Neuroprotective effects of a novel poly (ADP-ribose) polymerase-1 inhibitor, JPI-289, in hypoxic rat cortical neurons

Excessive activation of poly (ADP-ribose) polymerase-1 (PARP-1) is known to develop neuronal apoptosis, necrosis and inflammation after ischaemic brain injury. Therefore, PARP-1 inhibition after ischaemic stroke has been attempted in successful animal studies. The purpose of present work was to develop a novel water soluble PARP-1 inhibitor (JPI-289) and explore its neuroprotective effect on ischaemic injury in an in vitro model. The half-life of JPI-289 after intravenous or oral administration in rats was relatively long (1.4-1.5 hours) with 65.6% bioavailability. The inhibitor strongly inhibited PARP-1 activity (IC₅₀ =18.5 nmol/L) and cellular PAR formation (IC₅₀ =10.7 nmol/L) in the nanomolar range. In rat cortical neuronal cells, JPI-289 did not affect cell viability up to 1 mmol/L as assayed by Trypan blue staining (TBS) and lactate dehydrogenase (LDH) assay. Treatment of JPI-289 for 2 hours after 2 hours of oxygen glucose deprived (OGD) rat cortical neuron attenuated PARP activity and restored ATP and NAD+ levels. Apoptosis-associated molecules such as apoptosis inducing factor (AIF), cytochrome C and cleaved caspase-3 were reduced after JPI-289 treatment in the OGD model. The present findings suggest that the novel PARP-1 inhibitor, JPI-289, is a potential neuroprotective agent which could be useful as a treatment for acute ischaemic stroke.