Biological characteristics of Edgeworthia tomentosa (Thunb.) Nakai flowers and antimicrobial properties of their essential oils.

Edgeworthia tomentosa (Thunb.) Nakai belongs to Thymelaeaceae family, its alabastrum is used as the traditional Chinese medicine 'Buddleja Officinalis Maxim'. The present study was to elucidate the ultrastructure characteristics of the flower, the phytochemical composition of the aroma essential oils (EOs) and the relevant antimicrobial properties. There were exclusive characters of calyx, ovule, anther and pollen grain of the flowers under scanning electron microscopy. A total of 40 phytochemical components representing 98% of the EOs were successfully identified: monoterpenes and sesquiterpenes were the dominant terpenoids according to Kovats retention index and MS database. EOs exhibited a broad spectrum antimicrobial activity against Gram-positive and Gram-negative bacteria, the best bacteriostatic effect was against Diplococcus pneumonia with MIC and MBC values ranging between 7.8 and 62.5 and 26.0-71.0 μg/mL, respectively. These results demonstrate that the surface microscopic morphological characteristics of Edgeworthia chrysantha Lindl. flowers, are full-scale chemical composition and antimicrobial properties of the EOs.