Chemical Composition and Biological Activities of the Essential Oils from Different Parts of Rosa bracteata J.C.Wendl

<i>Rosa bracteata</i> J.C.Wendl. is a thorny, clump-forming or trailing perennial evergreen shrub native to China. The current analysis was designed to explore the chemical constituents and determine the in vitro antimicrobial, cytotoxic, and antioxidant properties of the essential oils (EOs) of the stems, leaves, and flowers of <i>Rosa bracteata</i> for the first time. The chemical composition of the essential oils obtained through hydro-distillation was characterized by means of gas chromatography-mass spectrometry (GC-MS) and gas chromatography with a flame ionization detector (GC-FID). Thirty-seven, thirty-six, and forty-two constituents were identified from leaf oil (LEO), stem oil (SEO), and flower oil (FEO), representing 96.3%, 95.9%, and 97.4% of the total oil constituents, respectively. The LEO was mainly composed of 1-pentadecene, <i>α</i>-cadinol, and hexadecanoic acid. However, the main identified components of SEO were (<i>E</i>)-nerolidol, phytol, and benzyl benzoate, and the main components of the flower oil were ethyl octanoate, octanoic acid, and α-cadinol. All of the EOs exhibited antibacterial activities against both Gram-positive and Gram-negative bacteria with MIC values ranging from 40.00 to 640.00 μg/mL. In addition, the checkerboard method demonstrates potent synergistic effects of <i>Rosa bracteata</i> EOs when combined with commercial antibiotics (chloramphenicol and streptomycin). In the MTT test, SEO (IC₅₀: 37.91 ± 2.10 to 51.15 ± 6.42 μg/mL) showed stronger cytotoxic activity against four cancer cell lines (MCF-7, A549, HepG2, and HCT-116) during the incubation time of 48 h in comparison to the EOs isolated from the other plant parts. Overall, these findings reveal the chemical composition and significant bioactivity of <i>R. bracteata</i> EOs for the first time, suggesting their potential as promising natural agents for therapeutic applications, especially in combination therapies to combat antibiotic resistance.