**3.1 Antibacterial activity of** *Cichorium intybus*

The results of antibacterial activity of ethanol, ethyl acetate and acetone extract from *Cichorium intybus* are presented on the Figure 2. Extracts showed different activity. Ethanol extract acted at concentrations of 2.5 mg/ml to 20mg/ml; ethyl acetate from 1.09 mg/ml to 8.75 mg/ml; acetone extract from 2.5 mg/ml to 5 mg/ml. Antibacterial activity of ethyl acetate and acetone extract is more pronounced than ethanol extract. Similar results were obtained by Nandagopal & Ranjitha Kumari, 2007, among tested extracts, ethyl acetate was one of the more active. Statistic analysis confirms the presented results. Activity of ethyl acetate (*p*EtAc=0.001) and acetone (*p*AcOH=0.002) extract was statistically significantly higher that the activity of ethanol extract. Acetone extract was the most active (*p*=0.018).

The tested bacteria manifested different sensitivity level to the tested extracts. MIC values were ranged from 1.09 mg/ml to 20 mg/ml. The most sensitive bacterium to the tested

Antibacterial Activity of Naturally Occurring Compounds from Selected Plants 11

Fig. 3. Antibacterial activity of *Salvia officinalis* extracts expressed as MIC values (mg/ml)

bacterium to tested extracts.

Iauk et al., 2003).

**3.3 Antibacterial activity of** *Melissa officinalis* 

Gram-positive bacteria were more sensitive than Gram-negative bacteria. MICs for *Bacillus subtilis* were showed at 5 mg/ml for ethanol extract, 10 mg/ml for ethyl acetate extract and 0.03 mg/ml for acetone extract. For *Staphylococcus aureus*, MIC of ethanol extract was 5 mg/ml, ethyl acetate 20 mg/ml and acetone 0.31 mg/ml, while *Staphylococcus aureus* ATCC 25923, as G+ bacterium, only showed sensitivity in relation to acetone extract (MIC = 0.15 mg/ml). Growth of the most of G- bacteria was not inhibited by action of ethanol and ethyl acetate extract on tested concentrations. Similar results were obtained by Veličković et al., 2003 where ethanol extract reacted poorly on G- in relation to G+ bacteria. The exception is *Pseudomonas aeruginosa* ATCC 27853, which is next to *Bacillus subtilis*, the most sensitive

The results of antibacterial activity of water, ethanol and ethyl acetate extract from *Melissa officinalis* are presented on the Figure 4. The tested extracts showed equable antibacterial activity, based on the results of statistic analysis, no difference was noted (*p*>0.05). Water extract acted in the interval from 0.31 mg/ml tо 20 mg/ml; ethanol extract from 0.62 mg/ml to >20 mg/ml, and ethyl acetate extract from 1.25 mg/ml to 20 mg/ml. Ethanol extract did not act on three species of Gram-negative bacteria. Antimicrobial activity of different *Melissa officinalis* extracts was also tested by other scientists who showed different level of antimicrobial activity with their research (Uzun et al., 2004; Ertürk, 2006;

The tested bacteria showed sensitivity at different concentrations. The concentrations were ranged from 0.31 tо 20 mg/ml. The greatest sensitivity was noted for standard strains: *Staphylococcus aureus*; *Escherichia coli* and *Pseudomonas aeruginosa* only to water extract.

Fig. 2. Antibacterial activity of *Cichorium intybus* extracts expressed as MIC values (mg/ml)

extracts was *Pseudomonas aeruginosa* ATCC 27853. MIC values for this bacterium were 2.5 mg/ml for ethanol and acetone extract, and 1.09 mg/ml for ethyl acetate extract. Bacteria *Bacillus subtilis, Enterobacter cloacae, Staphylococcus aureus* ATCC 25923 with 2.18 mg/ml, 2.5 mg/ml and 5 mg/ml values also manifested significant sensitivity. *Proteus mirabilis, Escherichia coli* ATCC 25922, according to ethanol extract, have showed the least sensitivity (MIC = 20 mg/ml), while they were more sensitive to the other two extracts. Similar results were obtained by other scientists. Petrović et al., 2004 noted the inhibitory effect of chicory extract also on phypopathogenic and human pathigenic bacteria. Acroum et al., 2009 showed the effect of methanol extract on Gram-positive bacteria (*Bacillus subtilis, Bacillus cereus, Staphylococcus aureus*) with the MIC values of 0.010 mg/ml and 0.075 mg/ml while the extract did not act on Gram-negative bacteria *Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneuminiae.* 

