Essential Oils from Leaves of Juniperus thurifera L., Exhibiting Antioxidant, Antifungal and Antibacterial Activities against Antibiotic-Resistant Microbes

Abstract

The antioxidant, antibacterial and antifungal properties of essential oils (EOs) of Juniperus thurifera L., a plant utilized in traditional, herbal medicine, were investigated. The EOs were extracted by use of a Clevenger apparatus and phytochemicals identified by gas chromatography coupled with mass spectrometry (GC/MS/MS). The antioxidant capacity of EOs of J. thurifera was determined by 2,2-diphenyl-1-picrylhydrazil (DPPH), total antioxidant capacity (TAC), and ferric reducing antioxidant power (FRAP). Antimicrobial activity of EOs of J. thurifera was determined against four fungal strains, Candida albicans; ATCC 10231, Aspergillus niger; MTCC 282, Aspergillus flavus; MTCC 9606 and Fusarium oxysporum; MTCC 9913 and four bacterial strains, Staphylococcus aureus; ATCC 6633, Escherichia coli; K12, Bacillus subtilis; DSM 6333, and Pseudomonas aeruginosa; CIP A22, by use of the disk diffusion method, and microdilution method used to determine the minimum inhibitory concentration (MIC). EOs of J. thurifera consisted of 31 compounds and were dominated by α-thujene (25%), elemol (12%) and muurolol (12%). Antioxidant activity recorded an IC50 of 24 ± 0.71 µg/mL (DPPF), EC50 of 0.19 ± 0.01 mg/mL (FRAP), and 9.3 × 102 ± 38 mg EAA/g (TAC). The EOs of J. thurifera exhibited significant antibacterial activity against all bacterial strains under investigation, especially P. aeruginosa; CIP A22 with an inhibition diameter of 28 ± 1.5 mm and MIC of 4.8 × 10 −2 ± 0. 001 µg/mL. EOs of J. thurifera also exhibited significant antifungal activity against C. albicans; ATCC 10231 and F. oxysporum; MTCC 9913 with an activity of 21 ± 2.1 mm, 32 ± 2.3%, and MIC of 9.5 × 10 −2 ± 0.001 Bioactive molecules found in EOs of J. thurifera could be used as an alternative solution to antibiotics available on the market to combat microbial resistance.

GC-MS Profiling, In Vitro Antioxidant, Antimicrobial, and In Silico NADPH Oxidase Inhibition Studies of Essential Oil of Juniperus thurifera Bark

“…e EC50 of EOEJT, BHT, and quercetin were 481.02 ± 5.25 μg/mL, 214.08 ± 2.51 μg/mL, and 189.11 ± 2.20 μg/mL, respectively (Figure 3(d)). e antioxidant power of EOEJT was slightly lower than that recorded for J. thurifera leaves in previous work with an EC50 of 190 μg/mL [13].…”

“…Juniperus thurifera ( Figure 1 ) was collected from a mountainous area in the Middle Atlas, Morocco before being identified by a botanist and given the voucher number (FJT/02D20). Next, the bark was isolated from the plant branches, and then cleaned and dried by use of an oven at 35°C before grinding into powder by use of an electric grinder [ 13 ].…”

“…Using a Clevenger device, 200 g of the plant powder was immersed in 800 mL of water before being mixed and heated at boiling temperature for two hours. Next, the essential oils (EOEJT) were recovered and placed at 4°C until further use [ 13 , 14 ].…”

“…The ionization energy was set to 70 eV, the ion source temperature was set at 200°C, the interface line temperature was 280°C, and the scan mass range was m / z 40–650.00. Volatile compounds of essential oil were identified by the use of the Kovats index and NIST-MS Search Version 2.0 [ 13 , 15 ].…”

“…Lafraxo et al [13] showed that the essential oil of Juniperus thurifera leaves exhibited potent antifungal activity vs. F. oxysporum and C. albicans at a concentration of 0.095 g/ mL.…”