Assessing Tunisia's urban air quality using combined lichens and Sentinel-5 satellite integration

In Tunisia, urban air pollution is becoming a bigger problem. This study used a combined strategy of biomonitoring with lichens and satellite mapping with Sentinel-5 satellite data processed in Google Earth Engine (GEE) to assess the air quality over metropolitan Tunis. Lichen diversity was surveyed across the green spaces of the Faculty of Science of Tunisia sites, revealing 15 species with a predominance of pollution-tolerant genera. The Index of Atmospheric Purity (IAP) calculated from the lichen data indicated poor air quality. Spatial patterns of pollutants sulfur dioxide (SO2), ozone (O3), nitrogen dioxide (NO2), carbon monoxide (CO), and aerosol index across Greater Tunis were analyzed from Sentinel-5 datasets on the GEE platform. The higher values of these indices in the research area indicate that it may be impacted by industrial activity and highlight the considerable role that vehicle traffic plays in air pollution. The results of the IAP, IBL, and the combined ground-based biomonitoring and satellite mapping techniques confirm poor air quality and an environment affected by atmospheric pollutants which will enable proactive air quality management strategies to be put in place in Tunisia's rapidly expanding cities.

Parietin, the Vibrant Natural Dye in Xanthoria parietina

The use of natural dyes in several areas is regulated by current European and non-European legislation, due to various problems with synthetic dyes. The analysis revealed that the lichen studied: Xanthoria parietina has potential natural dye sources and provides bright colors for extraction solvents. Furthermore, dyed wool and toile fabric have good fastness properties in ammonia fermentation and boiling water, both with and without mordants. The sample dyes with Xanthoria parietina were characterized by several analytical techniques: high-performance liquid chromatography with diode array detection (HPLC-DAD) and electrospray ionization with tandem mass spectrometry (HPLC-ESI-Q-ToF). As compounds from Xanthoria parietina form a complex with mordants and tissues, it is impossible to identify the molecules responsible for coloring using chromatographic techniques. However, we have evaluated the dyeing power of their major molecule, parietin. To further confirm the coloring power of the isolated parietin molecule, we performed a dye test with pure parietin. Thus, CIALAB analyses have shown parietin is the molecule responsible for the coloring obtained by Xanthoria parietina. The utilization of parietin derived from lichens facilitates the development of sustainable dyes for textile coloring, presenting an environmentally friendly alternative to synthetic dyes while simultaneously enriching lichen biodiversity.

Selecting the species to be used in lichen transplant surveys of air pollution in Tunisia

This study was undertaken with the aim of selecting one or more lichen species that are the most suitable for transplant-based surveys of air pollution in Tunisia, in areas where the local native lichen vegetation is scanty or missing at all. To this purpose, four epiphytic (tree inhabiting) lichen species (Evernia prunastri, Flavoparmelia caperata, Parmotrema perlatum, Ramalina farinacea) were collected from the Babouch forests, a remote and unpolluted area of NW Tunisia, and analyzed for their content of potentially toxic elements (PTEs), namely Al, As, Cd, Cr, Cu, Fe, Ni, Pb, Sb, and Zn, by ICP-MS. Moreover, also the physiological status of the lichen samples was evaluated by measuring their chlorophyll content, photosynthetic efficiency, and spectral reflectance. The results indicated a remarkable contribution of airborne soil and dust particles to the total PTE content, especially for the foliose species F. caperata and P. perlatum. The fruticose lichens E. prunastri and R. farinacea had a lower and similar content of PTEs, and hence were regarded as more suitable to be used in transplant studies, since are able to detect even minimal accumulation amounts. All lichen species were healthy, as emerged from the analysis of physiological parameters.

HPLC analysis, mycochemical contents and biological activities of two edible hypogeous ascomycetes: Tirmania nivea and Terfezia boudieri

Truffle, the hypogeous, ascomycetous macrofungus, has been recognized as a delicacy for centuries, and it is gaining elevated status in the culinary domain. The chemical composition and biological activities of aqueous extract and ground material of two desert Tunisian Tirmania nivea and Terfezia boudieri were studied for the first time. Using three assays antioxidant activity of the aqueous extract and ground material of the two truffles were investigated. Indeed, the aqueous extract and ground material of Terfezia boudieri showed the highest capacity for the DPPH scavenging test (IC₅₀ = 0.18 mg/mL) and with regard to the chelating power of iron (IC₅₀ = 0.22 mg/mL). At the same time, the highest capacity for iron reduction was recorded in the crude material of Tirmania nivea. Besides, the total phenolic, flavonoid, flavanol, tannin, and proanthocyanidin contents of both truffles extracts were determined. The ground material showed the best antibacterial activity for two ascomycetes against seven strains of bacteria. HPLC analysis of aqueous extracts showed that the predominant phenolic compounds in T. boudieri and T. nivea were gallic acid (33.25%) and myricetin (52.91%). Therefore, these truffles are a source of natural antioxidant and antimicrobial agents and could be used as a potential health food.

