Background: Previously, it was demonstrated that quinoid pigments of sea urchins exhibit antioxidant properties.
Objective: The work presents a comparative investigation of the antioxidant and antiaggregant action of polyhydroxy- 1,4-naphthoquinones: echinochrome A, spinochrome B, spinochrome C, spinochrome E, echinamine B, histochrome. The glycolytic enzyme glyceraldehyde-3-phospate dehydrogenase (GAPDH) was chosen as a possible natural target for the action of the quinones. GAPDH is easily affected by reaction oxygen species and prone to amyloid aggregation.
Methods: Influence of polyhydroxy-1,4-naphthoquinones on the enzymatic activity of GAPDH, on the oxidation of the enzyme by hydrogen peroxide as well as on its thermal aggregation and some thermodynamic parameters of the enzyme were investigated.
Results: It was demonstrated that spinochromes B and C decelerate the oxidation of GAPDH by hydrogen peroxide, but do not affect the GAPDH activity in the absence of H2O2. Echinichrome A and histochrome decelerate the oxidation of GAPDH by hydrogen peroxide and moderately inhibit the activity of GAPDH. Echinamine B and spinochrome E were shown to decrease significantly the activity of GAPDH. Spinochrome E exhibits a pronounced antiaggregant action, completely suppressing thermal aggregation of GAPDH. Echinochrome A and the spinochromes prevent chaperone hsp70 from blocking by oxidized and denatured forms of GAPDH.
Conclusion: Most of the quinoid pigments of sea urchins, as well as the derived preparation histochrome exhibit antioxidant action and prevent interaction of denatured proteins with each other and with chaperones. However, echinamine B and spinochrome E inhibit GAPDH, which is in agreement with previously described cytotoxic action of some polyhydroxy-1,4-naphthoquinones.