For the past few decades membrane
zinc metallopeptidases have been identified as important therapeutic targets in the control of
pain. In particular,
neutral endopeptidase (NEP) has been shown to play critical roles in the metabolism of the endogenous
peptides Met- and Leu-
enkephalins. In this study, we have evaluated the activity of a new fluorinated
peptidase inhibitor NESS002ie in both in vitro and in vivo assays.
NESS002ie has been compared to the
peptidomimetic compound
thiorphan and the previously reported NEP selective
thiol inhibitor C20. The
metallopeptidases inhibitory activity of
NESS002ie was tested in vitro using a highly, sensitive, continuous, fluorometric,
enzyme assay. Also, the
analgesic propriety of
NESS002ie,
thiorphan and C20 have been evaluated in vivo, by intraplantar, intravenous and intrathecal administration, through nociception assays based on
formalin test in mice.
Metallopeptidases assays have shown an inhibitory potency of
NESS002ie in the nanomolar range for NEP and
angiotensin-converting enzyme (ACE). The new fluorinated inhibitor showed higher
analgesic activity and bioavailability compared to
thiorphan and C20 when administered by both intravenous and
intrathecal injections. More significantly,
intrathecal injection of
NESS002ie reduced both the first and the second phases of the
formalin biphasic
pain response. In addition,
naltrindole and
naloxone reversed the
analgesic effect of
NESS002ie with a diverse profile. This study shows an improvement in relief of
inflammation and
pain, in vivo, using
NESS002ie compared to reference compounds
thiorphan and C20. This significant effect could be due to the replacement of isobutyl chain of the
thiol C20 with the trifluoromethyl group.