Crude extracts and essential oil of Platycladus orientalis (L.) Franco: a source of phenolics with antioxidant and antibacterial potential as assessed through a chemometric approach

The chemical composition, antioxidant properties and antibacterial activities of different extracts (water, ethanol, acetate ethyl and hexane) and essential oil from Platycladus orientalis leaves were analysed in this study. The essential oil was extracted by hydrodistillation, and its chemical composition was determined by gas chromatography coupled to mass spectrometry (GC-MS). The major components of the essential oil were alpha-pinene (40.2%), beta-phellandrene (9.3), alpha-cedrol (9.2%) and beta-caryophyllene (6.3%). Phytochemical analysis of crude extracts and essential oil revealed the richness of ethyl acetate and ethanolic extracts in total phenolic content (62.69 and 61.44 mg GAE/g DW, respectively). The antioxidant activities of all samples were evaluated by four different methods including total antioxidant activity (TAC), 1,1-diphenyl-2-picrylhydrazyl radical scavenging (DPPH), ABTS free radical scavenging activity (ABTS) and reducing power assay (RPA). Results showed that ethanol extract exhibited the highest antioxidant activity with all assays. The antimicrobial activity was evaluated by the disc diffusion method against five bacterial strains: Staphylococcus aureus CIP 53156, Bacillus subtilis CIP 5262, Micrococcus luteus CIP 5345, Salmonella enterica CIP 8039, and Escherichia coli CIP 53126. Results demonstrated that essential oil of P. orientalis leaves is more effective against the tested strains than extracts, especially against Micrococcus luteus and Staphylococcus aureus. This study argues the use of P. orientalis essential oil and ethanol extracts as a potential source of natural antioxidants and antimicrobial agents and supports the valorization of these natural substances in further application domains.