oleandrin and Stroke

Cardiac glycosides induce a strong immunological cancer cell cytotoxicity, in which the released intracellular components of dying tumor cells (e.g. calreticulin, HMGB1 and ATP) stimulate immunity and help in eradicating cancer. Among the cardiac glycosides, oleandrin is an inhibitor of P-glycoprotein expression and exerts excellent penetration through the blood-brain barrier which also harbors neuroprotective and anti-glioma efficacies. Cardiac glycosides also exert neuroprotective activities, one explanation for such an action is the metabolic arrest as a defense strategy against hypoxia. Recently, it was also shown that oleandrin increases survival of glioma-implanted mice alone and in synergy with temozolomide, which also associated with the release of brain derived neurotrophic factor and activation of its receptor TrkB. In conclusion, oleandrin strongly deserves to be studied as a candidate molecule in treatment of neurodegenerative and neurooncological diseases.

Topics: Animals; Cardenolides; Cardiac Glycosides; Glioblastoma; Humans; Neuroprotective Agents; Stroke

We previously reported neuroprotective activity of the botanical anti-cancer drug candidate PBI-05204, a supercritical CO2 extract of Nerium oleander, in brain slice and in vivo models of ischemic stroke. We showed that one component of this neuroprotective activity is mediated through its principal cardiac glycoside constituent, oleandrin, via induction of the potent neurotrophic factor brain-derived neurotrophic factor (BDNF). However, we also noted that the concentration-relation for PBI-05204 in the brain slice oxygen-glucose deprivation (OGD) model is considerably broader than that for oleandrin as a single agent. We thus surmised that PBI-05204 contains an additional neuroprotective component(s), distinct from oleandrin. We report here that neuroprotective activity is also provided by the triterpenoid constituents of PBI-05204, notably oleanolic acid. We demonstrate that a sub-fraction of PBI-05204 (Fraction 0-4) containing oleanolic and other triterpenoids, but without cardiac glycosides, induces the expression of cellular antioxidant gene transcription programs regulated through antioxidant transcriptional response elements (AREs). Finally, we show that Fraction 0-4 provides broad neuroprotection in organotypic brain slice models for neurodegeneration driven by amyloid precursor protein (APP) and tau implicated in Alzheimer's disease and frontotemporal dementias, respectively, in addition to ischemic injury modeled by OGD.

Topics: Animals; Antineoplastic Agents; Brain; Chemical Fractionation; Disease Models, Animal; Female; Glucose; Heterocyclic Compounds, 4 or More Rings; Humans; Male; Nerium; Neurodegenerative Diseases; Neuroprotective Agents; Oleanolic Acid; Organ Culture Techniques; Oxygen; Plant Extracts; Rats, Sprague-Dawley; Stroke

The principal active constituent of the botanical drug candidate PBI-05204, a supercritical CO(2) extract of Nerium oleander, is the cardiac glycoside oleandrin. PBI-05204 shows potent anticancer activity and is currently in phase I clinical trial as a treatment for patients with solid tumors. We have previously shown that neriifolin, which is structurally related to oleandrin, provides robust neuroprotection in brain slice and whole animal models of ischemic injury. However, neriifolin itself is not a suitable drug development candidate and the FDA-approved cardiac glycoside digoxin does not cross the blood-brain barrier. We report here that both oleandrin as well as the full PBI-05204 extract can also provide significant neuroprotection to neural tissues damaged by oxygen and glucose deprivation as occurs in ischemic stroke. Critically, we show that the neuroprotective activity of PBI-05204 is maintained for several hours of delay of administration after oxygen and glucose deprivation treatment. We provide evidence that the neuroprotective activity of PBI-05204 is mediated through oleandrin and/or other cardiac glycoside constituents, but that additional, non-cardiac glycoside components of PBI-05204 may also contribute to the observed neuroprotective activity. Finally, we show directly that both oleandrin and the protective activity of PBI-05204 are blood brain barrier penetrant in a novel model for in vivo neuroprotection. Together, these findings suggest clinical potential for PBI-05204 in the treatment of ischemic stroke and prevention of associated neuronal death.

Topics: Animals; Cardenolides; Cardiac Glycosides; Disease Models, Animal; Dose-Response Relationship, Drug; Gene Expression Regulation; Glucose; Hypoxia; In Vitro Techniques; Nerium; Neuroprotective Agents; Phytotherapy; Sodium-Potassium-Exchanging ATPase; Stroke; Time Factors; Transfection