Ascorbic acid (L-ascorbic acid) is a chemical compound, a synthesized vitamin C. While vitamin C is an organic compound, ascorbic acid is the purest form of vitamin C, but it is a chemical compound, a synthesized form of vitamin C. Both have the same molecular formula C₆H₈O₆.

Let's talk about ascorbic acid and then we'll talk about vitamin C.

The synthesis process takes place in different steps:

• Fermentation. Glucose is fermented using specific strains of bacteria or fungi, such as Gluconobacter oxydans or Aspergillus niger. This fermentation process converts glucose to sorbitol.
• Conversion.Sorbitol is oxidised to sorbose by a microbial or enzymatic oxidation process. This step usually involves the use of specific enzymes or microorganisms, such as Gluconobacter suboxydans or Acetobacter suboxydans.
• Isomerisation. Sorbose is isomerised to ketogulonic acid through a process of chemical or enzymatic isomerisation. This step typically involves the use of a catalyst, such as an acid or an enzyme called sorbose-5-phosphate isomerase.
• Oxidation and hydrolysis. Ketoglulonic acid is oxidised and hydrolysed to form 2-keto-L-gulonic acid. This step usually involves the use of oxidising agents, such as bromine or chlorine, followed by hydrolysis with acid or enzymes.
• Reduction. 2-Keto-L-gulonic acid is reduced to ascorbic acid, also known as vitamin C. This reduction can be achieved using various reducing agents, such as sodium borohydride or hydrogen gas in the presence of a catalyst.
• Purification. The synthesised ascorbic acid undergoes a purification process through crystallisation, filtration and drying to obtain the final product.

The synthesis of ascorbic acid may vary depending on the specific production process and the desired purity of the final product. Ascorbic acid can also be obtained from natural sources such as fruit and vegetables.

What it is used for and where

Medical

Ascorbic acid is not only an antioxidant, but has some biosynthetic peculiarities in different organisms as a co-substrate of several dioxygenases, a particular function in gene expression, the important role of regenerative enzymes, modulator of neuronal metabolism. It plays a key role in endogenous antioxidant defense and is cofactor in the production of carnitine and collagen.

Ascorbic acid insufficiency can occur in conditions of systemic oxidative stress, inflammation, sepsis, trauma. 

Many clinical and laboratory studies have established the effects of ascorbic acid in the treatment and prevention of cancer, with inhibition of prostate, ovarian, and pancreatic cancer cell growth, neuroblastoma cells, and inhibition of liver cancer growth and metastasis (1).

Food

It is added to the flour to improve water absorption resulting in increased volume and better product control during rising.

It has the number E300 in the list of European food additives as an antioxidant.

Cosmetics

Antioxidant agent. Ingredient that counteracts oxidative stress and prevents cell damage. Free radicals, pathological inflammatory processes, reactive nitrogen species and reactive oxygen species are responsible for the ageing process and many diseases caused by oxidation.

Buffering agent. It is an iingredient that can bring an alkaline or acid solution to a certain pH level and prevent it from changing, in practice a pH stabiliser that can effectively resist instability and pH change.

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.

Fragrance. It plays a decisive and important role in the formulation of cosmetic products as it provides the possibility of enhancing, masking or adding fragrance to the final product, increasing its marketability.  The consumer always expects to find a pleasant or distinctive scent in a cosmetic product.

For more information:

Ascorbic acid studies

Commercial ascorbic acid occurs as a fine white or nearly white crystalline powder or colorless crystals

Typical optimal characteristics of commercial ascorbic acid product

• Molecular Formula: C₆H₈O₆     HC₆H₇O₆
• Molecular Weight: 176.12  g/mol
• CAS: 50-81-7
• UNII PQ6CK8PD0R
• EC Number: 200-066-2    477-330-0
• DSSTox Substance ID: DTXSID5020106
• MDL number  MFCD00064328
• PubChem Substance ID 329749065
• InChI=1S/C6H8O6/c7-1-2(8)5-3(9)4(10)6(11)12-5/h2,5,7-10H,1H2/t2-,5+/m0/s1
• InChl Key      CIWBSHSKHKDKBQ-JLAZNSOCSA-N
• SMILES    C(C(C1C(=C(C(=O)O1)O)O)O)O
• IUPAC   (2R)-2-[(1S)-1,2-dihydroxyethyl]-3,4-dihydroxy-2H-furan-5-one
• ChEBI    29073

Synonyms:

• L(+)-Ascorbic acid
• l-ascorbic acid
• vitamin C
• Ascorbate, Sodium

Vitamin C is a water-soluble vitamin that must be consumed from external sources (mainly fruits and vegetables) because humans cannot synthesize it endogenously, whereas some animals can. From a health perspective, however, while dietary vitamin C from food has a protective association from early atherosclerosis, unfortunately, taking vitamin C supplements has an adverse association (2).

Vitamin C is is a simple low molecular weight carbohydrate and is necessary for tissue growth and repair in all parts of the body. The United States Institute of Medicine recommends a daily vitamin C intake of 75 milligrams per day for adult women and 90 milligrams per day for adult men.

Vitamin C It is used by our body to:

• make an important protein for skin, tendons, ligaments and blood vessels.
• heal wounds and scars.
• repair and maintain healthy cartilage, bones and teeth.
• In the food industry it is labeled as E300 in European food additives.

In the food industry it is labeled as E300 in European food additives.

In the human body it is used for the maintenance of the antioxidant defenses of the cell, it is a free radical scavenger. It also performs the important function of contributing to vitamin E regeneration. Vitamin C also cycles between an oxidized form (L-dehydroascorbic acid) and a reduced form (L-ascorbic acid). In addition, vitamin C is important for the absorption and metabolism of iron.

Vitamin C is one of many antioxidants. Antioxidants are substances that block some of the damage caused by free radicals.

Free radicals are formed when the body is in particular uncomfortable conditions, for example, when exposed to smoke or radiation, when ingesting too much saturated fat, etc. The accumulation of free radicals over time is largely responsible for the aging process. Free radicals can play a role in cancer, heart disease and arthritis.

The body is unable to produce vitamin C on its own and does not store it, therefore, it is important to get a certain amount of vitamin C from foods that contain it, daily.

It is used, in medicine, in the treatment of colds and flu.

In nature it is found in :

• Citrus fruits and juices, such as orange, lemon, grapefruit  
• Kiwi   
• Acerola
• Mango
• Papaya
• Pineapple
• Strawberries, raspberries, blueberries, cranberries
• Watermelon
• etc

References________________________________________________________________________

(1) Wan J, Zhou J, Fu L, Li Y, Zeng H, Xu X, Lv C, Jin H. Ascorbic Acid Inhibits Liver Cancer Growth and Metastasis in vitro and in vivo, Independent of Stemness Gene Regulation. Front Pharmacol. 2021 Aug 24;12:726015. doi: 10.3389/fphar.2021.726015. 

(2) Agarwal M, Mehta PK, Dwyer JH, Dwyer KM, Shircore AM, Nordstrom CK, Sun P, Paul-Labrador M, Yang Y, Merz CN. Differing Relations to Early Atherosclerosis between Vitamin C from Supplements vs. Food in the Los Angeles Atherosclerosis Study: A Prospective Cohort Study. Open Cardiovasc Med J. 2012;6:113-21. doi: 10.2174/1874192401206010113.