T. capitatus essential oil preserve milk quality and can extend its shelf life.
Cakile maritima is a local oilseed halophyte exhibiting potential for secondary metabolite production. In the present study, plant growth, leaf polyphenol content and antioxidant activity were ...comparatively analyzed in two
C. maritima Tunisian accessions (Jerba and Tabarka, respectively sampled from arid and humid bioclimatic stages) under salt constraint. Three-week-old plants were subjected to 0, 100, and 400
mM NaCl for 28
days under glasshouse conditions. A significant variability in salt response was found between both accessions: while Tabarka growth (shoot biomass, leaf expansion) was significantly restricted at 100 and 400
mM NaCl, compared to the control, Jerba growth increased at 100
mM before declining at 400
mM NaCl. The better behaviour of Jerba salt-challenged plants, compared to those of Tabarka, may be related to their higher polyphenol content (1.56- and 1.3-fold the control, at 100 and 400
mM NaCl respectively) and antioxidant activity (smaller IC
50 values for both 1,1-diphenyl-2-picrylhydrazyl and superoxide scavenging), associated with lower leaf MDA accumulation (ca. −66% of the control at 100
mM NaCl). Taken together, our findings suggest that halophytes may be interesting for production of antioxidant compounds, and that the accession-dependent capacity to induce antioxidative mechanisms in response to salt, may result in a corresponding variability for growth sustainability.
•Nanoencapsulation of essential oils facilitate their incorporation into foods.•40 formulations of thyme essential oil nanoencapsulation were evaluated.•Nanoemulsion with SDS as emulsifier present ...appropriate droplet diameter averages.•Nanoemulsion stability was investigated for 12 days at different temperatures.•Nanoencapsulation enhanced thyme essential oil antibacterial activities.
This work aimed to nanoencapsulate Thymus capitatus essential oil as natural food preservative. To fix ingredients type and concentrations, preliminary formulations were tested for their droplet size average and distribution. Emulsions stability was investigated for 12 days and the antibacterial activity of bulk and encapsulated essential oil were studied. Results showed that nanoemulsions containing 1% of SDS as emulsifier and 10% of dispersed phase containing 70% of the essential oil have an appropriate droplet diameter averages (around 110 nm). Stability tests demonstrated that nanoemulsions, stored at 4 °C, showed the highest stability. Moreover, antibacterial activity results exhibited the improvement of encapsulated T. capitatus essential oil efficiencies as compared to bulk one. In fact, nanoemulsion presented higher bacterial growth inhibition, lower minimum inhibitory and bactericidal concentrations, and better time kinetic results, as compared to bulk one. Gathered results provide useful information for designing effective natural preservatives that inhibit food bacterial spoilage.
Halophyte ability to withstand salt-triggered oxidative stress is governed by multiple biochemical mechanisms that facilitate retention and/or acquisition of water, protect chloroplast functioning, ...and maintain ion homeostasis. Most essential traits include the synthesis of osmolytes, specific proteins, and antioxidant molecules. This might explain the utilization of some halophytes as traditional medicinal and dietary plants. The present study aimed at assessing the phenolic content and antioxidant activities of some Tunisian halophytes (Cakile maritima, Limoniastrum monopetalum, Mesembryanthemum crystallinum, M. edule, Salsola kali, and Tamarix gallica), depending on biological (species, organ and developmental stage), environmental, and technical (extraction solvent) factors. The total polyphenol contents and antioxidant activities (DPPH and superoxide radicals scavenging activities, and iron chelating and reducing powers) were strongly affected by the above-cited factors. Such variability might be of great importance in terms of valorising these halophytes as a source of naturally secondary metabolites, and the methods for phenolic and antioxidant production.
