[Coenzyme Q10 in cancer chemotherapy--experimental studies on augmentation of the effects of masked compounds, especially in the combined chemotherapy with immunopotentiators].

Immunopotentiators may mitigate the depression of immunological function caused by the cancer itself or by chemotherapeutics. However, it has been found that these immunopotentiators reduce the metabolic activity of the host against drugs, including "masked" chemotherapeutics, which might be activated by metabolization in the body. Reported here is the result of serial experiments carried out on the activation of cyclophosphamide (CPM) in tumor-bearing animals, pretreated with phenobarbital, a drug-metabolizing enzyme inducer, and coenzyme Q10, a physiological activator of the electron transfer system in mitochondrias, in combination with immunopotentiators. Female Donryu rats (120 g body weight) implanted with Yoshida Sarcoma cells (YS) (2.5 X 10(6) i.p.) were treated with CPM (160 mg/kg X 1 i.p.), 84 hrs after implantation; the levels of the normustard-like substances (active metabolites of CPM) were serially measured. Some of the animals were also treated with PSK (125 mg/kg X 5 i.p.), a proteinpolysaccharide immunopotentiator obtained from mycelia of the Coriolus vesicolor, or with OK-432 (10 KE/kg X 5 i.m.), a streptococcal immunopotentiator. The results obtained were as follows: The blood levels of the normustard-like substances were lowered, i.e. the CPM activation was depressed in the YS-bearing rats and the depression was markedly intensified by PSK or OK-432 administration. Phenobarbital (40 mg/kg X 3 i.p.) or coenzyme Q10 (5 mg/rat X 5 i.p.) administration could mitigate the depression of the blood levels caused by the immunopotentiators, and the combination of phenobarbital with coenzyme Q10 could recover the blood levels up to those of the YS-bearing control rats, or even higher. YS-implanted (i.p.) rats treated with CPM+ immunopotentiators+coenzyme Q10 survived longer than those treated with CPM+immunopotentiators. These findings suggest the usefulness of coenzyme Q10 for the enhancement of cancer immunochemotherapy using masked compounds combined with immunopotentiators; all the more so, because coenzyme Q10 has also an immuno-stimulating effect, moreover, it presents almost no side effects in clinical application.