Tunisian Silybum Species: Important Sources of Polyphenols, Organic Acids, Minerals, and Proteins across Various Plant Organs.

Silybum marianum and Silybum eburneum are wild edible Mediterranean plants used in the human diet. This study presents the initial findings on the phytochemical characterization of Tunisian S. marianum and S. eburneum organs. It examined their mineral, sugar, organic acid, polyphenolic, and seed storage protein contents, as well as their antioxidant potential. In S. marianum, stems had high sodium and potassium contents, while the immature and mature seeds were rich in calcium and magnesium. However, S. eburneum had high potassium levels in stems and high sodium and calcium levels in the flowers. S. marianum showed substantial fructose variation among its organs. Conversely, S. eburneum exhibited significant heterogeneity in glucose, sucrose, and maltose levels across its organs, with maltose exclusively detected in the immature seeds. A notable organ-dependent distribution of organic acids was observed among the two species. Higher levels of phenolic contents were detected in both mature and immature seeds in both species compared to the other plant parts. The seeds possessed higher antioxidant activities than other plant organs. In both S. marianum and S. eburneum seeds, albumins and globulins were the predominant protein fractions. This study brings evidence supporting the important potential of Silybum organs as sources of nutrients with antioxidant properties for producing functional food.

Phytosynthesis of Zinc Oxide Nanoparticles Using Ceratonia siliqua L. and Evidence of Antimicrobial Activity.

Carob (Ceratonia siliqua L.) is a tree crop cultivated extensively in the eastern Mediterranean regions but that has become naturalized in other regions as well. The present study focused on the green synthesis of zinc oxide nanoparticles (ZnONPs) from Carob and their evaluation for antimicrobial activity in bacteria and fungi. The synthesized ZnONPs showed strong antibacterial activity against Staphylococcus aureus ATCC 25 923 (92%). The NPs inhibited the growth of pathogenic yeast strains, including Candida albicans ATCC90028, Candida krusei ATCC6258, and Candida neoformans ATCC14116, by 90%, 91%, and 82%, respectively, compared to the control. Fungal inhibition zones with the ZnONPs were 88.67% and 90%, respectively, larger for Aspergillus flavus 15UA005 and Aspergillus fumigatus ATCC204305, compared to control fungal growth. This study provides novel information relevant for plant-based development of new and potentially antimicrobial ZnONPs based on extracts. In particular, the development and application of phytogenic nanoparticles enhances the biocompatibility of nano-scale materials, thereby allowing to tune effects to prevent adverse outcomes in non-target biological systems.

Biochemical Characterization of Rare and Threatened Local Populations of Peas (Pisum sativum L.) Cultivated in the Arid Region of Southern Tunisia.

Pea (Pisum sativum L.) is an important legume for human and animal consumption, cultivated in many temperate regions of the world. In the present investigation, the seeds of twelve pea accessions collected from the arid regions of southern Tunisia, characterized by different colors of flowers and seed coats, were evaluated for their proteins, phenolic compounds and antioxidant activities. The protein content determined by the Bradford method ranged from 46.91 to 151.08 mg/g DW. The content of total phenol, total flavonoid and condensed tannin, ranging from 36.85 to 102.52 mg GAE/100 g DW, 6.95 to 48.11 mg QE/100 g DW, and 12.37 to 70.43 mg CE/100 g DW, respectively. These parameters were characterized respectively by the following three methods, the Folin-Ciocalteu reagent, the aluminum chloride and the vanillin assay. The LC-ESI/MS analysis identified the presence of 8 phenolic acids and 9 flavonoids which quinic acid, protocatechuic acid, hyperoside, and quercetin-3-O-rhamnosidewere detected as the most abundant compounds. Moreover, the antioxidant activity of pea seeds was evaluated by the ABTS+and DPPH tests. Indeed, DPPH and ABTS anti-free radical activity values ranged from 1.92 to 14.11 µmoL TEAC/g DW and 2.3 to 14.95 µmoL TEAC/g DW, respectively. The variability across the assessed traits revealed significant differences as computed by ANOVA tests. Else, the results showed significant correlations between seed coat color, seed shape, flower color and phenolic compounds. Therefore, genotypes characterized by a purple flower, brown seed coat, and wrinkled form had the highest levels of phenolic compounds and antioxidant activity. Correlation analysis revealed that phenolic compounds presented a strong positive correlation with antioxidant activities, while being negatively correlated with protein content. UPGMA cluster and Principal component analysis (PCA) revealed two main groups. This work highlights the nutritional value of P. sativum seeds as a good source of natural antioxidant compounds that may be useful in the food and pharmaceutical industries.

Assessment of the risks of copper- and zinc oxide-based nanoparticles used in Vigna radiata L. culture on food quality, human nutrition and health.

