Lichenochemical Screening and Antioxidant Capacity of Four Tunisian Lichen Species.

The phenolic composition and antioxidant capacity of four Tunisian lichen species, Cladonia rangiformis, Flavoparmelia caperata, Squamarina cartilaginea and Xanthoria parietina, were determined in order to provide a better understanding of their lichenochemical composition. Powdered material of F. caperata was the richest in total phenolic content (956.68 µg GAE g-1 DW) and S. cartilaginea in proanthocyanidin content (77.31 µg CE g-1 DW), while the acetone extract of X. parietina showed the highest flavonoid content (9.56 µg CE g-1 DW). The antioxidant capacity of all lichen extracts and crude material was evaluated by DPPH. scavenging, iron-chelating, and iron-reducing powers. Results showed that methanol extracts of S. cartilaginea had the highest DPPH. antioxidant capacity (IC50 =0.9 µg mL-1 ) and the highest iron-reducing power was attributed to the acetone extract of this species. All extracts of all species were further screened by Fourier-transform infrared spectroscopy (FT-IR) and nuclear resonance spectroscopy (NMR); results showed an abundance of phenols, aromatic compounds, and fatty acids. Overall, our results showed that the investigated species are a rich source of potentially bioactive compounds with valuable properties.

Untargeted metabolomics reveals changes in phenolic profile following in vitro large intestine fermentation of non-edible parts of Punica granatum L.

In this study, the untargeted phytochemical profile of non-edible parts of pomegranate (i.e., flowers, leaves and peels) was depicted by using untargeted metabolomics. Each sample was in vitro digested and then fermented simulating a large intestinal process, then monitoring the changes of phenolic bioaccessibility. The most abundant compounds in pomegranate extracts were polyphenols, terpenoids, sterols, alkaloids and amino acids. The untargeted metabolomic approach revealed a transformation of flavonoids over 24 h of in vitro fermentation. In particular, an increase in the % bioaccessibility for phenolic acids and tyrosols in flowers (probably due to the insoluble dietary fibre content, i.e., 27.1 g 100 g-1) was observed. Accordingly, the highest % bioaccessibility was detected after 24 h of in vitro large intestine fermentation for flower (i.e., 53.8%). Results showed that non-edible parts of pomegranate could be used as ingredients for the development of potential value-added food and industrial products.

Secondary Metabolites and Antioxidant Capacity of the Tunisian Lichen Diploschistes ocellatus (Ascomycota).

This study, the first to assess the total phenolic, flavonoid, tannins, and proanthocyanidin content of the Tunisian lichen Diploschistes ocellatus, determined the antioxidant capacity in scavenging 2,2 diphenyl-1-picrylhydrazyl (DPPH), as well as the ferric-reducing and iron-chelating powers. The phenolic compound content of D. ocellatus was shown to be related to antioxidant activity. The highest phenolic and flavonoid contents of extracts were obtained with acetone (286.3 µg GAE/g DW and 3.24 µg CE/g DW, respectively), while the highest tannin and proanthocyanidin contents were obtained with methanol (5.5 µg TAE/g DW and 35.12 µg CE/g DW, respectively). The highest DPPH' scavenging capacity and iron-chelating power of extracts were obtained with methanol (concentration providing 50% inhibition [IC50] = 0.029 mg/mL and IC50 = 0.425 mg/mL, respectively), while acetone extracts showed a higher reducing power (IC50 = 0.118 mg/mL).

Phenolic profiling and antioxidant capacity in flowers, leaves and peels of Tunisian cultivars of Punica granatum L.

The comprehensive phenolic fingerprints of flowers, peels and leaves of two Tunisian Punica granatum L. cultivars, namely Nabli and Gabsi, were investigated. The highest phenolic content was recorded in the Nabli flowers, followed by Gabsi peels extracts (152.6 and 125.8 mg gallic acid equivalent 100 g-1, respectively) while flavonoids and flavonols were highest in Gabsi peels (19.2 and 26.0 mg Rutin equivalent per 100 g-1). Besides, the antioxidant capacity was the highest in Gabsi peels (144.4 mg gallic acid equivalent 100 g-1) and in Nabli flowers (161.6 mg gallic acid equivalent per 100 g-1. Methanol extracts of all three plant portions of both cultivars were screened by ultra-high-performance liquid chromatography coupled to quadruple time of flight mass spectrometry, and the identified phenolics were further quantified. Nabli cultivar showed higher contents of flavonoids (in flowers and leaves), while phenolic acids were abundant in Gabsi leaves. Multivariate statistics highlighted differences in phenolic profile among organs and cultivars. These results showed that the pomegranate portions investigated are a valuable source of bioactive compounds with health-promoting properties, mainly belonging to the phenolic class of flavonoids.

