Efficacy of extracts of six medicinal plants of India against some pathogenic bacteria.

The sensitivity of the pathogenic multi-drug resistant bacteria (Aeromonas hydrophila, Bacillus licheniformis, Bacillus mycoides, Bacillus niacini, Bacillus subtilis, Escherichia coli, Geobacillus thermodenitrificans, Klebsiella pneumoniae, Paenibacillus koreensis, Paenibacillus larvae larvae, Proteus vulgaris, Pseudomonas aeruginosa, Pseudomonas flourescens, Pseudomonas putida and Staphylocccus aureus) was tested against aqueous, acetone and ethanol extracts of mature leaves of Mimosa pudica Linn. (Mimosaceae) and Moringa oleifera Lam. (Moringaceae), stems of Michelia champaca Linn. (Magnoliaceae) and Musa paradisiaca Linn.(Musaceae), roots of Momordica charantia Linn. (Cucurbitaceae) and Murraya koenigii Linn. (Rutaceae) by agar well diffusion method. Gatifloxacin was the most effective antibiotic against all the reference bacteria. Though all the extracts were found effective, the ethanol extract showed maximum inhibition against the test microorganisms followed by acetone and aqueous extract. Bacillus niacini is the most resistant bacteria and Klebsiella pneumoniae is the most sensitive bacteria against all the extracts used. MIC values of each bacterium were also determined.

In vitro synergistic effect of doxycycline & ofloxacin in combination with ethanolic leaf extract of Vangueria spinosa against four pathogenic bacteria.

Background & objectives: The in vitro antibacterial activity of ethanolic leaf extract of Vangueria spinosa Roxb. (Rubiaceae) alone and in combination with antibiotics (doxycycline and ofloxacin) by means of fractional inhibitory concentration indices (FICI) as well as by the use of time-kill assays against one Gram-positive bacterium (Staphylococcus aureus) and three Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) was studied. Methods: Antibacterial activity was assayed by using the microdilution method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for the ethanolic leaf extract of V. spinosa alone and also in combination with antibiotics using the fractional inhibitory concentration (FIC) and time-kill assay method. Synergism was also tested using checker board dilution method. Results: MIC/MBC values for ethanolic leaf extract of V. spinosa against all the tested bacteria ranged between 25.5 - 52.6/22.4 - 60.5 μg/ml, for doxycycline 4.0/4.0 - 4.5 μg/ml and for ofloxacin 0.625 - 2.5/1. 25 - 5.0 μg/ml respectively. The average log reduction in viable cell count in time-kill assay ranged between 2.4 log10 - 4.5 log10 cfu/ml after 1 h of interaction and between 3.9 log10 -5.0 log10 cfu/ml after 3 h interaction in 1 × MIC to 4 × MIC. When leaf extract and antibiotics were combined, the average log reduction in viable cell count for doxycycline from 1.5 log10 - 5.18 log10 cfu/ml and for ofloxacin 3.06 log10- 5.39 log10 cfu/ml. Synergistic actions were observed in all the cases except against P. aeruginosa which showed an additive effect for ofloxacin and plant extract combination. Interpretation & conclusions: This study provides a preliminary report of synergistic activity of V. spinosa Roxb, ethanolic leaf extract with antibiotics.

Antibacterial potentiality of Argemone mexicana solvent extracts against some pathogenic bacteria

The sensitivity of two Gram positive (Staphylococcus aureus and Bacillus subtilis) and two Gram negative (Escherichia coli and Pseudomonas aeruginosa) pathogenic multi-drug resistant bacteria was tested against the crude extracts (cold aqueous, hot aqueous, and methanol extracts) of leaves and seeds of Argemone mexicana L. (Papaveraceae) by agar well diffusion method. Though all the extracts were found effective, yet the methanol extract showed maximum inhibition against the test microorganisms followed by hot aqueous extract and cold aqueous extract.