Study on Echinacea Antioxidant

Echinacea purpurea is a perennial herb in the genus Echinacea, which grows mainly in southern Canada and North America. The purple coneflower's capitulum is borne singly at the stem or branch tip, and the receptacle is conical in shape. It has tubular flowers and ligulate flowers, which are usually rose or purple in color. Echinacea is popular for its high medicinal value and health benefits. Research on its pharmacological effects is becoming more and more extensive. Echinacea has strong anti-inflammatory and immune-enhancing effects, and is known worldwide as an “immune herb” that has attracted widespread attention from researchers at home and abroad [1-3]. Echinacea contains flavonoids, caffeic acid derivatives and other substances with strong antioxidant effects, which have a good repair effect on oxidative damage in animal bodies. It is a natural plant antioxidant that has yet to be further developed and researched [4].

1 Oxidative free radicals in animal bodies

In 1900, Comberg proposed the concept of “organic free radicals”. Free radicals, also known as free radicals in chemistry, refer to atoms or groups with asymmetric electrons formed when the covalent bonds in a compound molecule are cleaved under certain conditions. They are the products of normal body metabolism. Chemically unstable, they are prone to oxidation reactions with other molecules in the body, causing damage to lipids, nucleic acids, proteins, etc. [5].

The main free radicals in the body are oxygen free radicals, semiquinone free radicals and other free radicals with sulfur, carbon or nitrogen as the central atom. The main source of free radical activity in the body is oxygen free radicals (OFR). Important oxygen free radicals include lipid peroxide free radicals (LOO·), protonated superoxide anion free radicals (HO2 ·), lipid oxygen free radicals (LO·), hydroxyl free radicals (OH·) and superoxide anion free radicals (O2-). The characteristics of free radicals include: a short lifespan in the body, extremely active chemical properties, and a strong tendency to react with other substances to form new free radicals, resulting in a clear chain reaction [6-8].

In 2006, Valko et al. discovered that when animals are stressed or become ill, their metabolism becomes abnormal and suddenly produces a large number of reactive oxygen species (ROS) or reactive nitrogen species (RNS) free radicals. Excessive free radicals will exceed the reducing capacity of the body's enzymatic or non-enzymatic antioxidant system, putting the body in a state of oxidative stress. Oxidative stress can damage biological macromolecules such as DNA, biofilm lipids and proteins in the body, inhibit normal physiological functions, and ultimately lead to the occurrence of diseases and even death [9]. Studies have found that the body of animals can inhibit or slow down the production of free radicals through exogenous antioxidants, thereby repairing the oxidative damage caused to the body by free radicals [10]. Studies have found that many plants contain active ingredients with antioxidant effects, and are used to make health products that are antioxidant and anti-aging. The active ingredients in Echinacea purpurea have strong antioxidant activity. Its extract contains polyphenols, active polysaccharides and alkaloids, which also have strong antioxidant activity.

In recent years, many scholars at home and abroad have been studying the antioxidant properties of Echinacea purpurea. Lu Ying et al. found that the polyphenols in Echinacea purpurea extract have a good antioxidant effect [11]. Mao Shaochun et al. found that Echinacea has strong antioxidant activity and also has a certain scavenging effect on cigarette smoke free radicals [12]. Gao Yanni et al. studied the effect of Echinacea extract on the antioxidant performance indicators in the serum of broiler chickens and found that Echinacea extract contains a lot of phenolic compounds, which in turn have a significant scavenging effect on free radicals [13]. Therefore, by taking advantage of the antioxidant activity of the active ingredients in Echinacea, people have begun to add a certain proportion of Echinacea concentrate or extract to animal feed to increase the content of superoxide dismutase in animal serum, improve animal health and promote growth.

2 Antioxidant components of Echinacea extract

2.1 Polyphenols

The antioxidant activity of the polyphenols in Echinacea purpurea extract gradually increases with its molecular weight, and the strength of the antioxidant activity is positively correlated with its total phenol content. In addition, the antioxidant activity of Echinacea purpurea polyphenols is also closely related to the number and position of phenolic hydroxyl groups. It is currently one of the natural antioxidants that has been studied in depth [14, 15]. Flavonoids are a type of polyphenolic compound that have significant effects in terms of anti-oxidation and anti-aging [16]. The anti-oxidant activity of flavonoids is mainly manifested in the reduction of free radical production and scavenging of free radicals.

