Differential effects of acute and chronic treatment with the flavonoid chrysin on anxiety-like behavior and Fos immunoreactivity in the lateral septal nucleus in rats

The research progress on the anxiolytic effect of plant-derived flavonoids by regulating neurotransmitters

Phytopharmaceuticals have attracted a lot of attention due to their multicomponent and multiple targets. The natural phenolic chemicals known as flavonoids are found in a wide variety of plants, fruits, vegetables, and herbs. Recently, they have been found to have modulatory effects on anxiety disorders, with current research focusing on the modulation of neurotransmitters. There has not yet been a review of the various natural flavonoid monomer compounds and total plant flavonoids that have been found to have anxiolytic effects. The study on the anti-anxiety effects of plant-derived flavonoids on neurotransmitters was reviewed in this paper. We, therefore, anticipate that further study on the conformational interaction underlying flavonoids' anti-anxiety effects will offer a theoretical framework for the creation of pertinent treatments.

Behavioral Despair Is Blocked by the Flavonoid Chrysin (5,7-Dihydroxyflavone) in a Rat Model of Surgical Menopause

Women have a high susceptibility to the negative effects of stress. Hormonal changes experienced throughout their reproductive life partially contribute to a higher incidence of anxiety and depression symptoms, particularly, during natural or surgical menopause. In preclinical research, the flavonoid chrysin (5,7-dihydroxyflavone) exerts anxiolytic- and anti-despair-like effects; however, it is unknown whether chrysin exerts a protective effect against the behavioral changes produced by acute stress on locomotor activity and behavioral despair in rats at 12-weeks post-ovariectomy. Ovariectomized female Wistar rats were assigned to eight groups: vehicle group (10% DMSO), three groups with chrysin and three groups with the same dose of allopregnanolone (0.5, 1, and 2 mg/kg), and one group with diazepam (2 mg/kg). The treatments were administered for seven consecutive days and the effects were evaluated in the locomotor activity and swimming tests. Chrysin (2 mg/kg) increased the latency to first immobility and decreased the total immobility time in the swimming test as the reference drugs allopregnanolone and diazepam (2 mg/kg); while locomotor activity prevented the behavioral changes produced by swimming. In conclusion, chrysin exerts a protective effect against the behavioral changes induced by acute stress, similarly to the neurosteroid allopregnanolone and the benzodiazepine diazepam in rats subjected to a surgical menopause model.

Pharmacological, Neurochemical, and Behavioral Mechanisms Underlying the Anxiolytic- and Antidepressant-like Effects of Flavonoid Chrysin

Chrysin (5,7-dihydroxyflavone) is a flavonoid isolated from plants, such as Passiflora coerulea, Passiflora incarnata, and Matricaria chamomilla. This natural molecule exerts diverse pharmacological effects, which includes antioxidant, anti-inflammatory, anti-cancer, neuroprotective, and anti-apoptotic effects. Additionally, in brain structures, such as the hippocampus, prefrontal cortex, raphe nucleus, and striatum, involved in the physiopathology of anxiety and depression disorders, several neuropharmacological activities, including the activation of neurotransmitter systems (GABAergic, serotonergic, dopaminergic, and noradrenergic), neurotrophic factors, such as brain-derived neurotrophic factor and the nerve growth factor, and some signaling pathways are affected. The results showed that the anxiolytic and antidepressant-like effects of chrysin occurs through its interaction with specific neurotransmitter systems, principally the GABAergic and the serotonergic, and activation of other neurotrophic factors. However, it is not possible to discard the antioxidant and anti-inflammatory activities of chrysin while producing its anxiolytic- and antidepressant-like effects. Although these results have been obtained principally from pre-clinical research, they consistently demonstrate the potential therapeutic use of flavonoid chrysin as an anxiolytic and antidepressant agent. Therefore, this flavonoid could be considered as a promising novel therapy for anxiety and depression disorders.

