Review assesses neuroprotective qualities of polyphenols

By Olivia Haslam

- Last updated on GMT

Review assesses neuroprotective qualities of polyphenols

Related tags Polyphenols Polyphenol antioxidant Antioxidant Ischemic stroke Oxidative stress Green tea Free radicals neuroprotection

Free radicals in phytochemicals are noted for their neuroprotective actions but the clinical effectiveness of antioxidants in ischemic stroke is still unknown, a review has concluded.

Previous literature has shown that phytochemicals and other natural products not only scavenge oxygen free radicals but also improve the expressions of cellular antioxidant enzymes and molecules. Consequently, these products have been suggested to protect against reactive oxygen species (ROS) mediated cellular injury, such as ischemic stroke (IS).

A new review​, published in ‘Nutrients', provides an audit of the most pertinent information available in on polyphenolic compounds, specifically gallic acid, resveratrol, quercetin, kaempferol, mangiferin, epigallocatechin, and pinocembrin, with focus on their antioxidant effects and potential protective activity against IS.

Significance

A significant fraction of global mortality and disability is caused by stroke. Stroke is intricately linked to various processes, including excitotoxicity, inflammation, oxidative damage, ionic imbalances, apoptosis, angiogenesis, and neuroprotection. Acute stroke sets off an ischemic cascade that eventually kills neurons and permanently impairs their abilities to operate. Aortic arch atherosclerosis is one of the risk factors for ischemic stroke.

IS is brought on by obstruction of cerebral blood flow, which results in an inadequate supply of oxygen to the affected area. It is responsible for roughly 80–85 percent of all stroke cases.

The pathophysiologic chain of events that results in brain injury and stroke is significantly influenced by oxidative stress. Oxidative stress induces high toxicity during the acute phase and starts and/or fuels inflammation and late-stage apoptosis. Conditions of oxidative stress happen when the body's antioxidant defense is inadequate to prevent the formation and accumulation of reactive oxygen species (ROS).

Due to anti-inflammatory, antioxidant, and anti-proliferative effects, the dietary consumption of polyphenols from different sources of plants can offer protection against mortality caused by cardiovascular disease, previous studies report.​, and can provide protection against stroke in humans, animals, and in vitro studies.

The Review

The researchers in the current review assessed studies from databases including Scopus, Web of Science, PubMed, and Google Scholar, placing emphasis on polyphenolic compounds keywords, specifically gallic acid, resveratrol, quercetin, kaempferol, mangiferin, epigallocatechin, and pinocembrin.

This review showcases the importance of phytochemicals and other natural products in scavenging free radicals to improve antioxidant enzymes and other key molecules that are required for normal cellular activities. The authors state: "The use of polyphenols can tremendously prevent cell damage and edema during cerebral ischemic injury.”

It is noted in the review, that previous research indicates the stimulation of Gallic Acid (GA) could enhance cerebral antioxidant defense​, which is an effective approach to treating patients suffering from a stroke.

Previous study results report​ that Resveratrol (RS) may have significant therapeutic promise for managing cerebrovascular dysfunction.

In vitro studies have shown​ that Quercetin can reduce the aggregation of platelets, possibly through the inhibition of lipoxygenase and cyclooxygenase activity, concluding that the long-term intake of quercetin may protect against stroke.

The flavonol kaempferol (KFL) with an ability to cross the blood-brain-barrier (BBB), is potentially effect​ive against IS, due to its multi-target property that prevents and treats neurodegenerative diseases.

Mangiferin (MFN) has been said to exert potential antioxidant properties with an ability to scavenge free radicals. The compound possesses anti-inflammatory and anti-apoptotic activities​, which protect against several organ injuries caused by different factors.

What’s more, Epigallocatechin (EGCG) has been reported ​to decrease lipid peroxidation product levels while increasing enzymatic and non-enzymatic antioxidant levels, and is has potential to provide protection against cerebral ischemia damage.

Research has​ also shown the protective effects of pinocembrin on cerebral ischemic injury, with a wide therapeutic potential. In both in vitro and in vivo studies​, pinocembrin exhibited neuroprotective, anti-oxidative, and anti-inflammatory properties.

The review concludes that phytochemicals and other natural products, specifically gallic acid, resveratrol, quercetin, kaempferol, mangiferin, epigallocatechin, and pinocembrin, are involved in providing neuroprotection against IS via various cellular mechanisms, underscoring the need for additional research on these substances to ascertain their healthcare benefits for people.

Limitations

In discussing the limitations of this study, the authors state: “While there is no argument about the deleterious effects and detrimental contribution of free radicals to lesion progression after ischemic stroke, the clinical efficacy of antioxidants in this setting remains unclear, indicating the importance of further investigations of the cellular and molecular actions of polyphenols in neuroprotection.”

The report concludes: “Phytochemicals and other natural products, namely, gallic acid, resveratrol, quercetin, kaempferol, mangiferin, epigallocatechin, and pinocembrin, are involved in providing neuroprotection against IS via various cellular mechanisms, underscoring the need for further studies on these compounds to determine their healthcare benefits for humans.

“Free radicals are noted for detrimental contribution to the progression of lesions after ischemic stroke, but the clinical effectiveness of antioxidants in this situation is still unknown, highlighting the significance of further research into the cellular and molecular functions of polyphenols in neuroprotection.”

 

Journal: Nutrients

https://www.mdpi.com/2072-6643/15/5/1107

“Polyphenols Mediate Neuroprotection in Cerebral Ischemic Stroke—An Update”

Authors: Salaheldin Abdelraouf Abdelsalam, Kaviyarasi Renu, Hamad Abu Zahra, Basem M. Abdallah, Enas M. Ali, Vishnu Priya Veeraraghavan, Kalaiselvi Sivalingam, Larance Ronsard, Rebai Ben Ammar, Devanathadesikan Seshadri Vidya, Palaniyandi Karuppaiya, S. Y. Al-Ramadan and Peramaiyan Rajendran.

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