What Is the Difference Between Cysteine and Glutathione?

Glutathione (glutathione, r-glutamyl cysteingl + glycine, GSH) is a tripeptide containing a -amide bond and a thiol group. It consists of glutamic acid, cysteine, and glycine. It exists in almost every body Cell ^[1] .

Glutathione can help maintain normal immune system function, and has antioxidant and integrated detoxification effects ^[1] . The sulfhydryl group on cysteine is its active group (so often abbreviated as G-SH), which is easy to combine with certain drugs, toxins, etc., making it have an integrated detoxification effect ^[2] . Glutathione can be used not only in medicine, but also as a base for functional foods, and is widely used in functional foods such as delaying aging, enhancing immunity, and anti-tumor. ^[2]

Glutathione comes in two forms: reduced (G-SH) and oxidized (GSSG). Under physiological conditions, most of them are reduced glutathione. Glutathione reductase can catalyze the interconversion between the two types, and the coenzyme of this enzyme can also provide NADPH for the pentose phosphate bypass metabolism ^[2] .

Chinese name: Glutathione
Foreign name: glutathione
Abbreviation: GSH

basic component: Cysteine, glycine, glutamic acid
Main effect: Antioxidant, integrated detoxification, whitening, blemish
Storage method: Cool and dry place

Introduction to glutathione

Glutathione (glutathione, GSH) is a tripeptide that contains sulfhydryl, which is a combination of glutamic acid, cysteine, and glycine. It has antioxidant and integrated detoxification effects. The thiol group on cysteine is a glutathione active group (so glutathione is often abbreviated as G-SH), which is easy to interact with certain drugs (such as paracetamol), toxins (such as free radicals, iodoacetic acid, mustard gas, Lead, mercury, arsenic and other heavy metals), and has an integrated detoxification effect. Therefore, glutathione (especially glutathione in liver cells) can participate in biotransformation, thereby converting harmful poisons in the body into harmless substances and excreting them. Glutathione can also help maintain normal immune system function ^[3] .

Glutathione content distribution

Glutathione is widely present in animals and plants, and plays an important role in the body. It is high in baker's yeast, wheat germ, and animal liver, reaching 100 to 1000 mg / 100g, 26 to 34 mg / 100g in human blood, 58 to 73 mg / 100g in chicken blood, and pig blood. 10 ~ 15 mg / 100g, higher in tomatoes, pineapples, cucumbers (12 ~ 33 mg / 100g), but lower in sweet potatoes, mung bean sprouts, onions, and mushrooms (0.06 ~ 0.7 mg / 100g) ^{[ 4]} .

Glutathione physiological function

Detoxification effect: Combined with poison or drug to eliminate its toxic effect ^[5] ;
Participate in redox reactions: as an important reducing agent, participate in a variety of redox reactions in the body ^[5] ;
Protect the activity of thiolase: keep the active group of thiolase, SH, in a reduced state ^[5] ;
Maintain the stability of the red blood cell membrane structure: Eliminate the damaging effect of oxidants on the red blood cell membrane structure ^[5] .

Glutathione mechanism of action

GSH, as an important regulatory metabolic substance in the cell, is not only the cofactor of glyceraldehyde phosphate dehydrogenase, but also the coenzyme of glyoxalase and triose dehydrogenase. It participates in the tricarboxylic acid cycle and sugar metabolism in the body. Can activate a variety of enzymes, such as sulfhydryl (SH) enzyme-coenzyme, etc., thereby promoting sugar, fat and protein metabolism. The GSH molecule is characterized by active thiol groups (-SH), which is the most important functional group. It can participate in a variety of important biochemical reactions in the body, protect important thiol groups in the body from being oxidized and inactivated, and ensure energy metabolism and cell utilization. At the same time, it can directly reduce free radicals to acidic substances through the combination of thiol groups with free radicals in the body, thereby accelerating the excretion of free radicals and combating the damage of free radicals to important organs. Haddad et al. Found that GSH is involved in the regulation of lipopolysaccharide-induced cytokine transcription and the regulation of I-KB / NF-KB signaling pathways. Armstrong et al. Found that a decrease in GSH content is a potential early activation signal for apoptosis, and subsequent oxygen free radicals promote cell apoptosis ^[6] .

Main applications of glutathione

Glutathione Clinical Drug

Glutathione drugs are widely used in clinical practice. In addition to using its thiol group to chelate toxins such as heavy metals, fluorides, and mustard gas, it is also used in hepatitis, hemolytic diseases, keratitis, cataracts, and retinal diseases. Adjuvant treatment drugs. In recent years, Western scientists, especially Japanese scholars, have discovered that glutathione has the function of suppressing HIV ^[7] .

The latest research also shows that GSH can correct the imbalance of acetylcholine and cholinesterase and play an anti-allergic effect. It can also prevent skin aging and pigmentation, reduce the formation of melanin, improve the skin's antioxidant capacity and make the skin shiny. GSH also has a good effect in treating corneal disease and improving sexual function ^[7] .

