Manliang Tan, Ligang Zhou,* Meng Qin, Duan Li, Weibo Jiang, Ye Wang and Xiaojiang Hao

Abstract: An essential oil, which was obtained by water distillation from Russowia sogdiana (Bunge) B. Fedtsch. flowers, was analyzed by GC and GC/MS. The main constituents were identified as limonene (15.9%), trans-α-bergamotene (5.6%), salvial-4(14)-en-1-one (3.8%), carvone (3.6%), p-cymene (3.6%), trans-carveol (3.2%). Thirty-two components were separated and identified which accounted for over 62.1% of the total essential oil. The antimicrobial activity of R. sogdiana oil was studied using broth dilution test on seven bacterial strains, using mycelial growth test on three fungal strains. The oil exhibited a broad spectrum antibacterial activity against Gram-positive (Bacillus subtilis, Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli, Erwinia carotovora ssp. carotovora, Pseudomonas lachrymans, Xanthomonas vesicatoria, Agrobacterium tumefaciens) with minimum inhibitory concentration (MIC) values ranging from 0.2 mg/mL to 0.8 mg/mL. The oil also showed an important antifungal activity against fruit pathogenic fungi Glomerella cingulata, Botryodiplodia theobromea and Venturia pirina. Maximum antifungal activity was observed against G. cingulata mycelial growth which percentage inhibition was 51.8% at concentration of 100 μg/mL.

Animals and plants are easily infected by bacterial or fungal pathogens. When treated with antibiotics or agrochemicals for a period of time, these microorganisms tended to develop some resistances. This behavior stressed the need to look for new vegetal molecules that could be efficiently used as natural substitutes to antibiotics or agrochemicals. The antimicrobial activity of plant extracts, in particular essential oils, has been widely investigated for this purpose. Essential oils represent very complex mixtures of compounds, mainly monoterpenes and sesquiterpenes. They are known to possess a variety of biological properties, including antimicrobial activity (1, 2). Russowia sogdiana (Bunge) B. Fedtsch. (Cynareae, Asteraceae) is an annual herb with its great resource mainly growing in the southwest region of Xinjiang, China. Only one species is in the genus Russowia (3). Local people have used the flowers as beverage additives and to cure some digestive system infections for a long time (3). To the best of our knowledge, the essential oil composition as well as the antimicrobial activities of R. sogdiana, have not been studied previously. The purpose of this study was to determine the composition of R. sogdiana flower oil and to evaluate its antibacterial and antifungal activities.