Health Benefits of Phenolic Compounds in Bananas

Phenolic compounds in bananas are significant bioactive substances, widely studied for their potent antioxidant properties and associated health benefits. These compounds are present in both the pulp and peel of bananas, making the fruit a valuable addition to a healthy diet. The primary phenolic compounds identified in bananas include catechin, epicatechin, gallic acid, tannins, and anthocyanins.

Catechin and epicatechin, members of the flavonoid family, are particularly important for their strong antioxidant activity. Antioxidants like these neutralize harmful free radicals, unstable molecules that can damage cells and contribute to aging and various diseases, including heart disease and cancer. By reducing oxidative stress, catechin and epicatechin protect cellular health, potentially lowering the risk of chronic conditions. Additionally, these flavonoids have been associated with improved vascular function, which supports heart health by promoting better blood circulation and reducing blood pressure.

Gallic acid, another vital phenolic compound in bananas, is renowned for its anti-inflammatory and antimicrobial properties. Its ability to inhibit the growth of bacteria and viruses makes it a promising compound in promoting immune health. Furthermore, its anti-inflammatory effects can help in managing conditions like arthritis and other inflammatory diseases. This dual action of combating pathogens and reducing inflammation enhances the therapeutic potential of bananas.

Tannins, also present in bananas, have astringent properties that aid in wound healing by promoting tissue contraction and reducing bleeding. Their anti-inflammatory effects also help in alleviating irritation in the digestive tract, supporting gastrointestinal health.

Though present in smaller quantities, anthocyanins contribute to bananas' health profile. These pigments are typically responsible for the red, purple, and blue colors in fruits like berries, but in bananas, they provide subtle contributions to health by supporting cardiovascular function and potentially lowering the risk of certain cancers.

Overall, the diverse phenolic compounds found in bananas underscore the fruit's role as a functional food, with regular consumption providing both essential nutrients and bioactive substances that contribute to improved health outcomes and protection against chronic diseases.
Health Benefits of Phenolic Compounds in Bananas

Dopamine: Major phenolic constituent in banana peel

Banana peel and pulp have been shown to contain biogenic amines, such as serotonin, dopamine and norepinephrine. Dopamine levels ranged from 80-560 mg per 100 g in peel and 2.5-10 mg in pulp, even in ripened bananas ready to eat.

Dopamine displays anti-inflammatory activity and protects against intestinal injury by acting as modulator of eicosanoid synthesis.

Dopamine is easily absorbed by the body and is considered to play an important role in the control of Parkinson’s disease. Dopamine is a neurotransmitter, synthesized in both central nervous system and the periphery, that exerts its actions upon binding to G protein-coupled receptors. Dopamine receptors are widely expressed in the body and function in both the peripheral and the central nervous systems.

Dopamine is a catecholamine formed by removing a carboxyl group from L-DOPA. It plays an important role in the human brain and body as a neurotransmitter with great impact on our mood, ability to concentrate and emotional stability.

Dopamine can be a precursor in the biosynthesis of other related catecholamines such as norepinephrine and epinephrine. Norepinephrine is synthesized from dopamine by the catalytic action of DA 𝛽-hydroxylase in the presence of L-ascorbic acid and molecular oxygen (O2).
Dopamine: Major phenolic constituent in banana peel

Phenolics in banana: Gallic acid

Major polyphenolic compound found in banana having antioxidant properties and are known for providing health benefits. Antioxidants express their mechanism through chelation of metal ion, regulation of gene expression, and the co-antioxidants. Various phenolics present in banana have been identified as follows: gallic acid, catechin, epicatechin, tannins, and anthocyanins.

Gallic acid (3, 4, 5-trihydroxybenzoic acid) is one of the most abundant phenolic acids in the plant kingdom and naturally occurring polyphenolic compound found in processed beverages such as red wines and green teas. It occurs in plants in the form of free acids, esters, catechin derivatives and hydrolysable tannins.

Gallic acid extracted from different natural sources has been implicated to possess potency to ameliorate neurodegenerative disorders and aging. Furthermore, large number of reseach explorations are available to show its ability for the treatment of diabetes, ischemic heart diseases, ulcer and other ailments.

This compound also has been reported to have therapeutic activities in gastrointestinal, metabolic, cancer, and cardiovascular disorders.

Gallic acid and its derivatives such as lauryl gallate, propyl gallate, octyl gallate, tetradecyl gallate, and hexadecyl gallate, can inhibit the oxidation and rancidity of oils and fats and because of that, they can be useful as additives in the food industry.

Research suggested that gallic acid has neuroprotective activity against 6-OHDA induced oxidative stress via enhancement of cerebral antioxidant defense. Gallic acid, founded by investigators to antioxidant properties of polyphenols have been exploited in the inhibition of fibrillar protein deposits that lead to disorders like Alzheimer’s and Parkinson’s disease.
Phenolics in banana: Gallic acid

Antioxidant properties of banana

Bananas are the creamy flesh and sweet fruit, with firmness, which are packaged in their yellow jackets. Bananas are one of the most consumed fruits in tropical and subtropical regions.

Free radicals may be produced continuously which cause serious diseases, like heart disease, cancer, arthritis, inflammation and aging. Antioxidants are those agents which can scavenge the free radicals and inhibit the damage caused by them. The best antioxidants found in nature so far are vitamin C, vitamin E and the carotenoids.

Banana contains antioxidants and phytochemicals such as Vitamin-C, Vitamin-E, flavonoids and β-carotene which have free radical scavenging activity. Some enzymes of banana flesh increase the antioxidant capacity.

These tropical fruits have strong ability to protect themselves from the oxidative stress caused by the intense sunshine and high temperature by increasing their antioxidant levels. They are known as a weak primary antioxidant source but a powerful secondary antioxidant source.

Carbohydrates, norepinephrine, serotonin, dopamine, tryptophan, indole compounds, alkaloids, tannin, ascorbic acid, several flavonoids and related compounds (Leucocyanidin, quercetin and its 3-O-galactoside, 3-O-glucoside, and 3-O-rhamnosyl glucoside) have been isolated from the pulp of different bananas. Sterols such as β-sitosterol, campesterol, stigmasterol were isolated from the fruit, peel and plant.

Recent studies demonstrated that banana peel generally include higher phenolic compounds than that of banana pulps. It was reported carotenoids such as β-carotene, α-carotene and different xanthophylls in the range of 300–400 μg lutein equivalents/100 g. Researchers attributed antioxidant properties of banana peel to its gallocatechin content.
Antioxidant properties of banana

Dopamine in banana

Bananas are popular edible fruits. The major phenolics of banana include catecholamines, naringin and rutin. 

Dopamine and norepinephrine are the predominant catecholamines in banana peel and pulp; phenolics accumulate mainly in the peel.

Researchers found that the dopamine content in banana varied from 80-560 mg/100g in the peel and 2.5-10 mg/100 g in the pulp in Cavendish banana.

Dopamine is a strong, water soluble antioxidant. It has similar antioxidant potency to strong antioxidants such as gallocatechin gallate and AsA.

It is the primary substrate in enzymatic browning. It is further confirmed that dopamine is the only major phenolic constituent in banana peel.

Dopamine displays anti-inflammatory activity and protects against intestinal injury by acting as modulator of eicosanoid synthesis.

Dopamine is easily absorbed by the body and is considered to play an important role in the control of Parkinson’s disease.
Dopamine in banana