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

Abstract

The present study investigated the antioxidant and antimicrobial activities as well as characterized the chemical composition of the essential oils (EO) isolated from Artemisia flahaultii (EOF). EOF was extracted using hydro-distillation, and the chemical composition of EOF was ascertained by gas chromatography coupled with mass spectrometry (GC/MS). To assess antioxidant capacity, three tests were used: the 2,2-diphenyl-1-picrylhydrazil (DPPH), the total antioxidant capacity (TAC) and the ferric-reducing antioxidant power (FRAP) test. The antimicrobial activity of EOF was investigated using the diffusion assay and minimal inhibitory concentration assays (MICs). By use of in silico structure–activity simulations, the inhibitory potency against nicotinamide adenine dinucleotide phosphate (NADPH), physicochemical characters, pharmaco-centric properties and absorption, distribution, metabolism, excretion (ADME) characteristics of EOF were determined. GC/MS analysis reveals 25 components majorly composed of D-Limonene (22.09%) followed by β-pinene (15.22%), O-cymene (11.72%), β-vinylnaphthalene (10.47%) and benzene 2,4-pentadiynyl (9.04%). The capacity of DPPH scavenging by EOF scored an IC50 of 16.00 ± 0.20 µg/mL. TAC revealed that the examined oils contained considerable amounts of antioxidants, which were determined to be 1094.190 ± 31.515 mg ascorbic acid equivalents (AAE)/g EO. Results of the FRAP method showed that EOF exhibited activity with EC50 = 6.20 ± 0.60 µg/mL. Values for minimal inhibitory concentration (MIC) against certain clinically important pathogenic bacteria demonstrate EOF’s potent antibacterial activity. MIC values of 1.34, 1.79, and 4.47 μg/mL against E. coli, B. subtilis and S. aureus were observed respectively. EOF exhibited significant antifungal activities against two stains of fungi: F. oxysporum and C. albicans, with values of 10.70 and 2.23 μg/mL, respectively. Of the total, 25 essential oils were identified. 2,4-Di-tert-butylphenol and capillin were the most active molecules against NADPH. The ADME prediction revealed that EOF was characterized by useful physicochemical characteristics and pharmaco-centric properties. The findings of this study show that the EOF can be used as an alternative to treat microbial resistance. Based on the in silico studies, EOF can be used as an “eco-friendly” NADPH inhibitor.

Keywords

• free radicals
• antibacterial
• antifungal
• GC/MS
• structure–activity modeling
• natural products