Dietary flavonoids-rich Citrus reticulata peel extract interacts with CREB signaling to suppress seizures and linked neurobehavioral impairments in a kindling mouse model

Objectives: The citrus fruits peel contains a variety of bioactive metabolites that have shown multiple therapeutic effects. However, despite having substantial ethnomedicinal value, citrus peels remained underexplored and regarded as bio-waste. This present study was planned to investigate the effect of a characterized peel extract of Citrus reticulata c.v. (CRE) in pentylenetetrazole (PTZ)-induced kindling and associated cognitive and behavioral impairments in a mouse model.Methods: The kindled animals were treated daily with CRE (100 and 200 mg/kg) and challenged with a sub-effective dose of PTZ every 5th day to record the severity of seizures. In the end, different tests were performed to record behavioral and cognitive performance.Results: CRE-treated kindled animals showed a significant suppression in seizure severity following 20 days of the treatment. In the T-maze test, the extract treatment resulted in a marked increase in the spontaneous alternations, whereas it showed no change in anxiety behavior of kindled animals in the elevated plus-maze test. In both forced swim and tail suspension tests, CRE treatment demonstrated a considerable reduction in immobility time. However, no change in overall locomotion was observed in the open field test among all the groups. An increase in the hippocampal Creb and Bdnf expression and decreased glutamate-to-GABA ratio were observed in the CRE-treated kindled animals.Discussion: The results showed that CRE treatment suppresses epileptic seizures and associated cognitive deficits and depression-like behavior in kindled mice. The gene expression findings supported that the observed protective effects of CRE be due to its interaction with CREB signaling.

Behavioral Pharmacology of Five Uncommon Passiflora Species Indicates Sedative and Anxiolytic-like Potential

BACKGROUND

There are over 500 species in the Passiflora genus, and while some of them are very well known in folk medicine for their anxiolytic effects, very little is known for the other genus representants, which could also present medicinal effects.

OBJECTIVE

In this study, we performed an interspecific pharmacological comparison of five little investigated Passiflora species, all native to Brazil: P. bahiensis, P. coccinea, P. quadrangularis, P. sidaefolia, and P. vitifolia.

METHOD

Extracts were administered to mice before behavioral testing, which included a general pharmacological screening and anxiolytic-like effect investigation.

RESULTS

Three of the species [P. coccinea, P. quadrangularis, and P. sidaefolia] induced a decrease in locomotor activity of mice; P. coccinea also reduced the latency to sleep. Importantly, none of the species interfered with motor coordination. Oral administration evoked no severe signs of toxicity even at higher doses. Regarding the anxiolytic-like profile, P. sidaefolia reduced the anxious-like behavior in the Holeboard test in a similar way to the positive control, Passiflora incarnata, while not affecting total motricity.

CONCLUSION

These results indicate that P. coccinea, P. quadrangularis, and P. sidaefolia reduced the general activity of mice and confer a calmative/sedative potential to these three species, which must be further elucidated by future investigations.

The cross-talk between dopaminergic and nitric oxide systems in the medial septal nucleus, and their distinct effects on anxiety-like behaviors in male rats

Anxiety disorders, which have a noticeable global prevalence and may be caused by many factors, include a spectrum of disorders that share features of excessive fear- and anxiety-related behavioral disturbances. Different brain areas and neurotransmitter systems have been under investigation for anxiety-related disorders. In this study, we investigated the possible interaction between the dopaminergic and nitric oxide (NO) neurotransmitter systems in the medial septal nucleus and their roles in anxiety-like behaviors using elevated plus-maze (EPM) test in male rats. Our results showed that: (i) both D1-and D2-like receptor agonists, SKF-38393 and quinpirole, augmented anxiety-like behaviors at their two highest applied doses in the EPM test; (ii) both D1-and D2-like receptor antagonists, SCH- 23390 and sulpiride, reduced anxiety-like behaviors at their two highest applied doses in the EPM test; (iii) L-Arginine, a NO precursor, increased anxiety-like behaviors, but L-NAME, a non-specific nitric oxide synthase (NOS) inhibitor, reduced them in the EPM test; (iv) L-NAME could not reverse the anxiety-like parameters produced by SKF-38393, but it significantly reduced the anxiety-like behaviors induced by quinpirole; (v) Neither SCH- 23390 nor sulpiride changed anxiety-related behaviors induced by L-Arginine. It can be concluded that both dopaminergic and nitric oxide systems in the medial septal nucleus are involved in modulating anxiety-like behaviors. While NO has an involvement in the exerted effects by the D2-like agonist, such effects were not observed at the applied range of the doses for D1-and D2-like antagonists.

