In Vitro and In Silico Studies of Antimicrobial, and Antioxidant Activities of Chemically Characterized Essential Oil of Artemisia flahaultii L. (Asteraceae)

Origanum majorana L. polyphenols: in vivo antiepileptic effect, in silico evaluation of their bioavailability, and interaction with the NMDA receptor

Introduction: Epilepsy is a chronic brain disease characterized by repeated seizures and caused by excessive glutamate receptor activation. Many plants are traditionally used in the treatment of this disease. This study aimed to evaluate the bioavailability of a polyphenolic extract obtained from Origanum majorana L. (OMP) leaves, as well as its antiepileptic activity and its potential mechanism of action. Methods: We have developed and validated a simple, rapid, and accurate stability-indicating reversed-phase liquid chromatographic method for the simultaneous determination of caffeine and quercetin in rat plasma. The OMP antiepileptic effect was evaluated with pilocarpine-induced seizures, and a docking method was used to determine the possible interaction between caffeic acid and quercetin with the N-methyl-D-aspartate (NMDA) receptor. Results and Discussion: Both compounds tested showed low bioavailability in unchanged form. However, the tested extract showed an anticonvulsant effect due to the considerably delayed onset of seizures in the pilocarpine model at a dose of 100 mg/kg. The molecular docking proved a high-affinity interaction between the caffeic acid and quercetin with the NMDA receptor. Taken together, OLP polyphenols demonstrated good antiepileptic activity, probably due to the interaction of quercetin, caffeic acid, or their metabolites with the NMDA receptor.

Volatile Constituents in Essential Oil from Leaves of Withania adpressa Coss. Ex Exhibit Potent Antioxidant and Antimicrobial Properties against Clinically-Relevant Pathogens

Withania adpressa Coss. ex is a plant used in traditional medications. Antioxidant, antibacterial, and antifungal properties of the essential oil from leaves of Withania adpressa Coss ex. (EOW) were investigated. EOW was extracted using a Clevenger apparatus, and its volatile compounds were characterized by GC-MS. Antioxidant potency was determined using DPPH, FRAP, and TAC assays. Antibacterial effects were determined vs. Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, and Streptococcus pneumonia; while its antifungal efficacy was determined vs. Candida albicans, Aspergillus flavus, Aspergillus niger, and Fusarium oxysporum using the disc diffusion and minimum inhibitory concentration bioassays. A chromatographic analysis showed that EOW contained eight phytochemical compounds constituting 99.14% of the total mass of oil. Caryophyllene (24.74%), Longifolene (21.37%), δ-Cadinene (19.08%), and Carene (14.86%) were predominant compounds in EOW. The concentrations required to inhibit 50% of free radical (IC50) values of antioxidant activities of EOW were 0.031 ± 0.006 mg/mL (DPPH), 0.011 ± 0.003 mg/mL (FRAP), and 846.25 ± 1.07 mg AAE/g (TAC). Inhibition zone diameters of EOW vs. bacteria were 18.11 ± 0.5 mm (E. coli), 17.10 ± 0.42 mm (S. aureus), 12.13 ± 0.31 mm (K. pneumoniae), and 11.09 ± 0.47 mm (S. pneumoniae), while MIC values were 51 ± 3, 47 ± 5, 46 ± 3 and 31 ± 1 µg/mL, respectively. Inhibition zone diameters of EOW vs. fungi were 31.32 ± 1.32, 29.00 ± 1.5, 27.63 ± 2.10, and 24.51 ± s1.07 mm for A. flavus, C. albicans, F. oxysporum, and A. niger, respectively. MIC values were 8.41 ± 0.40, 28.04 ± 0.26, 9.05 ± 0.76, and 22.26 ± 0.55 µg/mL, respectively. Importantly, the highest dose of EOW (1 mg/mL) showed negligible (~5%) cytotoxicity against MCF-12, a normal human epithelial cell line derived from the mammary gland, thus underscoring its wide safety and selectivity against tested microbes. To sum it up, EOW has exhibited promising antioxidant and antimicrobial properties, which suggests potential to abrogate antibiotic resistance.