Antimicrobial properties of aqueous extracts from three medicinal plants growing wild in arid regions of Tunisia

Figures & data

Table 1.  Antimicrobial activity of various extracts of Juniperus phoenicea, Pistacia atlantica and Oudneya africana as evaluated by the agar diffusion test.

Plant Species	Extraction method	Extract^a	Bacterial inhibition zone radii
			Li	Ln	Lm	Pa	Ec
Juniperus phoenicea
	1	Aqueous	12.5 ± 0.7	11.5 ± 0.7	11.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	1	Acetone precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	1	Acetone supernatant	11.0 ± 1.4	10.5 ± 0.7	10.5 ± 0.7	0.0 ± 0.0	0.0 ± 0.0
	1	Methanol precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	1	Methanol supernatant	10.5 ± 0.7	10.5 ± 0.7	10.5 ± 0.7	0.0 ± 0.0	0.0 ± 0.0
	2	Aqueous	8.5 ± 0.7	7.0 ± 0.0	7.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	2	Acetone precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	2	Acetone supernatant	8.5 ± 0.7	8.5 ± 0.7	8.5 ± 0.7	0.0 ± 0.0	0.0 ± 0.0
	2	Methanol precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	2	Methanol supernatant	8.0 ± 0.0	9.0 ± 0.0	7.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	3	Aqueous	10.5 ± 0.7	10.5 ± 0.7	9.5 ± 0.7	9.5 ± 0.7	9.5 ± 0.7
	3	Acetone precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	3	Acetone supernatant	15.5 ± 0.7	13.5 ± 0.7	13.5 ± 0.7	11.5 ± 0.7	9.5 ± 0.7
	3	Methanol precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	3	Methanol supernatant	17.0 ± 0.7	13.0 ± 1.4	13.5 ± 0.7	8.5 ± 0.7	8.5 ± 0.7
Pistacia atlantica
	1	Aqueous	8.0 ± 0.0	8.0 ± 0.0	8.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	1	Acetone precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	1	Acetone supernatant	8.5 ± 0.7	8.5 ± 0.7	8.5 ± 0.7	0.0 ± 0.0	0.0 ± 0.0
	1	Methanol precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	1	Methanol supernatant	11.5 ± 0.7	9.5 ± 0.7	9.5 ± 0.7	0.0 ± 0.0	0.0 ± 0.0
	2	Aqueous	13.5 ± 0.7	11.5 ± 0.7	6.5 ± 0.7	0.0 ± 0.0	0.0 ± 0.0
	2	Acetone precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	2	Acetone supernatant	14.0 ± 0.0	10.0 ± 0.0	9.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	2	Methanol precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	2	Methanol supernatant	9.0 ± 0.7	9.5 ± 0.7	6.5 ± 0.7	0.0 ± 0.0	0.0 ± 0.0
	3	Aqueous	6.5 ± 0.7	10.0 ± 0.0	10.5 ± 0.7	8.0 ± 0.0	10.0 ± 0.0
	3	Acetone precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	3	Acetone supernatant	9.0 ± 1.4	8.5 ± 0.7	10.0 ± 0.0	8.5 ± 0.7	9.5 ± 0.7
	3	Methanol precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	3	Methanol supernatant	14.0 ± 0.0	12.0 ± 0.0	12.0 ± 0.0	6.5 ± 0.7	8.0 ± 0.0
Oudneya africana
	1	Aqueous	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	1	Acetone precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	1	Acetone supernatant	6.5 ± 0.7	6.5 ± 0.7	6.5 ± 0.7	0.0 ± 0.0	0.0 ± 0.0
	1	Methanol precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	1	Methanol supernatant	6.5 ± 0.7	6.5 ± 0.7	6.5 ± 0.7	0.0 ± 0.0	0.0 ± 0.0
	2	Aqueous	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	2	Acetone precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	2	Acetone supernatant	16.0 ± 1.4	13.5 ± 0.7	13.5 ± 0.7	0.0 ± 0.0	0.0 ± 0.0
	2	Methanol precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	2	Methanol supernatant	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	3	Aqueous	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	3	Acetone precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	3	Acetone supernatant	11.5 ± 0.7	11.0 ± 0.0	11.0 ± 0.0	8.0 ± 0.0	9.5 ± 0.7
	3	Methanol precipitate	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
	3	Methanol supernatant	0.0 ± 0.0	6.5 ± 0.7	6.5 ± 0.7	6.5 ± 0.7	6.5 ± 0.7
Antibiotic		Ampicillin (0. 05 mg/mL)	11.5 ± 0.7	11.0 ± 1.4	12.5 ± 0.7	6.5 ± 0.7	17.5 ± 1.4

^aConcentration adjusted to  5 mg/mL.

Li: Listeria ivanovii RBL30; Ln: Listeria innocua RBL29; Lm: Listeria monocytogenes LSD530; Pa: Pseudomonas aeruginosa ATCC 15442; Ec: Escherichia coli ATCC 25922.

Figure 1.  Growth of Listeria monocytogenes (A, C, E) and Escherichia coli (B, D, F) in the presence of extracts (by method 3) of seeds of (A, B) Juniperus phoenicea, (C, D) Pistacia atlantica and (E, F) Oudneya africana (acetone-soluble portion) in tryptic soy broth. Concentrations (mg/mL) of extract were 12.5 (triangle), 6.25 (square), 3.125 (diamond) and 0 (circle).

Table 2.  Determination of MIC of selected plant extracts against food-borne pathogens.

Strains	Minimal inhibitory concentration (mg/mL)
	J. phoenicea	P. atlantica	O. africana	Antibiotic
	JP-M3	PA-M3	OA-M3-AS	Ampicillin
L. monocyt-ogenes	1.56	1.56	1.56	0.016
L. ivanovii	1.56	1.56	1.56	0.016
L. innocua	1.56	3.12	1.56 - 3.12	0.016
E. coli	3.12	1.56	1.56 - 3.12	0.004 - 0.008
P. aeruginosa	3.12	3.12	3.12 - 6.25	> 0.128