Interaction of sanguinarine and chelerythrine with compounds containing mercapto group is fast reversible complexation based on non-bonding intermolecular interactions. Only uncharged pseudobase forms of these alkaloids enter in the complexation. A negatively charged group either bonded to the mercapto compound or supplied by the solution participates in the complex formation.Constants for the binding of uncharged sanguinarine with human and bovin serum albumins are 332000+/-8 499 and 141000+/-14 400 l/mol, respectively. For the uncharged form of chelerythrine, the constants are 2 970 000+/-360 000 and 1 380 000+/-2600 l/mol for human and bovine serum albumins, respectively.
