Harvestmen (Arachnida: Opiliones) as Overlooked Predators of Anurans in the Neotropics

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  Harvestmen (Arachnida: Opiliones) as Overlooked Predators of Anurans in the Neotropics ABSTRACT Arthropods are traditionally viewed as invertebrate prey and as predators of other invertebrates, whereas vertebrates are typically considered their predators. However, this paradigm has increasingly been challenged, particularly among arachnids. While several invertebrates are well documented as frog predators, the capacity of particular groups, such as harvestmen (Opiliones), to prey on vertebrates has remained largely anecdotal. Here we report novel field observations of anuran predation by multiple Cranaidae harvestman species across several Neotropical localities. These records include the active capture and consumption of live frogs, demonstrating their role as opportunistic mesopredators. Our findings expand current knowledge of Opiliones ecology by confirming that vertebrate predation occurs across multiple species and localities. Our results suggest that vertebrate consumption...

Identification and designing an analgesic opioid cyclic peptide from Defensin 4 of Mesobuthus martensii Karsch scorpion venom with more effectiveness than morphine

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Identification and designing an analgesic opioid cyclic peptide from Defensin 4 of Mesobuthus martensii Karsch scorpion venom with more effectiveness than morphine

Abstract

Considering the limitations of use and side effects of existing analgesics, the discovery of new analgesics is necessary. Venoms of organisms are an important source of analgesic peptides. In this study, using computational biology methods such as molecular docking simulation, molecular dynamics, and predictions of physicochemical and biological properties based on various machine learning algorithms, a non-toxic 9-amino acid peptide from Defensin 4 of Mesobuthus martensii Karsch scorpion venom was discovered for the first time and named Buthicyclin. The peptide was synthesized cyclically by creating a disulfide bond, and its secondary structure was determined by Circular Dichroism (CD). Next, peptide toxicity was evaluated using MTT, hemolysis, and lethal dose (LD50) methods. Subsequently, in animal tests using Tail-flick, Hot plate, and Formalin-induced paw-licking methods, the analgesic effects of Buthicyclin in acute and inflammatory pain were evaluated, and its possible analgesic mechanism was determined. Buthicyclin has a coil-like structure and can be considered a cyclic coil with a disulfide bond. This peptide is non-toxic so its LD50 of this peptide was higher than 20 mg/kg. All analgesic tests showed that Buthicyclin peptide, at 1 mg/kg and 2 mg/kg (significantly greater), was more potent and stable than 2 mg/kg morphine in all time intervals. The results also indicated that Buthicyclin could exert its analgesic effects through binding to opioid receptors. Given the potent and long-lasting analgesic effects of Buthicyclin and its non-toxicity, Buthicyclin can be considered a promising candidate for new analgesic drugs. However, this claim requires more preclinical and clinical trials.
Aliakbari, F., Rahmati, S., Ghanbari, A., Madanchi, H., & Rashidy-Pour, A. (2025). Identification and designing an analgesic opioid cyclic peptide from Defensin 4 of Mesobuthus martensii Karsch scorpion venom with more effectiveness than morphine. Biomedicine & Pharmacotherapy, 188, 118139. https://doi.org/10.1016/j.biopha.2025.118139