What Is the Use and Benefit of Echinacea Extract Chicoric Acid?

Problems such as antibiotic resistance, drug residues in animal products, and environmental pollution have seriously affected the sustainable development of the livestock industry. Therefore, the discovery of natural feed additives with antibiotic-replacement properties from natural plants has become a research hotspot in animal husbandry in recent years [1]. Cichoric acid (CA), as an important polyphenolic compound, is widely distributed in plants and is mainly found in ferns [2]. Studies have shown that cichoric acid not only has antioxidant, anti-inflammatory, and immunity-enhancing effects[3], but also has the potential to intervene in metabolic diseases such as obesity[4]. Cichoric acid can promote animal growth, effectively enhance animal immunity, and has anti-inflammatory and anti-diarrhea effects. This paper reviews the molecular structure, physical and chemical properties, stability and biological activity of chicoric acid, and describes the application of the Echinacea plant extract chicoric acid in hypoxic environments to improve animal production, with the aim of providing a reference for the in-depth research, development and utilization of chicoric acid in animal production.

1 Structure and properties of chicoric acid

1.1 Molecular structure

Cichoric acid was first isolated and identified from the leaves of Cichorium intybus L. by Scarpati in 1958 [5]. Because chicoric acid contains two chiral carbon atoms in its structure, there are three stereoisomers: L-chicoric acid, D-chicoric acid and racemic-chicoric acid [6-8]. The chemical structures of the stereoisomers of chicoric acid are shown in Figure 1.

1.2 Physical and chemical properties

The melting point of chicoric acid crystals is 206 °C, and they are needle-like in shape [9]. Chicoric acid reacts violently with ferric chloride to form a greenish-black complex; it reacts with alkalis to turn yellow, and the color reaction is related to the air conditions [9-10]. Its color reaction can be used to conveniently detect chicoric acid.

1.3 Stability

Cichoric acid belongs to the phenolic compounds, and its chemical stability is greatly affected by the ambient temperature and pH value. Studies have shown that the chemical properties of cichoric acid are most stable at a pH of 3 [11]. Therefore, the addition of acidic substances such as citric acid, malic acid and hibiscus during the extraction of cichoric acid can significantly improve the stability of cichoric acid and increase the success rate of extraction. The content of chicoric acid in fruit juice drinks did not change significantly after 3 months of storage at 4 °C. The effect of different food systems on the stability of chicoric acid varies. Overall, food systems can maintain the stability of chicoric acid to a certain extent and protect it from degradation [12].

2 Biological activity of chicoric acid

2.1 Antioxidant

As a phenolic compound, chicoric acid has a high oxygen radical scavenging capacity. Cichoric acid can promote the production of antioxidant enzymes in different cells, reduce intracellular ROS levels, protect cells from free radical-induced cytotoxicity, exert pharmacological effects against oxidative damage, and exert antioxidant activity by mediating the Keap1/Nrf2, NF-κB, and MAPK oxidative stress pathways.

Studies have shown that 50% ethanol-treated Echinacea purpurea flower extract (56.03 mg/g) has good antioxidant properties [13]. Jiang Ling [14] found that Echinacea purpurea L. extract has strong free radical scavenging and hydroxyl radical capacity, and can inhibit lipid peroxidation. Chicoric acid extract can significantly inhibit the oxidation and rancidity of lard and rapeseed oil. Chicoric acid has a stronger antioxidant effect on lard than on rapeseed oil, and the higher the concentration of chicoric acid, the better the antioxidant effect on lard and rapeseed oil.

Studies have quantitatively evaluated the free radical scavenging ability of caffeic acid, chlorogenic acid, tartaric acid and chicoric acid in Echinacea purpurea root and its derivatives. For example, chicoric acid has a strong scavenging effect on DDPH free radicals (EC50=6.6 microM) [15] and OH free radicals [16], while the effect of caffeic acid is relatively poor (EC50=20.5 microM). The average EC50 values of Echinacea purpurea, E. palida and E. angustifolia were 134, 167 and 231 g/L respectively [17], and the antioxidant effect of its extract, echinacoside, is stronger than that of caffeic acid, chlorogenic acid and tartaric acid [15-17].

