The increase in O2 nodule-conductance under phosphorus deficiency varies among genotypes in Medicago truncatula.

The effect of phosphorus deficiency on plant growth, nodulation, and symbiotic nitrogen fixation as well as, the nodulated-roots oxygen consumption, nodule permeability and conductance to the oxygen diffusion of Medicago truncatula-Sinorhizobium meliloti symbiosis were studied. Three lines, namely TN6.18, originated from local populations, F83005.5 originated from Var (France) and Jemalong 6, a reference cultivar from Australia, were hydroponically grown in nutrient solution supplied with 5 µmol (P deficient) and 15 µmol (P sufficient: Control), under semi-controlled conditions in a glasshouse. A genotypic variation in tolerance to P deficiency was found: TN6.18 was the most tolerant line whereas F83005.5 was the most sensitive. The relative tolerance of TN6.18 was concomitant with the greater P requirement, the higher N2 fixation, the stimulation of nodule respiration and the less increases of conductance to the oxygen diffusion in nodules tissues. The higher P use efficiency for nodule growth and for symbiotic nitrogen fixation was detected in the tolerant line. Results suggest that the tolerance to P deficiency seems to depend on thehost plant ability to reallocate P from both leaves and roots to their nodules. P is needed in high energy demand conditions to maintain adequate nodule activity and prevent negative effects of the O2 excess on the nitrogenase.

Polysaccharides in CO2 enriched Arthrospira platensis: Structure, physico-chemical properties, antioxidant and cytotoxicity activities and laser burn wound healing in rats.

This work was undertaken to determine the structural characteristics of polysaccharides extracted from CO2-enriched Arthrospiraplatensis (Spirulina Water Soluble Polysaccharide: SWSP), as well as its antioxidant activities, cytotoxic effects and laser burn wound healing in rats. This SWSP was structurally characterized by Scanning Electron Microscopy (SEM), Fourier-transformed infrared (FT-IR), X-ray diffraction (XRD), high-performance liquid chromatography (HPLC), and thin layer chromatography (TLC). This novel polysaccharide was found to have an average molecular weight of 6.21 kDa. It is a hetero-polysaccharide composed of rhamnose, xylose, glucose and mannose. According to XRD and FT-IR spectra, the SWSP showed a semi-crystalline structure. It is composed of 100 to 500 µm geometric shaped units with flat surfaces and it was found to inhibit the proliferation of human colon (HCT-116) and breast (MCF-7) cancers. This polysaccharide display potential antioxidant activities determined through three different assays: scavenging activity against 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS), 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) scavenging assay and ferric reducing antioxidant power assay (FRAP). Results strongly support the beneficial effects of the SWSP to accelerate wound healing in rats. Indeed, its application significantly increased tissue re-epithelization and remodeling phases, after 8 days of the experiment. Findings herein demonstrated that SWSP could be a novel auspicious source of natural wound healing closure and/or cytotoxic remedy.

Phytochemical Profiling and Biological Potential of Prunus dulcis Shell Extracts.

Prunus dulcis is one of the most widely cultivated species in the world. Its fruit (almond) is rich in various nutritious and bioactive compounds that exert several beneficial effects. The aim of this study was to determine the chemical profile and evaluate the biological potential in vitro of almond shell extracts. The chemical analysis of shell extracts led to the identification of 15 compounds by HPLC-DAD, of which 11 were first detected in the almond plant. Twenty-six volatile compounds were identified by the GC-MS technique; among them, seven were firstly detected in the studied plant. For the biological activities, the extracts demonstrated moderate inhibition potential against the antioxidant, antidiabetic, and cytotoxic activities. The methanol extract at 50 µg/mL showed the highest antioxidant (45%) and antidiabetic activities (45% against alpha-glucosidase and 31% against alpha-amylase extracts), while the cyclohexane and dichloromethane at 50 µg/mL showed the highest cytotoxic activity towards Hela (32.2% with cyclohexane) and RAW 264-7 (45% with dichloromethane). Overall, these findings demonstrate the potential of almond shell extracts as a source of bioactive compounds that could be applied in the pharmaceutical and medical fields.

Polysaccharides from South Tunisian Moringa alterniflora Leaves: Characterization, Cytotoxicity, Antioxidant Activity, and Laser Burn Wound Healing in Rats.

