Plasma
ubiquinone,
coenzyme Q10 or
CoQ10 has been analyzed in plasma together with
alpha-tocopherol and free
cholesterol in healthy sedentary male subjects (SS), endurance trained male athletes (ET) and male patients with severe
ischemic heart disease (IHD). Higher means were found in SS compared to both IHD and ET. Moreover, the ratios
CoQ10 and
alpha-tocopherol over free
cholesterol were higher. In all groups significant relationships were found between the two products of the
mevalonate pathway:
CoQ10 and
cholesterol (r ranged 0.66-0.86, p less than 0.01). The two lipophilic
antioxidants,
CoQ10 and
alpha-tocopherol, were interrelated only in IHD (r = 0.86, p less than 0.001), borderline in SS (r = 0.51, p less than 0.05) but not in ET. It is assumed that plasma free
cholesterol reflects the capacity to transport
lipids and lipophilic compounds in blood. With metabolic stress and an elevated radical formation as in IHD and ET, the lower
CoQ10 and
alpha-tocopherol to
cholesterol ratios mirror a subsequent toll on the scavenging potential. The difference in
LDL levels between IHD and ET and the different storage capacity of
CoQ10 and
alpha-tocopherol might explain the tight coupling in IHD but not in ET. It is possible that the toll reflects both an intra- and extracellular radical quenching activity. The joint effect of the two lipophilic, extracellular
antioxidants CoQ10 and
alpha-tocopherol role in protecting e.g.
LDL particles from peroxidation is suggested.