Phenolic profiling and antioxidant capacity of Calligonum azel Maire, a Tunisian desert plant.

The comprehensive phenolic fingerprint of Calligonum azel Maire plant fractions, collected from the Tunisian Desert, have been assessed for the first time as a source of natural antioxidants. Total phenolic content (TPC), Trolox Equivalent Antioxidant Capacity (TEAC) in scavenging DPPH, ABTS+ and Ferric Reducing Antioxidant Power (FRAP) were determined. C. azel Maire showed a relevant content in phenolic compounds, which are related to the antioxidant activity. The flowers presented the highest antioxidant capacity against DPPH free radicals, while the leaves showed the highest scavenging capacity against ABTS. As for the FRAP assay, results showed that the roots had the highest ferric reducing antioxidant power. Methanol extracts of the four organs were screened by ultra high performance liquid chromatography coupled to quadruple time of flight mass spectrometry and the identified phenolics were further quantified. Flavones and flavanols were the most abundant phenolic compounds identified, and were quantitatively measured as luteolin and catechin equivalents. Although the phenolic profile was diverse between the four organs, the obtained results showed that Calligonum azel Maire is an excellent source of various natural antioxidants with high radical scavenging capacities, which could be used in food preservation. Further studies on the isolation of such compounds appear to be of high interest.

Barks Essential Oil, Secondary Metabolites and Biological Activities of Four Organs of Tunisian Calligonum azel Maire.

This study is the first to investigate the chemical composition of barks essential oil (EO), secondary metabolites and biological activities of the MeOH and infusions extracts of seeds, leaves, barks and roots of Calligonum azel Maire (Polygonaceae) harvested from Tunisian desert. The gas chromatography/mass spectrometry (GC/MS) results showed the presence of fifty-four compounds in barks EO. The major components were: viridiflorol (14.6%), α-eudesmol (8.65%), trans-caryophyllene (6.72%), elemol (6.63%), ß-eudesmol (6.21%). The obtained results showed that C. azel is a very rich plant in secondary metabolites. High contents in polyphenols, flavonoids and tannins were observed in both extracts of all studied organs. Significant differences were found between both extracts of the four organs. Thus, polyphenols and tannins were more abundant in leaves infusion extract, while, flavonoids showed a high level in barks extract. The antioxidant activity data demonstrated that all extracts showed strong antioxidant and radical scavenging activities. The MeOH extracts presented potential for antibacterial and antifungal activities against all tested microorganisms. The inhibition zones diameters and minimal inhibitrice concentration values were in the range of 9 - 15 mm and 2.5 - 20 µg/ml, respectively. This study demonstrated that C. azel can be regarded as an excellent plant source for natural antimicrobial agents.

Evaluation of Calligonum azel Maire, a North African desert plant, for its nutritional potential as a sustainable food and feed.

This study is the first to evaluate the potential of Calligonum azel Maire as a food ingredient. The plant materials flowers, leaves, stems and roots were analyzed by wet-chemical and instrumental methods for major and minor composition. The highest protein and sugar contents were recorded in the flowers (17.8% and 1.6% respectively), while the fat content was most abundant in the leaves (2.9%). Hexane extracts screened by gas chromatography (GC) for fatty acid composition showed 14 major compounds such as oleic acid, linoleic acid and palmitic acid, but also ω3 and ω6 unsaturated fatty acids. The essential oils extracted by hydrodistillation were screened by GC/MS and 31 compounds were identified including estragole, naphthalene, anethole, phytol and curcumene. The HPLC-DAD screening revealed that the methanolic extracts do not contain any pharmacologically active compound with adverse properties, but quercetin, hordenine and vanillin were abundant in the flowers, leaves and roots. Proton nuclear magnetic resonance (1H NMR) spectroscopy showed that glucose, sucrose and fructose were abundant in acetone and methanol extracts, while urea and glycerol were abundant in the aqueous extracts. A sensory evaluation of the aqueous infusions showed properties of the flowers reminiscent of other herbal teas. In conclusion, our results corroborate the suitability of the traditionally described use of Calligonum azel Maire as food and feed. The further study of this plant as a sustainable nutritional ingredient appears to be worthwhile.