Saffron and its major constituents against neurodegenerative diseases: A mechanistic review

BACKGROUND

Neurodegeneration has been recognized as the main pathophysiological alteration in the majority of brain-related diseases. Despite contemporary attempts to provide acceptable medicinal therapies, the conclusion has not been much beneficial. Besides, the complex pathophysiological mechanisms behind neurodegenerative diseases (NDDs) urge the needs for finding novel multi-target agents. Accordingly, saffron with major active constituents and as multi-targeting agents have shown beneficial effects in modulating NDDs with higher efficacy and lower side effects.

PURPOSE

The present study provides a systematic and comprehensive review of the existing in vitro, in vivo, and clinical data on the effectiveness, and signaling pathways of saffron and its key phytochemical components in the management of NDDs. The need to develop novel saffron delivery systems is also considered.

METHODS

Studies were identified through a systematic and comprehensive search in Science Direct, PubMed, and Scopus databases through April 30, 2024. The whole saffron major constituents (e.g., saffron, crocin, crocetin, picrocrocin, and safranal) and NDDs (e.g., neuro*, spinal cord injury, multiple sclerosis, amyotrophic lateral sclerosis, Huntington*, Parkinson*, Alzheimer*, and brain) were selected as keywords to find related studies. In the systematic analysis, 64 articles were directly included in the current study. Additional reports were added within the comprehensive studies in the review.

RESULTS

Saffron and its active metabolites crocin, crocetin, safranal, and picrocrocin have shown acceptable efficacy in managing NDDs like Alzheimer's disease, Parkinson's disease, Attention deficit hyperactivity disorder, depression, and other NDDs via modulating apoptotic (e.g., caspases, Bax/Bcl-2, cytochrome c, and death receptors), inflammatory (e.g., NF-κB, IL-1β, IL-6, TNF-α, and COX-2), and oxidative strass (e.g., Nrf2, GSH, GPx, CAT, SOD, MDA, ROS, and nitrite) signaling pathways. The presented in vitro, in vivo, and clinical evidences showed us a better future of controlling NDDs with higher efficacy, while decreasing associated side effects with no significant toxicity. Additionally, employing novel delivery systems could increase the efficacy of saffron phytoconstituents to resolve the issues pharmacokinetic limitations.

CONCLUSION

Saffron and its major constituents employ anti-inflammatory, anti-apoptotic and antioxidant mechanisms in modulating several dysregulated-signaling pathways in NDDs. However, further research is necessary to elucidate the precise underlying mechanisms in exploring the feasibility of using saffron active compounds against NDDs. More studies should focus on dose-response relationships, long-term effects, highlighting key mechanisms, and designing more well-controlled clinical trials. Additionally, developing stable and cost-benefit novel delivery systems in future works helps to remove the pharmacokinetic limitations of saffron major constituents.

Accumulated HIIT inhibits anxiety and depression, improves cognitive function, and memory-related proteins in the hippocampus of aged rats

This study aimed to compare the effects of High-Intensity Interval Training (HIIT) performed in a single session(1xHIIT) versus three daily sessions (3xHIIT) on fitness level and behavior of aged rats. Eighteen-month-old Wistar rats were assigned to Untrained (UN), 1xHIIT, or 3xHIIT (n = 12/group). Both groups, 1xHIIT and 3xHIIT, performed 15 min of a treadmill running HIIT protocol during 8 weeks. 1xHIIT protocol consisted of a single daily session of 15 min, while the 3xHIIT performed three daily sessions of 5 min with a 4 h interval between the sessions. Morris Water Maze (MWM) task was used to evaluate spatial learning and memory. Splash test, Forced Swim test, and Elevated Plus Maze task (EPM) were used to evaluate anhedonic, depressive-like, and anxious behaviors, respectively. Rats were euthanized, and the hippocampus was harvested for western blot analyses (CaMKII and BDNF). Both HIIT protocols improved VO2max and spatial memory. Notably, only the 3xHIIT protocol attenuated anxious and depressive-like behaviors. Western blot analyses of the hippocampus revealed that both HIIT protocols increased BDNF levels. BDNF levels were higher in the 3xHIIT when compared with 1xHIIT group, and we observed increasement of the CamKII levels just in the 3x HIIT group. Therefore, this study provides evidence indicating that accumulated HIIT sessions is more effective than traditional daily HIIT sessions in improving fitness level, cognitive function, memory, inhibiting the development of mood disorders, and enhancing BDNF and CaMKII levels in the hippocampus of aged rats.

