(Arg)9 (Nona-L-arginine;Peptide R9) is a cell-penetrating peptide; exhibits neuroprotective activity with an IC50 of 0.78 μM in the glutamic acid model. IC50: 0.78 μM (neuroprotection)[1]
Poly-arginine (e.g. (Arg)9) and arginine-rich peptides (e.g. TAT, penetratin), which belong to a class of peptides with cell-penetrating properties are neuroprotective. (Arg)9 provides significant neuroprotection in a dose-response manner following glutamic acid exposure (IC50=0.78 μM). Following kainic acid exposure, (Arg)9 is neuroprotective, but less effective than in the glutamic acid model (IC50=0.81 μM). (Arg)9 also shows neuroprotection following in vitro ischemia (IC50=6 μM)[1].
(Arg)9) (D-isoform) is neuroprotective in rat stroke models. (Arg)9) is highly neuroprotective, with efficacy increasing with increasing arginine content, has the capacity to reduce glutamic acid-induced neuronal calcium influx and requires heparan sulfate preotoglycan-mediated endocytosis to induce a neuroprotective effect[2]. (Arg)9) (D-isoform) administered intravenously at a dose of 1000 nmol/kg 30 min after permanent middle cerebral artery occlusion (MCAO) reduces infarct volume[3].
[1]. Meloni BP, et al. The neuroprotective efficacy of cell-penetrating peptides TAT, penetratin, Arg-9, and Pep-1 in glutamic acid, kainic acid, and in vitro ischemia injury models using primary cortical neuronal cultures. Cell Mol Neurobiol. 2014 Mar;34(2):173-81. [2]. Meloni BP, et al. Poly-arginine and arginine-rich peptides are neuroprotective in stroke models. J Cereb Blood Flow Metab. 2015 Jun;35(6):993-1004. [3]. Milani D, et al. Poly-arginine peptides reduce infarct volume in a permanent middle cerebral artery rat strokemodel. BMC Neurosci. 2016 May 3;17(1):19.