During the last decade there has been growing interest in the formulation of new cosmetic, food and pharmaceutical products containing natural compounds with antioxidant activity and other beneficial properties. Aromatic and medicinal plants have always been the major source of bioactive compounds, especially, wild thyme (Thymbra capitata L.), which has been used since ancient times for its valuable health benefits that could be attributed to the richness of polyphenolic compounds. This study was undertaken with the following aims: to estimate the total polyphenolic content (TPC); to evaluate the antioxidant activity; to identify and quantify the phenolic compounds of post-distilled residues of Tunisian thyme, and their contribution to the antioxidant activity. The TPC, as determined by the Folin–Ciocalteu method, was found to reach the values of 126.7 and 107.84 mg gallic acid equivalent/g plant dry weight (mg GAE/g PDW). The antioxidant activity, which is assessed by DPPH and FRAP assays, reached the values of 42.97–45.64 μg/mL and 42.22–50.21 mMFe²⁺/mg PDW, respectively. HPLC analysis revealed the presence of fourteen polyphenolic compounds, of which diosmin and rosmarinic acid were found to be the most abundant (24.26 to 33.80 and 22.0.1 to 26.29 mg/g PDW, respectively). An important correlation was found between the antioxidant activity and several identified phenolic compounds (p < 0.05). The findings revealed that thyme post-distilled residues have an effective natural antioxidant potential due to their high concentration of bioactive molecules, and they appear to be useful in the pharmaceutical, cosmetic, and food industries, with beneficial effects on human health. Therefore, supplementing a balanced diet with herbs may have beneficial health effects.

This study aims to evaluate the interspecific variation in polyphenolic profiles and biological activities of acorn flours from three native Tunisian Quercus L. species (Q. ilex L., Q. suber L., and Q. canariensis Willd.). Q. canariensis extracts are the richest in total phenolic, flavonoid and hydrolysable tannin contents. Six phenolic compounds were identified by HPLC-DAD analysis. Chlorogenic acid was the dominant compound in Q. canariensis and Q. ilex acorns. Whereas in Q. suber, caffeic acid was the main component and, along with trans-ferulic acid, was exclusive to this species. Hyperoside was notably identified in Q. canariensis. The UHPLC-DAD-MS analysis of hydrolysable tannins revealed twelve compounds. Acorns of Q. canariensis and Q. suber were dominated by ellagitannins, whereas Q. ilex contained mainly gallotannins. To our knowledge, these compounds are identified for the first time in Tunisian acorns. Q. canariensis exhibited the strongest antioxidant potential with DPPH, ABTS and FRAP assays, as well as the highest antibiofilm and anti-α-amylase activities. All extracts inhibited ATCC pathogenic bacterial strains while largely sparing the beneficial probiotic Limosilactobacillus fermentum. This result indicates a selective antibacterial effect not previously reported for Quercus acorns. Q. canariensis may represent a potential source of functional food ingredient, nutraceuticals, and pharmaceuticals, which remains to be confirmed through in vivo investigations.

The present work describes an efficient micropropagation and callus induction protocol of Limbarda crithmoïdes L. (Asteraceae), a halophyte species with medicinal and horticultural interests. The objective was to identify the culture media that support the best organogenesis and callogenic expressions of four types of aerial explants; nodal and internodal segments and leaf portions, by varying the mineral composition of twenty culture media by adding increasing concentrations of Na⁺ (from 0-100 mM) and K⁺ (from 0-50 mM). After two months of culture, parameters relating to the various expressions of organogenesis and callogenesis were measured. Results showed that the K⁺ and Na⁺ interactions affect the explants development. The combination of high concentrations of Na⁺ (50, 100 mM) and K⁺ (50 mM) ions allowed the most important regeneration of the axillary shoots (70.6-100%), root neoformation (82.6-96.1%) and callus induction (76.3-100%). Rooted plantlets with well-developed axillary shoots have been successfully acclimatized with a 93% of survival rate. The selected media would allow a large-scale multiplication of this medicinal species, without adding exogenous phytohormones, and could be used for the micropropagation of other threatened halophyte species or for the production of callus; rich in secondary metabolites.

The glucosinolate (GSL) profiles in different plant parts of the wild-growing species Lepidium draba L. (syn. Cardaria draba Desv.) (Brassicaceae) from Tunisia and Croatia were determined using UHPLC-DAD-MS/MS. The predominant GSLs in both Tunisian and Croatian samples were glucoraphanin and glucosinalbin, with the leaves and flowers being the richest sources. The study also revealed previously unreported GSLs in L. draba, methionine-derived glucoiberin, glucoalyssin, glucohesperin, and glucolesquerellin, as well as tryptophan-derived glucobrassicin and 4-methoxyglucobrassicin. In addition to the variability of GSL content across different plant parts, this study has also shown the limitations of indirect GSL analysis by isothiocyanates using GC-MS, which can lead to incorrect identification of GSLs due to thermal degradation of the isothiocyanates produced.