Oxidative Stress Biomarkers in Equine Erythrocytes and Plasma after in vitro Treatment with an Aqueous Leaf Extract of Coelogyne brachyptera Rchb. f. (Orchidaceae)

Abstract

Many orchids have been used as medicinal plants for many years in China, Japan, India, and some other countries. They showed many health-beneficial functions, such as the protection of cells against free radicals and oxidative stress possessing hepatoprotection, cardioprotection, gastroprotection, neuroprotection, and other properties. This study aimed to investigate the oxidative stress biomarkers [2-thiobarbituric acid reactive substances (TBARS), aldehydic and ketonic derivatives of oxidatively modified proteins (OMP), and total antioxidant capacity (TAC)] in the equine erythrocytes and plasma after in vitro incubation with an extract derived from leaves of Coelogyne brachyptera Rchb. f. The leaves of C. brachyptera plants, cultivated under glasshouse conditions, were sampled at M.M. Gryshko National Botanic Garden (NBG), National Academy of Science of Ukraine. Freshly collected leaves were washed, weighed, crushed, and homogenized in 0.1M phosphate buffer (pH 7.4) (in the proportion of 1:19, w/w). The equine plasma and erythrocyte aliquots were used in the study. The pellet of blood was re-suspended in phosphate buffer (pH 7.4). A volume of 0.1 mL of the C. brachyptera extract was added to 1.9 mL of clean equine erythrocytes or 1.9 mL of plasma. For positive control (blank), 0.1M phosphate buffer (pH 7.4) added to erythrocytes or plasma was used. Results of our study revealed that erythrocytes were more sensitive to the action of an extract derived from leaves of C. brachyptera. The levels of aldehydic and ketonic derivatives of oxidatively modified proteins in the treated erythrocytes were significantly decreased, while these parameters were no-changed in the equine plasma. The treatment of equine erythrocytes by extract derived from leaves of C. brachyptera increased lipid peroxidation. On the other hand, plasma TBARS level after treatment by extract derived from leaves of C. brachyptera was at the same level as in untreated controls. The level of total antioxidant capacity was not-significantly changed after treatment both in equine plasma and erythrocytes. Studies concerning the antioxidant properties of orchids are continued in our laboratory.