Glutathione antioxidant effect

As an important antioxidant in the body, glutathione can scavenge free radicals in the body; because GSH itself is susceptible to oxidation by certain substances, it can protect the thiol groups in many proteins and enzymes in the body from being harmful The substance is oxidized to ensure the normal functioning of molecular physiological functions such as proteins and enzymes. The content of glutathione in human red blood cells is large, which is of great significance for protecting the thiol group of proteins on the red blood cell membrane and preventing hemolysis ^[7] .

Glutathione food additive

Adding glutathione to food can have unexpected effects:

1. It can be added to the noodle products to reduce it. It not only shortens the time for making bread to one-half or one-third of the original, greatly improves labor conditions, and plays a role of strengthening food nutrition and other functions ^[8] .

2. Adding it to yogurt and infant food is equivalent to vitamin C, which can act as a stabilizer ^[8] .

3. Mixing it into fish cake can prevent the color from deepening ^[8] .

4, added to meat products and cheese and other foods, with the effect of strengthening the flavor ^[8] .

Glutathione detection

There are many methods for detecting glutathione. The commonly used methods are iodometric method , DTNB (Ellman reagent) method , sodium nitrosyl ferricyanide method , fluorescence method , tetraoxopyrimidine method , and high performance liquid chromatography (HPLC). The above methods have their own advantages. In the detection of GSH content, a suitable, sensitive and accurate detection method can be selected according to the actual situation ^[9] .

DTNB Glutathione DTNB colorimetry

Principle: DTNB reacts with the thiol group of glutathione to produce yellow 5-thio- 2 -nitrobenzoic acid, which has a maximum absorption peak at a wavelength of 412 nm, while DTNB has almost no absorption peak above 400 nm. Add a small amount of DTNB to the glutathione-containing sample, measure the absorption value at 412 nm, and then determine the glutathione content based on the value of the absorption value ^[9] .

Method steps:

1. Preparation of DTNB stock solution: 0.01 mol / L DTNB was dissolved in 0.05 mol / L phosphate buffer solution (pH 7.0) to form DTNB stock solution ^[9] .

2. Preparation of DTNB analysis solution: Dilute the DTNB storage solution 100 times with Tris-HCl buffer solution of pH 8.0 at 0.5 mol / L, and prepare a DTNB analysis solution. Keep it in the dark, and it is currently used ^[9] .

3. Operation steps: Take 0.5 mL of glutathione standard solution or sample solution (0.1 ~ 3.0 mol / L), add it to 1.5 mL of NaOH solution with a concentration of 0.15 mol / L, and then add 3% formaldehyde 05 mL of the solution was reacted at pH 8.0 and 25 ° C for 2 minutes. After the reaction was completed, 0.5 mL of the reaction solution was added to the DTNB analysis solution, and the reaction was performed at 25 ° C for 5 minutes. The absorption value was measured at a wavelength of 412 nm. According to the absorbance of the two, calculate the difference and substitute it into the standard curve to calculate the glutathione content ^[9] .

Glutathione iodine assay

Principle: Use the reducing ability of glutathione to react with potassium iodate. When glutathione is completely reacted, potassium iodate will oxidize potassium iodide to iodine, and iodine will turn the starch indicator blue, which is the end point of titration ^9] .

Operation steps : accurately weigh 0.05 mg of glutathione sample, put it into a 10 mL beaker, dissolve it with 2% HPO ₃ , transfer it to a 100 mL volumetric flask, and make up to 100 mL with water. Pipette 5 mL of the above solution into a 100 mL Erlenmeyer flask, add 5 mL of 2% HPO ₃ solution to make it 10 mL, and then add 1 mL of 5% potassium iodide and 2 drops of starch indicator. Using 0.001 mol / L potassium iodate titration to consume 0.001 mol / L potassium iodate is consistent with the theoretical value of 2.445 mL, the glutathione content in the finished product is 100% ^[9] .

Calculation formula:

In the formula, V-volume (mL) of 0.001 mol / L potassium iodate consumed, 2.445-100% volume (mL) should be consumed ^[9] .

Glutathione high performance liquid chromatography

Principle : High performance liquid chromatography is a process of continuous separation due to differences in the partition coefficient, affinity, molecular size, and adsorption capacity of the solute between the same phase and the mobile phase ^[9] .

Operation steps :

Chromatographic conditions

Column: Kromasil C18 (4.6 mm × 250 mm, 5 m) ^[9] .

Mobile phase: mixed solution of sodium dihydrogen phosphate and sodium octane sulfonate (3.0 g of sodium dihydrogen phosphate, 1.0 g of sodium octane sulfonate, dissolve in water and make up to 500 mL, adjust the solution pH to 3 with phosphoric acid): acetonitrile = 96: 4 (volume ratio) ^[9] .

Detection wavelength: 210 nm, flow rate 0.8 mL / min, column temperature 30 ° C, and injection volume 10 L ^[9] .

make standard solution

Accurately weigh an appropriate amount of glutathione standard, dissolve it in a volumetric flask with deionized water, mix evenly and make up to a volume of 25 g / mL, 50 g / mL, 100 Vg / mL, 200 g / mL, 400 g / mL, 800 g / mL series concentration sample solution, as the standard solution ^[9] .

sample preparation

Accurately weigh the glutathione sample, add deionized water and mix well to make a sample solution with a concentration of 25 ~ 800 g / mL as the analysis solution ^[9] .

