Nigella sativa (NS) is a plant that has long been utilized in traditional medicine as a treatment for certain diseases. The aim of this work was to valorize the essential oil (EO) of this species by phytochemical analysis and antimicrobial and antioxidant evaluation. EO was extracted by hydrodistillation from the seeds of Nigella sativa (EO-NS). Phytochemical content of EO-NS was evaluated by use of gas chromatography coupled to mass spectrometry (GC-MS/MS). Antioxidant ability was in vitro determined by use of three assays: 2.2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing power (FRAP), and total antioxidant capacity (TAC) relative to two synthetic antioxidants: BHT and quercetin. Antimicrobial effect was evaluated against four clinically important bacterial strains (Staphylococcus aureus, ATCC 6633; Escherichia coli, K12; Bacillus subtilis, DSM 6333; and Proteus mirabilis, ATCC 29906) and against four fungal strains (Candida albicans, ATCC 10231; Aspergillus niger, MTCC 282; Aspergillus flavus, MTCC 9606; and Fusarium oxysporum, MTCC 9913). Fifteen constituents that accounted for the majority of the mass of the EO-NS were identified and quantified by use of GC-MSMS. The main component was O-cymene (37.82%), followed by carvacrol (17.68%), α-pinene (10.09%), trans-sabinene hydrate (9.90%), and 4-terpineol (7.15%). EO-NS exhibited significant antioxidant activity with IC50, EC50, and total antioxidant capacity (TAC) of <math xmlns="http://www.w3.org/1998/Math/MathML" id="M1"> <mn>0.017</mn> <mo>±</mo> <mn>0.0002</mn> </math> , <math xmlns="http://www.w3.org/1998/Math/MathML" id="M2"> <mn>0.1196</mn> <mo>±</mo> <mn>0.012</mn> </math> , and <math xmlns="http://www.w3.org/1998/Math/MathML" id="M3"> <mn>114.059</mn> <mo>±</mo> <mn>0.97</mn> </math> mg EAA/g, respectively. Additionally, EO-NS exhibited promising antibacterial activity on all strains under investigation, especially on E. coli K12 resulting in inhibition diameter of <math xmlns="http://www.w3.org/1998/Math/MathML" id="M4"> <mn>38.67</mn> <mo>±</mo> <mn>0.58</mn> </math> mm and a minimum inhibitory concentration (MIC) of <math xmlns="http://www.w3.org/1998/Math/MathML" id="M5"> <mn>1.34</mn> <mo>±</mo> <mn>0.00</mn> </math> μg/mL. Also, EO-NS had significant antifungal efficacy, with a percentage of inhibition of <math xmlns="http://www.w3.org/1998/Math/MathML" id="M6"> <mn>67.45</mn> <mo>±</mo> <mn>2.31</mn> </math> % and MIC of <math xmlns="http://www.w3.org/1998/Math/MathML" id="M7"> <mn>2.69</mn> <mo>±</mo> <mn>0.00</mn> </math> μg/mL against F. oxysporum, MTCC 9913 and with a diameter of inhibition <math xmlns="http://www.w3.org/1998/Math/MathML" id="M8"> <mn>42</mn> <mo>±</mo> <mn>0.00</mn> </math> mm and MIC of <math xmlns="http://www.w3.org/1998/Math/MathML" id="M9"> <mn>0.67</mn> <mo>±</mo> <mn>0.00</mn> </math> μg/mL against C. albicans. To minimize development of antibiotic-resistant bacteria, EO-NS can be utilized as a natural, alternative to synthetic antibiotics and antioxidants to treat free radicals implicated in microbial infection-related inflammatory reactions.

Organic fractions and extracts of willow (Salix safsaf) leaves, produced by sequential solvent extraction as well as infusion and decoction, exhibited anticancer potencies in four cancerous cell lines, including breast (MCF-7), colorectal (HCT-116), cervical (HeLa) and liver (HepG2). Results of the MTT assay revealed that chloroform (CHCl3) and ethyl acetate (EtOAc)-soluble fractions exhibited specific anticancer activities as marginal toxicities were observed against two non-cancerous control cell lines (BJ-1 and MCF-12). Ultra-high-resolution mass spectrometry Q-Exactive™ HF Hybrid Quadrupole-Orbitrap™ coupled with liquid chromatography (UHPLC) indicated that both extracts are enriched in features belonging to major phenolic and purine derivatives. Fluorescence-activated cell sorter analysis (FACS), employing annexin V-FITC/PI double staining indicated that the observed cytotoxic potency was mediated via apoptosis. FACS analysis, monitoring the increase in fluorescence signal, associated with oxidation of DCFH to DCF, indicated that the mechanism of apoptosis is independent of reactive oxygen species (ROS). Results of immunoblotting and RT-qPCR assays showed that treatment with organic fractions under investigation resulted in significant up-regulation of pro-apoptotic protein and mRNA markers for Caspase-3, p53 and Bax, whereas it resulted in a significant reduction in amounts of both protein and mRNA of the anti-apoptotic marker Bcl-2. FACS analysis also indicated that pre-treatment and co-treatment of human amniotic epithelial (WISH) cells exposed to the ROS H2O2 with EtOAc fraction provide a cytoprotective and antioxidant capacity against generated oxidative stress. In conclusion, our findings highlight the importance of natural phenolic and flavonoid compounds with unparalleled and unique antioxidant and anticancer properties.