Georgia D. Ioannou

The Mediterranean basin is a global biodiversity hotspot characterized by a high frequency of halophytic flora, which have evolved specialized metabolic adaptations to thrive under hypersaline, drought, and high-UV conditions. These physiological mechanisms facilitate the biosynthesis of diverse secondary metabolites, which have garnered significant attention for their antimicrobial and antifungal properties. This review critically evaluates the antimicrobial potential of nine prominent Mediterranean halophytes, namely Cakile maritima, Crithmum maritimum, Eryngium maritimum, Juncus acutus, Juncus maritimus, Limbarda crithmoides, Otanthus maritimus, Pancratium maritimum, and Salicornia europaea, synthesizing data on their phytochemical profiles and efficacy against foodborne, clinical, and agricultural pathogens. The findings indicate that several extracts and essential oils exhibit potent inhibitory effects, with minimum inhibitory concentration (MIC) values often comparable to or even lower than those of established antibiotics, notably against Staphylococcus spp., Salmonella spp., and various Candida species. These halophyte extracts are also used successfully to control microbial contamination in the production of plant- and animal-based foods. Despite the significant potential for agricultural and food sectors, full commercialization requires addressing challenges related to field-level efficacy, formulation stability, and comprehensive toxicological safety. Overall, this study underlines the role of Mediterranean halophytes as resilient bio-factories capable of providing sustainable, natural solutions to pressing antimicrobial resistance and food security challenges.

The present study investigated the use of natural deep eutectic solvents (NaDESs) combined with ultrasound-assisted extraction (UAE) for the efficient recovery of anthocyanins and antioxidant phenolics from Damask rose (DR). A wide range of environmentally friendly solvents was screened, and choline chloride–propylene glycol (ChCl-PG) was identified as the most effective extraction medium. The extraction conditions were optimized using response surface methodology (RSM) and artificial neural network (ANN) models to maximize anthocyanin and phenolic contents, as well as antioxidant activity. Under the optimal parameters, the DR extracts exhibited relatively high levels of bioactive compounds, including total anthocyanin content of 5.2–5.3 mg cyanidin-3-glucoside equivalents g⁻¹ sample, total phenolic content of 63.4–64.2 mg gallic acid equivalents g⁻¹ sample, along with substantial antioxidant potential (DPPH: 68.2–68.8% inhibition, FRAP: 581.6–591.9 μmol Trolox equivalents g⁻¹ sample). Chromatographic analysis of the optimum extract revealed cyanidin as the predominant anthocyanidin in DR, and its stability was further evaluated, revealing improved preservation under dark conditions at lower temperatures over a 15-day storage period. Moreover, the IC₅₀ values confirmed antimicrobial effects against the tested foodborne pathogens. Furthermore, the inhibitory effect of the DR extract remained stable against S. aureus and S. cerevisiae throughout the storage period. Overall, the findings demonstrate that NaDES-UAE is a promising and sustainable approach for obtaining anthocyanin-rich DR extracts with antioxidant and antimicrobial potential.

In this study, an optimized environmentally friendly procedure was employed to enhance the sustainable utilization of phenolic antioxidants derived from aloe vera rind by-products. The procedure involved the application of ultrasound-assisted extraction (UAE) in combination with deep eutectic solvents (DESs). Eleven different DESs and three conventional solvents were employed as extraction media for polyphenolic compounds. Choline chloride–citric acid (ChCl-CA) was selected as the most suitable extractant, considering its extraction efficiency in relation to the total phenolic content. The operating conditions of UAE were optimized and modeled by the use of response surface methodology in order to maximize the yield of total phenolics and antioxidant capacity. The optimal operational parameters for the UAE procedure were determined to be 16.5 min, 74% (v/v) DES in water, and a solvent-to-solid ratio equal to 192. HPLC analysis, which was performed on the optimum extract, revealed significant levels of phenolics present in the aloe rind. Efficient recovery of the extracted antioxidants was obtained by the use of solid-phase extraction (SPE) and polyamide cartridges. The ChCl-CA DES exhibited excellent recycling capability with a yield of over 90% through SPE. Finally, the greenness of the method was evaluated using the green AGREE and AGREEprep metrics. The results highlighted the sustainability and the greenness of the proposed extraction procedure for the aloe by-product.

In recent years, carob and its derived products have gained wide attention due to their health-promoting effects, which are mainly attributed to their phenolic compounds. Carob samples (carob pulps, powders, and syrups) were analyzed to investigate their phenolic profile using high-performance liquid chromatography (HPLC), with gallic acid and rutin being the most abundant compounds. Moreover, the antioxidant capacity and total phenolic content of the samples were estimated through DPPH (IC₅₀ 98.83–488.47 mg extract/mL), FRAP (48.58–144.32 μmol TE/g product), and Folin–Ciocalteu (7.20–23.18 mg GAE/g product) spectrophotometric assays. The effect of thermal treatment and geographical origin of carobs and carob-derived products on their phenolic composition was assessed. Both factors significantly affect the concentrations of secondary metabolites and, therefore, samples’ antioxidant activity (p-value < 10⁻⁷). The obtained results (antioxidant activity and phenolic profile) were evaluated via chemometrics, through a preliminary principal component analysis (PCA) and orthogonal partial least square-discriminant analysis (OPLS-DA). The OPLS-DA model performed satisfactorily, differentiating all samples according to their matrix. Our results indicate that polyphenols and antioxidant capacity can be chemical markers for the classification of carob and its derived products.

An ultrasound-assisted method was used for the extraction of phenolics from defatted black cumin seeds (Nigella sativa L.), and the effects of several extraction factors on the total phenolic content and DPPH radical scavenging activity were investigated. To improve the extraction efficiency of phenolics from black cumin seed by ultrasonic-assisted extraction, the optimal extraction conditions were determined as follows: ethanol concentration of 59.1%, extraction temperature of 44.6 °C and extraction time of 32.5 min. Under these conditions, the total phenolic content and DPPH radical scavenging activity increased by about 70% and 38%, respectively, compared with conventional extraction. Furthermore, a complementary quantitative analysis of individual phenolic compounds was carried out using the HPLC-UV technique. The phenolic composition revealed high amounts of epicatechin (1.88–2.37 mg/g) and rutin (0.96–1.21 mg/g) in the black cumin seed extracts. Ultrasonic-assisted extraction can be a useful extraction method for the recovery of polyphenols from defatted black cumin seeds.

Extracts derived from the Ceratonia siliqua L. (carob) tree have been widely studied for their ability to prevent many diseases mainly due to the presence of polyphenolic compounds. In this study, we explored, for the first time, the anti-cancer properties of Cypriot carobs. We produced extracts from ripe and unripe whole carobs, pulp and seeds using solvents with different polarities. We measured the ability of the extracts to inhibit proliferation and induce apoptosis in cancer and normal immortalized breast cells, using the MTT assay, cell cycle analysis and Western Blotting. The extracts’ total polyphenol content and anti-oxidant action was evaluated using the Folin–Ciocalteu method and the DPPH assay. Finally, we used LC-MS analysis to identify and quantify polyphenols in the most effective extracts. Our results demonstrate that the anti-proliferative capacity of carob extracts varied with the stage of carob maturity and the extraction solvent. The Diethyl-ether and Ethyl acetate extracts derived from the ripe whole fruit had high Myricetin content and also displayed specific activity against cancer cells. Their mechanism of action involved caspase-dependent and independent apoptosis. Our results indicate that extracts from Cypriot carobs may have potential uses in the development of nutritional supplements and pharmaceuticals.