In the present study, a nanoemulsion was developed to improve the functional performance of Thymus capitatus essential oil (thyme EO) as natural food preservative. Thyme EO was submitted to ...phytochemical prospection and its safety limit was evaluated by acute oral toxicity. Hereafter, the EO was nanoencapsulated and the antioxidant and antibacterial activities of bulk and encapsulated EO were examined. Results showed that concentrations up to 2g·kg−1b.w. of T. capitatus EO did not present any toxic effects. Moreover, results exhibited an enhancement of nanoencapsulated EO antibacterial activity. In fact, nanoemulsion demonstrated higher growth inhibition diameters than free EO (15.8 and 9.8mm, against Staphylococcus aureus, respectively). Furthermore, nanoemulsion exhibited significant lower minimum inhibitory concentration against all tested bacteria than bulk EO. However, nanoencapsulating T. capitatus EO decreased significantly its antioxidant activity. Indeed, for DPPH test, free EO IC50 concentrations were considerably lower than those of the nanoencapsulated form (300 and 390μg·mL−1, respectively). As well, the capacity of T. capitatus EO to inhibit the β-carotene bleaching has been reduced after its nanoencapsulation. These results provide useful information for designing effective natural preservative able to inhibit food bacterial spoilage.
•T. capitatus essential oil did not present any toxic effect.•Thyme essential oil exhibited high antimicrobial and antioxidant activities.•Nanoencapsulation enhance markedly thyme essential oil antibacterial activity.•Free and nanoencapsulated essential oil may be used as safe food preservative.
Tamarix gallica is a halophytic species having hepatotonic and stimulant properties, as it was traditionally used in the treatment of various liver disorders. Leaf and flower infusion have ...anti-inflammatory and anti-diarrheic proprieties. In this work, we have investigated antioxidant and antimicrobial activities of leaf and flower extracts and their phenolic composition. Results showed that flowers exhibit a higher antioxidant activity as compared to the leaves, IC
50 values of the flower extracts are being 1.3 (β-carotene bleaching) to 19 times (lipid peroxidation inhibition) lower than those for leaves. Accordingly, flower extracts exhibited the highest total phenolic content (135.35
mg
GAE/g
DW) and RP-HPLC analysis showed that syringic acid, isoquercitin as well as catechin were the major phenolics. Furthermore, Tamarix extracts showed appreciable antibacterial properties against human pathogen strains. The mean inhibition zone was from 0 to 6.5
mm when the concentration increased from 2 to 100
mg/l. The strongest activity was recorded against
Micrococcus luteus and the lowest activity was observed against
Escherichia coli. Moreover, organ extracts show a weakly to moderate activity against the tested
Candida. These findings suggest that Tamarix may be considered as an interesting source of antioxidants for therapeutic or nutraceutical industries and for food manufactures.
The current study aimed to evaluate Tunisian Tamarix africana Poir biological activities. In this study, novel biological activities of the shoot extracts related to their phenolics investigated. ...Secondary metabolite contents, antioxidant, anti-inflammatory and cytotoxic activities of four extracts (hexane, dichloromethane, methanol and water) were investigated. Antioxidant activities were assessed via in vitro and ex vivo assays. Besides, anticancer activity was investigated against human lung carcinoma (A-549) and colon adenocarcinoma (DLD-1) cells. The anti-inflammatory ability was evaluated via inhibition of LPS-induced NO production in RAW 264.7 macrophage cell lines. Methanol and water extracts displayed the highest antioxidant (IC
50
= 3.3 and 4.3 µg/mL respectively), which are correlated activities correlated with phenolic contents. Hexane extract exhibited an important anti-inflammatory effect inhibiting NO ability by 100% at 80 µg/mL. Besides, T. africana extracts were found to be active against A-549 lung carcinoma cells with IC
50
values ranging from 20 to 34 µg/mL. These results suggested that T. africana is considered as a potential source of readily accessible natural molecules with a promising effect on human health and diseases.
Introduction
Drought stress is one of the most devastating environmental stressors, especially in the arid and semi-arid regions of the world. Considering the major constraints that drought stress ...poses to crop production and the consequent yield losses in food crops, breeding for climate-resilient crops is an efficient means to mitigate stress conditions.
