The Influence of Propolis Ingestion on Redox State of Human Serum Albumin: a Study of Patients under Severe Oxidative Stress

Human serum albumin (HSA) is a mixture of mercaptalbumin (HMA, reduced form) and nonmercaptalbumin (HNA, oxidized form). HMA, possessing a single sulfhydryl residue, is responsible for the largest fraction of reactive sulfhydryl in extracellular fluids and therefore it seems to participate largely in the extracellular antioxidant system. We have developed a convenient high-performance liquid chromatographic (HPLC) system for the clear separation from HSA to HMA and HNA. By this method, a mean value of [HMA/(HMA+HNA)], i.e. f(HMA) for healthy young male subjects was 73.2% (n = 20). In the present study, we examined the influence of propolis ingestion on the redox state of HSA from patients under severe oxidative stress such as a cancer therapy. In the case of a patient with liver cirrhosis and esophageal cancer (male, 68 yr), f(HMA) value before the radiation therapy without propolis ingestion was 66.6%. However, during the radiation therapy for 2 weeks, he took ten propolis tablets/day (525 mg of Brazilian propolis extract/day) every day and continued to take them for more 4 weeks. Values for f(HMA) just before, immediately after, and 4 weeks after radiation therapy, were 63.5, 67.7 and 74.1%, respectively. These evidences suggest that oxidative status due to the radiation therapy might be attenuated by propolis supplementation. Furthermore, a gradual increase in f(HMA) value indicates that the antioxidant properties of propolis might augment the total antioxidant capacity of the patient with cancer.