Carnitine is an amino acid derivative of the human organism, an enzyme and was discovered at the beginning of this century, but was almost forgotten by biochemists until interest in fatty acid metabolism brought it back into the spotlight some 50 years ago.

Industrially it appears in the form of a white powder

What it is used for and where

Cosmetics

It performs a number of interesting acts.

Anti-static agent. Static electricity build-up has a direct influence on products and causes electrostatic adsorption. The antistatic ingredient reduces static build-up and surface resistivity on the surface of the skin and hair. 

Hair conditioning agent. A significant number of ingredients with specific and targeted purposes can co-exist in a hair shampoo: cleansers, conditioners, thickeners, mattifying agents, sequestering agents, fragrances, preservatives, special additives. However, the indispensable ingredients are the cleansers and conditioners as they are necessary and sufficient for hair cleansing and manageability. The others have commercial and non-essential accessory acts such as: appearance, perfume, colouring, etc. Hair conditioning agents have the task of increasing shine, manageability and volume, and reducing static electricity, especially after treatments such as colouring, ironing, waving, drying and brushing. They are, in practice, dispersants that may contain cationic surfactants, thickeners, emollients, polymers. The typology of hair conditioning agents includes: intensive conditioners, instant conditioners, thickening conditioners, drying conditioners. 

Surfactant - Cleansing agent. Cosmetic products used to cleanse the skin utilise the surfactant action that produces a lowering of the surface tension of the stratum corneum, facilitating the removal of dirt and impurities. 

Surfactant - Foam booster. This has the function of introducing gas bubbles into the water for a purely aesthetic factor, which does not affect the cleansing process, but only satisfies the commercial aspect of the cleanser by helping to spread the cleanser on the hair. This helps in the commercial success of a shampoo formulation. Since sebum has an inhibiting action on the bubble, more foam is produced in the event of a second shampoo.

Viscosity-increasing agent, aqueous. Since viscosity is important to increase the chemical and physical stability of the product, Viscosity Enhancing Agent, aqueous is an important dosage factor in gels, suspensions, emulsions, solutions. Increasing viscosity makes formulations less sedimentary and more homogeneously thickened. 

Medical

Carnitine is synthesised in many eukaryotic organisms and its biosynthesis is initiated by the methylation of lysine. It plays a key role in the metabolism of fatty acids in the mitochondria (1).

Carnitine, however, is not considered an essential nutrient and is present in many foods, mainly those from animal sources.  Lysine and methionine are necessary ingredients for carnitine biosynthesis. 

All body tissues can produce deoxy-carnitine but, in humans, the enzyme that enables the hydroxylation of deoxy-carnitine to carnitine is only found in the liver, brain and kidneys (2).

The most relevant studies on carnitine have been selected with a summary of their contents:

Carnitine studies

Molecular Formula    C₇H₁₅NO₃

Molecular Weight 161.201 g/mol

CAS: 406-76-8  461-06-3

EC Number: 206-976-6

Synonyms: 

• DL-Carnitine
• 3-hydroxy-4-(trimethylammonio)butanoate
• Carnitine [INN]
• Carnitine chloride
• (+-)-Carnitine
• 3-Hydroxy-4-trimethylammoniobutyrat
• 3-hydroxy-4-(trimethylazaniumyl)butanoate
• (3-Carboxy-2-hydroxypropyl)trimethylammonium hydroxide inner salt
• (1)-(3-Carboxy-2-hydroxypropyl)trimethylammonium hydroxide

Carnitine-containing ingredients:

Butyryl-L-carnitine      

Empirical Formula (Hill Notation): C11H21NO4

Molecular Weight: 231.29

CAS Number: 25576-40-3

Isobutyryl-L-carnitine

Empirical Formula (Hill Notation): C11H21NO4

Molecular Weight: 231.29

CAS Number: 25518-49-4

Propionyl-L-carnitine

Empirical Formula (Hill Notation): C10H19NO4

Molecular Weight: 217.26

CAS Number: 20064-19-1

Decanoyl-L-carnitine

Empirical Formula (Hill Notation): C17H33NO4

Molecular Weight: 315.45

CAS Number: 3992-45-8

L-Carnitine hydrochloride

Linear Formula: (CH3)3N+CH2CH(OH)CH2CO2H · Cl-

Molecular Weight: 197.66

CAS Number: 6645-46-1

L-Carnitine inner salt

Linear Formula: (CH3)3N+CH2CH(OH)CH2COO-

Molecular Weight: 161.20

CAS Number: 541-15-1

(±)-Carnitine hydrochloride

Linear Formula: (CH3)3N(Cl)CH2CH(OH)CH2COOH

Molecular Weight: 197.66

CAS Number: 461-05-2

References____________________________________________________________________

(1) Bremer J.  Carnitine—metabolism and functions. Physiol. Rev. 1983;63:1420–80.

(2) Jacob C, Belleville F.   L-carnitine: metabolism, functions and value in pathology.  Pathol Biol (Paris). 1992 Nov;40(9):910-9.