Corrin and porphyrin macrocycles

Corrin and porphyrin macrocycles are essential tetrapyrrole structures that serve as the core of vital biological cofactors and prosthetic groups. Porphyrins are characterized by a highly conjugated, aromatic 20-carbon ring system that coordinates metal ions, most notably iron in heme and magnesium in chlorophyll [1, 2]. These complexes are fundamental to physiological processes such as oxygen transport, electron transfer in the respiratory chain, and photosynthesis. Corrin macrocycles are structurally related but feature a direct bond between two pyrrole rings, creating a more contracted and less aromatic ring that coordinates cobalt to form cobalamin (Vitamin B12) [3]. These macrocycles are critical for cellular respiration, DNA synthesis, and nerve function, and their metabolic dysregulation leads to conditions such as porphyria and pernicious anemia [4, 6]. In a therapeutic context, porphyrin derivatives are utilized in photodynamic therapy (PDT) as photosensitizers that generate reactive oxygen species to target cancer cells [5]. Additionally, corrin derivatives like hydroxocobalamin are used to treat B12 deficiency and serve as an antidote for cyanide poisoning by chelating the cyanide ion. Understanding the chemistry of these macrocycles is essential for developing treatments for metabolic disorders and advancing targeted oncological therapies.

Other names

TetrapyrrolesPorphyrinoidsCyclic tetrapyrrolesMacrocyclic cofactors

These macrocycles act as essential cofactors that coordinate metal ions to facilitate electron transfer, oxygen binding, and enzymatic catalysis; in therapy, they are used for nutritional supplementation, as cyanide chelators, or as photosensitizers that generate cytotoxic reactive oxygen species upon light activation [1, 3, 5].