E627 or Disodium guanylate or Sodium 5'-guanylate or Disodium guanosine 5-monophosphate is a chemical compound. The general structure of guanosine monophosphate consists of a guanine base, a ribose sugar, and a phosphate group. In the case of disodium guanylate, two sodium ions are associated with the phosphate group, balancing its negative charge.

The name defines the structure of the molecule:

• "Disodium" refers to the presence of two sodium ions (Na⁺).
• "Guanylate" refers to guanosine monophosphate, a guanosine nucleoside molecule (composed of guanine attached to a ribose sugar) linked to a phosphate group.

The synthesis process takes place in several steps:

• Step 1: Preparation of raw materials, guanosine and sodium hydroxide.
• Step 2: Reaction. Guanosine reacts with sodium hydroxide to produce guanylate.
• Step 3: Ion exchange. Guanylate reacts with sodium ions to form disodium guanylate.
• Step 4: Purification and drying. The resulting disodium guanylate is then purified, typically through filtration and washing, and dried.

It appears as white powder.

Food

It is a food additive included in the list of European food additives under the number E627 used as flavoring agent very often accompanied by monosodium glutamate.

Studies

Lysine at a concentration of 1% and sodium guanylate (300 mg / kg) reduced sensory defects caused by the replacement of 50% salt with potassium chloride, allowing the preparation of sensibly acceptable fermented sausages, with a 50% decrease in sodium (1).

The use of potassium chloride (KCl) has been studied to maintain both the salty taste and to replace the preservative effects of salt when the sodium content in the natural cheese is reduced. Salt substitutes can influence taste because of inherent flavors, such as bitter and metallic, the use of aromatic agents has been investigated for their ability to modulate some of these unwanted sensor effects, including Guanilate. disodium (2).

Study to supress the technological and sensory defects caused by NaCl reduction in low-fat Bologna-type sausages (3).

Study to determine the interaction between the human umami receptor hT1R1 and a ligand while avoiding the cross-talk among various signal pathways in cells (3).

Cosmetics

Humectant. Hygroscopic compound used to minimise water loss in the skin and to prevent it from drying out by facilitating faster and greater absorption of water into the stratum corneum of the epidermis.  The epidermis is the most superficial of the three layers that make up human skin (epidermis, dermis and hypodermis) and is the layer that maintains hydration in all three layers. In turn, the epidermis is composed of five layers: horny, the most superficial, granular, spinous, shiny, and basal. Humectants have the ability to retain the water they attract from the air in the stratum corneum and have the function of moisturising the skin. They are best used before emollients, which are oil-based.

Skin conditioning agent. It is the mainstay of topical skin treatment as it has the function of restoring, increasing or improving skin tolerance to external factors, including melanocyte tolerance. The most important function of the conditioning agent is to prevent skin dehydration, but the subject is rather complex and involves emollients and humectants that can be added in the formulation.

Skin conditioning agent - Emollient. Emollients have the characteristic of enhancing the skin barrier through a source of exogenous lipids that adhere to the skin, improving barrier properties by filling gaps in intercorneocyte clusters to improve hydration while protecting against inflammation. In practice, they have the ability to create a barrier that prevents transepidermal water loss.  Emollients are described as degreasing or refreshing additives that improve the lipid content of the upper layers of the skin by preventing degreasing and drying of the skin. The problem with emollients is that many have a strong lipophilic character and are identified as occlusive ingredients; they are oily and fatty materials that remain on the skin surface and reduce transepidermal water loss. In cosmetics, emollients and moisturisers are often considered synonymous with humectants and occlusives.

Safety

Disodium guanylate is often used in conjunction with monosodium glutamate (MSG) and disodium inosinate; the combination is known as disodium 5'-ribonucleotides. It is commonly found in instant noodles, potato chips, and snacks, among other foods. It is generally considered safe for consumption, but it is a purine, so individuals who need to avoid or limit purines in their diet (such as people with gout) should be aware of this.

In the latest study of 25 March 2014 published by EFSA, which is the European Food Safety Authority (1), it was found that the component Disodium guanosine 5-monophosphate is considered safe for animals and consumers. However, considering the lack of information on the production process, caution is advised. Textually :

However, considering the lack of information on the production process, these conclusions apply only to the compounds „per se‟ and their extrapolation to any feed additive containing these compounds is not possible. In the absence of any data related to hazard to the user it would be prudent to regard disodium 5′- guanylate and disodium 5′-inosinateand their mixture as potentially hazardous to workers by skin or inhalation exposure. (5)

In the minimum quantities in which it is included in food or cosmetics, it is of no concern. Check for cumulative intake.

• Molecular formula: C₁₀H₁₂N₅Na₂O₈P
• Molecular weight: 407.184281
• CAS:   5550-12-9
• EC number       226-914-1

Synonyms:

• Sodium guanylate
• Disodium GMP
• Guanosine 5'-(disodium phosphate)
• 5'-Guanylic acid, disodium salt
• Disodium guanosine-5'-monophosphate
• Guanosine 5'-monophosphate, disodium salt
• Disodium guanosine 5'-monophosphate
• 5'-Guanylic acid, sodium salt

References__________________________________________________________________

(1) Campagnol PC, dos Santos BA, Terra NN, Pollonio MA. Lysine, disodium guanylate and disodium inosinate as flavor enhancers in low-sodium fermented sausages.  Meat Sci. 2012 Jul;91(3):334-8. doi: 10.1016/j.meatsci.2012.02.012. 

(2) Grummer J, Bobowski N, Karalus M, Vickers Z, Schoenfuss T. Use of potassium chloride and flavor enhancers in low sodium Cheddar cheese.    J Dairy Sci. 2013 Mar;96(3):1401-18. doi: 10.3168/jds.2012-6057. Epub 2013 Jan 17.

(3) Campagnol PCB, Dos Santos BA, Lorenzo JM, Cichoski AJ.  A combined approach to decrease the technological and sensory defects caused by fat and sodium reduction in Bologna-type sausages.   Food Sci Technol Int. 2017 Sep;23(6):471-479. doi: 10.1177/1082013217701859. 

(4) Huang Y, Lu D, Liu H, Liu S, Jiang S, Pang GC, Liu Y. Preliminary research on the receptor-ligand recognition mechanism of umami by an hT1R1 biosensor.   Food Funct. 2019 Feb 25. doi: 10.1039/c8fo02522c.

(5) EFSA , Scientific Opinion on the safety and efficacy of disodium 5?-ribonucleotides, disodium 5?-guanylate, disodium 5?-inosinate for all animal species and categories
25 marzo 2014 Opinion of the Scientific Committee/Scientific Panel