alpha-synuclein and crocin

Long-term exposure to organophosphates might result in neurodegenerative diseases, comprising Parkinson's disease. Malathion is an organophosphate pesticide with high neurotoxicity. Oxidative stress, apoptosis, and α-synuclein accumulation are important underlying mechanisms in Parkinson's disease. According to studies, crocin, an active constituent of saffron, has anti-apoptotic, anti-inflammatory, and antioxidant properties. Thus, the effect of crocin on malathion-induced striatal biochemical deficits in rats was investigated in this study. Six groups of male Wistar rats were used: 1. control (normal saline); 2. malathion (100 mg/kg/day, i.p.); 3. crocin (10 mg/kg/day, i.p.) + malathion; 4. levodopa (10 mg/kg/day, i.p.) + malathion; 5. crocin (40 mg/kg/day, i.p.); and 6. polyethylene glycol (PEG) (vehicle of levodopa) groups. The drugs were administered for 28 days. The amounts of Bcl-2, Bax, and caspases 3, 8, and 9 proteins in the striatum were measured by western blotting. Also, the amounts of protein and mRNA level of the α-synuclein in striatum tissue were measured by western blotting and RT-qPCR methods. Malathion induced apoptosis by increasing the amount of Bax/Bcl2 ratio and caspases 3 and 9 proteins in rat striatum tissue. It also increased the protein and mRNA level of α-synuclein in striatal tissue. Co-administration of crocin or levodopa with malathion inhibited the toxic effects of malathion on striatal tissue. Crocin ameliorates the neurotoxic effect of malathion by its anti-apoptotic activity and regulating the expression of proteins involved in Parkinson's disease pathogenesis. As a result, crocin has the potential to be used as a treatment for malathion-induced neurotoxicity.

Topics: alpha-Synuclein; Animals; Anti-Inflammatory Agents; Apoptosis; bcl-2-Associated X Protein; Carotenoids; Levodopa; Malathion; Male; Oxidative Stress; Parkinson Disease; Rats; Rats, Wistar; RNA, Messenger

The aggregation of human alpha-synuclein (hαS) is pivotally implicated in the development of most types of synucleinopathies. Molecules that can inhibit or reverse the aggregation process of amyloidogenic proteins have potential therapeutic value. The anti-aggregating activity of multiple carotenoid compounds has been reported over the past decades against a growing list of amyloidogenic polypeptides. Here, we aimed to determine whether crocin, the main carotenoid glycoside component of saffron, would inhibit hαS aggregation or could disassemble its preformed fibrils. By employing a series of biochemical and biophysical techniques, crocin was exhibited to inhibit hαS fibrillation in a dose-dependent fashion by stabilizing very early aggregation intermediates in off-pathway non-toxic conformations with little β-sheet content. We also observed that crocin at high concentrations could efficiently destabilize mature fibrils and disassemble them into seeding-incompetent intermediates by altering their β-sheet conformation and reshaping their structure. Our atomistic molecular dynamics (MD) simulations demonstrated that crocin molecules bind to both the non amyloid-β component (NAC) region and C-terminal domain of hαS. These interactions could thereby stabilize the autoinhibitory conformation of the protein and prevent it from adopting aggregation-prone structures. MD simulations further suggested that ligand molecules prefer to reside longitudinally along the fibril axis onto the edges of the inter-protofilament interface where they establish hydrogen and hydrophobic bonds with steric zipper stabilizing residues. These interactions turned out to destabilize hαS fibrils by altering the interstrand twist angles, increasing the rigidity of the fibril core, and elevating its radius of gyration. Our findings suggest the potential pharmaceutical implication of crocin in synucleinopathies.

Topics: alpha-Synuclein; Amyloid; Carotenoids; Humans; Molecular Dynamics Simulation

α-Synuclein is a presynaptic neuronal protein that is abundant in the human brain and is linked genetically and neuropathologically to Parkinson's disease (PD). The E46K mutation of the α-synuclein gene has been linked to autosomal dominant early-onset of PD. Crocin is a carotenoid chemical compound of saffron that has been shown antioxidant and neural protective activity. This study examined the effect of Crocin in preventing the amyloid fibril in the E46K α-synuclein, through in vitro studies and computational simulations. The result demonstrated that Crocin acts as a molecular chaperone to prevent amyloid fibril formation of E46K α-synuclein in a concentration-dependent manner. In fact, Crocin redirects E46K α-synuclein from a fibril-formation pathway towards an amorphous aggregation pathway or at least reduce its aggregation tendency. Combined results from molecular dynamics and docking studies indicate that the inhibitory effect of the Crocin may be due to binding of the Crocin with the hydrophobic region (contact interface) of the α-synuclein which has the propensity to form amyloid aggregate. The results indicated Crocin can potentially bind to the C-terminal and mainly NAC (central hydrophobic region) domain of the E46K α-synuclein, and stabilizes the protein by masking the polymerization hotspot and consequently converting the protein into amyloid fibrils. These results support that Crocin is a effective inhibitor of E46K α-synuclein fibrillization and it could be considered as a potential therapeutic agent in the treatment of Parkinson disease.

Topics: alpha-Synuclein; Amyloid; Carotenoids; Computer Simulation; Humans; Molecular Docking Simulation; Molecular Dynamics Simulation; Mutation; Neurons; Parkinson Disease; Spectrometry, Fluorescence

Saffron, the stigma of Crocus sativus Linné (Iridaceae family), has been known to inhibit aggregation of β-amyloid, a nerve tissue protein. α-Synuclein (αS) is a 140-amino acid protein found abundantly in various regions of the brain. Its abnormal aggregation and accumulation in nerve tissue are said to cause neurodegenerative diseases such as Parkinson's disease, Lewy body dementia, and multiple-system atrophy. This study (part of this study was presented at the 137th Annual Meeting of the Pharmaceutical Society of Japan) examined the effects of saffron, its constituents (crocin-1, crocin-2, crocetin, and safranal), and crocetin structural analogs (hexadecanedioic acid, norbixin, and trans, trans-muconic acid) on αS aggregation, and αS fibril dissociation. Saffron dose-dependently inhibited αS aggregation and dissociated αS fibrils by thioflavin T fluorescence assay. These effects were observed by transmission electron microscopy, which showed reduced and shortened αS fibrils. Crocin-1, crocin-2, and crocetin showed anti-aggregation and fibril dissociation effects, with crocetin being the most potent. The effects of norbixin were weaker than those of crocetin, and the other crocetin structural analogs showed no effects. These results show that saffron and its constituents (crocin-1, crocin-2, and crocetin) can be effective in preventing and treating diseases caused by abnormal αS aggregation.

Topics: alpha-Synuclein; Carotenoids; Crocus; Plant Extracts; Vitamin A