Phenolic Powerhouses: The Health Benefits of Citrus Fruits and Sweet Lime

Citrus fruits are rich in bioactive compounds, particularly phenolics, which are responsible for their diverse health benefits. Phenolic substances, also known as polyphenols, are characterized by their aromatic ring structure with one or more hydroxy groups and functional derivatives. These compounds, found abundantly in citrus fruits, include phenolic acids and flavonoids such as flavones, flavanones, and flavonols. These phenolics exhibit a wide range of physiological properties, including anti-inflammatory, antiallergic, anticarcinogenic, antihypertensive, and antiarthritic activities.

Sweet lime (Citrus limetta), a popular type of citrus fruit, is often consumed fresh or as juice, which is highly regarded for its polyphenolic content. The phenolic acids present in sweet lime include caffeic, p-coumaric, sinapic, ferulic, and chlorogenic acids. These compounds, acting as secondary metabolites, possess potent antioxidant properties, contributing significantly to the fruit's health benefits.

Caffeic acid, widely present in plant-based foods, is known for its antioxidant and anti-inflammatory effects. Recent studies suggest that caffeic acid may also modulate the immune system, offering protective effects against various diseases. P-coumaric acid, a hydroxy derivative of cinnamic acid, exhibits antioxidant, antimicrobial, antimutagenic, and immunoregulatory activities. These properties make p-coumaric acid a valuable compound in enhancing human health and preventing diseases.

Ferulic acid (FA), or 4-hydroxy-3-methoxycinnamic acid, is another significant phenolic compound found in sweet lime. As a major constituent of plant cell walls, ferulic acid serves as a powerful antioxidant. It is extensively used in anti-aging skincare products due to its ability to neutralize free radicals and protect the skin from damage.

Chlorogenic acid, a member of the hydroxycinnamic acid family, contributes to the sour and bitter taste of sweet lime juice. This compound not only enhances the fruit's flavor profile but also offers health benefits through its antioxidant properties. Chlorogenic acid has been linked to reduced risk of cardiovascular diseases and improved metabolic health.

Recent research continues to highlight the importance of these phenolic compounds in citrus fruits. Studies have shown that regular consumption of citrus fruits can lead to improved cardiovascular health, reduced inflammation, and enhanced immune function. The bioactive compounds in citrus fruits, particularly sweet lime, play a crucial role in promoting health and preventing chronic diseases, making them an essential part of a balanced diet.
Phenolic Powerhouses: The Health Benefits of Citrus Fruits and Sweet Lime

Phenol punicalagin in pomegranate

Pomegranate, botanically known as Punica granatum, is an edible fruit enriched with a valuable substances with high antioxidant capacity.

Pomegranate is a rich source of many phenolic compounds including ellagitannins (punicalagin, punicalin, pedunculagin, gallagic acid, ellagic acid, ellagitannin and gallotannins), anthocyanins (cyanidin, delphinidin and pelargonidin glycosides), flavonoids (quercetin, kaempferol and luteolin glycosides).

These pomegranate phenolic compounds have several health-promoting effects such as antioxidative, anti-inflammatory, antimicrobial, antidiabetic, and antitumor properties.

Around 92% of pomegranate antioxidant activity comes from hydrolysable tannins. Epidemiological studies have shown that reduced cancer mortality and cerebrovascular and cardio disease are associated with consumption of phenolic-rich fruits.

Punicalagin is an ellagitannin, a type of hydrolysable tannin, is the largest molecular weight and most abundant polyphenol known. Punicalagin is reported to have anti-inflammatory, anti-cancer and anti-atherosclerotic properties.

Punicalagin is found in α and β forms in plants of the genera Myrtales such as Terminalia catappa, Terminalia myriocarpa and Punica granatum (pomegranate).
Phenol punicalagin in pomegranate

Antioxidant in fruit

The oxidative reactions proceeding in food are the main cause of its deterioration. They are responsible for the nutritional value losses, as well as aroma, taste and texture degradation.

Fruits and also vegetables are considered a good source of antioxidants, which are beneficial in protecting the human body against damage induced by free radicals and other reactive oxygen (ROS) and nitrogen (RNS) species.

An antioxidant can be defined as any substance which significantly delays or prevents oxidation of oxidizable substrate when present at low concentration compared to that of an oxidizable substrate.

The natural antioxidants are a stable part of nutrition as they occur in almost all edible plant products. Polyphenols are the most numerous groups of antioxidant components, and they are present in fruits and vegetables.

