Essential Oil Analysis and Antimicrobial Evaluation of Three Aromatic Plant Species Growing in Saudi Arabia

Abstract

Arabian flora is a rich source of bioactive compounds. In this study, we investigated three aromatic plant species with the aim of finding valuable sources of antimicrobial agents against common pathogenic microorganisms. We focused especially on microorganisms, which cause outbreaks of infectious disease during mass gatherings and pilgrimages season in Saudi Arabia. The essential oils of three aromatic plant species were hydrodistilled from flowering aerial parts of Lavandula pubescens Decne. and Pulicaria incisa subsp. candolleana E.Gamal-Eldin, and from leaves, stems, ripe and unripe fruits of Juniperus procera Hochst. Ex Endl. They were subsequently analyzed by gas chromatography-mass spectrometry (GC-MS). The main constituents of L. pubescens were found to be carvacrol (55.7%), methyl carvacrol (13.4%), and β-bisabolene (9.1%). P. incisa subsp. Candolleana essential oil was rich in linalool (33.0%), chrysanthenone (10.3%), eugenol (8.9%), and cis-chrysanthenol (8.0%); the major components of J. procera essential oil were α-pinene (31.3–62.5%) and δ-3-carene (7.3–30.3%). These essential oils were tested against thirteen American Type Culture Collection (ATCC) strains of Gram-positive and Gram-negative bacteria using the agar diffusion assay. The only effective essential oil was that of L. pubescens and the most sensitive strains were Acinetobacter baumannii, Salmonella typhimurium, Shigella sonnei, Enterococcus faecalis and Staphylococcus epidermidis. Carvacrol, the major constituent of L. pubescens, was tested on these strains and was compared with vancomycin, amikacin, and ciprofloxacin. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays of L. pubescens essential oil and carvacrol revealed that Gram-negative strains were more susceptible than the Gram-positive ones.

Fumigant Toxicity and Feeding Deterrent Activity of Essential Oils from Lavandula dentata, Juniperus procera, and Mentha longifolia against the Land Snail Monacha obstructa

“…Nevertheless, other studies reported different major components in L. dentata EO, such as linalool, linalyl acetate, and α-terpinolene [43,44]. Consistent with our results, α-pinene was the major component in the EO of J. procera from East Africa and Saudi Arabia [45,46]. Among the components of the Saudi J. procera extract, α-pinene and α-humulene were reported by Abdelghany et al [29].…”

Facing Resistant Bacteria with Plant Essential Oils: Reviewing the Oregano Case

“…In this context, Tiwari et al [ 57 ] reviewed the activity of Lythrum salicaria plant extracts against P. aeruginosa and A. baumannii . Similarly, El-Said et al [ 8 ] evaluated the effect of 15 essential oils via agar diffusion on Salmonella enterica strains. Among all the plants, T. vulgaris and L. graveolens showed the highest efficacy with inhibition halos >20 mm.…”

“…In addition, the antibacterial potential of these oils was reported against P. aeruginosa (MIC 2–4 % v/v ) and A. baumannii (MIC 0.25–0.37% v/v ). In addition, El-Said et al [ 8 ] examined essential oils from L. pubescens , P. incisa subsp. candolleana and J. procera against 13 Gram-positive and Gram-negative strains.…”

“…Some studies have investigated how these compounds carry out their activity. In the review by Sarrazin et al [ 82 ], it is mentioned that the hydroxyl group and delocalized electrons represent a key element for this activity, in addition to the aromatic ring that makes these compounds more hydrophobic, which is related to greater interaction with the bacterial membrane [ 8 ]. In this context, deeper studies regarding the contribution of each constituent in essential oil are needed to understand their action.…”

“…enterica and serovar Typhimurium, reporting their efficacy in a range of 0.5–1 mg/mL. On the other hand, El-Said et al [ 8 ] evidenced the antibacterial efficacy of Lippia pubescens , presenting inhibition halos of 10 to 24 mm for E. faecalis, S. epidermidis . A. baumannii , and S. Typhimurium.…”