Cichoric acid alleviates N-methyl-d-aspartate-induced retinal damage in rats by reducing the production of reactive oxygen species and inhibiting lipid peroxidation [18]. Cichoric acid can reduce the production of ROS and MDA in a H2O2-induced oxidative damage model in zebrafish larvae, activate the antioxidant enzymes SOD and GSH-Px, and protect against liver damage through the antioxidant effects of cichoric acid [19]. Chicoric acid can mediate the upregulation of Nrf2 signaling in the Keap1/Nrf2 transcriptional pathway, transcriptionally regulate the downstream expression of antioxidant enzymes in cells (including HO-1 and NQO-1), and reduce oxidative stress induced by LPS in mice [19-22].

Chicoric acid exerts an antioxidant effect by regulating nuclear factor erythroid 2-related factor 2 (Nrf2) and peroxisome proliferator-activated receptor gamma coactivator 1alpha (PGC-1alpha) [21,23]. Activation of Nrf-2 and PGC-1a suppresses ROS-induced cytotoxicity by upregulating genes involved in antioxidant responses and enhancing the mitochondrial antioxidant defense system [17,20,24]. It alleviates Fe2+-induced liposome oxidation damage and inhibits the peroxidation of linoleic acid lipids [20]. Chicoric acid plays a preventive role in the improvement of oxidative stress and inflammation through the AMPK/Nrf2/NF-kB signaling pathway, and maintains the biological activity of the intestinal microbiota in mice with HFD-induced NAFLD [25]. Chicoric acid, as an AMPK activator, can downregulate the protein level of NF-κB and upregulate the nuclear protein level of Nrf2 in mice on a high-fat diet. It also reduces the level of malondialdehyde (MDA) in the serum of HFD mice and increases the activity of superoxide dismutase (SOD) in the serum [23,26].

2.2 Anti-inflammatory

chicoric acid can improve lipopolysaccharide (LPS)-induced inflammation. The reduction in inflammation is associated with downregulation of nuclear factor κB (NF-κB) and tumor necrosis factor-α (TNF-α) [21,27-29], which are two major regulators of the inflammatory response [30-31]. Chicoric acid also exerts an anti-inflammatory effect by down-regulating nitric oxide synthase, cyclooxygenase 2 (COX-2), prostaglandin E2 (PGE2), interleukin 1b (IL-1b), IL-12 and IL-18 pro-inflammatory factors [32-34].

Li et al. [35] investigated the role of chicoric acid in d-galactosamine (d-GalN)-induced acute liver injury in mice, and showed that chicoric acid alleviates inflammation and reduces d-GalN-induced mortality by inhibiting mitogen-activated protein kinases (MAPKs) and nuclear factor-κB (NF-κB). Chicoric acid downregulates the expression of NF-κB/p65 and p38/MAPK proteins, inhibits NF-κB/p65 and p38/MAPK from entering the nucleus and binding to the corresponding target sequences, and exerts an anti-inflammatory effect on LPS-treated rats [14]. Cichoric acid can significantly inhibit the overproduction of inflammatory cytokines IL-1β, TNF-α and PGE2 in rats with collagen-induced arthritis (CIA), and can also significantly inhibit the levels of NF-κB, p65, TNF-α and COX-2 in the synovial tissue of CIA rats [32].

2.3 Improves immunity

Echinacea is native to the United States and southern Canada, and is a well-known “immune” plant[36-37]. The species Echinacea angustifolia, Echinacea palida and Echinacea purpurea have a long history of use as immunomodulators and immunostimulants[37].

Echinacoside can effectively regulate the immune response of macrophages in vitro, significantly reducing the levels of NF-κB, TNF-α and NO in mouse macrophages stimulated by lipopolysaccharide (LPS) [29]. Echinacoside treats chronically stressed mice by regulating norepinephrine (NA), dopamine (DA) and serotonin (5-HT). Cichoric acid regulates stress by elevating plasma corticosterone levels and significantly reducing depleted ascorbic acid, cholesterol, and corticosterone levels in the adrenal gland, promoting the immune response of stressed mice [38].

