Phytochemical Analysis, Antioxidant, and Antimicrobial Activities of Ducrosia flabellifolia: A Combined Experimental and Computational Approaches

In Vitro Screening of Antimicrobial and Anti-Coagulant Activities, ADME Profiling, and Molecular Docking Study of Citrus limon L. and Citrus paradisi L. Cold-Pressed Volatile Oils

Citrus, which belongs to the Rutaceae family, is a very widespread genus in the Mediterranean Basin. In Tunisia, various parts of these spontaneous or cultivated plants are used in common dishes or in traditional medicine. The purpose of this work was to investigate C. limon and C. paradisi essential oil (EO). The samples were studied for their chemical composition using SPME/MS, as well as their antibacterial and antifungal activities. Prothrombin time (PT) and activated partial thromboplastin time (aPTT) methods were used to evaluate the anticoagulant potentialities. The obtained results show that both essential oils are rich in monoterpenes hydrocarbons, whereby limonene is the main compound in C. paradisi EO (86.8%) and C. limon EO (60.6%). Moreover, C. paradisi EO contains β-pinene (13.3%), sabinene (2.2%) and α-pinene (2.1%). The antibacterial assay of the essential oils showed important bactericidal and fungicidal effects against all strains tested. In fact, the MICs values of C. limon EO ranged from 0.625 to 2.5 mg/mL against all Gram-positive and Gram-negative bacteria, and from 6.25 to 12.5 mg/mL for Candida spp. strains, while C. paradisi EO was more active against all bacteria with low MICs values ranging from 0.192 to 0.786 mg/mL, and about 1.5 mg/mL against Candida species. Both tested Citrus EOs exhibited interesting anticoagulant activities as compared to heparin. The molecular docking approach was used to study the binding affinity and molecular interactions of all identified compounds with active sites of cytidine deaminase from Klebsiella pneumoniae (PDB: 6K63) and the C (30) carotenoid dehydrosqualene synthase from Staphylococcus aureus (PDB: 2ZCQ). The obtained results show that limonene had the highest binding score of -4.6 kcal.mol-1 with 6K63 enzyme, and -6.7 kcal.mol-1 with 2ZCQ receptor. The ADME profiling of the major constituents confirmed their important pharmacokinetic and drug-like properties. Hence, the obtained results highlight the potential use of both C. limon and C. paradisi essential oils as sources of bioactive compounds with antibacterial, antifungal, and anti-coagulant activities.

Illicium verum L. (Star Anise) Essential Oil: GC/MS Profile, Molecular Docking Study, In Silico ADME Profiling, Quorum Sensing, and Biofilm-Inhibiting Effect on Foodborne Bacteria

Illicium verum, or star anise, has many uses ranging from culinary to religious. It has been used in the food industry since ancient times. The main purpose of this study was to determine the chemical composition, antibacterial, antibiofilm, and anti-quorum sensing activities of the essential oil (EO) obtained via hydro-distillation of the aerial parts of Illicium verum. Twenty-four components were identified representing 92.55% of the analyzed essential oil. (E)-anethole (83.68%), limonene (3.19%), and α-pinene (0.71%) were the main constituents of I. verum EO. The results show that the obtained EO was effective against eight bacterial strains to different degrees. Concerning the antibiofilm activity, trans-anethole was more effective against biofilm formation than the essential oil when tested using sub-inhibitory concentrations. The results of anti-swarming activity tested against P. aeruginosa PAO1 revealed that I. verum EO possesses more potent inhibitory effects on the swarming behavior of PAO1 when compared to trans-anethole, with the percentage reaching 38% at a concentration of 100 µg/mL. The ADME profiling of the identified phytocompounds confirmed their important pharmacokinetic and drug-likeness properties. The in silico study using a molecular docking approach revealed a high binding score between the identified compounds with known target enzymes involved in antibacterial and anti-quorum sensing (QS) activities. Overall, the obtained results suggest I. verum EO to be a potentially good antimicrobial agent to prevent food contamination with foodborne pathogenic bacteria.

Chestnut Shell Polyphenols Inhibit the Growth of Three Food-Spoilage Bacteria by Regulating Key Enzymes of Metabolism