2.2 Active polysaccharides

Polysaccharides are polymeric sugar high-molecular carbohydrates formed by the polymerisation of 10 or more monosaccharides. Modern research has shown that polysaccharides can achieve antioxidant effects by directly scavenging active oxygen and complexing metal ions necessary for the production of active oxygen[17]. Research on Echinacea polysaccharides should focus on improving the extraction process to increase the yield and purity of its active ingredients. The structure-activity relationship and mechanism of action of active polysaccharide molecules should also be studied.

2.3 Alkaloids

Lloyd first reported in 1897 that Echinacea purpurea contains alkaloids. Alkaloids also have antioxidant effects, but the antioxidant effects of alkaloids in Echinacea purpurea need to be further studied.

3 Molecular mechanism of Echinacea purpurea's antioxidant properties

The mechanism of the antioxidant components in Echinacea purpurea extract is mainly that antioxidant molecules act on free radical-related enzymes, directly scavenging or inhibiting free radicals.

3.1 Antioxidant mechanism of action on free radical-related enzymes

There are various oxidases in living organisms that can induce the production of free radicals, such as lipoxygenase, P-450 enzymes, myeloperoxidase and cyclooxygenase. The greater the amount and activity of these oxidases, the greater the amount of free radicals produced by the body and the more serious the damage. Studies have shown that the active ingredients in some plant extracts can inhibit the production of free radicals at the source by inhibiting the activity of certain oxidases. Quercetin and curcumin, which are flavonoids, can reduce the activity of nitric oxide synthase and play an antioxidant role during ischemia-reperfusion injury [18]. Echinacea also contains flavonoids, which should theoretically have this effect, but further tests are needed to prove this.

Superoxide dismutase, catalase, glutathione peroxidase and peroxidase in the animal body have the functions of protecting, removing and repairing damage caused by excessive free radicals, thereby achieving self-protection of the animal body. The strength of their effects is positively correlated with the quantity and activity of the enzymes. Superoxide dismutase is the main scavenger of superoxide anions in the body. Superoxide dismutase catalytically breaks down superoxide anions into hydrogen peroxide, which is then converted into oxygen and water by catalase. Hydrogen peroxide can also be converted into water by catalase and reduced glutathione (GSH) through catalysis, while oxidized glutathione is also produced. Studies have found that the flavonoids in echinacea can enhance the activity of superoxide dismutase, glutathione peroxidase and catalase [19]. It can therefore be inferred that echinacea is effective in combating free radical production and damage in animal bodies.

3.2 Antioxidant action mechanism for direct scavenging or inhibiting free radicals

Studies have shown that the polyphenols contained in Echinacea purpurea (echinacoside, chlorogenic acid, chicoric acid, artichoke acid and caffeic acid) have strong antioxidant and free radical scavenging abilities in the body. Polyphenols protect the collagen in the skin from damage by scavenging reactive oxygen species and secondary free radicals with carbon, nitrogen and sulphur radicals. Polyphenols also inhibit the development of inflammation, lipid oxidation and the production of free radicals, and prevent the degradation of type III collagen caused by free radicals [20]. The main mechanism of action is that the active ingredients in the Echinacea purpurea extract act as electron or hydrogen proton donors, indirectly inhibiting free radicals or directly destroying them, in order to terminate the chain reaction of free radicals and exert their antioxidant function.

4 Outlook

In actual production, there are many reasons that can induce excessive oxidation in the animal body, such as insufficient intake of necessary substances in the feed or improper proportions, pathological factors, environmental factors, etc. [21]. Excessive oxidation can affect the animal's production performance, induce various diseases, and even cause death, resulting in serious economic losses [22]. Echinacea is a natural plant with immune-enhancing and antioxidant properties, and research, development and utilization of its antioxidant effects are of great significance. However, there is currently very little research on the mechanism of action of the active ingredients (antioxidant molecules) of Echinacea at home and abroad, so it is necessary to conduct in-depth research to provide a theoretical basis for the development and utilization of Echinacea.

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