Study shows that the highest polyphenol concentration was found in seeds and peels of grapes (9207 mg catechin/100 g d.w. in red grape seeds and 8220 in white grape seeds, and respectively 5129 and 3794 in their peels) (Acta Sci. Pol., Technol. Aliment. 6(3) 2007, 29-36).

The main pigments in fruits include carotenoids contributing red, yellow, and orange (for example, apricot and tomato); flavonoids contributing yellow (for example, citrus); anthocyanidins contributing red, purple, and blue (for example, grape and blueberry).

These pigments have powerful antioxidant activities and multiple health benefits, such as antitumor, antimicrobial, anti-inflammation properties. delaying aging, repairing the nervous system, and anti-atherogenicity.

Some flavonoids have high antioxidant activity than vitamin C, gluthione and β-carotene.

Carotenoids are also antioxidant that effective active oxygen scavengers with provitamin activity and can reduce oxidative stress in the human body. Almost all fruits contain carotenoids. Some typical fruits that are rich in carotenoids are including goji berries, tomato, and apricot.
Antioxidant in fruit

Raspberry phenolic compounds

The wide range of values reported for various classes of phenolic in berries reflect differences in genetics, cultural practices, environmental growing conditions, and possibly maturation. It was reported that the color of raspberry juice correlated with the total phenolic.

Black raspberries had the highest ORAC (Oxygen Radical Absorbance), anthocyanin and phenolic compounds. Anthocyanins are the major phenolics present in black raspberries, with levels ranging from 464 to 627 mg/100 g FW.

Black raspberries also contain appreciable levels of total ellagic acid which most likely is due to high concentrations of ellagitannins in the fruit.

Red raspberry seeds contained more phenolic compounds (ellagic acid content) than pulp, but leaves had a higher content than seeds or pulp. Phenolic compounds ellagic acid, a dimeric derivative of gallic acid, is suggested as an anti- carcinogenic/anti-mutagenic compound. It is present in plants in the form of hydrolysable tannins called ellagitannins.

 Only red raspberries had detectable amounts of procyanidin oligomers (monomer, dimers and trimers).
Raspberry phenolic compounds

Antioxidants content in dragon fruit

Dragon fruit poses medicinal properties. This fruit is a natural source of antioxidants.

Antioxidant prevents colon cancer and diabetes, neutralizes toxic substances like heavy metals, reduces cholesterol, and high blood pressure.

It control high sugar levels, prevents cancer and bleeding and promotes dental health. Phenolic compounds, namely hydroycinnamates, have been reported in the pulp of dragon fruit.

The total phenolic contents of flesh (42.4 mg of gallic acid equivalents (GAE)/100 g of flesh fresh weight and peel (39.7 mg of GAE/100 g of peel fresh weight) of dragon fruit were similar.

The flavonoid contents of flesh and peel did not vary much (7.21 mg vs. 8.33 mg of catechin equivalents/100 g of flesh and peel matters).

The betacyanin content in red-fleshed dragon fruit juice is 525.3 mg/L, while betaxanthins of 5.3 mg/L has been reported in the juice of fed-flesh dragon fruit. Betacyanin protect against oxidative stress-related disorders.
Antioxidants content in dragon fruit 

Phenolic compound in blueberries

Blueberries are a sweet, succulent fruit grown in many parts of the world.

Phenolic compounds are prominent in blueberries strongly refract light and contribute up to 32% to soluble solid readings from a refractometer. Recent interest in health-promoting compound has spurned the production of blueberries. Blueberries contain phenolic compounds such as flavonoids, phenolic acids, procyanidins, lignans, stilbenes and polymeric tannins.

Phenolic compounds present in berries have a varying effect in inhibition of the growth of pathogenic bacteria.

Blueberries contain antioxidant compound called ellagic acid, which blocks metabolic pathways that can lead to cancer. Ellagic acid is a natural phenol antioxidant. It is the dilactone of hexahydroxydiphenic acid. 

Published in Journal of Agricultural and Food Chemistry (September 2005) show that phenolic compounds in blueberries can inhibit colon cancer growth and kill existing cancer cells in the body.

The primary active component in blueberries in a phenolic compound called anthocyanins. These substance give blueberries their rich blue color.

In addition to their antioxidant activity, blueberries have been found to protect against urinary tract infections, improve ‘tired eyes’ and possibly reduce the effects of aging.
Phenolic compound in blueberries