Endocrine Abstracts

Whereas oxidative reactions occur in all tissues and organs, the thyroid gland constitutes such an organ, in which oxidative processes are indispensable for physiological functions. Thus, with additional oxidative abuse caused by several factors, increased oxidative damage to macromolecules may occur in the thyroid. In turn, numerous metabolic reactions occurring in the liver create favourable conditions for huge oxidative stress.

Melatonin is a well-known antioxidant and free radical scavenger, with protective effects against oxidative damage perfectly documented in many tissues, the thyroid and the liver included.

Caffeic acid phenethyl ester (CAPE), a component of honeybee propolis, has been suggested to be also an effective antioxidant. It is even used as a protective agent during chemotherapy and radiotherapy regimens.

The aim of the study was to evaluate the effects of CAPE on experimentally-induced oxidative damage in porcine thyroid and liver homogenates, and to compare the results with protective effects of melatonin.

Fenton reaction (Fe²⁺+H₂O₂→Fe³⁺+^•OH+OH⁻) substrates were used to induce oxidative damage to membrane lipids (lipid peroxidation, LPO). Then, tissue homogenates were incubated in the presence of either CAPE or melatonin (0.1–500 μM) and, additionally, in the presence of Fenton reaction substrates.

Whereas CAPE decreased basal LPO in a concentration-dependent manner in both tissues, melatonin did not change the basal LPO level. When antioxidants were used together with Fenton reaction substrates, they prevented – in concentration dependent manner and to a similar extent – experimentally-induced LPO in both the thyroid and the liver.

Protective antioxidative effects of CAPE in the thyroid and the liver are similar to those caused by melatonin. CAPE constitutes a promising agent in terms of its application in experimental and, possibly, clinical studies.