Effects of Eicosanoid Biosynthesis Inhibitors on Selected Oxidative Stress Biomarkers in the Midgut of Galleria mellonella (Lepidoptera: Pyralidae) Larvae

Abstract

Abstract Eicosandoids, or icosanoids, are signaling compounds created by the oxidation of 20-carbon fatty acids. They control many complex physiological and immunological functions in vertebrate and invertebrate animals. This study tested the hypothesis that eicosanoids act in insect antioxidant defense. The effects of 3 eicosanoid biosynthesis inhibitors (EBIs) – dexamethasone, esculetin, and phenidone – on the oxidative stress indicator, malondialdehyde (MDA), and the detoxification enzyme, glutathione S-transferase (GST), was examined in the midgut of larvae of the greater wax moth, Galleria mellonella (L.). The larvae were reared on artificial diets supplemented with 0.001, 0.01, 0.1 or 1.0% of the EBIs. Esculetin, which is a lipoxygenase inhibitor, significantly increased MDA content; whereas, GST activity was significantly increased at only the highest concentration tested. Dexamethasone, a phospholipase A2 inhibitor, significantly increased MDA content and GST activity at concentrations of 0.01, 0....