Mycochemical Contents and Biological Activities of Three Wild Mushrooms from Tunisia

The objective of the current study was to compare the mycochemical composition and biological activities of two extracts (aqueous extracts and ground materials prepared with the QUENCHER approach) of three wild Basidiomy-cetes, Agaricus vaporarius, Lactarius deliciosus, and Lycoperdon pyriforme, collected from a region located in the north of Tunisia. Mycochemical analysis in terms of total phenolic compounds, flavonoids, flavanols, proanthocyanidins, and tannin contents were determined. In addition, the antioxidant activities of the mushrooms were evaluated using three assays (2,2-di-phenyl-1-picrylhydrazyl free radical scavenging, ferric reducing antioxidant power assay, and metal chelating assay). Their antimicrobial activities were assessed against seven bacterial species. The obtained data revealed the presence of significant differences between secondary metabolites and the biological activities of the different tested extracts. Extracts of Basidiomy-cetes prepared with the QUENCHER approach had higher total phenolic content and antimicrobial activity against the evaluated strains. Antioxidant activity showed that the water extract had the greatest activity. The water extracts were analyzed with high-performance liquid chromatography, and the results showed that these three wild macromycetes contain a wide variety of antioxidant compounds in addition to many other bioactive compounds of nutritional and therapeutic interest.

Green Roccella phycopsis Ach. mediated silver nanoparticles: synthesis, characterization, phenolic content, antioxidant, antibacterial and anti-acetylcholinesterase capacities

In this study, we develop here for the first time an easy, eco-friendly method for synthesizing silver nanoparticles (AgNPs) using the lichen Roccella phycopsis. AgNPs formation was first determined by a color change of the lichen filtrate to brown, subsequent to addition of AgNO₃ solution, and confirmed by a maximum absorbance peak at 425 nm in UV-vis spectrum. Scanning electron microscope images showed a spherical shape with a size distribution between 11 and 18 nm, while the elemental composition was elucidated by the energy dispersive X-ray spectroscopy. The chemical compounds responsible for reduction and stabilization of silver nanoparticles were detected by Frourier transform infrared spectroscopy analysis. The synthesized R. phycopsis silver nanoparticles displayed a strong antioxidant activity. Further, the antibacterial activity was more effective against Gram-negative than Gram-positive bacteria. Besides, the R. phycopsis-AgNPs were potent in inhibiting acetylcholinesterase enzyme with IC₅₀ value of 1.65 ± 0.07 mg/mL.

Does the lichenicolous fungus Heterocephalacria bachmannii affect the antimicrobial potential of its host Cladonia foliacea?

The effects of the lichenicolous fungus Heterocephalacria bachmannii on the antimicrobial potential of the lichen Cladonia foliacea demonstrated that the extracts investigated have antimicrobial potential against gram-positive and negative bacteria, and yeast, and inhibit the germination of fungal spores. Inhibition activity varied considerably depending on the extract, the bacterial species, and the absence or presence of H. bachmannii; unparasitised C. foliacea has a higher antimicrobial activity. Methanol and acetone extracts of C. foliacea alone have higher inhibition diameters than C. foliacea with H. bachmannii against Enterobacter cloacae; the methanol extract of C. foliacea showed the best inhibition (250 µg/ml). C. foliacea also has a high lysozyme potential against Streptococcus agalactiae and Staphylococcus aureus. Fungal hyphae of Alternaria alternata were more affected by the methanol extract from C. foliacea.

In vitro evaluation of lysozyme activity and antimicrobial effect of extracts from four Tunisian lichens: Diploschistes ocellatus, Flavoparmelia caperata, Squamarina cartilaginea and Xanthoria parietina

Since lichens have been recognised as a potential natural source of bioactive substances, the aim of this study was to investigate the antimicrobial, lysozyme and antifungal effects of methanol, acetone and quencher extracts from four lichens: Diploschistes ocellatus, Flavoparmelia caperata, Squamarina cartilaginea and Xanthoria parietina. The results showed that the tested extracts had antimicrobial activity against Gram-positive and Gram-negative bacteria and anti-candida, and inhibit the spore germination of tested fungi. The different extracts varied in their effect as determined by the diameter of the inhibition zone, the highest values being observed with the methanol and acetone extracts (29.5 and 27.5 mm, respectively) for S. cartilaginea against Enterococcus faecalis. For powdered material (quencher), F. caperata showed the highest inhibition diameter (25.5 mm) against Staphylococcus aureus. The Minimum Inhibitory Concentration (MIC) values varied from 125 to 2000 μg mL^-1. Methanol extracts of S. cartilaginea were more active against Enterobacter cloacae (MIC 125 µg mL^-1) and Staphylococcus aureus (MIC 125 µg mL^-1), and also affected lysozyme activity against Staphylococcus aureus, as well as the morphology of fungal hyphae. This study demonstrated that the investigated species are a potential source of bioactive compounds which are potentially important antimicrobial agents.

