Antioxidant activity of aqueous methanol extracts from the lucanid beetle,Serrognathus platymelus castanicolor Motschulsky (Coleoptera: Lucanidae)

The objective of this study was to evaluate the antioxidant properties of extracts of the lucanid beetle, Serrognathus platymelus castanicolor Motschulsky, obtained at different growth stages. The antioxidant activities of six different extracts were determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), and singlet oxygen (¹O₂). The activity level of pupal methanol extracts (PME) was higher in the DPPH and ABTS radical scavenging assays, whereas that of the water extracts was weaker in all assays. The ¹O₂ quenching ability of the PME was comparable to that of ascorbic acid (effective concentration of 50% ¹O₂ quenching: EC₅₀ = 0.184 mg/ml^-1 and 0.167 mg/ml^-1, respectively). The free radical scavenging antioxidant ability of the extracts significantly altered phenolic contents, important factors in the potency of antioxidant capacity. Our results suggest that these extracts may reduce oxidative stress in living organisms and reduce oxidative damage in insects under unfavorable conditions.