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In Vitro Antibacterial Activity of Medicinal Plant Extracts

Tahseen Ullah* and Noor ul Amin

The University of Agriculture Peshawar, Khyber Pakhtunkhwa, Pakistan.

*Correspondence | Tahseen Ullah, The University of Agriculture Peshawar, Khyber Pakhtunkhwa, Pakistan; Email:


Antibacterial activities of four medicinal plants, Silybum marianum, Berberus lycium, Peganum harmala and Curcuma longa and standard antibiotic tetracycline was carried out in the biosafety level 3 Microbiology Lab, Faculty of Life Sciences, University of Bradford, Bradford, UK. Two different concentrations (low, 5 mg/ml and high extracts, 300 mg/ml) of these plants were evaluate against two different bacterial strains i.e. Bacillus subtilis and E. coli using disc diffusion method to uncover antibacterial potential of the plants extracts. The antibacterial investigation was performed in three replicates using disc diffusion technique using Nutrient Agar Media for the growth of B. subtilis and E. coli bacteria. The ANOVA for inhibitions zones indicates the effect of plants, bacteria strains, and concentration on growth of bacteria in the bacteria growth culture medium and their interactions. The plants crude extracts were having significant effects on the bacterial growth in bacteria growth medium while bacterial strains and concentrations have also significant affected the bacteria growth and zone of inhibitions by different concentration. However, the various concentration and bacterial strains were having significant effect on bacteria growth at 0.05 level of Probability. The interaction effect of plant bacteria, plant concentration was non-significant and concentration bacteria interactions have significant effect on growth inhibition of Bacteria. However, the three ways interaction between plants, bacteria and concentration was non-significantly affected the bacteria growth in the culture. The mean table indicate all the plants have showed antibacterial activities. The maximum activity was reported in C. longa which seem to be most active and lowest value was recorded in S. marianum. The maximum inhibition zone has been reported as 20 mm for the C. longa extracts and minimum has been observed for S. marianum as 13 mm. In case of concentration the maximum inhibition zone 20.58 mm was recorded with 300 mg (high concentration) while 14.6 mm was recorded for 5 mg (low concentration). In case of bacterial strains, the E. coli gram positive bacteria was significantly more visible in growth by developing inhibition zone of 20.5 mm while minimum was recorded in Bacillus gram negative bacteria that is 14.7 mm. The result indicates that different plant extracts, different concentrations and different bacterial strains may affect bacterial growth inhibition differently. Therefore, further investigation into determining minimum effective concentration, plants specific activity and search for active plant metabolite would explore effective natural therapy or antibiotic for multidrug resistance pathogenic plants and human bacterias. 

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Pakistan Journal of Agricultural Research


Vol.37, Iss. 1, Pages 1-87


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