Phytochemical properties have recently increased the popularity of plant polysaccharides as wound dressing materials. This work aims at studying the structural characteristics of polysaccharides extracted from Moringa leaves (Moringa Leaves Water Soluble Polysaccharide: MLWSP), and its antioxidant activities, cytotoxic effects, and laser burn wound healing effects in rats. This MLWSP was structurally characterized. Results showed 175.21 KDa and 18.6%, respectively, for the molecular weight and the yield of the novel extracted polysaccharide. It is a hetero-polysaccharide containing arabinose, rhamnose, and galactose. XRD suggested a semi-crystalline structure of the studied polymer and FT-IR results revealed a typical polysaccharide structure. It is composed of 50 to 500 µm rocky-shaped units with rough surfaces and it was found to inhibit the proliferation of the human colon (HCT-116) (IC50 = 36 ± 2.5 µg/mL), breast (MCF-7) (IC50 = 48 ± 3.2), and ovary cancers (IC50 = 24 ± 8.1). The MLWSP showed significant antioxidant effects compared to Trolox (CI50 = 0.001 mg/g). Moreover, promising wound healing results were displayed. The effect of MLWSP hydrogel application on laser burn injuries stimulated wound contraction, re-epithelization, and remodeling phases 8 days after treatment. The wound healing potential of MLWSP may be due to its significant antioxidant activity and/or the huge amount of monosaccharide molecules.

Optimizing Alternative Substrate for Tomato Production in Arid Zone: Lesson from Growth, Water Relations, Chlorophyll Fluorescence, and Photosynthesis.

Soilless culture is considered the mostpromising, intensive, and sustainable approach with various advantages for plant production in terms of saving water and nutrients. It can provide consumers with sufficient and high-quality food. However, the commonly used growing substrate for soilless cultivation, coconut fiber (CF), is usually imported and expensive or even unavailable. The objectives of this study were to investigate the impact of local organic farm resources substrates on tomato (Solanum lycopersicum L.) plant growth, water relations, photosynthesis, chlorophyll fluorescence, and phytochemical analysis of fruits in a hydroponics culture system. Two growth substrates were evaluated: date-palm waste composted with animal manure (7:3 w/w) (DPAM) and date-palm trunk compost (DPT). CF and local soil were utilized as positive and negative controls, respectively, in randomized blocks. The results revealed that DPAM substrate enhanced plant growth and physiology: shoot development, leaves tissues hydration, and photosynthetic parameters, as well as chlorophyll fluorescence. However, DPT and CF improved fruit quality: water, mineral, sugar, and protein content. The antioxidant activity of the fruit extract was the greater in DPAM, reaching 13.8 mg GAEg-1 DW. This value wasdecreased in soil by 40%. Photosynthesis activity was the most important in DPAM with 12 µmol CO2 m-2 s-1, and only 6.4 µmol CO2 m-2 s-1 in the soil condition. However, regarding the non-photochemical quenching, the dissipated light energy was greater in soil (0.096 ± 0.02) than in DPAM (0.025 ± 0.04). Date-palm waste-based substrates improved tomato vegetative growth and fruit quality as compared to soil-based culture. Date-palm waste-based substrates supplemented with manure appear to be promising and less expensive alternatives to the coconut fiber substrate extensively used in soilless crops in North Africa.

Physicochemical, techno-functional, and antioxidant properties of a novel bacterial exopolysaccharide in cooked beef sausage.

This work investigates the effects of partial replacement of vitamin C (Vit C) with a purified exopolysaccharide (EPS-Ca6) produced by Lactobacillus sp. Ca6, on the antioxidant activities of cooked beef sausages during refrigerated storage. The physicochemical, techno-functional and viscosity properties of EPS-Ca6 were also studied. Functional properties of EPS-Ca6 were determined based on Water Holding Capacity (WHC), Oil Holding Capacity (OHC), emulsification activity, and foaming ability. EPS-Ca6 demonstrated excellent emulsifying and emulsion stabilizing properties. It was able to emulsify several food-grade oils and hydrophobic compounds, particularly corn oil and diesel with emulsification indexes of 90 and 100%, respectively at a concentration of 0.5%. The effect of EPS-Ca6 on oxidative processes in cooked beef sausages during storage up to 12days at 4°C was evaluated. The obtained results showed a high rate (p<0.05) of oxymyoglobin (OxyMb) and low lipid oxidation. Overall, our findings provided evidence that EPS-Ca6 could be used as a natural additive for maintaining storage stability of cooked beef sausages, and could replace synthetic polymer in several industrial applications.