Total Lipid Extracts of Honeybee Drone Larvae Are Modulated by Extraction Temperature and Display Consistent Anti-Inflammatory Potential.

Abstract

Honeybee drone larvae are male bees that develop from unfertilized eggs and play a role in colony reproduction. The nutritional value of honeybee drone larvae is due to their high protein, lipid, and other nutrient contents, making them a profitable food source for humans in some cultures. Drone larvae lipids (DLLs) contribute to drone development; however, few studies have explored their substantial compositions and bioactive functions. In this study, we carried out DLL lipidomics analysis using UPLC-Q-Exactive-Orbitrap-MS prior to in vitro anti-inflammatory activity analysis. The results highlighted the importance of the extraction temperature on the DLL composition. A total of 21 lipids were found in the DLL extract, mostly categorized into five groups: nine phospholipids, three sphingolipids, two neutral lipids, one plant glycoglycerolipid, four lipid acyl, and others. Drying extraction at -20 °C produced more sphingolipids, phospholipids, and unsaturated fatty acids. Of 37 fatty acids, 18 were displayed at -20 °C degrees, as shown by GC-MS quantitative analysis. Myristic (246.99 ± 13.19 μg/g), palmitic (1707.87 ± 60.53 μg/g), stearic (852.32 ± 24.17 μg/g), and oleic (2463.03 ± 149.61 μg/g) acids were the predominant fatty acids. Furthermore, we examined the significant in vitro anti-inflammatory effects of DLL (-20 °C) using lipopolysaccharide (LPS)-challenged RAW264.7 cells. Nitric oxide (NO) and reactive oxygen (ROS) production and mRNA expression of IL-6, IL-10, COX-2, and iNOS were significantly decreased, demonstrating the anti-inflammatory function of DLL. Overall, this study provided insight into the lipid composition of DLL, revealed the influence of temperature, and explored the functionality of DLL (-20 °C), allowing for further application of DLLs as functional foods.