2.4 Regulates fat metabolism

Cichoric acid can reduce weight gain in mice induced by a high-fat diet [25, 32]. It prevents lipid metabolic disorders in obese patients by improving cell morphology and liver lipid levels [39]. Chicoric acid can inhibit the expression of peroxisome proliferator-activated receptor c and CCAAT/enhancer binding protein a, which are related to fibrosis, apoptosis and fat production in mice on a methionine and choline deficient (MCD) diet [33]. High-fat diet (HFD)-fed C57BL/6 mice supplemented with chicoric acid reduced body weight and white adipose tissue weight, alleviated hyperglycemia and dyslipidemia, and reduced liver steatosis in HFD-fed mice [25,39]. Cichoric acid can prevent the histological damage (steatosis-inflammation-fibrosis) caused by early and late diabetes in rats, as well as the downregulation of SREBP-1c and PPARα genes after liver steatosis is induced [39]. Cichoric acid can significantly change the morphology and viability of 3T3-L1 preadipocytes [40-41]. Chicoric acid induces the regulation of ROS through the mitochondrial pathway, which mediates the inhibition of PGC-1α and FoxO4 protein expression in 3T3-L1 pre-adipocytes in the PI3K/Akt signaling pathway [40]. The p38-mitogen-activated protein kinase (MAPK) signaling pathway inhibits the viability of 3T3-L1 pre-adipocytes [41], and induces mitochondrial dysfunction in 3T3-L1 pre-adipocytes in a concentration- and time-dependent manner, which in turn leads to apoptosis [40-41].

2.5 Liver protection

It has been found that chicoric acid can reduce the accumulation of triglycerides (TG) in the liver of rats caused by acute alcohol intake [39,42], inhibits the increase in ROS levels and the expression of TNF-α and nitric oxide synthase (iNOS) mRNA in RAW264.7 macrophages treated with LPS in the liver, and interferes with iNOS-dependent signaling to reduce acute alcoholic liver injury [42]. Studies have also shown that chicoric acid protects the liver from high-fat or alcohol-induced fat accumulation and liver steatosis by reducing the liver Bax/Bcl-2 ratio and inhibiting fatty acid synthase and pro-inflammatory cytokines (including TNF-α, IL-6, COX-2 and JNK) [32].

Glucose metabolism is the primary metabolic pathway that provides energy for the body, and its regulation is controlled by the combined action of multiple signaling pathways. Disorders of glucose metabolism can lead to systemic chronic complications and damage to various organs and tissues in the body. Chicoric acid is a phenolic acid that can regulate glucose metabolism disorders and has the effect of lowering blood sugar [43]. 50% ethanol Echinacea purpurea flower extract chicoric acid (IC50 is 0.28 g/L) inhibits α-glucosidase associated with type 2 diabetes in a concentration-dependent manner, and has good potential for controlling hyperglycemia and hypertension [13]. Cichoric acid can alleviate weight loss in diabetic mice, increase the exercise speed and exercise vitality of mice, lower blood glucose, increase fasting insulin concentration, down-regulate the insulin resistance index, and improve insulin sensitivity and glucose sensitivity. Cichoric acid alleviates apoptosis of islet tissue induced by streptozotocin (MLD-STZ) by inhibiting mitochondrial apoptosis signal transduction, mitigates islet tissue apoptosis induced by streptozotocin (MLD-STZ), and through the insulin signaling pathway, affects cellular glucose uptake and glycogen synthesis capacity, alleviates functional damage, improves insulin resistance in adipocytes, and has the potential to regulate body glucose homeostasis and improve diabetes and its complications [43-44].

3 Application of chicoric acid in animal production

3.1 Application of chicoric acid in poultry production

Wang Shuqin et al. [45] showed that Echinacea purpurea extract (cichoric acid) can enhance the humoral and cellular immunity of broilers, increase their Newcastle disease antibody and natural killer (NK) cell activity, enhance the antiviral and lysing effects of NK cells, and increase the immune levels of broiler red blood cells. Han Ruochan et al. [46] showed that encapsulated chicoric acid can enhance the immunity of laying hens and has an immunological synergistic effect on the immune effect of the Newcastle disease vaccine.

