**1. Introduction**

The Centipedes of the Chilopoda class are venomous arthropods that are widely distributed throughout the world [1–3]. The pair of glands, located in each jaw, produce venom that is used to kill or immobilize its prey by inoculation [4–6]. These animals are well adapted to urban areas and are commonly found in backyards and other home areas, and because of this, they often pose a danger to humans by injecting their venom as a defense [2]. The symptoms and complications induced by the envenomation caused by centipedes indicate that its venom comprises a natural set of proteins, peptides, and enzymes with a rich diversity of biological activities [7]. Most of the recent studies of the genus *Scolopendra* have indicated that the venom of a single centipede contains more than 500 proteins [8–10].

Centipedes' venoms have been used for hundreds of years in traditional Chinese medicine, as well as in Korea and other countries in East Asia to treat many disorders such as stroke, hemiplegia, epilepsy, cough, tetanus, burns, cardiovascular diseases, and myocutaneous disease, among others [11,12]. These historical and ethnopharmacological practices indicate that these animals' toxins could be explored for therapeutic uses and drug development. Despite this, the pharmacological properties of the toxins and the accidental envenomation of humans have not been studied extensively.

In Brazil, epidemiological data on accidents with centipedes are also very scarce. However, two retrospective studies that include occurrences recorded at the Vital Brazil Hospital of the Butantan Institute, São Paulo, Brazil, showed that the majority of accidents with centipedes were caused by the *Cryptops* and *Otostigmus* genus, with the first being responsible for more than 60% of the cases reported [2,13]. The envenomation symptoms are characterized by burning pain, paresthesia, edema, and local hemorrhage, and can develop into superficial necrosis [2,13,14]. A systemic reaction, although rare, may occur [15–20].

The toxicology of centipede venom has been understudied in Brazil, and the scarce literature that does exist generally refers to species of the Scolopendridae family, especially the genus *Scolopendra* [21–23]; this is mainly due to the difficulties of obtaining sufficient amounts of venom to conduct biological activities. In this context, the extraction of centipede venom can be time-consuming, and the yields are typically very low, even when it is extracted through electrostimulation [24].

To date, only Malta, et al. (2008) [25] have explored this class of venom in the literature, demonstrating nociception induction, edema, and myotoxicity in mice. However, this study was unable to further characterize the venom due to the difficulty of isolating the venom's toxins. Therefore, the identification of proteins and peptides responsible for the symptoms in human envenomation is highly important for the development of better treatments. In addition, these molecules may have applications in toxinology, immunology, ecology, agriculture, and pharmacy. Thus, the present study, based on the transcriptome and proteome approaches, reports the gene expression profile of the venom gland, identifies novel toxins and characterizes a new toxin that has been named Cryptoxin-1.

#### **2. Results**
