Biological function of chlorogenic acid and its application in aquaculture
Introduction: Chlorogenic acid is a polyphenolic secondary metabolite that is widely present in plants. It has antibacterial, anti-inflammatory, antioxidant and other effects, and has a wide range of application prospects in the livestock and poultry breeding industry. This article mainly reviews the biological function of chlorogenic acid and its application in aquaculture. The full text has been published in the first issue of "Feed Industry" in 2019.
Chlorogenic acid (CGA) is a depsidic acid composed of caffeic acid and quinic acid in plants. It is widely found in dicotyledonous plants and ferns. Among them, Eucommia, coffee, honeysuckle, wild chrysanthemum, etc. High content of CGA, in addition, apples, carrots, kiwi fruit, wheat, potatoes and other vegetable and fruit crops also contain chlorogenic acid . Chlorogenic acid has various biological activities such as antibacterial, antiviral, antioxidant, anti-inflammatory, lowering blood lipid and blood sugar, and regulating immunity . At present, chlorogenic acid with multiple functions has become one of the research hotspots of natural products, and is widely used in food, medicine and other industries. However, its application in animal husbandry is relatively rare. This article mainly reviews the function of chlorogenic acid and its application in aquaculture, and provides a scientific basis and reference for the popularization and application of chlorogenic acid in aquaculture.
1. Physical and chemical properties of chlorogenic acid
Chlorogenic acid, also known as coffee tannin, is a polar organic acid with low stability and easy isomerization. It is mainly produced in plants through the shikimic acid pathway in aerobic respiration. The chlorogenic acid produced is usually Mixtures such as methyl chlorogenic acid, ethyl chlorogenic acid, monocaffeoylquinic acid. Its chemical name is 3-O-caffeic phthaloquinic acid, its molecular formula is C16H18O9, and its molecular weight is 354.30 . The solubility of chlorogenic acid is only 4% at room temperature, and the melting point is 208 °C. When the temperature is 110 °C, it will form an anhydrous compound. Its hemihydrate is white or light yellow needle-like crystals, which are easily soluble in organic solvents (such as ethanol). , acetone, methanol, etc.), slightly soluble in ethyl acetate, insoluble in benzene, ether and chloroform, etc.
2. The chlorogenic acid benefits
2.1 Antibacterial and antiviral
Chlorogenic acid is an important component of bactericidal drugs, which has a wide range of bacteriostatic or bactericidal effects, and can effectively inhibit or kill pathogenic bacteria such as Escherichia coli, Staphylococcus aureus, Shigella spp. On the one hand, chlorogenic acid can inhibit the activity of bacterial-related metabolic enzymes, affecting the digestion and absorption of nutrients by vegetative bacteria, thereby inhibiting the growth and reproduction of bacteria . On the other hand, increased membrane permeability is a major factor in the mechanism of antimicrobial activity, whereas chlorogenic acid, a polar organic acid, is able to bind to bacterial surfaces and increase the loss of cell integrity due to membrane permeability, The nucleotides, enzymes and nutrients in bacteria are leaked out, thereby inhibiting the growth of bacteria.
Current studies have shown that chlorogenic acid has inhibitory effects on viruses such as human immunodeficiency virus (HIV), adenovirus, hepatitis B virus, herpes simplex virus (HSV), and porcine reproductive and respiratory syndrome virus (PRRSV) . The antiviral mechanism of chlorogenic acid may be related to inhibiting the expression of viral nucleoprotein to form new virus particles and blocking the release and spread of progeny virus particles of infected cells. The virus mechanism is still unclear, and the specific mechanism of action still needs to be further explored .
Chlorogenic acid is a kind of high-efficiency natural antioxidant with phenolic hydroxyl groups. In complex reactions in the body, it can block the chain reaction of free radicals by forming stable semi-quinone free radicals, and at the same time, it can also reduce Fe3+ by itself. And scavenge chemical free radicals and reactive oxygen species to play an antioxidant role . The antioxidant mechanism of chlorogenic acid is mainly divided into three types: ①Hydrogen atom transfer mechanism (HAT), that is, free radicals abstract hydrogen atoms from the phenolic hydroxyl group of chlorogenic acid to form phenoxy radicals, which can pass through intramolecular hydrogen atoms. The keys are stable. ②Single electron accompanying proton transfer mechanism (SET), that is, when an electron transfer occurs to generate a positive ion radical, then a proton transfer is formed to complete the hydrogen extraction process, forming a phenoxy radical stabilized by intramolecular resonance, blocking or slowing down the free radical base chain reaction . (3) Metal ion complexation mechanism. Free metal ions in animals and plants can generate hydroxyl radicals through Fenton reaction, causing damage to the body, while chlorogenic acid can complex powerful metal ions to reduce the production of hydroxyl radicals . In addition to its own antioxidant effect, chlorogenic acid also has synergistic antioxidant effect. It has good synergistic antioxidant effect with α-tocopherol, β-carotene, rutin, etc. The soluble free radical system is better than the water-soluble free radical system . At present, the mechanism of synergistic antioxidant effect of chlorogenic acid is mainly divided into five types: phenolic hydroxyl regeneration theory, oxidative coupling theory, oxygen absorption mechanism, formation of new antioxidant theory, interface theory, but these theoretical studies have not been in-depth, specific The mechanism of action needs further study.
