Chemical Composition, Antioxidant, Antibacterial, and Antibiofilm Activities of Backhousia citriodora Essential Oil

Abstract

The essential oil of Backhousia citriodora, commonly known as lemon myrtle oil, possesses various beneficial properties due to its richness in bioactive compounds. This study aimed to characterize the chemical profile of the essential oil isolated from leaves of Backhousia citriodora (BCEO) and its biological properties, including antioxidant, antibacterial, and antibiofilm activities. Using gas chromatography–mass spectrometry, 21 compounds were identified in BCEO, representing 98.50% of the total oil content. The isomers of citral, geranial (52.13%), and neral (37.65%) were detected as the main constituents. The evaluation of DPPH radical scavenging activity and ferric reducing antioxidant power showed that BCEO exhibited strong antioxidant activity at IC50 of 42.57 μg/mL and EC50 of 20.03 μg/mL, respectively. The antibacterial activity results showed that BCEO exhibited stronger antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis) than against Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae). For the agar disk diffusion method, S. epidermidis was the most sensitive to BCEO with an inhibition zone diameter of 50.17 mm, followed by S. aureus (31.13 mm), E. coli (20.33 mm), and K. pneumoniae (12.67 mm). The results from the microdilution method showed that BCEO exhibited the highest activity against S. epidermidis and S. aureus, with the minimal inhibitory concentration (MIC) value of 6.25 μL/mL. BCEO acts as a potent antibiofilm agent with dual actions, inhibiting (85.10% to 96.44%) and eradicating (70.92% to 90.73%) of the biofilms formed by the four tested bacteria strains, compared with streptomycin (biofilm inhibition, 67.65% to 94.29% and biofilm eradication, 49.97% to 89.73%). This study highlights that BCEO can potentially be a natural antioxidant agent, antibacterial agent, and antibiofilm agent that could be applied in the pharmaceutical and food industries. To the best of the authors’ knowledge, this is the first report, on the antibiofilm activity of BCEO against four common nosocomial pathogens.

Phytochemical Variability, In Vitro and In Vivo Biological Investigations, and In Silico Antibacterial Mechanisms of Mentha piperita Essential Oils Collected from Two Different Regions in Morocco

“…Furthermore, our findings were in agreement with studies in which the antioxidant activity could be attributed to the major monoterpenoids such as menthone (29.4%), carvone (70.25%), and Levomenthol (43.32%) [ 45 , 68 , 69 ]. Several studies have shown that enhanced antioxidant properties are found in EOs [ 70 ]. Hence, the chemical compounds of EO from M. piperita might work individually or synergistically as natural antioxidants.…”

Chemical Composition and Antioxidant Activity of the Essential Oils of Citral-Rich Chemotype Cinnamomum camphora and Cinnamomum bodinieri

“…The citral (60.5–88.7%) was the main component in the EOCC, equal to or better than the citral-rich plants, including Backhousia citriodra (85–95%) [ 4 , 26 ]; Litsea cubeba (70–90%) [ 42 ]; Cymbopogan flexuosus (65–85%) [ 43 ]; Ocimum gratissimum (65–75%) [ 44 ]; Lippia citriodor (30–60%) [ 1 , 45 ]; Citrus aurantium bigarade (25–30%) [ 46 ]. The citral chemotype C. camphora and C. bodinieri , as the evergreen tree, had more advantages for extracting citral in terms of biomass, oil yield of essential oil and citral content; moreover, their tending and harvesting can be mechanized.…”

“…The antioxidation of natural plant essential oils is very important for their application in the fields of medicine, food and spices, which overcome the deleterious effect of chemically synthesized antioxidants. The 2,2-diphenyl-1 picrylhydrazyl (DPPH) free radical scavenging test, scavenging 2,2′-azinobis(3-ethylbenzo thiazoline-6-sulfonic acid) diammonium salt radical (ABTS) and the ability of Ferric reducing antioxidant power (FRAP) are the most common methods used to evaluate the antioxidant activity of compounds, and various phytoconstituents and their potential antioxidant activities have been reported previously [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. In terms of the C. camphora’s antioxidant activities, linalool, eucalyptol, camphor and borneol chemotypes with strong scavenging activity against 2,2-diphenyl-1 picrylhydrazyl (DPPH) were proved [ 17 ].…”

Beyond the Risk of Biofilms: An Up-and-Coming Battleground of Bacterial Life and Potential Antibiofilm Agents

“…Furthermore, these oils appear to be effective at inactivating many microbes without causing resistance to antimicrobials [ 147 ]. Its low toxicity to mammalian cells, quick environmental decomposition, and the availability of diversified essential oils make them potential antibiofilm agents [ 148 , 149 , 150 ]. Some of the recently reported essential oils and their antibiofilm activities against different pathogenic microbial strains are discussed below and summarized in Table 4 .…”