#### **3.2 Antibacterial activity of** *Salvia officinalis*

The acetone extract was the most reactive extract at this testing (*p*EtOH=0,004; *p*EtAc=0,001), while there was no statistically significant difference between ethanol and ethyl acetate extracts in acting. Ethanol and ethyl acetate extract showed the activity at concentrations from 2.5 mg/ml to >20 mg/ml, and acetone extract from 0.02 mg/ml to 20 mg/ml (Figure 3.). The reason for good results which acetone extract showed can also be saught in the fact that acetone is a good extractant, of low toxicity and high extractional capacity (Eloff, 1998). Similar results for acetone extract were also obtained by (Horiuchi et al., 2007), MIC values were from 256 µg/ml tо 512 µg/ml.

The tested bacteria, except for *Pseudomonas aeruginosa* and *Escherichiа coli*, showed a significant sensitivity in relation to acetone extract. MIC values were below 1 mg/ml.

Fig. 2. Antibacterial activity of *Cichorium intybus* extracts expressed as MIC values (mg/ml)

extracts was *Pseudomonas aeruginosa* ATCC 27853. MIC values for this bacterium were 2.5 mg/ml for ethanol and acetone extract, and 1.09 mg/ml for ethyl acetate extract. Bacteria *Bacillus subtilis, Enterobacter cloacae, Staphylococcus aureus* ATCC 25923 with 2.18 mg/ml, 2.5 mg/ml and 5 mg/ml values also manifested significant sensitivity. *Proteus mirabilis, Escherichia coli* ATCC 25922, according to ethanol extract, have showed the least sensitivity (MIC = 20 mg/ml), while they were more sensitive to the other two extracts. Similar results were obtained by other scientists. Petrović et al., 2004 noted the inhibitory effect of chicory extract also on phypopathogenic and human pathigenic bacteria. Acroum et al., 2009 showed the effect of methanol extract on Gram-positive bacteria (*Bacillus subtilis, Bacillus cereus, Staphylococcus aureus*) with the MIC values of 0.010 mg/ml and 0.075 mg/ml while the extract did not act on Gram-negative bacteria *Escherichia coli, Pseudomonas aeruginosa,* 

The acetone extract was the most reactive extract at this testing (*p*EtOH=0,004; *p*EtAc=0,001), while there was no statistically significant difference between ethanol and ethyl acetate extracts in acting. Ethanol and ethyl acetate extract showed the activity at concentrations from 2.5 mg/ml to >20 mg/ml, and acetone extract from 0.02 mg/ml to 20 mg/ml (Figure 3.). The reason for good results which acetone extract showed can also be saught in the fact that acetone is a good extractant, of low toxicity and high extractional capacity (Eloff, 1998). Similar results for acetone extract were also obtained by (Horiuchi et al., 2007), MIC values

The tested bacteria, except for *Pseudomonas aeruginosa* and *Escherichiа coli*, showed a significant sensitivity in relation to acetone extract. MIC values were below 1 mg/ml.

*Klebsiella pneuminiae.* 

**3.2 Antibacterial activity of** *Salvia officinalis* 

were from 256 µg/ml tо 512 µg/ml.

Fig. 3. Antibacterial activity of *Salvia officinalis* extracts expressed as MIC values (mg/ml)

Gram-positive bacteria were more sensitive than Gram-negative bacteria. MICs for *Bacillus subtilis* were showed at 5 mg/ml for ethanol extract, 10 mg/ml for ethyl acetate extract and 0.03 mg/ml for acetone extract. For *Staphylococcus aureus*, MIC of ethanol extract was 5 mg/ml, ethyl acetate 20 mg/ml and acetone 0.31 mg/ml, while *Staphylococcus aureus* ATCC 25923, as G+ bacterium, only showed sensitivity in relation to acetone extract (MIC = 0.15 mg/ml). Growth of the most of G- bacteria was not inhibited by action of ethanol and ethyl acetate extract on tested concentrations. Similar results were obtained by Veličković et al., 2003 where ethanol extract reacted poorly on G in relation to G+ bacteria. The exception is *Pseudomonas aeruginosa* ATCC 27853, which is next to *Bacillus subtilis*, the most sensitive bacterium to tested extracts.
