Antimicrobial Activity of Leaf Extracts of Eupatorium Triplinerve Vehl. against Some Human Pathogenic Bacteria and Phytopathogenic Fungi

Petroleum ether, carbon tetrachloride, chloroform, and ethyl acetate extracts of Eupatorium triplinerve Vehl. leaves were investigated for their antimicrobial activities against 11 human pathogenic bacteria and six phytopathogenic fungi. The crude extracts showed good activity against the organisms tested herein. The chloroform extract exhibited the largest zone of inhibition (22 mm in diam with 1000 μg/disc extract) against Vibrio and the highest inhibition of fungal radial mycelial growth (73.5% with 100 μg extract/ml medium) against Colletotrichum corchori. The chloroform extract exhibited the lowest MIC against Vibrio (250 μg/ml) and C. corchori (62.5 μg/ml). It appeared that E. triplinerve could be a potential natural source of new antimicrobial agent. Most of the people in rural and urban areas of the world were depended on the medicinal plants for the treatment of infectious diseases. The Ayurvedic and Unani systems of medicines are widely used by the people of Indian subcontinent. Among the different plant derivetives, secondary metabolites proved to be the most important group of compounds that showed wide range of antibacterial and antifungal activity (Ahmed et al. 2002, Rahman et al. 1999). Eupatorium triplinerve (Compositae) is a slender herb with narrow lanceolate leaves and large number of pedicelled flower-heads at the top of the branch, cultivated in Chittagong and Chittagong Hill Tracts. Extract of the plant is used as antiseptic, and in the treatment of various ulcers and haemorrhages (Ghani 1698). This paper reports the result of antimicrobial activity of E. triplinerve on folk usages by traditional practitioners in Tribal areas of Bangladesh. Fresh leaves of Eupatorium triplinerve were collected from Chittagong University campus, Chittagong, Bangladesh. The cleaned leaf samples were cut into small pieces (1-2 cm), air dried and ground to fine powder mechanically. 50 g of the dried powders were kept overnight in petroleum ether, chloroform, ethyl acetate and carbon tetrachloride. The extracts thus obtained were filtered, centrifuged at 5000 rpm for 20 minutes and then concentrated to a gummy material under reduced pressure at 50o C by rotary vacuum evaporator. The gummy material was then transferred to small vials and dried and termed as crude extract. The crude extract against 11 human pathogenic bacteria viz., Shigella dysenteriae AE 14396, S. sonnei CRL.(ICDDR,B), Salmonella typhi AE 14612, S. paratyphi AE 14613, Bacillus subtilis BTCC 17, B. megaterium BTCC 18, B. cereus BTCC 19, Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa CRL(ICDDR’B), Escherichia coli ATCC 25922 and INABA ET (Vibrio) AE 14748 and five phytopathogenic fungi, viz., Alternaria alternata (Fr.) Kedissler., Curvularia lunata (Wakker) Boedijn, Colletotrichum corchori Ikata (Yoshida), Fusarium equiseti (Corda) Sacc., Macrophomina phaseolina (Maubl) Ashby. and Botryodiplodia theobromae Pat were tested. The in vitro antibacterial and antifungal activity of plant material was determined by disc diffusion method (Bauer et al. 1966) and poisoned food technique (Miah et al. 1990). MuellerHinton agar and Potato dextrose agar media were used for culturing of bacteria and fungi, respectively. MICs of the crude extracts were determined by broth macrodilution method (Jones et al. 1985). *Corresponding author. 90 RAHMAN AND JUNAID All the crude extracts (1000 μg/disc) exhibited moderate to good antibacterial activity against the bacterial pathogens tested herein and the largest zone of inhibition (22 mm in diam) was recorded against Vibrio (Table 1). Antibacterial antibiotic ampicillin (20 μg/disc) was also found to be active against all the bacteria tested herein. Table 1. Antibacterial activity of crude leaf extracts from Eupatorium triplinerve. Diameter of zone of inhibition (mm) (Crude extract 1000 μg/disc) Bacteria Petroleum ether Carbon tetrachloride Chloroform Ethyl acetate Ampicillin (20 μg/disc) Bacillus subtilis Ehr. Cohn B. megaterium de Bary B. cereus Frank & Frank. Staphylococcus aureus Rosen. Escherichi. coli INABA ET(Vibrio) Shigella dysenteriae Cast. & Chal. S. sonnei Weldin Salmonella typhi Warren & Scott. S. paratyphi Cast. & Chal Pseudomonas aeruginosa Migula 13 10 12 13 11 12 10 10 11 11 10 17 16 19 19 17 18 16 17 17 16 16 20 18 20 20 19 22 18 18 19 20 19 20 16 20 21 18 21 16 18 21 20 18 19 16 18 22 10 15 22 20 20 17 10 Standard antibacterial antibiotic. The chloroform extract exhibited the lowest MIC value (125 μg/ml) against Vibrio (Table 2). Similar antibacterial activity of some other plant extracts has been reported previously (Rahman et al. 1998, Sarker et al. 1991). Table 2. MICs of crude leaf extracts from Eupatorium triplinerve against test bacteria. MIC (Crude extract μg/ml medium) Bacteria Petrolium ether Carbon tetrachloride Chloroform Ethyl acetate Bacillus subtilis B. megaterium B. cereus Staphylococcus aureus E. coli INABA ET (Vibrio) Shigella dysenteriae S. sonnei Salmonella typhi S. paratyphi Pseudomonas aeruginosa 75