Materials and methods
This study aimed at evaluating the response of four squash (
Cucurbita maxima
Duchesne) landraces to drought stress at germination and at plant stage. Drought stress was induced by different concentrations of D-mannitol (-0.24, -0.47 and -0.73 MPa). The tested parameters at germination stage included germination percentage, seedling vigor index, seed water absorbance and seedling growth potential. At the plant stage, leaf chlorophyll and carotenoids content, chlorophyll fluorescence, evapotranspiration, photosynthesis activity and several biomarkers, namely malondialdehyde, proline, total phenols content, total flavonoids content and DPPH radical scavenging activity were evaluated in both roots and leaves.
Results and discussion
Our results indicate a magnitude of drought stress effects reflected via repression of germination and seedling growth as well as adjustments in physiological functions at later growth stages, in a genotype depended manner. Among landraces, "751" and "746" showed better performance, as evidenced by higher seed germination and seedling growth potential even at high stress levels (-0.47 and - 0.73 MPa), whereas "747" was the most sensitive landrace to drought stress at both tested stages. In conclusion, our findings highlight the importance of squash landraces selection for the identification of elite genotypes with increased tolerance to drought stress.
This work focuses on the variability of
(Forssk.) Webb bioactive compounds as a function of the plant cycle. The main results showed that it exhibited the highest percentage of polyunsaturated fatty ...acids, along with superior levels of vitamin C and total phenolic compounds (66.49%, 645.6 mg·100 g
¹ FW and 23.9 mg GAE·g
¹, respectively) at the vegetative stage. Instead, at the flowering and mature fruiting stages,
(Forssk.) Webb exhibited notable contents of proline (25.4 μmol·g
¹ DW) and carotenoids (27.2 μg·g
¹ FW), respectively. The gathered data concerning the antioxidant activity highlighted the effectiveness of the vegetative stage in comparison to the other periods. Actually, IC
and EC
values of the hydromethanolic extract obtained from the plant shoots at the vegetative stage were of 23, 380, 410, 1160 and 960 μg·mL
(DPPH
and ABTS
radicals scavenging activity, reducing power, chelating power and β-carotene bleaching activity, respectively). Furthermore, the four studied stages showed appreciable antibacterial capacities against human pathogens with a higher efficiency of the vegetative stage extract. Finally, the LC-DAD-ESI/MS
analysis revealed the predominance of isoflavonoids as main class of phenolic compounds and demonstrates that individual phenolic biosynthesis was clearly different as a function of plant growth. These findings highlight that reaching the optimum efficiency of
(Forssk.) Webb is closely linked to the physiological stage.
Salt stress is considered as one of the most common abiotic stresses reducing the productivity and fruit quality of crop plants. The present study was carried out to assess the salt tolerance among ...15 local squash (
Duchesne) landraces. Different salt (NaCl) concentrations of 0, 100, 200 and 300 mM were selected in order to evaluate the response of the study germplasm to salt stress based on 12 agronomic parameters and 3 biochemical traits, proline, malondialdehyde (MDA) and chlorophylls. A varied effect of the salt stress level was observed among the studied landraces based on germination potential, as well as on growth and biochemical parameters at seedling stage. Results showed that all landraces were drastically affected at high stress level with a significant variation in their stress response, indicating the existence of considerable genetic variability. Landraces "746" and "747" were the best performing cultivars across stress levels, whereas "1007", "1008" and "1009" were the most negatively affected. Based on the tested landrace performance, four landraceswere selected and further evaluated at biochemical level, focusing on the determination of compounds that play a key role in the ability to withstand salt stress. The mean MDA content across landraces was generally increased in stressed plants, as compared to the control treatment; the increase was attributed to a peak in MDA content at specific stress levels. In particular, "746" and "1007" showed the maximum content at 100 mM NaCl, while in landrace "751", MDA content reached its peak at 300 mM NaCl. In addition, the response of most landraces to salt stress involved an increase in free proline content, with the exception of "746", with the maximum content being observed either at 200 mM ("748" and "751" landraces) or at 300 mM NaCl, where only "747" expressed the highest content. These findings can be extrapolated into efforts to develop more salt-tolerant squash landraces and exhaust the possibilities of using saline water or soils under changing climate conditions.
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