Table 2. Anti-Helicobacter pylori Effect of Piper Essential Oils^a.

	inhibition %
sample conc. (μg/mL)	P. longum	white pepper	P. cubeba	P. nigrum	clarithromycin
125	100 ± 0	100 ± 0	100 ± 0	100 ± 0	100 ± 0
62.5	100 ± 0	100 ± 0	100 ± 0	100 ± 0	100 ± 0
31.25	100 ± 0	100 ± 0	100 ± 0	100 ± 0	100 ± 0
15.63	100 ± 0	100 ± 0	100 ± 0	100 ± 0	100 ± 0
7.81	100 ± 0	100 ± 0	100 ± 0	100 ± 0	100 ± 0
3.9	100 ± 0	100 ± 0	89.41 ± 0.52	82.32 ± 0.83	100 ± 0
1.95	100 ± 0	84.41 ± 1.96	72.32 ± 1.30	50.37 ± 0.82	100 ± 0
0.98	91.17 ± 0.55	61.60 ± 0.73	56.73 ± 0.59	22.31 ± 0.88	91.98 ± 0.42
0.48	73.44 ± 1.45	29.97 ± 0.87	29.10 ± 0.18	9.84 ± 0.51	86.28 ± 1.27
0.24	50.74 ± 0.87	16.82 ± 1.04	12.99 ± 0.85	0	81.83 ± 0.43
0	0	0	0	0	0
MIC (μg/mL)	1.95	3.9	7.81	7.81	1.95

^aThe test was done using the standard MTT assay to determine the bacterial growth. For MIC, different concentrations of the tested oils or reference antibiotic clarithromycin were prepared in DMSO (final concentration ranges in the wells were 125 to 0.24 μg/mL). Results are expressed as means ± SD of triplicate values.