UPEI-400, a conjugate of lipoic acid and scopoletin, mediates neuroprotection in a rat model of ischemia/reperfusion

Previously, our laboratory provided evidence that lipoic acid (LA) covalently bonded to various antioxidants, resulted in enhanced neuroprotection compared to LA on its own. The naturally occurring compound scopoletin, a coumarin derivative, has been shown in various in vitro studies to have both antioxidant and anti-inflammatory mechanism of actions. The present investigation was designed to determine if scopoletin on its own, or a co-drug consisting of LA and scopoletin covalently bonded together, named UPEI-400, would be capable of demonstrating a similar neuroprotective efficacy. Using a rat stroke model, male rats were anesthetized (Inactin®; 100 mg/kg, iv), the middle cerebral artery was permanently occluded for 6 h (pMCAO), or in separate animals, occluded for 30 min followed by 5.5 h of reperfusion (ischemia/reperfusion; I/R). Pre-administration of either scopoletin or UPEI-400 significantly decreased infarct volume in the I/R model (p < 0.05), but not in the pMCAO model of stroke. UPEI-400 was ∼1000 times more potent compared to scopoletin alone. Since UPEI-400 was only effective in a model of I/R, it is possible that it may act to enhance neuronal antioxidant capacity and/or upregulate anti-inflammatory pathways to prevent the neuronal cell death.