Comparison of Antioxidant and Antiacetylcholinesterase Activities of Different Extracts of Tunisia Maclura pomifera (Rafin.) Schneid Fruit In Vitro and In Vivo

Background: Maclura pomifera a member of Moraceae family, is a tropical plant with ethnobotanical uses. Objectives: The present study aimed to evaluate bioactive compounds, antioxidants, and acetylcholinesterase (AChE) inhibitory activities of different extracts of Tunisia M. pomifera (Rafin.) Schneid fruit in vitro and in vivo. Methods: Organic extracts in different polarities (chloroform, ethyl acetate, and acetone) were extracted from different parts of the fruit of M. pomifera (exocarp, mesocarp, and pips). Phenolic content, antioxidant activity, and anti-AChE activity were determined. The anti-amnesic effects of ethyl acetate extract of the exocarp of M. pomifera were measured in galactose-induced memory deficit mice by the Y maze. The levels of biomarkers and AChE activity were determined in brain tissues. Results: The obtained results showed that the ethyl acetate extract of exocarp contains the highest content of flavonoids and polyphenols 22.3mg quercetin equivalents per g of dry weight and 718.6 mg gallic acid equivalents per g of dry weight. The evaluation of antioxidant activities highlighted that the ethyl acetate extract of exocarp was the most active element. The study of the AChE inhibitory power demonstrated that the ethyl acetate extract of the exocarp had the greatest inhibitory activity. The ethyl acetate extract from the exocarp ameliorated cognitive performance and reversed the oxidative damage as compared to galactose group. Conclusion: M. pomifera fruit is a good source of natural antioxidants, which might help prevent oxidative stress-related damage and memory impairment in such mental disorders as Alzheimer’s disease (AD).

Determination of phenolic compounds by MALDI-TOF and essential oil composition by GC-MS during three development stages of Origanum majorana L

This study aimed to investigate the effect of the maturation process of sweet marjoram (Origanum majorana L.) on essential oil composition, the phenolic profile of ethanolic extract and their antioxidant capacities. The essential oil composition was studied at three stages of maturity by GC-MS. Thirty compounds were detected representing 100% of the total essential oil. p-Menth-1-en-4-ol was the major compound (37.15-76.94%) followed by cyclohexanol-3,3,5 trimethyl (5.41-15.99%) and α-terpineol (0.94-11.34%). During the maturation process, an accumulation of oxygenated monoterpenes was observed. The phenolic composition was studied using matrix-assisted laser desorption/ionization time of flight. The analysis showed the presence of short flavonoid monomers at all stages of maturation. The antioxidant capacity of ethanolic extracts and essential oils was evaluated using the DPPH assay, iron chelating power and reducing power assay. The highest phenolic content and antioxidant capacity were found at flowering stage. These findings on essential oil composition, phenolic profile and antioxidant capacity of O. majorana at three different stages of development provide more information on how these secondary metabolites are accumulated.

In vitro digestion, antioxidant and antiacetylcholinesterase activities of two species of Ruta: Ruta chalepensis and Ruta montana

CONTEXT

Ruta genus (Rutaceae) is abundantly used and described in the most ancient systematic records of medical practice of the Mediterranean world. In Tunisia, this genus is represented by two medicinal and aromatic shrubs: Ruta chalepensis L. and Ruta montana L.

OBJECTIVE

This study investigates the antioxidant and acetylcholinesterase inhibition (AChE) activities before and after in vitro gastrointestinal metabolism of leaf decoction of R. chalepensis and R. montana.

MATERIALS AND METHODS

We study, in vitro, the effect of the gastrointestinal juices gastric (1.75 mL) or pancreatic (2.5 mL) juices, on the biological activity by the measurement of the antioxidant activity and AChE inhibition during 4 h of decoction extract obtained from the leaves of the two species of Ruta.

RESULTS

The results showed that the ability to inhibit the AChE enzyme was similar; being the greatest inhibitory activity exhibited by the ethanol extract (IC₅₀=12 ± 1.1 μg/mL) obtained from leaves of R. chalepensis.

CONCLUSION

In conclusion, we showed that there was no appreciable degradation and that the activity was kept constant after gastric and pancreatic juice digestion.

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%), β-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.