RESUMO
Some retinoids or porphyrins can form radical pairs, alter transfer of electrons, and increase synthesis of reactive oxygen species in the mitochondrial respiratory chain. This leads to cell damage and apoptosis. We propose that co-application of an external static magnetic field of several to several hundreds miliTesla (mT) can enhance those effects by further alteration of electron flow in the mitochondrial respiratory chain, facilitation of forbidden transitions from the triplet to the singlet state of retinoid or porphyrin radicals, and modification of radical pair amount. Since electron flow in the mitochondrial respiratory chain seems to possess fractal dynamics, the magnetic field can initiate self- organization of the flow into more regular patterns, and create optimal conditions for damage of cancer cells without any detriment for the normal counterparts. External low magnetic field should improve effectiveness and selectivity of retinoid chemoprevention or porphyrin photodynamic therapy.