2.3 Regulate glucose and lipid metabolism
The body's glucose metabolism is inseparable from the body's health. When the body's glucose metabolism is disordered, it is easy to cause metabolic syndrome such as diabetes. Peng Bingjie et al. studied the effect of chlorogenic acid on glucose metabolism in skeletal muscle of high-fat-fed rats and found that chlorogenic acid can regulate the expression of glucose metabolism-related mRMA and insulin sensitivity in PI3K/Akt pathway and AMPK pathway. Improves glucose metabolism in skeletal muscle and significantly reduces body weight gain in rats. With the advancement of technology, studies have found that the mechanisms of chlorogenic acid regulating the body's glucose metabolism mainly include : inhibiting the activity of related enzymes in the body's glucose metabolism pathway; regulating the secretion of hormones related to glucose metabolism in the body, improving insulin resistance; inhibiting glucose metabolism Formation of end-products of acetylation (AGEs); activation of AMP-activated protein kinase (AMPK) and increased transfer of glucose transporter (GLUT-4), thereby increasing glucose transport.
Chlorogenic acid can not only regulate the body's blood sugar metabolism, but also has a certain regulatory effect on the body's fat metabolism. In a large number of human experiments and obese animal models, chlorogenic acid can improve the body's blood lipid level and inhibit the increase of liver fat content. Studies have shown that the mechanism of chlorogenic acid regulating fat metabolism is mainly: inhibiting the activities of related metabolic enzymes in fat metabolism pathways; affecting the expression of key enzyme genes in fat synthesis, catabolism and fatty acid oxidation; regulating the secretion of adipokines in adipose tissue; increasing Peroxisome proliferator-activated receptors (PPARs) and decreased hepatic X receptor (LXR) expression. Current studies have found that there are three main subtypes of PPARs: PPARα, PPARγ, and PPARβ. PPARα can induce the expression of fatty acid transporter (FATP) and fatty acid transferase (FAT), and play a very important role in fat β oxidation. PPARγ plays a very important role in the mutual transformation of brown fat cells and white cells, and it can also enhance the body's sensitivity to insulin. The liver X receptor alpha (LXRα) in LXR can directly activate genes encoding fatty acid synthase (FAS) and lipase acetyl-CoA carboxylase (ACC) to regulate fatty acid and triglyceride synthesis.
Inflammation is a physiological response to tissue damage caused by exogenous or endogenous sources. Exogenous inducers include pathogen-associated molecular patterns, virulence factors, allergens, foreign bodies, and toxic compounds, and endogenous inducers of inflammation result from cellular signaling. Chlorogenic acid has shown good anti-inflammatory effects in different animal and human inflammation models. Studies have found that chlorogenic acid can down-regulate pro-inflammatory cytokines [interleukin-6 (IL-6)] by inhibiting the activity of two signaling pathways, nuclear transcription factor kappa B (NF-κB) and Toll-like receptor 4 (TLR4). , tumor necrosis factor-α (TNF-α)], chemokines [monocyte chemoattractant protein-1 (MCP-1), interleukin-8 (IL-8)] and cell adhesion molecules [intercellular adhesion The expression of factors such as molecule-1 (IVAM-1), vascular cell adhesion molecule-1 (VCAM-1)], thereby exerting anti-inflammatory effect and relieving body damage.