The present article aims to assess the phytotoxic effects of copper and zinc oxide nanoparticles (Cu NPs, ZnO NPs) on mung bean (Vigna radiata L.) and their possible risk on food quality and safety. We also study the molecular mechanisms underlying the toxicity of nanosized Cu and ZnO. Seeds of mung bean were germinated under increasing concentrations of Cu NPs and ZnO NPs (10, 100, 1000, 2000 mg/L). We analyzed levels of free amino acids, total soluble sugars, minerals, polyphenols and antioxidant capacity. Our results showed that depending on the concentrations used of Cu NPs and ZnO NPs, the physiology of seed germination and embryo growth were modified. Both free metal ions and nanoparticles themselves may impact plant cellular and physiological processes. At 10 mg/L, an improvement of the nutritive properties, in terms of content in free amino acids, total soluble sugars, essential minerals, antioxidant polyphenols and flavonoids, was shown. However, higher concentrations (100-2000 mg/L) caused an alteration in the nutritional balance, which was revealed by the decrease in contents and quality of phenolic compounds, macronutrients (Na, Mg, Ca) and micronutrients (Cu, Fe, Mn, Zn, K). The overall effects of Cu and ZnO nanoparticles seem to interfere with the bioavailability of mineral and organic nutrients and alter the beneficial properties of the antioxidant phytochemicals, mineral compounds, phenolic acids and flavonoids. This may result in a potential hazard to human food and health, at some critical doses of nanofertilizers. This study may contribute in the guidelines to the safe use of nanofertilizers or nanosafety, for more health benefit and less potential risks.

Seasonal environmental changes affect differently the physiological and biochemical responses of two Limonium species in Sabkha biotope.

To cope with abiotic stresses, the halophytes use various tolerance mechanisms that are not all known for some species of halophytes. This work aimed to model the responses of two halophytes, Limonium pruinosum and Limonium tunetanum, to changing environmental conditions over a year in Sabkha biotope, Tunisia. Our findings indicated that the model could describe well the seasonal variations of all studied traits over a year in this region (R2  > 0.80). The pH, electrical conductivity (EC), and mineral composition (i.e., Sodium [Na+ ], potassium [K+ ], calcium [Ca2+ ], and magnesium [Mg2+ ] concentrations] in the soil significantly varied during the year (P < 0.01). The highest soil Na+ concentration was found during the dry period (June-August), which matched with a high Na+ content in the aerial parts (i.e., 2455.1 and 3366.0 µmol g-1 SDM in August for L. pruinosum and L. tunetanum, respectively). This accumulation is concomitant with a deficit in nutrients, particularly K+ and Mg2+ and, to a lesser extent, Ca2+ . Following these disturbances, both species decreased their photosynthetic activity, water potential as well as the relative water content to a lesser extent, especially in August. To counteract these harmful effects, these species have accumulated organic substances, but in a different way. Indeed, L. pruinosum accumulated sucrose, fructose, and citrate, while L. tunetanum accumulated sucrose, xylitol, citrate, and malate, indicating a major role of these osmolytes in the stress tolerance mechanisms. In both species, the results also showed that all traits were highly correlated with the edaphic variables (i.e., pH, EC, Na+ , K+ , Ca2+ , and Mg2+ concentrations) and with temperature as the climatic variable.

Moringa oleifera leaves: could solvent and extraction method affect phenolic composition and bioactivities?

This study was carried out to evaluate the effect of extraction methods (direct maceration (DM) and successive maceration (SM)) and solvents (dichloromethane (DCM), ethyl acetate (EAc), butanol (But), and aqueous extraction (Aqu)) on the phenolic composition and biological activities of Moringa oleifera leaves cultivated for the first time in Tunisia. Total polyphenol content (TPC), total flavonoid content (TFC) and LC-MS analysis were performed for all extracts. Antioxidant potential by DPPH, metal chelating, and FRAP assays, antibacterial activity against Staphylococcus aureus (ATCC 29213) and Escherichia coli (ATCC 25922) by the minimum inhibitory concentration method (MIC) and cytotoxic properties against lung cancer cells (A549), were determined. Phenolic compounds and biological activities of M. oleifera leaves depend on the method and the solvent used for the extraction of these bioactive substances. The But extract prepared by SM method exhibited the highest amounts of TPC (103.06 ± 0.5 mg GAE/g DE) and showed the strongest potential antioxidant (CI50 = 0.26 mg/mL on DPPH test), antibacterial (MIC = 250 µg/mL) and cytotoxic activities (GI50 = 69.9 µg/mL). LC-MS analysis showed that 28 phenolic compounds of 33 tested standards were found in M. oleifera leaves. The But extract obtained by SM method exhibited the highest amounts of rutin, quercetin and syringic acid.

Protective effects of Mentha spicata against nicotine-induced toxicity in liver and erythrocytes of Wistar rats.

The aim of this study was to investigate the protective effect of Mentha spicata supplementation against nicotine-induced oxidative damage in the liver and erythrocytes of Wistar rats. Bioactive substances were determined by liquid chromatography - electrospray ionization - tandem mass spectrometry analysis. Animals were divided into 4 groups of 6 rats each: a normal control group, a nicotine-treated group (1 mg/kg), a group receiving M. spicata extract (100 mg/kg), and a group receiving both M. spicata extract (100 mg/kg) and nicotine (1 mg/kg). Many phenolic acids were identified in the M. spicata aqueous extract. After 2 months of treatment, nicotine induced an increase in the level of white blood cells and a marked decrease in erythrocytes, hemoglobin, and haematocrit. Aspartate transaminase, alanine transaminase, alkaline phosphatase, and lactate dehydrogenase activities were also found to be higher in nicotine-treated group than those of the control group. Furthermore, nicotine-treated rats exhibited oxidative stress, as evidenced by a decrease in antioxidant enzymes activities and an increase in lipid peroxidation level in liver and erythrocytes. Interestingly, the oral administration of M. spicata extract by nicotine-treated rats alleviated such disturbances. M. spicata contained bioactive compounds that possess important antioxidant potential and protected liver and erythrocytes against nicotine-induced damage.