Fu Haining et al. [47] showed through experiments that the high-dose and medium-dose groups of Echinacea purpurea extract can significantly increase the chicken serum antibody titer, promote the proliferation of peripheral blood lymphocytes, and improve the immune organ protection rate. To a certain extent, it has the biological effect of increasing weight gain and reducing feed conversion ratio, indicating that Echinacea purpurea extract can enhance the immune effect of the chicken new crown vaccine. Hao Zhihui et al. [48] added Echinacea purpurea extract to the diet of broiler chickens, and the results showed that Echinacea purpurea extract can significantly increase the thymus index and bursa index of broiler chickens, and improve the antioxidant capacity and immune capacity of broiler chickens by increasing the white blood cell count, red blood cell count and red blood cell volume, and enhance the antibody titer against Newcastle disease. Niu Xiaofei et al. [49] found that Echinacea purpurea extract can significantly increase the antibody titer of fowlpox virus in chicken peripheral blood, improve the production performance of broilers, and the most suitable dosage is 0.5 mL/bird.

3.2 Application of echinacoside in the production of aquatic animals

Tang Xuelian et al. [50] showed that adding echinacea extracts with different concentrations of chicoric acid to the feed of Pengze crucian carp (Carassius auratus var. Pengze) can significantly reduce the hydroxyl free radicals and malondialdehyde content in the carp serum, increase the activity of superoxide dismutase, catalase and glutathione reductase, significantly improving Pengzeqing's antioxidant capacity. Ren Yonglin [51] added 0.2% Echinacea purpurea extract to carp bait, and found that it could reduce the bait factor to varying degrees, increase the weight gain and yield of carp. Echinacea purpurea extract can effectively improve the growth performance, immune function and resistance to Aeromonas hydrophila of carp. Echinacea extract can therefore be used as an excellent herbal immune enhancer in aquaculture.

3.3 Effect of echinacoside on animals in a hypoxic environment

Wu Hua's[52] research showed that Echinacea extract (echinacoside) at different concentrations can be used as a non-specific immune stimulant to promote the proliferation of peripheral blood mononuclear cells and inhibit the expression of apoptosis factors, enhance the metabolism of nutrients in grazing yaks, improve mitochondrial activity in grazing yaks under hypoxic conditions, enhance the yak's adaptability to low oxygen at high altitudes, and improve immune function. Li Chunsheng's [53] research shows that early weaned calves fed a certain dose of Echinacea purpurea extract (cichoric acid) after supplementary feeding can significantly increase the lymphocyte transformation rate of calves and improve their immune function. It also has a certain effect in preventing and treating yak calf diarrhea. Research by Asun Xian et al. [54] showed that adding chicoric acid during the perinatal period of grazing yaks can help to remove free radicals in the yak's body, reduce lipid peroxidation in the calf's body after birth, improve the body's oxidative state under oxidative stress, and improve the antioxidant capacity of grazing yaks during the perinatal period.

Wang Xiaoqin et al. [55] found that chicoric acid can significantly improve the total antioxidant capacity of the serum of grazing yaks and significantly reduce the degree of lipid oxidation in the serum, indicating that the chicoric acid in the Echinacea purpurea extract can to some extent improve the antioxidant capacity of grazing yaks. Wu Hua et al. [56] fed yaks with different doses of chicoric acid, which was shown to significantly increase the content of white blood cells, red blood cells and hemoglobin in yak blood, improve the yak's adaptability to high altitude and low oxygen environments, and play a positive role in improving immunity and resisting inflammatory reactions. Liu Jiahua et al. [57] fed SD rats with different concentrations of chicoric acid under hypoxic conditions. The results showed that chicoric acid could increase the oxygen uptake and oxygen carrying capacity of SD rat blood, regulate acid-base balance, improve vascular damage, promote cardiac contraction and relieve myocardial damage, thereby enhancing the SD rat's adaptability to the hypoxic environment at high altitudes, and the effect is optimal in the high-dose group.

4 Conclusion

Echinacea purpurea extract chicoric acid, as a natural green feed additive, has antioxidant, anti-inflammatory, and immune-enhancing effects, and has the potential to intervene in metabolic diseases such as obesity. Follow-up studies have been carried out on the mechanism of Echinacea purpurea extract-chicoric acid in yak low-oxygen adaptation and oxidative stress, aiming to explore the effects of chicoric acid as a natural feed additive on the growth performance, antioxidant capacity or immune function of livestock and poultry under hypoxic conditions, under the premise of replacing antibiotics. Chicoric acid has broad prospects as a natural antioxidant and green feed additive that promotes growth and prevents disease, and provides a reference for the development and utilization of chicoric acid as a feed additive in high-altitude hypoxic areas.

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