An updated review on the versatile role of chrysin in neurological diseases: Chemistry, pharmacology, and drug delivery approaches

Neurological diseases are responsible for a large number of morbidities and mortalities in the world. Flavonoids are phytochemicals that possess various health-promoting impacts. Chrysin, a natural flavonoid isolated from diverse fruits, vegetables, and even mushrooms, has several pharmacological activities comprising antioxidant, anti-inflammatory, antiapoptotic, anticancer, and neuroprotective effects. The current study was designed to review the relationship between chrysin administration and neurological complications by discussing the feasible mechanism and signaling pathways. Herein, we mentioned the sources, pharmacological properties, chemistry, and drug delivery systems associated with chrysin pharmacotherapy. The role of chrysin was discussed in depression, anxiety, neuroinflammation, Alzheimer's disease, Parkinson's disease, Huntington's disease, epilepsy, cerebral ischemia, spinal cord injury, neuropathy, Multiple Sclerosis, and Guillain-Barré Syndrome. The findings indicate that chrysin has protective effects against neurological conditions by modulating oxidative stress, inflammation, and apoptosis in animal models. However, more studies should be done to clear the neuroprotective effects of chrysin.

Chrysin: Perspectives on Contemporary Status and Future Possibilities as Pro-Health Agent

Chrysin belongs to the group of natural polyphenols. It can be found, among others, in honey, propolis and fruits and has a wide range of biological activities, including the prevention of oxidative stress, inflammation, neurodegeneration and carcinogenesis. Being a part of the human diet, chrysin is considered to be a promising compound to be used in the prevention of many diseases, including cancers, diabetes and neurodegenerative diseases such as Alzheimer's or Parkinson's. Nevertheless, due to the low solubility of chrysin in water and under physiological conditions, its bioavailability is low. For this reason, attempts at its functionalization have been undertaken, aiming to increase its absorption and thus augment its in vivo therapeutic efficacy. The aim of this review is to summarize the most recent research on chrysin, including its sources, metabolism, pro-health effects and the effects of its functionalization on biological activity and pharmacological efficacy, evaluated both in vitro and in vivo.

Chrysin, but not flavone backbone, decreases anxiety-like behavior in animal screens

Chrysin (5,7-dihydroxyflavone), a nutraceutical flavonoid present in diverse plants, has a backbone structure shared with the flavone backbone, with additional hydroxyl groups that confers its antioxidant properties and effects at the GABA_A receptor complex. However, whether these effects are due to the hydroxyl groups is unknown. Here we report the effects of chrysin or the flavone backbone (1 mg/kg) in rats subjected to the elevated plus-maze and the locomotor activity test, as well as in the zebrafish evaluated in light/dark model. Chrysin, but not flavone, increased entries and time in the open arms of the elevated plus-maze, as well as time on white compartment of the light/dark model in zebrafish. These effects were comparable to diazepam, and were devoid of motor effects in both tests, as well as in the locomotor activity test. On the other hand, flavone decreased risk assessment in the light/dark test but increased rearing in the locomotor activity test in rats, suggesting effects threat information gathering; important species differences suggest new avenues of research. It is suggested that the specific effects of chrysin in relation to flavone include more of a mechanism of action in which in addition to its action at the GABA_A/benzodiazepine receptor complex also could be involved its free radical scavenging abilities, which require specific research. Preprint: https://doi.org/10.1101/575514; Data and scripts:https://github.com/lanec-unifesspa/chrysin.

Herbal Medicinal Products from Passiflora for Anxiety: An Unexploited Potential

Herbal medicines containing Passiflora species have been widely used to treat anxiety since ancient times. The species Passiflora incarnata L. is included in many Pharmacopoeias, and it is the most used species in food, cosmetic, and pharmaceutical industries. However, there are around 600 species of the genus Passiflora and probably other species that can be used safely. Thus, this article was based on a search into the uses of the main species of the genus Passiflora with anxiolytic activity and its main secondary metabolites and some pharmacological studies, patents, and registered products containing Passiflora. Furthermore, the Brazilian Regulatory Health Agency Datavisa, Medicines and Healthcare Products Regulatory Agency of the United Kingdom, and the European Medicines Agency websites were consulted. The results showed that Passiflora species have health benefits but clinical trials are still scarce. The complexity of Passiflora extracts creates challenges for the development of herbal medicines. P. incarnata is the most studied species of the genus and the most used in natural anxiolytic herbal medicine formulations. However, there are hundreds of Passiflora species potentially useful for medicinal and nutraceutical purposes that are still little explored.