Structure-Based Discovery of Thiosemicarbazone Metalloproteinase Inhibitors for Hemorrhage Treatment in Snakebites

Abstract

The venoms of snakes are composed by many toxins, which are responsible for various toxic effects including intense pain, bleeding disorders, and local tissue damage caused by hemorrhage and necrosis. The snake venom metalloproteinases (SVMPs) are proteolytic zinc-dependent enzymes acting in different hemostatic mechanisms. In this work, a structure-based molecular modeling strategy was used for the rational design, by means of a homology 3D model of an SVMP isolated from venom (BpMP-I), followed by synthesis and evaluation of new thiosemicarbazones as the first inhibitors of the SVMP. Besides being effective for the SVMP inhibition, two molecules were shown to be effective also, inhibiting hemorrhage caused by the whole venom. Docking studies on metalloproteinases from other snake species suggest that the thiosemicarbazones activity is not confined to BpMP-I, but seems to be a common feature of metzincins.

Recent Advances in Next Generation Snakebite Antivenoms

“…As these studies indicate that the half-life of batimastat and marimastat is on par with existing antivenom, these small molecule inhibitors seem promising as supplements to existing antivenoms. In a different study, Ferreira et al utilised a combination of in vitro, in silico, and in vivo experiments in an attempt to design, synthesise, and evaluate enzyme inhibitors, which could be used as fortifying supplements for antivenoms [33]. The rational design strategy for the small molecule enzyme inhibitors employed available sequence data on the metalloproteinase BpMP-I from Bothrops pauloensis and the crystal structure of the homologous BaP-I from Bothrops asper to create a 3D model of BpMP-1, which was used to create a docking model for the inhibitors.…”

“…The rational design strategy for the small molecule enzyme inhibitors employed available sequence data on the metalloproteinase BpMP-I from Bothrops pauloensis and the crystal structure of the homologous BaP-I from Bothrops asper to create a 3D model of BpMP-1, which was used to create a docking model for the inhibitors. Since these toxins are dependent on zinc ions, molecules containing zinc chelating groups were generated and tested for their ability to inhibit the metalloproteinase in an azocasein assay [33]. Based on these results and the predicted docking geometries of these molecules and the toxin BpMP-I, two improved versions (5a and 5b) of the most promising molecule (2b) were designed ( Figure 3).…”

“…Bioinformatic models predicted that the molecules possibly bind quite well to different SVMPs, although this was not explored experimentally. Finally, it was demonstrated that compound 5B interacts with Zn2+, which likely explains its inhibiting activity on Zn2+-dependant metalloproteinases [33]. Using a phage display approach, preliminary work on toxin-neutralizing peptides has also been reported [34].…”

“…Similar to Ferreira et al, O'brien and colleagues chose to follow an approach of rationally designing, synthesising, and evaluating a molecule capable of neutralising venom activities [33,37]. They synthesised various nanoparticles from different mixtures of four components and tested their abilities to neutralise PLA2 activity of whole venoms from Bungarus caerulus, Naja mossambica, and Apis mellifera ( Figure 5).…”

Interactions between Triterpenes and a P-I Type Snake Venom Metalloproteinase: Molecular Simulations and Experiments

“…Different synthetic and natural compounds have demonstrated potential for neutralizing the proteolytic and pharmacological activities of SVMPs, including peptidomimetics Batimastat and Marimastat [ 16 , 17 ], zinc chelating agents such as EDTA, TPEN, DTPA or TTD [ 17 , 18 ], synthetic compounds, such as quinolinones [ 19 ] or thiosemicarbazones [ 20 ], and plant derived inhibitors, such as phenolic compounds [ 21 , 22 ], diterpenoids [ 23 ] and triterpenic acids [ 24 ]. In addition, computational approaches, such as molecular docking and molecular dynamics simulations have been used to study the interaction mechanisms of SVMP inhibitors and to identify new candidate compounds which were subsequently verified in experiments [ 20 , 25 , 26 , 27 ]. Molecular docking is commonly used to predict binding poses and to estimate binding affinity due to its low computational cost; however, molecular dynamics simulations coupled with approximate [ 28 ] or rigorous [ 29 ] free energy calculation techniques can provide more reliable results than the simple scoring functions used in docking.…”