Send Orders for Reprints to reprints@benthamscience.net Venoms and Toxins, хххх, хх, 1-00 1 2666-1217/хх $65.00+.00 © хххх Bentham Science Publishers RESEARCH ARTICLE Top-down and Bottom-up Approaches Revealed New Categories of Pep- tides from the Venom of Moroccan Scorpion Androctonus mauretanicus Khadija Daoudi 1,2 , Christian Malosse 3 , Bouchra Darkaoui 1 , Salma Chakir 1 , Fatima Chgoury 1 , Rachi- da Cadi 2 , Jean-Marc Sabatier 4 , Julia Chamot-Rooke 3 and Naoual Oukkache 1,* 1 Laboratory of Venoms and Toxins, Pasteur Institute of Morocco, 1 Place Louis Pasteur, Casablanca 20250, Moroc- co; 2 Laboratory of Molecular Genetics, Physiopathology and Biotechnology, Faculty of Sciences Ain Chock, Hassan II University of Casablanca, B.P 5366 Maarif, Casablanca, Morocco ; 3 Mass spectrometry for Biology Unit, Institut Pas- teur, CNRS USR 2000, 28 rue du Docteur Roux, 75015 Paris, France; 4 Laboratory INSERM UMR 1097, University of Aix Marseille, 163, Parc Scientifique et Technologique de Luminy, Avenue de Luminy, Bâtiment TPR2, Case 939, Mar- seille 13 2888, France ARTICLE HISTORY Received: June 10, 2020 Revised: August 25, 2020 Accepted: January 11, 2021 DOI: 10.2174/2666121701666210401120929 Abstract: Background: Androctonus mauretanicus (Am ) is one of the most hazardous scorpions in Morocco and has a highly toxic venom responsible for severe cases of envenomation. However, few studies have focused on deciphering its proteic composition. Objectives: Herein, we aim to map out the complete proteome of the Am venom filtrate to highlight its complexity and the polymorphism of its toxic content. This, in turn, will lead to a deeper unders- tanding of the toxins’ mechanism of action and will help uncover those with therapeutic potential. Methods: Top-down and bottom-up proteomic approaches were used complementarily to decipher the proteome of the Am venom. These approaches were carried out on nano-high liquid chromatog- raphy coupled to nano-electrospray tandem mass spectrometry (Nano-LC-ESI-MS/MS). Results: Am venom encloses a complex mixture of 269 different compounds with molecular weights ranging from 1618.74 to 14 214.84 Da. The most abundant ones showed masses from 6185.92 to 7899.53 Da (53.89%) followed by those ranging from 2079.25 to 5969.63 Da (37.81%). Interestingly, the combination of the results of both approaches allowed the screening of a total of 112 peptides. The highest percentage was represented by neuropeptides (87%), including NaTxs, KTxs, ClTxs, venom proteins, venom neuropeptides, and myotropic neuropeptides. Moreover, other peptides were identified, such as antimicrobial peptides, amphipathic peptides, cysteine-rich venom peptides, enzymes, kunitz-type inhibitors and orphan peptides. Conclusion: The Am venom appears to contain a great number of diverse peptides, some of which could prospectively be exploited for their pharmaceutical potential. Keywords: Scorpion venom, Androctonus mauretanicus scorpion, toxins, top-down, bottom-up, venomic. 1. INTRODUCTION Envenomations induced from scorpion stings represent a real threat to public health in several countries of South America, Africa, the Middle East, and Asia. The numbers for scorpion stings are still rising annually, accounting for about 1.2 M of cases and 3250 deaths [1]. In Morocco, due to its great diversity in scorpion fauna [2], scorpionism represents 50 to 60% of animal-related in- toxications, as reported by the Poison Control and Pharma- covigilance Center of Morocco (CAPM) [3-5]. Clinical manifestations resulting from scorpion enveno- mations can range from local pain to lung edema, coma and * Address correspondence to this author at the Laboratory of Venoms and Toxins, Pasteur Institute of Morocco, 1 Place Louis Pasteur, Casablanca 20250, Morocco; oukkache.naoual@gmail.com death [6-10] depending on different factors such as the spe- cies, the quantity, and the composition of the venom [ 11, 12]. Scorpion venom is a very complex mixture of compo- nents with different molecular weights that includes salts, lipids, biogenic amines, enzymes, peptides (neurotoxins), an- timicrobial peptides and other uncharacterized molecules [13-18]. Androctonus mauretanicus (Am ) is considered to be the most dangerous scorpion species in Morocco. This scorpion belongs to the Buthidae family and is responsible for 83% of lethal scorpion stings reported by CAPM [19]. Its venom is known for its high complexity and toxicity, with an LD50 value ranging from 2 to 4 μg/mouse (by intravenous injec- tion) [20, 21]. The earlier findings on the Am venom profiling have been performed using classical workflows, giving only a par-