Stilbazulenyl Nitrone, a Second-Generation Azulenyl Nitrone Antioxidant, Confers Enduring Neuroprotection in Experimental Focal Cerebral Ischemia in the Rat: Neurobehavior, Histopathology, and Pharmacokinetics

Abstract

Stilbazulenyl nitrone (STAZN) is a potent lipophilic secondgeneration azulenyl nitrone antioxidant, which is highly neuroprotective in rodent models of cerebral ischemia and trauma. This study was conducted to establish whether the neuroprotection induced by STAZN persists with chronic survival and to characterize STAZNЈs pharmacokinetics. Physiologically regulated rats received a 2-h middle cerebral artery occlusion by intraluminal suture and were treated with either STAZN [four 0.6 mg/kg doses i.p. administered at 2 (i.e., onset of recirculation), 4, 24, and 48 h; n ϭ 16] or dimethyl sulfoxide vehicle (n ϭ 11). They received sequential neurobehavioral examinations followed by quantitative neuropathology at 30 days. STAZN improved neurological deficits compared with vehicle controls, beginning within Ͻ2 h of the first dose and persisting throughout a 30-day survival. Large cystic necrotic infarcts were common in vehicle-treated rats but infrequent in STAZN-treated rats, and noninfarcted forebrain tissue was increased on average by 15%. In normal rats administered 5 mg/kg STAZN i.v. in Solutol HS 15/ethanol/saline vehicle, STAZN blood levels exhibited a biexponential decline, with an initial half-life of 28 min and a subsequent slow decay with half-life of ϳ7 h. STAZN tissue levels at 2 to 3 h were, on average, 2.5% of blood levels in forebrain, 56% in myocardium, and 41% in kidney. STAZN was concentrated in liver with initial concentrations averaging 5.2-fold above blood levels and a subsequent linear decline of 40% between 24 and 72 h. These results establish that STAZN confers enduring ischemic neuroprotection, has a long circulating half-life, and penetrates well into brain and other organs-characteristics favoring its potential therapeutic utility.

Neuroprotective effect of STAZN, a novel azulenyl nitrone antioxidant, in focal cerebral ischemia in rats: Dose–response and therapeutic window

“…This was not the case prior to MCAo, or at any later survival time (Table 1). Temperature did not affect the extent of tissue salvage achieved with STAZN (0.7 mg/kg) as compared to controls seen in earlier studies (Ginsberg, Becker et al 2003;Ley, Vigdorchik et al 2005). Furthermore, the STAZN dose-response findings in the present study were not confounded by temperature because there were no significant temperature differences between STAZN treatment groups.…”

“…These two sets of results provide important insights into the scope of the neuroprotection conferred by STAZN and support the well-known role of oxygen radicals in contributing to the pathophysiological cascade of molecular events leading to ischemic tissue damage (Schaller, Graf et al 2003). Earlier studies demonstrated that STAZN (0.7 mg/kg, given after 2 hours of ischemia, at the onset of reperfusion) was highly neuroprotective in the MCA suture-occlusion model of transient focal cerebral ischemia (Ginsberg, Becker et al 2003), and that the neuroprotective effect persisted at 30 days (Ley, Vigdorchik et al 2005). The present study confirms our earlier findings for the intermediate dose of STAZN (0.7 mg/ kg).…”

“…In preclinical and initial clinical studies, neurological improvement was observed when NXY-059, a disulfonyl-substituted α-phenyl nitrone, was given up to 6 hours after the onset of ischemia (Kuroda, Tsuchidate, et al 1999;Zivin 2007) However, the recently completed SAINT II multicenter clinical trial failed to confirm a significant benefit of NXY-059 for the treatment of stroke compared to controls (Shuaib 2007). In contrast to NXY-059, STAZN is a much more lipophilic nitrone that would therefore be expected to have higher blood-brain barrier penetration (Ley, Vigdorchik et al 2005); in addition, STAZN is a much more potent freeradical scavenger that effectively inhibits lipid peroxidation (Becker, Ley et al 2002;Mojumdar, Becker et al 2004). …”

“…ANOVA revealed a significant inter-group difference for both cortical infarction (p=0.041) and total infarct volume (p=0.014). Total infarct volume (corrected for brain swelling (Ley, Vigdorchik et al 2005)), averaged 148 ± 55 mm 3 (mean ± SD) in the pooled controls. STAZN treatment at the 0.7 mg/kg dose reduced the volume of total infarction to 75 ± 60 mm 3 -a mean reduction of 51%.…”

“…This fact has provided the rationale for the testing of various antioxidant therapeutics in animal models of cerebral ischemia (Margaill, Plotkine et al 2005;Weinberger 2006). We have previously demonstrated the marked, enduring neuroprotective effects of a novel antioxidant free-radical scavenger, stilbazulenyl nitrone (STAZN), in transient focal cerebral ischemia (Ginsberg, Becker et al 2003;Ley, Vigdorchik et al 2005). The successful translation of antioxidant therapy from animal models to the clinic, however, is not always straightforward (Committee.…”