Diplodomica II. Repugnatorial secretion of Ecuadorian endemic millipede Rhinocricus sp. (Diplopoda, Spirobolida, Rhinocricidae) from Orellana Province, Amazonia, Ecuador

Millipedes (Myriapoda: Diplopoda), with more than 80.000 species, represent one of oldest and evolutivelly successful classes of invertebrates. The order Spirobolida is dominantly tropical in its distribution and diversification and the family Rhinocricidae is wide distributed in the Ecuadorian edaphic fauna inhabiting in the Amazonia region. Their repugnatorial secretions constitute a source of biologically active metabolites with a great molecular diversity. The millipede collected were stimulated mechanically and an ejected fluid was subjected to structural analysis. The spectral (FTIR, NMR-¹H/¹³C) and chromatographic-mass data (GC-MS) analysis of the defensive-repugnatorial secretion of the endemic millipede Rhinocricus sp., inhabiting in the Ama-zonian region of Orellana, Republic of Ecuador, and chemical evidence (chromogenic reactions: KI starch paper and rodanine test in aqueous ammonia) as well, reveled the quinonoide composition of the secretion. Was identified 2-methyl-3-methoxy-1,4-benzoquinone as an active major component. It can be ejaculated from dorsolateral ozo-pores in the event of strong mechanical irritation, disturbance and predator attack in natural conditions. The defensive secretion showed an interesting biocide effect vs. human pathogens at concentrations in the interval of 7.25 μg/mL and 34.4 μg/mL for Fonsecae pedrosoi and Candida albicans respectively. 2-methyl-3-methoxy-1,4-benzoquinone is one of the most prevalent active substance in the defensive secretions in the orders Spirobolida and Spirostreptida, independently of geographical distribution of taxa. This is the first report related to chemical composition of repugnatorial secretion of Ecuadorian Rhinocricidae from Amazonian region. The results concerning biological action and its detailed mechanism of action (repellent, microbiocidal, virucidal and insecticidal effects) will be reported soon.