The Crocus sativus Compounds trans-Crocin 4 and trans-Crocetin Modulate the Amyloidogenic Pathway and Tau Misprocessing in Alzheimer Disease Neuronal Cell Culture Models

Crocus sativus L. natural compounds have been extensively used in traditional medicine for thousands of years. Recent research evidence is now emerging in support of its therapeutic potential for different pathologies including neurodegenerative diseases. Herein, the C. sativus L. natural compounds trans-crocin 4 and trans-crocetin were selected for in depth molecular characterization of their potentially protective effects against Alzheimer’s Disease (AD), utilizing two AD neuronal cell culture models (SH-SY5Y overexpressing APP and PC12 expressing hyperphosphorylated tau). Biologically relevant concentrations, ranging from 0.1 μM to 1 mM, applied for 24 h or 72 h, were well tolerated by differentiated wild type SH-SY5Y and PC12 cells. When tested on neuronally differentiated SH-SY5Y-APP both trans-crocin 4 and trans-crocetin had significant effects against amyloidogenic pathways. Trans-crocin 4 significantly decreased of β-secretase, a key enzyme of the amyloidogenic pathway, and APP-C99, while it decreased γ-secretases that generate toxic beta-amyloid peptides. Similarly, trans-crocetin treatment led to a reduction in β- and γ-secretases, as well as to accumulation of cellular AβPP. When tested on the neuronally differentiated PC12-htau cells, both compounds proved effective in suppressing the active forms of GSK3β and ERK1/2 kinases, as well as significantly reducing total tau and tau phosphorylation. Collectively, our data demonstrate a potent effect of trans-crocin 4 and trans-crocetin in suppressing key molecular pathways of AD pathogenesis, rendering them a promising tool in the prevention and potentially the treatment of AD.

administration in mice, while it shows penetration through the blood brain barrier

A novel, fit-for-purpose, highly sensitive, analytical UPLC-PDA methodology was developed and fully validated, according to ICH, FDA and EMA guidelines, for the rapid and accurate quantification of trans-crocin 4 (TC4) and crocetin (CRC) in mice plasma and brain after i.p. administration. A PDA based methodology shows a wider applicability as it is cost effective and can be easily and seamlessly adopted by the pharma industry. The separation of the analytes was performed on a C18 Hypersil Gold column with 2.5 min run time, employing the internal standard (ISTD) methodology. The two methods were successfully applied for the determination of CRC and TC4 in mouse plasma and brain after i.p. administration of TC4 (50 mg/kg) in a time range of 0-240 min. Due to the selection of i.p. administration route, the first-pass metabolism and/or gastric hydrolysis were bypassed, a fact that enhanced the bioavailability of TC4. Furthermore, TC4 was found to be capable of crossing the Blood Brain Barrier (BBB) and build up levels in the mouse brain, regardless of its highly hydrophilic character. CRC was not detected in any plasma or brain sample, although it has been reported that TC4 quickly hydrolyzes to CRC after p.o. administration. Therefore i.p. administration could be used in the case of TC4 for the accurate determination of its biological role. Overall, the developed methodology offers important information about the bioavailability of TC4 in mouse plasma and for the first time, demonstrates the ability of TC4 to penetrate the BBB and localize inside the brain.