Mandarin, one of the winter fruits commonly used in the preparation of foods and juices, is a fruit native to China and Southeast Asia. In this work, essential oils (EOs) obtained from by-products of the Citrus reticulata Blanco flavedo of five cultivars present and cultivated within the Botanical Garden of Palermo were chemically and biologically studied: C. reticulata ‘Avana’ (C1), C. reticulata ‘Tardivo di Ciaculli’ (C2), C. reticulata ‘Bombajensis’ (C3), C. reticulata ‘Aurantifolia’ (C4), and C. reticulata ‘Padre Bernardino’ (C5). The GC and GC-MS analysis performed on all the extracted samples clearly highlighted the notable presence of limonene, a characteristic hydrocarbon monoterpene of EOs of the Citrus genus. C1, C2, C3, C4, and C5 were tested in relation to their possible antibacterial and allelopathic activity, also highlighting the activity of limonene, the main compound. For the antibacterial activity, eight different bacterial strains were used, both Gram-positive and Gram-negative (Staphylococcus aureus, Proteus vulgaris, Klebsiella pneumoniae, Enterobacter cloacae, Pseudomonas aeruginosa, Escherichia coli, Salmonella typhi, and Enterobacter aerogens). For the allelopathic effect, two model systems were chosen: the germination of radish seeds (Raphanus sativus L.) and of spores in the moss Tortula muralis (Hedw.). The EOs from all cultivars showed pronounced antibacterial effects against all strains with an MIC comprised in the range of 16–256 μg/mL. Limonene showed the highest activity with an MIC between 4 and 16. The allelopathic effects showed a decrease in the percentage of seed germination, root, and epicotyl growth on Raphanus and a strong reduction in the germination of Tortula spores with an alteration in the development of the protonema. Limonene showed the same but more intense allelopathic activity.

Nigella sativa, or black cumin, is used as a spice in cooking and as a food supplement like seeds or oil for its biological properties, including antioxidant capacity, anti-inflammatory action, and support for the immune system. In the present study, the chemical composition and biological activities of the Nigella sativa seeds’ fatty oil (NS) were investigated. The analytical composition was carried out by several techniques, such as GC-MS spectrometry and ¹H- and ¹³C-NMR spectroscopies using appropriate internal standards. The GC-MS analysis highlighted the presence of palmitic and linoleic acid as major compounds. The antioxidant potential was evaluated through the DPPH radical-scavenging assay, and, furthermore, the NS effect on intracellular reactive oxygen species (ROS) levels was assessed in HaCaT cells (non-tumorigenic human keratinocytes) under oxidative stress induced by hydrogen peroxide. The cytotoxic and genotoxic profiles were evaluated on Caco-2 cells (human colorectal adenocarcinoma cells) using the CCK-8 viability assay and the Comet assay, respectively. Overall, the results demonstrated that NS possessed antioxidant activity, as evidenced by concentration-dependent DPPH radical scavenging and reduced intracellular ROS levels in HaCaT cells under oxidative stress. In Caco-2 colorectal cancer cells, NS induced significant cytotoxicity and DNA damage at higher concentrations, suggesting potential genotoxic effects. These findings support the dual role of NS as a natural antioxidant and a promising candidate for nutraceutical and dermatological applications, including those targeting oxidative stress-related conditions and cancer.

Phosphorus is a key nutrient regulating algal growth and eutrophication in aquatic systems, yet its isolated effect on microalgae-based wastewater treatment remains underexplored. This study evaluated how varying phosphorus loads drive microalgal community structure and purification performance in controlled photobioreactors fed synthetic wastewater. The synthetic wastewater was formulated with constant carbon and nitrogen but graded phosphorus at C/N/P ratios of 100/5/1, 100/5/10, and 100/5/20 under 6000 lux, a 14 h photoperiod, and 24 ± 2 °C with a 15-day hydraulic retention time. Monitoring of chlorophyll a, pH, total and volatile suspended solids, and algal composition showed that phosphorus enrichment significantly increased chlorophyll a (up to 43.9 µg/L at 20 mg P/L) and particulate biomass (TSS and VSS), while pH remained near neutral to slightly alkaline, with no significant differences among the three bioreactors. Although the same core taxa—Chlorella spp., Scenedesmus spp., Navicula spp., and filamentous algae were present across all bioreactors, their relative abundances shifted significantly with phosphorus concentration. A two-way ANOVA confirmed a highly significant interaction between bioreactor (P level) and genus (p < 0.001), demonstrating phosphorus-driven changes in the microalgal community. Notably, filamentous cyanobacteria (Anabaena spp.) were undetectable in the low- and medium-phosphorus treatments but emerged prominently only at the highest phosphorus level (20 mg/L). Nutrient removal efficiencies peaked in this high-phosphorus bioreactor (C), achieving 85% for bCOD, 78% for nitrogen, and >70% for phosphorus. These results show that phosphorus loading drives predictable shifts in microalgal community composition toward fast-growing algae and cyanobacteria and that these shifts likely contribute to enhanced nutrient removal. The findings support optimization of phosphorus supply and hydraulic residence time in low-cost, sunlight-driven systems to improve polishing performance for small settlements in arid regions.

Atriplex halimus is a medicinal plant traditionally used for various therapeutic purposes. This study evaluated the antioxidant, anti-inflammatory, cytotoxic, genotoxic, and anti-arthritic activities of the A. halimus aqueous extract (AHA). Anti-arthritic effects were investigated in Complete Freund’s Adjuvant (CFA)-induced arthritic rats treated with AHA (150 or 300 mg/kg) for 21 days. AHA significantly reduced paw swelling and arthritis severity and improved body weight, while a non-significant reduction in spleen enlargement was observed. Hematological and biochemical parameters were restored toward normal values, indicating anti-inflammatory, hepatoprotective, and nephroprotective effects. The extract also reduced oxidative stress by decreasing nitric oxide (NO) and malondialdehyde (MDA) levels and increasing glutathione (GSH) content and catalase (CAT) activity. Histopathological examination confirmed reduced inflammatory infiltration and protection against bone damage. Phytochemical analysis revealed polyphenols, flavonoids, and tannins, consistent with its antioxidant activity in DPPH, ABTS, CUPRAC, and o-phenanthroline assays. AHA also showed anti-inflammatory activity by inhibiting bovine serum albumin denaturation. The extract induced a moderate concentration-dependent reduction in HeLa cell viability without cytotoxicity toward HaCaT cells. Comet assay results demonstrated DNA damage in HeLa cells at higher concentrations, while AHA significantly suppressed zymosan-induced IL-1β gene expression. These findings indicate that AHA is a promising natural source of bioactive compounds with diverse biological activities.