Effects of Constituents Identified in the Adults of Tenebrio molitor on Antioxidant and Anti-BACE-1 Activities

Abstract

Insects have been widely used as traditional foods and medicines treating human diseases worldwide. In addition, components of insect body are rich in nutrients such as unsaturated fatty acids, proteins, vitamins, and minerals. Therefore, development for using them as health supplement and functional foods has been expected. Active oxygen with free radicals is structurally unstable, and usually reacting with surrounding substances, causing fatal oxidative damage to intracellular proteins, lipid molecules and DNA. In addition, human beta amyloid precursor proteinase (BACE-1) is known to cause senile dementia as a major enzyme responsible for amyloid plaque production. In this study, antioxidative and BACE-1 inhibitory components were isolated and identified from various species of mealworm (Tenebrio molitor) adults by various chromatographic and instrumental analyzes. Nine compounds such as fatty acids such as linolenic acid and flavonoid compounds such as catechin were isolated as antioxidant components. The IC50 values of these compounds were between 77.65 and 623.23 μM, and showed lower antioxidative activity than ascorbic acid, a positive control compound. In addition, 12 compounds such as fatty acids such as linolenic acid and steroid compounds such as ergosterol were separated as BACE-1 inhibitory components. IC50 values of these compounds were between 28.41 and 676.65 μM, which showed lower BACE-1 inhibitory activity than eigallocatechin gallate, a positive control compound. In this study, the AChE inhibitory activity of all the isolated compounds was investigated. Otherwise, by the analysis of quantitative structure-activity relationship (QSAR) for 41 fatty acids and 29 flavonoids related, most of the unsaturated fatty acids showed potential bioactivity than the saturated fatty acids and phenol in flavonoid exhibited the positive impact. Multiple regression analysis also showed the structure have certain correlation to their bioactivity. The further studies will focus on the mechanisms of antioxidant and anti-BACE-1 of the isolated compounds.