In recent decades, it was found that vitamins affect biological functions in ways other than
their long-known functions; niacin is the best example of a water-soluble vitamin known to possess
multiple actions. Biotin, also known as vitamin B7 or vitamin H, is a water-soluble B-complex vitamin
that serves as a covalently-bound coenzyme of carboxylases. It is now well documented that biotin has
actions other than participating in classical enzyme catalysis reactions. Several lines of evidence have
demonstrated that pharmacological concentrations of biotin affect glucose and lipid metabolism,
hypertension, reproduction, development, and immunity. The effect of biotin on these functions is
related to its actions at the transcriptional, translational, and post-translational levels. The bestsupported
mechanism involved in the genetic effects of biotin is the soluble guanylate cyclase/protein
kinase G (PKG) signaling cascade. Although there are commercially-available products containing
pharmacological concentrations of biotin, the toxic effects of biotin have been poorly studied. This
review summarizes the known actions and molecular mechanisms of pharmacological doses of biotin in
animals and current information regarding biotin toxicity.
Keywords: Biotin toxicity, biotin, gene expression, guanylate cyclase, histone biotinylation, pharmacological effects.
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