Vitamin B2 - riboflavin

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Occurrence and structure

Riboflavin is also found in plant and animal products, especially in abundance milk and Dairy products. Its structure is characterized by a tricyclic (consisting of three rings) isoalloxazine ring to which a ribitol residue is attached. Furthermore, vitamin B2 is in: Broccoli, asparagus, spinach eggs and whole grain products contain.


It occurs in FMN (F.lavinM.ononucleotide) and FAD (F.lavinA.denin-D.inucleotide), which are important electron acceptors. This means that they can accept two protons (H +) and two electrons (e-), which are released in a reaction, as the reaction product no longer needs them. It looks like this: FAD à FADH2. This reaction is called a Hydrogenation (Adding hydrogen) and the resulting product are the reduction equivalents already mentioned above, which then supply energy in the respiratory chain. About 1.5 ATP Per FADH2. From that FAD and FMN participate in reactions in which they are hydrogenated, it can be concluded that they are cofactors of reactions in which starting materials (Raw materials) are dehydrated (i.e. electrons are withdrawn from them / hydrogen is withdrawn).For example, they can be found in the following reactions / metabolic pathways

  • Beta oxidation (Breakdown of fatty acids, helpers of acyl-CoA dehydrogenase)
  • oxidative / dehydrogenative deamination (Splitting off of amino groups)
  • Complex I of the respiratory chain (for the meaning of the respiratory chain, see above)

Deficiency symptoms

The symptoms of a lack of riboflavin (vitamin B2) are rather unspecific, as it occurs everywhere in the body. Changes in the Oral mucosa cause.

Overview of vitamins

Water-soluble (hydrophilic) vitamins:

  • Vitamin B1 - thiamine
  • Vitamin B2 - riboflavin
  • Vitamin B3 - niacin
  • Vitamin B5 - pantothenic acid
  • Vitamin B6 - pyridoxal / pyridoxine / pyridoxamine
  • Vitamin B7 - biotin
  • Vitamin B9 - folic acid
  • Vitamin B12 - Cobalamin

Fat-soluble (hydrophobic) vitamins:

  • Vitamin A - retinol
  • Vitamin C - ascorbic acid
  • Vitamin D - calcitriol
  • Vitamin E - tocopherol
  • Vitamin K - phylloquinone / menaquinone