Interaction of aerobic exercise and crocin improves memory, learning and hypocampic tau and neurotrophins gene expression in rats treated with trimethytin as a model of Alzheimer's disease

INTRODUCTION

Alzheimer's disease (AD) is characterized by progressive cognitive decline and a reduction in hippocampal neurotrophins, in which trimethytin (TMT) infusion causes tangles and neuronal dysfunction, creating an AD-like model in rats. Previous studies have demonstrated that crocin, which has anti-inflammatory properties, can enhance learning, memory acquisition, and cognitive behavior. This study aimed to assess the combined impact of aerobic exercise and crocin on memory, learning, and hippocampal Tau and neurotrophins gene expression in AD-like model rats.

METHODS

Forty male Sprague Dawley rats were randomly divided into five groups: (1) healthy control, (2) Alzheimer's control, (3) endurance training, (4) crocin consumption, and (5) endurance training + crocin. Alzheimer's induction was achieved in groups 2-5 through intraperitoneal injection of 8 mg/kg TMT. Rats in groups 3 and 5 engaged in treadmill running three sessions per week, 15-30 min per session, at a speed of 15-20 m/min for eight weeks, and groups 4 and 5 received daily crocin supplementation of 25 mg/kg.

RESULTS

Alzheimer's induction with TMT showed significant reduction in memory, learning, NGF, BDNF, and TrkB gene expression, and increase in tau gene expression (all p < 0.05). Notably, endurance training and crocin consumption separately significantly increased memory, learning, NGF, BDNF, and TrkB gene expression while significantly decreasing tau gene expression (all p < 0.05). Importantly, combined endurance training with crocin yielded the most profound effects on memory (p = 0.001), NGF (p = 0.002), BDNF (p = 0.001), and TrkB (p = 0.003) gene expression (p < 0.005), as well as a reduction in tau gene expression (p = 0.001).

CONCLUSION

These findings underscore the possible impact of endurance training, particularly when coupled with crocin, on enhancing memory, learning, and neurotrophin gene expression and reducing tau gene expression in Alzheimer's rats. These results highlight the possibility of synergistic interventions for improved therapeutic outcomes.

Effect of training and crocin supplementation on mitochondrial biogenesis and redox-sensitive transcription factors in liver tissue of type 2 diabetic rats

Present study investigated the effect of continued training (CT) and interval training (IT) with crocin (C) supplementation on mitochondrial biogenesis and redox-sensitive transcription factors in liver tissue of type 2 diabetes (T2D) rats. Forty-eight high fat diet and streptozotocin- induced diabetic rats (mean age: 20 weeks, mean weight: 360.12 ± 12.11 g) were randomly divided into six groups including: (1) sham (Sh), (2) CT, (3) IT, (4) C (25 mg/kg/day), (5) CT + C, and (6) IT + C. IT and CT were performed 8 weeks for five sessions per week on treadmill with 80-85% and 50-55% of maximum speed running respectively. IT, CT and C decreased AP1 and increased LCAD (p ≤ .05); C increased SIRT1 (p ≤ .05); IT + C and CT + C decreased AP1 as well as increased NF-κB and LCAD (p ≤ .05); IT + C increased SIRT1, SIRST3 and PGC1-α (p ≤ .05). It appears that IT along with C compared to CT and C have favourable effect on mitochondrial biogenesis factors.

