Abstract
This work was conducted to study the chemical composition, antioxidant, antibacterial, and antifungal activities of essential oil and hydrolat from Withania frutescens. The essential oil was extracted by hydrodistillation. The chemical characterization was performed using gas chromatography-mass spectrometry (GC/MS). The antioxidant activity was studied using four different assays (DPPH, TAC, FRAP, and β-carotene bleaching). The antibacterial activity test was carried out on multidrug-resistant bacteria including Gram-negative and Gram-positive strains. Antifungal activity was tested on Candida albicans and Saccharomyces cerevisiae. The yield of essential oil (EO) obtained by hydrodistillation of W. frutescens was 0.31% majorly composed of camphor, α-thujone, carvacrol, and thymol. Regarding the antioxidant activities, the concentration of the sample required to inhibit 50% of radicals (IC50) of EO and hydrolat were 14.031 ± 0.012 and 232.081 ± 3.047 µg/mL (DPPH), 4.618 ± 0.045 and 8.997 ± 0.147 µg/mL (FRAP), 0.091 ± 0.007 and 0.131 ± 0.004 mg AAE/mg (TAC), 74.141 ± 1.040% and 40.850 ± 0.083% (β-carotene), respectively. Concerning the antibacterial activity of essential oil and hydrolat, the minimum inhibitory concentration (MIC) values found were 0.006 ± 0.001 and 6.125 ± 0.541 µg/mL (Escherichia coli 57), 0.003 ± 0.001 and 6.125 ± 0.068 µg/mL (Klebsiella pneumoniae), 0.001 ± 0.0 and 6.125 ± 0.046 µg/mL (Pseudomonas aeruginosa) and 0.012 ± 0.003 and 6.125 ± 0.571 µg/mL (Staphylococcus aureus), respectively. MIC values of essential oil and hydrolat vs. both C. albicans and S. cerevisiae were lower than 1/20,480 µg/mL. Based on the findings obtained, essential oils of Withania frutescens can be used as promising natural agents to fight free radical damage and nosocomial antibiotic-resistant microbes.
Highlights
Nosocomial infections caused by certain microbial strains remain a major cause of mortality and morbidity worldwide [1]
The low sensitivity of Gram-negative microorganisms to antibacterial agents may be explained by the fact that they have an outer membrane surrounding the cell wall, which limits the diffusion of hydrophobic compounds through its lipopolysaccharide coating
Chemical Characterization of Essential Oil by gas chromatography-mass spectrometry (GC/MS) The identification of different chemical compounds contained in essential oils was carried out by gas chromatography coupled to a mass spectrometer
Summary
Nosocomial infections caused by certain microbial strains remain a major cause of mortality and morbidity worldwide [1]. IIst pislathnut sagfiatitninsgt athnatitbtihoetipc-rreesseinsttawntomrkicarimobeeds.to study the chemical composition, antioxidant, antibacterial, and antifungal activities of both essential oils and hydrolat from this plant. The results obtained in this work showed that the percentage of free radical inhibition of both EO and hydrolat was 74.141 ± 1.040% and 40.850 ± 0.083%, respectively (Table 2) This activity remained significantly lower than that of BHT used as positive controls. These obtained findings were used to perform a comparison with those reported in the previous literature, which showed that species belonging to genera Withania possessed antioxidant power with 57% and 36% for the roots and leaves, respectively [22]. The decrease in the negative control absorbance was the most important, followed by the hydrolat, es7seonf -15 tial oil, and BHT (Figure 4)
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