Table 3.

Minimal inhibitory concentration (MIC) values, and inhibition obtained at the maximal solubility in 3.5% DMSO of the compounds tested in this study, against H. pylori 26695 strain cell cultures.

Inhibitor	MW	MICa		Maximal solubility		% of H. pylori cell culture inhibition at inhibitor maximal solubility
		[µg mL−1]	[µM]	[µg mL−1]	[µM]
DMSO	78.13	–	–	55.0b	–	60e
				38.5b	–	26e
				27.5b	–	0e
2,6-diCl-Pu	189.00	473	2500	236	1250	93
6BnO-2Cl-Pu	260.68	–	–	25c	95c	35
				91d	350d	75
6BnS-2Cl-Pu	276.74	69d	250d	11.1	40	92
6BnS-Pu	242.3	48d	200d	21	85	83
6BnS-2Cl-Pu-9dr	393.87	79d	200d	4.3c	10.8c	5
metronidazole	171.15	8f	47	2g	12g	89–92
kanamycin	484.5	0.5–64f	1.1–132	25g	52g	92–96
BHI medium untreated with H. pylori	–	–	–	–	–	95h

The results are presented as the mean of three repetitions (see Materials and methods).

^aMIC is the minimal concentration used in the series of 2-fold dilutions that gave full inhibition of H. pylori cell culture growth, i.e. comparable to that observed for the positive control with 25 µg/mL kanamycin, i.e. by 92–96%.

^bThese correspond to 5%, 3.5%, and 2.5% (v/v), respectively, and in this case, this is not the maximal solubility; DMSO density 1.1 g/cm³.

^cIt was a maximal concentration possible to obtain in given conditions (at this concentration saturation was observed, see Table S1).

^dInhibitor partially precipitated, so actual concentration of dissolved compound is lower.

^eIn each experiment, the inhibition by DMSO was always checked to see its effect in this particular case, and compared with the effect of the HpPNP inhibitor tested. It was necessary as inhibition observed for the particular % of DMSO differs slightly among the experiments.

^fMTZ according to³⁶, kanamycin according to³².

^gIn this case this concentration is not the maximal solubility.

^hIn this case there is no H. pylori, so the value shown is treated as a negative control.