Draw standard curve

The prepared glutathione standard solution was pipetted for 10 L respectively for determination. The standard curve was drawn based on the concentration and peak area of glutathione production technology, and the regression equation of the curve was obtained according to the standard curve. The change in the peak area should be linear with the mass concentration of glutathione, and its fit should be above 0.9995 ^[9] .

Determination of samples

Take 10 L of glutathione sample analysis solution and measure it by high performance liquid chromatography. The peak area of the sample solution is obtained, and the glutathione content is calculated according to the regression equation ^[9] .

Glutathione Drug Information

Glutathione trade name

Artmore Moran, Ting Nuo, Sontex, Tate, Guradin ^[10]

Glutathione preparation specifications

Tablets: 0.1 g; powder injections: 0.3 g, 0.6 g ^[10] .

Glutathione pharmacological action

Glutathione is a tripeptide compound containing a thiol group, which has important physiological activities such as activating the redox system, activating enzymes, and detoxifying the body. Glutathione exists in reduced and oxidized forms in the body. Its active ingredient is reduced glutathione, which participates in the tricarboxylic acid cycle and sugar metabolism in the body, promotes high energy production in the body, and acts as a coenzyme. Reduced glutathione is the co-group of glyceraldehyde phosphate deoxygenase, and also the coenzyme of glyoxalase and triose phosphate deaminase. Reduced glutathione can activate SH enzymes in the body, promote the metabolism of carbohydrates, fats and proteins to regulate the metabolic process of cell membranes. Reduced glutathione can combine with a variety of exogenous and endogenous toxic substances to produce attenuating substances ^[10] .

Glutathione indication

This product is used for adjuvant treatment of chronic liver diseases. Including liver damage caused by virality, drug toxicity, and alcohol toxicity. It can also be used for poisoning of organophosphorus, amino or nitro aromatic compounds ^[10] .

Glutathione dosage

oral

It is placed between the buccal mucosa and the gums. Adults take 0.4 g (4 tablets) 3 times a day, usually a course of treatment every 12 weeks ^[10] .

IM and IV

(1) can be used as adjuvant drugs for chemotherapy (cisplatin, cyclophosphamide, doxorubicin, daunorubicin, bleomycin), can reduce the damage caused by chemotherapy without affecting the curative effect, thereby increasing the dose of chemotherapy ^{[10 ]} .

The first dose was 1500 mg / m ² , dissolved in 100 ml of normal saline or 5% glucose injection, and administered intravenously within 15 minutes; on the second to fifth day, intramuscular injection, 600 mg per day. Immediately after cyclophosphamide treatment, a 15-minute intravenous infusion should be used to reduce the effects of chemotherapy on the urinary system. For cisplatin treatment, the dosage of reduced glutathione should not exceed 35mg / mg cisplatin, so as not to affect the chemotherapy, or follow the doctor's advice ^[10] .

(2) It can be used for adjuvant treatment of liver injury caused by alcohol, virus, drugs and other chemicals.

For viral hepatitis, 1200 mg, once / day, intravenous drip, 30 days; Severe hepatitis, 1200 ~ 2400 mg, once / day, intravenous drip, 30 days; Active liver cirrhosis, 1200 mg, 1 time / day, intravenous drip, 30 days; fatty liver, 1800 mg, 1 time / day, intravenous drip, 30 days; alcoholic hepatitis, 1800 mg, 1 time / day, intravenous drip, 14 ~ 30 days; drug-induced hepatitis, 1200 ~ 1800 mg, once / day, intravenous drip, 14 to 30 days ^[10] .

(3) For adjuvant use of radiotherapy, administered after irradiation, at a dose of 1500 mg / m ² , or as prescribed by a doctor ^[10] .

(4) It can be used for the treatment of hypoxemia, with a dose of 500 mg / m, dissolved in 100 ml of physiological saline, administered intravenously, and thereafter maintained at 300 to 600 mg intramuscularly daily ^[10] .

(5) Caution for use: (300-600 mg) must be completely dissolved in the dissolving solution during intramuscular injection, and the dissolving solution must be clear and colorless. For intravenous administration, the drug can be dissolved in a lysate and then slowly injected. Intravenous infusion requires at least 20 ml of lysate ^[10] .

Glutathione adverse reactions

1. Mild oral discomfort such as leukoplakia, ulcers, exfoliation of tongue, and pain in the oral mucosa ^[10] .

2. Rare sudden rash ^[10] .

3 Occasionally anorexia, nausea, vomiting, upper abdominal pain, etc. It disappeared after stopping the medicine, and the injection was mild local pain ^[10] .

Glutathione considerations

1. When oral adverse reactions occur, it is recommended to discontinue this product ^[10] .

2. Keep out of reach of children ^[10] .

3 Phenylketonuria should be used with caution ^[10] .

4 The dissolved solution was used immediately, and the remaining medicinal solution could not be used again ^[10] .

5. Intramuscular injection is limited to use when this route of administration is needed, and repeated injections at the same site should be avoided ^[10] .