3. Applied research in aquaculture
3.1 Application in pig industry
As a green and pollution-free plant extract, chlorogenic acid has achieved good application results in the pig industry. Liu Ying et al. found that adding chlorogenic acid to the diet of weaned piglets could improve their growth performance and antioxidant capacity. Huang Shaowen et al. studied the effects of chlorogenic acid and vitamin E on reproduction and antioxidant performance of sows and found that dietary supplementation of 120 UI/kg vitamin E and 300 mg/kg chlorogenic acid could significantly improve the birth rate of piglets. weight, enhance the antioxidant capacity of piglets. Long Cimin showed that adding 800 g/t of chlorogenic acid to the diet can significantly reduce the feed-to-grill ratio (F/G) of fattening pigs and improve the carcass quality and pork quality. Zhou Yan reported that adding Eucommia ulmoides leaf polyphenols rich in chlorogenic acid into the diet of finishing pigs can significantly increase the final weight and average daily weight gain, significantly reduce the feed-to-meat ratio, improve the muscle quality of the longissimus dorsi, regulate Fat metabolism. Chen Peng et al. found that Eucommia ulmoides extract containing chlorogenic acid could significantly increase the average daily weight gain of weaned piglets, improve growth performance, and significantly reduce serum alanine aminotransferase (ALT) and alkaline phosphatase (AKP) activities. Relieve body inflammation. Liu Zexue et al. showed that chlorogenic acid can significantly reduce the feed-to-weight ratio and diarrhea rate of piglets, reduce the cost per kilogram of weight gain, and improve the growth performance and economic benefits of piglets. Lai Xing reported that adding chlorogenic acid to the diets of weaned piglets can significantly increase the final weight, average daily gain, and average feed intake, significantly reduce the ratio of feed to meat, promote the development of immune organs, and improve immunity. .
3.2 Application in poultry industry
Chen Yumin et al. found that adding Eucommia ulmoides extract chlorogenic acid to the diet of Aiba Yijia chickens can increase daily weight gain, reduce the ratio of feed to meat, and improve immune function. Lv Wuxing et al. studied the effects of Eucommia ulmoides extracts on the production performance and intestinal microbial flora of Sanhuang chickens and found that Eucommia ulmoides extracts containing chlorogenic acid could significantly increase the average daily weight gain of Sanhuang chickens and significantly reduce the E. coli in the cecum. quantity. Zhang Junmin et al showed that adding Eucommia ulmoides extract containing chlorogenic acid could increase the slaughter rate, improve growth performance and meat quality. Research by Wang Rui et al. showed that adding chlorogenic acid-containing extract to Gushi chicken feed can improve its growth performance and improve its slaughter performance. Niu Ruiping pointed out that adding chlorogenic acid-rich dandelion extract to the diet of broilers can improve their growth performance and immune function.
3.3 Application in fisheries
Li Naishun et al.studied the effects of chlorogenic acid on the growth, non-specific immune indexes and muscle quality of grass carp fingerlings and found that the weight gain rate of 0.04% chlorogenic acid was significantly increased, the feed coefficient was significantly reduced, and the liver superoxide The dismutase activity was significantly increased, and the isoleucine, histidine, valine, essential amino acids, total amino acids, and crude protein content in the muscles were significantly increased. Zhang Chun et al showed that dietary supplementation of 200 mg/kg chlorogenic acid could significantly increase the relative weight gain rate, plasma lysozyme activity and catalase (CAT) activity of Jian carp, and significantly reduce malondialdehyde ( MDA) content, thereby improving the growth performance, immunity and antioxidant capacity of Jian carp. Song Wenhua et al. found that adding 0.08% chlorogenic acid to the diet of juvenile grass carp could significantly increase the end weight, liver-to-body ratio, and alkaline phosphatase activity (AKP) of juvenile grass carp. Chen Xiaoan research shows that adding 200 mg/kg chlorogenic acid to the herring diet can significantly reduce the feed coefficient and improve the growth performance, significantly improve the spleen index, muscle protein level, arginine content, and then promote immune function growth and growth. Improve meat quality. Wen Anxiang et al. studied the effect of different doses of chlorogenic acid on the production performance and antioxidant capacity of Chinese soft-shelled turtle, and found that adding 200 mg/kg could significantly improve the growth, skirt and muscle collagen content, antioxidant capacity of Chinese soft-shelled turtle. Oxidative capacity, significantly lowers muscle cholesterol levels.
Chlorogenic acid is a natural compound with various biologically active functions and is widely used in various industries. my country has abundant plant resources that can extract chlorogenic acid, but there are still many problems in domestic research on the extraction, synthesis and activity of chlorogenic acid, which hinder its utilization. First, the mechanism of action of chlorogenic acid is not yet clear; second, the extraction and synthesis technology is not yet mature, and the industrial chain has not been formed; third, the production cost is high, and the economic benefit is not high; fourth, the application research in the aquaculture industry is less. Therefore, we still need to do a lot of research on the application of chlorogenic acid, understand its mechanism of action from the molecular level, improve its extraction and synthesis process, reduce its production cost, and tap its application potential.