Antimicrobial Potential of Essential Oils from Aromatic Plant Ocimum sp.; A Comparative Biochemical Profiling and In-Silico Analysis

Abstract

Medicinal and aromatic plants (MAPs) are a rich source of bioactive compounds that are immensely important due to their potential use in pharmacological and agricultural applications. Here, we have evaluated the antimicrobial activity of essential oils (EOs) from three different species of Ocimum: O. gratissimum (EO1), O. tenuiflorum (EO2), and O. sanctum (EO3). The EOs were screened for antibacterial activity against pathogenic strains of Escherichia coli, Enterobacter cloacae and methicillin-resistant Staphylococcus aureus (MRSA). The essential oils EO1 and EO3 showed significant growth inhibition of the tested bacteria. Likewise, all EOs exhibited antifungal potential against the broad-spectrum plant fungal pathogen Sclerotinia sclerotiorum that causes white-mould disease in plants. Moreover, the antimicrobial potential of the EOs correlates well with their antioxidant activity determined by DPPH free radical scavenging activity. The biochemical analysis of the EOs employing high-performance thin-layer chromatography, gas chromatography-mass spectrometry, and Fourier transform infrared spectroscopy, revealed the presence of distinct phytoconstituents that might be responsible for their differential bioactivity. Furthermore, an in-silico evaluation of the candidate phytoconstituents using molecular docking analysis suggests their potential for antimicrobial applications. Altogether, our results clearly show that EO1 and EO3 possess promising antimicrobial properties, and therefore could be utilized as a potential antimicrobial agent.

In Silico Study for Algerian Essential Oils as Antimicrobial Agents against Multidrug-Resistant Bacteria Isolated from Pus Samples

“…Therefore, antibiotic agents compete with p-amino benzoic acid to bind with the dihydropteroate synthetase (PDB ID: 2VEG) with much greater affinity and inhibit the formation of dihydrofolic acid. In line with the affinity showed by β-cubebene towards 2VEG (−6.1 kcal/mol) reported by Salvi et al [ 48 ], the sesquiterpenes in the current study—α-humulene and viridoflorol—showed similar affinity ( Table 5 ).…”

“…Antibiotics bind to 3SRW and inhibit thymidine synthesis, which eventually affects DNA synthesis. In agreement with Jianu et al [ 49 ] and Salvi et al [ 48 ], sesquiterpenes exhibited higher in silico binding affinity towards 3SRW than well-known antibiotics used against enzymes such as trimethoprim. Viridiflorol had the highest binding energy (−8.1 kcal/mol) among all the examined volatiles towards all receptors included in the study.…”

“…In Gram-positive bacteria, topoisomerase 4 catalyzes the separation of daughter strands following replication. The molecular-docking analysis for the major volatiles in the potent antibacterial EOs of the present study revealed that 1,8-cineole and sesquiterpenes showed the highest binding affinity towards topoisomerase 4 (PDB ID: 3RAE), with −6.0 to −6.5 kcal/mol ( Table 5 ), which is comparable to the binding affinity of O. gratissimum , O. tenuiflorum , and O. sanctum EOs volatiles reported by Salvi et al [ 48 ] and higher than the volatiles of Mentha × smithiana essential oil [ 13 ].…”

“…Therefore, the assumption that one of the antibacterial mechanisms of the EO’s monoterpene components is the suppression of bacterial-wall synthesis by inhibiting the D-alanine–d-alanine ligase enzyme is highly plausible. The binding-affinity energy of thymol recorded in the current study was superior compared to the literature [ 13 , 48 ] and opens the prospects for using EOs rich in thymol as antibacterial agents against MDR isolates. In Gram-positive bacteria, topoisomerase 4 catalyzes the separation of daughter strands following replication.…”

In vitro and in silico β-lactamase inhibitory properties and phytochemical profile of Ocimum basilicum cultivated in central delta of Egypt

“…These discs were transferred to MHA plates containing the test organism then were incubated at 37 °C for 24 h. After incubation, the diameter of the inhibition zone was measured and if it was found to be increased by ≥5 mm for either antibiotic combined with clavulanic acid, this was considered as evidence for the production of an ESBL (Schwaber et al. 2004 ; Jain and Mondal 2008 ).…”