Composition, in vitro Cytotoxic, and Antimicrobial Activities of the Flower Essential Oil of Diospyros discolor from Taiwan

This study investigated the chemical composition, in vitro cytotoxic, and antimicrobial activities of the essential oil isolated from the flower of Diospyros discolor from Taiwan. The essential oil was isolated using hydrodistillation in a Clevenger-type apparatus, and characterized by GC-FID and GC-MS. Twenty-eight compounds were identified, representing 100% of the oil. The main components identified were (2 Z,6 E)-farnesol (35.0%), α-cadinol (10.9%), ( E)-nerolidol (6.9%), α-humulene (6.0%), τ-cadinol (5.6%), β-caryophyllene (5.3%), and τ-muurolol (5.3%). The oil exhibited cytotoxic activity against human colon, liver, and lung cancer cells. The active compounds were β-caryophyllene, α-humulene, τ-cadinol, τ-muurolol, α-cadinol, and (2 Z,6 E)-farnesol. The antimicrobial activity of the oil was tested by the disc diffusion and micro-broth dilution methods against ten microbial species. The oil exhibited moderate to strong growth suppression against Bacillus cereus, Staphylococcus aureus, S. epidermidis, Escherichia coli, Enterobacter aerogenes, and Candida albicans, with inhibition zones of 40 to 52 mm and MIC values of 31.25–62.5 μg/mL, respectively. For the antimicrobial activities of the oil, the active compounds were determined to be α-cadinol, τ-cadinol, τ-muurolol and (2 Z,6 E)-farnesol.