Phytochemical profile and antimicrobial activity of essential oils from two Syzygium species against selected oral pathogens

Abstract

Background The genus Syzygium (Myrtaceae) comprises several essential oil-rich species that are utilized traditionally for treating tooth infections and toothache. The current study aimed to extract essential oils (EOs) from the leaves of Syzygium samarangense and Syzygium malaccense cultivated in Egypt for the first time and screen their antimicrobial potential against oral-related pathogens. Methods The intended EOs were extracted using hydrodistillation (HD) by boiling fresh leaves with distilled water; supercritical fluid (SF) by extracting the dried leaves using supercritical CO2 at 40 °C and 150 bar; and the headspace (HS) in which the fresh leaves were heated in a glass vial and the vaporized aroma were analyzed. The volatile constituents were analyzed using GC/MS and identified by comparing the experimental Kovats' retention indices with the literature. The antimicrobial activity was assessed against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Candida albicans using agar diffusion, microwell dilution, and biofilm formation assays. Statistical significance (p < 0.05) was determined by applying one-way ANOVA and Duncan's post hoc test. Results The yield of the extracted EOs differs between the applied methods, and the SF approach harvested the maximum (0.52–0.46%). The GC–MS analysis of SF EOs revealed a discrepancy between the two species. Since S. malaccense showed an abundance of hydrocarbons represented mainly by squalene (60.60%), S. samarangense was deemed to have oxygenated sesquiterpenes exemplified in globulol (52.09%). On the other side, the HD and HS EOs were sequentially comparable, while differed in the percentage of their majors. γ-terpinene (33.06%) pioneered the HS-derived aroma of S. malaccense, while S. samarangense was abundant with α-pinene (30.18%). Concurrently, the HD EOs of S. malaccense and S. samarangense were commonly denoted by caryophyllene oxide (8.19%-18.48%), p-cymene (16.02%- 19.50%), and γ-terpinene (12.20%-17.84). Ultimately, both species EOs exhibited broad-spectrum antimicrobial potential, although the HD EO was more potent than the SF EO. The HD EOs of both species potently inhibited the growth of E. coli (MIC 3.75 µL/mL) and suppressed C. albicans biofilm formation by 83.43 and 87.27%, respectively. The SF-EOs efficiently suppressed the biofilm formation of Gram-positive bacteria by 76.45%-82.95%. Conclusion EOs extracted from both species by different methods possessed a unique blend of volatile components with broad-spectrum antimicrobial activity. They were promoted as bioactive hits for controlling oral infections, however further investigations concerning their safety in clinical settings are needed.

Antibacterial Activity of Herbal Essential Oils against Gram-positive and Gram-negative Bacteria with a Potential for Multidrug Resistance

“…The antibiotics tested (Tetracycline TC, Gentamicin CN, Streptomycin S, and Amoxicillin AMP) exhibited antibacterial effects against the tested bacteria. Gentamicin was the most effective against all bacteria, while Amoxicillin showed the lowest antibacterial activity (Salem, et al, 2023).…”

“…Recent reports have indicated that many healthcare-associated, antimicrobialresistant bacteria are not only multidrug-resistant pathogens but also broadly drug-resistant and pandrug-resistant bacteria (Singh & Katoch, 2020). Medicinal plants, known for their therapeutic properties and beneficial pharmacological effects on the human body, are recognized as alternative sources of drugs that could potentially be effective in treating these problematic bacterial infections (Salem et al, 2023, Al-Haj et al, 2019, Boadu & Asase, 2017. a Essential oils, which are volatile terpene hydrocarbons, and their oxygenated derivatives are secondary metabolites, are known for their concentrated natural pharmacologically active ingredients (Boadu & Asase, 2017).…”

Exploring essential oil-based bio-composites: molecular docking and in vitro analysis for oral bacterial biofilm inhibition

“…These are mainly comprised of low molecular weight compounds, including monoterpenes and phenolic compounds ( Gheorghita et al, 2022 ). Since ancient times, EOs, including clove oil, have been used in oral hygiene as anti-inflammatory and antimicrobial agents ( Saleem et al, 2023 ). The significant antimicrobial activities of EOs are mainly due to their interference with bacterial membranes due to their hydrophobic nature, which affects cellular structures, and their efflux pump, enzymatic inhibition (β-lactamase), and strong antioxidant properties ( Devi et al, 2010 ; Oliveira et al, 2022 ).…”