Abstract: Millipedes (Diplopoda) are a common name for animals in the Myriapoda group of Arthropoda, which are one of the earliest groups of terrestrial animals on the Earth. Most millipede species have chemical defense glands that secrete chemicals such as phenols, quinones, and hydrogen cyanide. These substances could exhibit potent repellent, anti-feeding activities and contact toxicity against natural predators, and display significant antiinflammatory and anticancer effects, making them valuable for research and development. However, distinct types and derivatives of chemical defense compounds have evolved in different millipede species due to varying natural selection pressures during natural evolution. This has greatly increased the variety of chemical defense compounds in millipedes. We review the types and functions of compounds found in millipedes, and discuss the future research directions, aiming to provide a reference for studying millipede chemical defense and system evolution, as well as natural product chemicals.

Key words: millipede, benzoquinone, chemical defense, natural product