Intra- and extracellular antioxidant capacities of the new water-soluble form of curcumin (NDS27) on stimulated neutrophils and HL-60 cells

Phagocytic cells, especially neutrophils (PMNs) are specialized in the production of reactive oxygen species
(ROS) to kill pathogenic agents, but an excessive ROS production is associated with tissue damages
and inflammatory diseases. Phagocytes are thus prime therapeutic targets to control inflammatory events
associated to ROS production. Nowadays, there is a growing interest for the use of polyphenols to modulate
the inflammatory response. The aim of this work was to study the antioxidant effect of NDS27, a
highly water-soluble form of the polyphenolic molecule curcumin, on in vitro stimulated equine PMNs
and human promyelocytic leukemia cells (HL-60). NDS27 was either pre-incubated with cells and eliminated
before their activation (intracellular effect) or let in the medium (extracellular effect). Our results
indicate that NDS27 significantly and dose-dependently (10 6 M–10 4 M) inhibited the ROS production
in both cell types without affecting their viability. NDS27 was able to cross and interact with cell membrane,
especially for HL-60 cells, while we observed a better intracellular antioxidant effect with PMNs.
The activity of myeloperoxidase (MPO) released by PMNs and HL-60 cells, was decreased by NDS27, but
more efficiently for PMNs. These results suggested that the greater efficiency of NDS27 in PMNs is due to
an inhibitory effect on cells which are more mature for ROS production, probably by targeting the
enzymes implied in respiratory burst like MPO. The modulatory effect of NDS27 on the oxidant activity
of cells involved in immune and inflammatory responses opens perspectives for a therapeutic control of
pathologies with excessive inflammatory reactions.