Study on Eupatorium triplinerve Vahl from South India, A Rich Source for Thymohydroquinone dimethylether and its Antimicrobial Activity

Abstract

The seasonal variations, composition and the antimicrobial activity of essential oils from the stem and leaves of Eupatorium triplinerve Vahl were analyzed by gas chromatography-mass spectometry (GC-MS), the components of the essential oils were identified by comparing their mass spectra fragmentation patterns, RI and by the comparison with the literature data. The oil content ranged from 0.25-0.40 %, with comparable in two different seasons. The essential oil obtained from the leaves and the stem was characterized by a very high content of thymohydroquinone dimethylether, i.e. 80.3-86.9 % of the total oil (higher percentage in stem) when compared with the reported values in India (20-40 %). Other oil constituents occurring in much lower amounts were β-caryophyllene (4-6 %), β-eudesmene (6-10 %). The antimicrobial activities of the volatile oil and thymohydroquinone dimethylether were evaluated against four bacterial and four fungal strains using disc diffusion assay method. The stem and leaf essential oils found to have significant antimicrobial effect compared to that of thymohydroquinone dimethylether. Hence the antimicrobial effect of the volatile oil could be attributed to its minor components. The E. triplinerve can be recommended for a new chemotype from south India due to the dominant occurrence of thymohydroquinone dimethylether.