The microbial contamination of food poses a threat to human health. Chestnut shells, which are byproducts of chestnut processing, contain polyphenols that exert various physiological effects, and thus have the potential to be used in food preservation. This study investigates the bacteriostatic effect and mechanism(s) of the action of chestnut shell polyphenols (CSPs) on three food-spoilage bacteria, namely Bacillus subtilis, Pseudomonas fragi, and Escherichia coli. To this end, the effect of CSPs on the ultrastructure of each bacterium was determined using scanning electron microscopy and transmission electron microscopy. Moreover, gene expression was analyzed using RT-qPCR. Subsequent molecular docking analysis was employed to elucidate the mechanism of action employed by CSPs via the inhibition of key enzymes. Ultrastructure analysis showed that CSPs damaged the bacterial cell wall and increased permeability. At 0.313 mg/mL, CSPs significantly increased the activity of alkaline phosphatase and lactate dehydrogenase, as well as protein leakage (p < 0.05), whereas the activity of the tricarboxylic acid (TCA) cycle enzymes, isocitrate dehydrogenase and α-ketoglutarate dehydrogenase, were inhibited (p < 0.05). The expression levels of the TCA-related genes gltA, icd, sucA, atpA, citA, odhA, IS178_RS16090, and IS178_RS16290 are also significantly downregulated by CSP treatment (p < 0.05). Moreover, CSPs inhibit respiration and energy metabolism, including ATPase activity and adenosine triphosphate (ATP) synthesis (p < 0.05). Molecular docking determined that proanthocyanidins B1 and C1, the main components of CSPs, are responsible for the antibacterial activity. Therefore, as natural antibacterial substances, CSPs have considerable potential for development and application as natural food preservatives.

GC/MS Profiling, Antibacterial, Anti-Quorum Sensing, and Antibiofilm Properties of Anethum graveolens L. Essential Oil: Molecular Docking Study and In-Silico ADME Profiling

Anethum graveolens L. has been known as an aromatic, medicinal, and culinary herb since ancient times. The main purpose of this study was to determine the chemical composition, antibacterial, antibiofilm, and anti-quorum sensing activities of the essential oil (EO) obtained by hydro-distillation of the aerial parts. Twelve components were identified, representing 92.55% of the analyzed essential oil. Limonene (48.05%), carvone (37.94%), cis-dihydrocarvone (3.5%), and trans-carvone (1.07%) were the main identified constituents. Results showed that the obtained EO was effective against eight bacterial strains at different degrees. Concerning the antibiofilm activity, limonene was more effective against biofilm formation than the essential oil when tested using sub-inhibitory concentrations. The results of anti-swarming activity tested against P. aeruginosa PAO1 revealed that A. graveolens induced more potent inhibitory effects in the swarming behavior of the PAO1 strain when compared to limonene, with a percentage reaching 33.33% at a concentration of 100 µg/mL. The ADME profiling of the identified phytocompounds confirms their important pharmacokinetic and drug-like properties. The in-silico study using molecular docking approaches reveals a high binding score between the identified compounds and known target enzymes involved in antibacterial and anti-quorum sensing (QS) activities. Overall, the obtained results highlight the possible use of A. graveolens EO to prevent food contamination with foodborne pathogenic bacteria.

Chemical Composition of Ducrosia flabellifolia L. Methanolic Extract and Volatile Oil: ADME Properties, In Vitro and In Silico Screening of Antimicrobial, Antioxidant and Anticancer Activities

In the present study, the chemical composition of the volatile oil and methanolic extract from Ducrosia flabellifolia Boiss. was investigated. The antimicrobial, antioxidant, and anticancer activities of the methanolic extract from D. flabellifolia aerial parts were screened using experimental and computational approaches. Results have reported the identification of decanal (28.31%) and dodecanal (16.93%) as major compounds in the essential oil obtained through hydrodistillation. Farnesyl pyrophosphate, Methyl 7-desoxypurpurogallin-7-carboxylate trimethyl ether, Dihydro-Obliquin, Gummiferol, 2-Phenylaminoadenosine, and 2,4,6,8,10-dodecapentaenal, on the other hand, were the dominant compounds in the methanolic extract. Moreover, the tested extract was active against a large collection of bacteria and yeast strains with diameter of growth inhibition ranging from 6.67 ± 0.57 mm to 17.00 ± 1.73 mm, with bacteriostatic and fungicidal activities against almost all tested microorganisms. In addition, D. flabellifolia methanolic extract was dominated by phenolic compounds (33.85 ± 1.63 mg of gallic acid equivalent per gram of extract) and was able to trap DPPH• and ABTS•+ radicals with IC50 about 0.05 ± 0 mg/mL and 0.105 ± 0 mg/mL, respectively. The highest percentages of anticancer activity were recorded at 500 µg/mL for all cancer cell lines with IC50 about 240. 56 µg/mL (A-549), 202.94 µg/mL (HCT-116), and 154.44 µg/mL (MCF-7). The in-silico approach showed that D. flabellifolia identified compounds bound 1HD2, 2XCT, 2QZW, and 3LN1 with high affinities, which together with molecular interactions and the bond network satisfactorily explain the experimental results using antimicrobial, antioxidant, and anticancer assays. The obtained results highlighted the ethnopharmacological properties of the rare desertic D. flabellifolia plant species growing wild in Hail region (Saudi Arabia).