Protective role of IGF-1 and GLP-1 signaling activation in neurological dysfunctions

Insulin-like growth factor-1 (IGF-1), a pleiotropic polypeptide, plays an essential role in CNS development and maturation. Glucagon-like peptide-1 (GLP-1) is an endogenous incretin hormone that regulates blood glucose levels and fatty acid oxidation in the brain. GLP-1 also exhibits similar functions and growth factor-like properties to IGF-1, which is likely how it exerts its neuroprotective effects. Recent preclinical and clinical evidence indicate that IGF-1 and GLP-1, apart from regulating growth and development, prevent neuronal death mediated by amyloidogenesis, cerebral glucose deprivation, neuroinflammation and apoptosis through modulation of PI3/Akt kinase, mammalian target of rapamycin (mTOR) and mitogen-activated protein kinase (MAPK/ERK). IGF-1 resistance and GLP-1 deficiency impair protective cellular signaling mechanisms, contributing to the progression of neurodegenerative diseases. Over the past decades, IGF-1 and GLP-1 have emerged as an essential component of the neuronal system and as potential therapeutic targets for several neurodegenerative and neuropsychiatric dysfunctions. There is substantial evidence that IGF-1 and GLP-1 analogues penetrate the blood-brain barrier (BBB) and exhibit neuroprotective functions, including synaptic formation, neuronal plasticity, protein synthesis, and autophagy. Conclusively, this review represents the therapeutic potential of IGF-1 and GLP-1 signaling target activators in ameliorating neurological disorders.

Crocin molecular signaling pathways at a glance: A comprehensive review

Crocin is a hydrophilic carotenoid that is synthesized in the flowers of the Crocus genus. Numerous in vitro and in vivo research projects have been published about the biological and pharmacological properties and toxicity of crocin. Crocin acts as a memory enhancer, anxiolytic, aphrodisiac, antidepressant, neuroprotective, and so on. Here, we introduce an updated and comprehensive review of crocin molecular mechanisms based on previously examined and mentioned in the literature. Different studies confirmed the significant effect of crocin to control pathological conditions, including oxidative stress, inflammation, metabolic disorders, neurodegenerative disorders, and cancer. The neuroprotective effect of crocin could be related to the activation of phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT)/mammalian target of rapamycin (mTOR), Notch, and cyclic-AMP response element-binding protein signaling pathways. The crocin also protects the cardiovascular system through the inhibitory effect on toll-like receptors. The regulatory effect of crocin on PI3K/AKT/mTOR, AMP-activated protein kinase, mitogen-activated protein kinases (MAPK), and peroxisome proliferator-activated receptor pathways can play an effective role in the treatment of metabolic disorders. The crocin has anticancer activity through the PI3K/AKT/mTOR, MAPK, vascular endothelial growth factor, Wnt/β-catenin, and Janus kinases-signal transducer and activator of transcription suppression. Also, the nuclear factor-erythroid factor 2-related factor 2 and p53 signaling pathway activation may be effective in the anticancer effect of crocin. Finally, among signaling pathways regulated by crocin, the most important ones seem to be those related to the regulatory effect on the PI3K/AKT/mTOR pathway.

Mental Health Benefits of Exercise and Genistein in Elderly Rats

Elderly is a part of life that is associated with physical and mental disorders. The present study aimed to investigate the effect of 8 weeks of high-intensity interval training (HIIT) along with genistein (Ge) on memory, anxiety, physical persistence and aerobic power in elderly rats. Forty elderly rats were randomly assigned to five groups of eight rats including 1) control (C), 2) sham (Sh), 3) HIIT, 4) HIIT+Ge, and 5)Ge. During 8-week groups 3 and 4 performed HIIT for three sessions per week and groups 4 and 5 received 60 mg/kg/day Ge peritoneally. Physical persistence (by forced swimming test), memory (by shuttle box and Y maze tests), anxiety (by elevated plus-maze test) and aerobic power (by exhaustive running on treadmill) were measured. HIIT, Ge, and HIIT+Ge significantly increased physical persistence and memory (P ≤0.05), HIIT and HIIT+Ge significantly decrease anxiety and increased aerobic power (P ≤0.05) and HIIT+Ge had higher effect on the decrease of anxiety and increase of memory compared to HIIT and Ge (P≤0.05). Although HIIT and Ge alone can enhance physical persistence, memory and anxiety in elderly rats nevertheless it seems that HIIT simultaneously with Ge has more favorable mental health benefits compared to HIIT and Ge alone.