Trigonelline is a natural chemical substance found in coffee beans, among other places. Trigonelline is a precursor in the body for the synthesis of nicotinic acid or vitamin B3. Nicotinic acid is found in various coenzymes. A deficiency of vitamin B3 leads, among other things, to the skin disease pellagra, which can ultimately result in dementia.
What is trigonelline?
Trigonelline is a substance consisting of an alkaloid of trigonellines and an N-methyl derivative. Artificial synthesis of trigonelline is possible using nicotinic acid and iodomethane, which are first heated and then treated with silver(I) oxide. In its pure form, trigonelline is colorless. The molecular formula of the substance is C87H7NO2. Trigonelline exists in a solid state and forms a hydrochloride. It dissolves in water as well as in warm ethanol and alcohol. Other names for trigonelline are:
- Caffearine or Caffearin,
- Gynesin,
- Betainicotinate,
- N-methyl nicotinate,
- 1-methylpyridine-1-um-3-carboxylate, and
- Nicotinic acid-N-methylbetaine.
Function, effect and tasks
Trigonelline forms the starting material for vitamin B3 or nicotinic acid, among other things. Roasting coffee beans demythilizes the trigonelline in the beans and converts it to nicotinic acid. Nicotinic acid is involved in various metabolic processes in the human body and influences the metabolism of protein, fat and carbohydrates, among other things. Nicotinic acid is a building block of the coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). In biology, coenzymes are biocatalysts that assist the actual enzymes in their work. NAD participates in both oxidative and reductive processes – depending on whether the coenzyme itself is in its reduced or oxidized form (NAD+). For example, it serves as a biochemical assistant to dehydrogenases. Dehydrogenases are various specialized enzymes that participate, among other things, in the breakdown of alcohol in the liver. The dehydrogenases split off a negatively charged hydrogen atom from their substrate and pass it on to NAD. NADP is a coenzyme that also participates in the redox reaction. It can exist in two different forms: NADP+ is the oxidized form, and NADPH represents the reduced form. The coenzyme belongs to the respiratory chain. In this process, NADH oxidizes to NADPH, producing ATP. In addition, NADPH assists in the synthesis and breakdown of fatty acids, the processing of glucose, and the breakdown of amino acids.
Formation, occurrence, properties, and optimal values
Trigonelline occurs in many plants and is found there mainly in the seeds. The substance serves as a base there. Coffee beans are rich in trigonelline: one bean contains about 0.3-1.3% of it. However, the seeds of fenugreek contain even more trigonelline, at 3%. The exact amount depends not only on how much trigonelline the plant itself produces, but also on how the coffee beans are roasted. On average, a cup of coffee (150 ml from 7.5 g of roasted coffee) contains 27 mg of trigonelline, with the Arabica variety producing slightly more and the Robusta variety producing slightly less. The heat of roasting affects the molecular structure and can demethylate it, that is, split off a methyl molecule. The product is nicotinic acid (niacin). The B vitamin consists of a pyridine ring and a carboxyl group. Humans need 15-20 mg of nicotinic acid per day. Foods high in nicotinic acid include poultry, game, fish, liver, dairy products, eggs, mushrooms, cashews, whole grains, and brewer’s yeast. An overdose is reached only with 1.5-3 g. However, when coffee beans are roasted, trigonelline can also decarboxylate: In this case, it is not methyl that separates from the molecule, but a carbon dioxide molecule. Enzymes can also effect this conversion without heat.
Diseases and disorders
Trigonelline is not normally the main source of nicotinic acid in the human body; however, it may become more important in an unbalanced diet. Deficiency of nicotinic acid initially leads to irritability, sleep disturbances, loss of appetite, and impaired concentration. As it progresses, dermatitis, diarrhea, inflammation of the mucous membranes of the mouth, stomach, and intestines, and symptoms of depression may also occur. Severe deficiency of nicotinic acid in the human body triggers pellagra.This is a skin disease found mainly in poorly developed regions of southern Europe and the Americas. The clinical picture manifests itself in dermatitis, diarrhea and dementia. The dementia occurs in the form of an organic psychosyndrome, i.e. it is of physiological origin, but manifests itself on a psychological level. Presumably, tryptophan plays a mediating role in this process. Treatment of pellagra provides for administration of nicotinic acid or nicotinamide. In addition, treatment of other deficiencies may be required, as hypovitaminosis often affects other vitamins and minerals. Nicotinic acid overdose is also possible. If a person consumes a dose of more than 1.5-3 g of nicotinic acid, hypervitaminosis is present. The consequences are dilatation of skin vessels (flush) and cardiovascular symptoms. Severe overdose of more than 2.5 g per day may cause dizziness and/or the drop in blood pressure. Drop in blood pressure or hypotension is manifested by dizziness, headache, tremors, easy fatigability, concentration problems, pallor, cold hands and feet, syncope, and tachycardia. There is also an increased risk of injury if fainting occurs. Nicotinic acid overdose also manifests in the blood, which has elevated uric acid levels.
