Borneol-type essential oil is extracted from the plant Cinnamomum burmannii (Nees T. Nees) Blume, a plant belonging to the genus Cinnamomum burmannii. It is a natural volatile aromatic oil with promising application prospects. Current domestic and international studies on this essential oil largely focus on its chemical composition and biological activities. However, a systematic toxicological safety evaluation remains lacking. This study systematically evaluated the safety of this essential oil for edible and dermal contact use through local irritation tests, acute and subchronic oral toxicity assays, and a series of genotoxicity tests. The results show that, in the local irritation test, 100% (volume fraction, same below) borneol-type Cinnamomum burmannii essential oil causes mild skin irritation in rabbits; continuous application of 50% borneol-type Cinnamomum burmannii essential oil for 14 days does not induce obvious skin irritation responses. Furthermore, the oil exhibits mild acute eye irritation to rabbit ocular mucosa, with only transient conjunctival congestion and edema observed, and no significant damage to the iris or cornea. Oral toxicity tests indicate that the acute oral toxicity in KM mice is classified as practically non-toxic. After 90 days of subchronic oral administration in SD rats, no significant differences were observed in weight gain, food intake, or food efficiency between the treated and control groups for either sex during the experimental period. Regarding genotoxicity, both the bacterial reverse mutation assay (Ames test) and the in vitro mammalian cell chromosome aberration assay yielded negative results, indicating that the essential oil causes no mutagenic or chromosomal damage, either with or without a metabolic activation system. In conclusion, under the experimental conditions of this study, borneol-type Cinnamomum burmannii essential oil demonstrates a high level of safety for use.

To investigate the effects of different components of borneol essential oil, separated by molecular distillation, on the motility and biofilm formation of Escherichia coli, the study was conducted as follows: First, gas chromatography-mass spectrometry (GC-MS) was employed to analyze the volatile components of the crude borneol essential oil, its light fraction, and its heavy fraction. Next, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the three components against E. coli ATCC 25922 were determined using the double dilution method and plate coating method, respectively. Finally, the impact of these three components on the swimming and swarming motility, as well as biofilm formation of E. coli ATCC 25922, was studied using motility assays and crystal violet staining. The results show that the crude borneol essential oil, light fraction, and heavy fraction contain 27, 24, and 19 volatile components, respectively. The highest relative content of volatile components is D-borneol (19. 93%) in the crude oil, eucalyptol (19.36%) in the light fraction, and D-borneol (28.92%) in the heavy fraction.The MIC and MBC of the crude oil, light fraction, and heavy fraction against E. coli are 6.25 µL/mL, and all three components are able to delay bacterial growth at sub-inhibitory concentrations. At 1/2 MIC and 1/4 MIC, all three borneol essential oil components reduce the swimming and swarming motility of E. coli and inhibited biofilm formation. The heavy fraction of borneol essential oil exhibits superior inhibition of E. coli motility and biofilm formation compared to the crude oil and light fraction. These findings indicate that molecular distillation can enrich the antibacterial active components in borneol essential oil, effectively enhancing its added value and demonstrating broad application prospects.