NO‐flurbiprofen reduces amyloid‐β, is neuroprotective in cell culture, and enhances cognition in response to cholinergic blockade

Abstract

The non‐steroidal anti‐inflammatory drug flurbiprofen is a selective amyloid lowering agent which has been studied clinically in Alzheimer’s disease. HCT‐1026 is an ester prodrug of flurbiprofen incorporating a nitrate carrier moiety that in vivo provides NO bioactivity and an improved safety profile. In vitro, HCT‐1026 retained the cyclooxygenase inhibitory and non‐steroidal anti‐inflammatory drug activity of flurbiprofen, but at concentrations at which levels of amyloid‐β 1–42 amino acid were lowered by flurbiprofen, amyloid‐β 1–42 amino acid levels were elevated 200% by HCT‐1026. Conversely, at lower concentrations, HCT‐1026 behaved as a selective amyloid lowering agent with greater potency than flurbiprofen. The difference in concentration–responses between flurbiprofen and HCT‐1026 in vitro suggests different cellular targets; and in no case did a combination of nitrate drug with flurbiprofen provide similar actions. In vivo, HCT‐1026 was observed to reverse cognitive deficits induced by scopolamine in two behavioral assays; activity that was also shown by a classical nitrate drug, but not by flurbiprofen. The ability to restore aversive memory and spatial working and reference memory after cholinergic blockade has been demonstrated by other agents that stimulate NO/cGMP signaling. These observations add positively to the preclinical profile of HCT‐1026 and NO chimeras in Alzheimer’s disease.

Inhibition of Amyloidogenesis by Nonsteroidal Anti-inflammatory Drugs and Their Hybrid Nitrates

“…1A). In contrast, the hybrid nitrate derivative 2 , as we have reported previously, 28 showed biphasic activity. The full concentration-response data for 2 showed SALA activity more potent than 1 and similar to 11a at low concentrations, and in contrast, SARA activity at > 10 µM (Fig.…”

“…31 Flurbiprofen ( 1 ) itself was a modest inhibitor of iNOS induction in RAW cells treated with LPS and no evidence of toxicity was seen at the lower concentration tested (Table 1). 28, 32, 33 …”

“…However, this SALA activity of hybrid nitrate NSAIDs towards Aβ 1–42 modulation is unlikely to be associated with NO activity delivered by the nitrate functionality, since we have previously noted that the classical nitrate ISMN is without activity in this assay. 28 The alkyl ester linker of the hybrid nitrates, 2 and 26a , is expected to be labile towards non-specific esterase activity; therefore it was important to test a hybrid nitrate with a stable linker. The amide linked nitrate, 27 , was synthesized expressly to test if the more labile ester linker of 2 and 26a was essential for the observed anti-amyloidogenic activity.…”

“…24 An alternative approach to developing a gastric-sparing NSAID has been to incorporate a gastroprotective organic nitrate moiety in a so-called NO-donating NSAID (NO-NSAID) to counteract the NSAID-induced inhibition of prostaglandin synthesis. 25 HCT-1026 ( 2 ), 26 an NO-NSAID prodrug of 1 , has been reported: i) to reduce Aβ load in an amyloid transgenic mouse model; 27 ii) to reverse cognitive deficits in mice under cholinergic blockade; 28 and, iii) to reduce inflammatory markers, including iNOS, in adult rats injected with Aβ 1–42 . 29 …”

An NO Donor Approach to Neuroprotective and Procognitive Estrogen Therapy Overcomes Loss of NO Synthase Function and Potentially Thrombotic Risk

“…Furthermore, criteria for training are uniform across all treatment groups. Previously, we have shown NO-donors to reverse cognitive deficits induced by attenuation of cholinergic signaling [50], [51], [52], [53]. In animals administered scopolamine to induce amnesia, all treatments except FDMA and inorganic nitrate induced complete reversal of the memory deficit, with NO-DMA and DMA showing equi-efficacious activity (Fig.…”