**Background**
Spinal cord injury (SCI) often leads to severe neurological deficits due to the rapid onset of neuronal cell death and subsequent chronic dysfunction. A critical driver of this pathology is the overactivation of calpains, which are calcium-dependent cysteine proteases. The activation of calpains contributes to the degradation of cytoskeletal proteins and the triggering of apoptotic pathways, exacerbating the damage to the spinal cord. Consequently, targeting calpain activity has become a significant area of research for developing neuroprotective strategies to improve motor function and recovery after SCI. In this context, we will introduce a potent inhibitor of calpain and cathepsin proteases – ALLM.
**Definition**
ALLM is a potent calpain inhibitor II used to prevent neuronal cell death and improve neurological outcomes. According to the ALLM description, this compound effectively targets both calpain and cathepsin proteases to exert its protective effects.
**In Vitro and In Vivo Studies**
The ALLM biological activity has been extensively evaluated in both cellular and animal models. In vitro studies assessing cytotoxicity showed that ALLM exhibited low toxicity across various cell lines; specifically, the CC50 values were greater than 100 μM in human A549, Caco-2, dog MDCK, and African green monkey Vero cells. Additionally, antiviral activity was observed in HeLa cells with an IC50 of 23.7 μM against human rhinovirus-14, and an EC50 of 2.07 μM against SARS-CoV-2 in Vero E6 cells.
Regarding ALLM in vivo efficacy, research using adult male Wistar rats (280-300g) in a compression-induced spinal cord injury model demonstrated significant therapeutic potential. Administration of ALLM at a dose of 0.5 mg/kg, injected intraperitoneally every 24 hours for 5 days, successfully inhibited the activation of calpain without affecting the activation of caspase 3, thereby preventing neuronal cell death. Furthermore, treatment with ALLM at doses ranging from 0.05 to 2.5 mg/kg (i.p.; every 24 hours for 1 week) resulted in significantly improved motor function and reduced motor disturbances. In conclusion, ALLM is a potent calpain inhibitor that holds promise for the treatment of neuronal damage and the restoration of motor function following spinal cord injury.
Keywords
ALLM, 110115-07-6, Calpain inhibitor II, Proteasome, Cathepsin, neuronal, cell, chronic, neurological, function, spinal, cord, injury, motor, Inhibitor
References
[1] Stangl V, et al. Long-term up-regulation of eNOS and improvement of endothelial function by inhibition of the ubiquitin-proteasome pathway. FASEB J. 2004 Feb;18(2):272-9.
[2] Arataki S, et al. Calpain inhibitors prevent neuronal cell death and ameliorate motor disturbances after compression-induced spinal cord injury in rats. J Neurotrauma. 2005 Mar;22(3):398-406.