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Ethnopharmacology Relevance: Pain often causes a series of abnormal changes in physiology and psychology, which can lead to disease and even death. Drug therapy is the most basic and commonly used method for pain relief and management. Interestingly, at present, hundreds of traditional Chinese medicines have been reported to be used for pain relief, most of which are monomer preparations, which have been developed into new painkillers. Corydalis yanhusuo is a representative of one of these medicines and is available for pain relief., Aim of the Study: This study aims to determine the analgesic effect and the potential targets of the monomers derived from Corydalis yanhusuo, and to explore any possible associated cardiac risk factors., Materials and Methods: In this study, four monomers derived from Corydalis yanhusuo (tetrahydropalmatine, corydaline, protopine, dehydrocorydaline) were tested in vivo, using the formalin-induced pain model to determine their analgesic properties. Their potential targets were also determined using whole cell patch clamp recordings and myocardial enzyme assays., Results: The results showed that all monomers showed analgesic activity and inhibited the peak currents, promoted the activation and inactivation phases of Nav1.7, which indicating that Nav1.7 might be involved in the analgesic mechanism of Corydalis yanhusuo. Protopine increased the level of creatine kinase-MB (CK-MB) and inhibited the peak currents, promoted the activation and inactivation phases of Nav1.5, indicating that Nav1.5 might be involved in the cardiac risk associated with protopine treatment., Conclusion: These data showed that tetrahydropalmatine produced the best analgesic effect and the lowest cardiac risk. Thus, voltage gated sodium channels (VGSCs) might be the main targets associated with Corydalis yanhusuo. This study, therefore, provides valuable information for future studies and use of traditional Chines medicines for the alleviation of pain., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Ethnopharmacology Relevance: Pain is an unpleasant sensory and emotional experience, often accompanied by the occurrence of a variety of diseases. More than 800 kinds of traditional Chinese medicines (TCM) has now been reported for pain relief and several monomers have been developed into novel analgesic drugs. Bupleurum chinense and Angelica biserrata were representatives of the TCM that are currently available for the treatment of pain., Aim of the Study: The study aims to detect the potential analgesic activity of each monomer of Bupleurum chinense and Angelica biserrata and to explore whether Nav1.7 is one of the targets for its analgesic activity., Materials and Methods: In this study, five monomers from Bupleurum chinense (Saikosaponin A, Saikosaponin B1, Saikosaponin B2, Saikosaponin C, Saikosaponin D) and five monomers from the Angelica biserrata (Osthole, Xanthotoxin, Imperatorin, Isoimperatorin, Psoralen) were examined by whole-cell patch-clamp on Nav1.7, which was closely associated with pain. Classical mouse pain models were also used to further verify the analgesic activity in vivo., Results: The results showed that monomers of Saikosaponins and Angelica biserrata all inhibited the peak currents of Nav1.7, indicating that Nav1.7 might be involved in the analgesic mechanism of Saikosaponins and Angelica biserrata. Among them, Saikosaponin A and Imperatorin showed the strongest inhibitory effect on Nav1.7. Furthermore, both Saikosaponin A and Imperatorin showed inhibitory effects on thermal pain and formalin-induced pain in phase II in vivo., Conclusion: The results provide valuable information for future studies on the potential of TCM in alleviating pain., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Anti-tumour-analgesic peptide (AGAP), one scorpion toxin purified from Buthus martensii Karsch, was known as its analgesic and anti-tumour activities. Trp38, a conserved aromatic residue of AGAP, might play important roles in its interaction with sodium channels. In this study, a mutant W38F was generated and effects of W38F were examined on hNav1.4, hNav1.5 and hNav1.7 by using whole-cell patch-clamp, which were closely associated to the biotoxicity of skeletal and cardiac muscles and pain signalling. The data showed that W38F decreased the inhibition effects of peak currents of hNav1.7, hNav1.4 and hNav1.5 compared with AGAP, notably, W38F reduced the analgesic activity compared with AGAP. The results suggested that Trp38 be a crucial amino acid involved in the interaction with these three sodium channels. The decreased analgesic activity of W38F might result from its much less inhibition of hNav1.7. These findings provided more information about the relationship between structure and function of AGAP and may facilitate the modification of other scorpion toxins with pharmacological effects., (© Crown copyright 2020.)

Scorpion venom is composed of a large number of bioactive peptides which display important pharmacological activities. In this study we have carried out a study of the functional role of the arginine residue at position 58 in the site RC comprising the reverse turn (8-12) and C-terminal residues 58-64. A polymerase chain reaction was used to substitute this arginine residue with a single amino acid such as alanine, glycine and lysine. The mutants were expressed in soluble form in E. coli, and purified by affinity chromatography. After target peptide purity identification, the recombinant peptides underwent a circular dichroism analysis and a study of their analgesic activity in mice. The results indicated that a single residue modification can affect the pharmacological activity. Our efforts establish a sound basis for further study of the structure-function determinants of the analgesic effect., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Pain affects approximately 30% of people and places a large economic and social burden on society. Despite the availability of a range of analgesics, complete alleviation of symptoms still rarely occurred. Effective and safe drugs for the treatment of pain are still an unmet clinical need. In recent years, the voltage-gated sodium channels (VGSCs) have been recognized as potential targets for analgesic development. VGSCs are major players in generating and propagating action potentials. They represent an appealing target for the development of new and safer drugs in the treatment of pain. The majority of the research has been focused on Nav1.7 in particular, other VGSC subtypes, such as Nav1.1, Nav1.3, Nav1.6, Nav1.8 and Nav1.9 have recently come to the forefront of analgesic research. Peptides from scorpion have been proved to be a valuable tool in neuroscience, playing a significant role in the identification and characterization of VGSC subtypes and many of them resulting in analgesia in pain. This review assesses the potential of scorpion toxin targeting VGSCs for analgesic development., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Scorpion venom contains a large variety of biologically active peptides. However, most of these peptides have not been identified and characterized. Peptides with three disulfide bridges, existing in the scorpion venom, have not been studied in detail and have been poorly characterized until now. Here, we report the recombinant expression and functional characterization of two kinds of venom peptides (BmKBTx and BmNaL-3SS2) with three disulfide bridges. This study adopted an effective Escherichia coli system. The genes for BmKBTx and BmNaL-3SS2 were obtained by polymerase chain reaction and cloned to the pSYPU-1b vector. After expression and purification, the two recombinant proteins were subjected to an analgesic activity assay in mice and whole-cell patchclamp recording of hNav1.7-CHO cell lines. Functional tests showed that BmKBTx and BmNaL- 3SS2 have analgesic activity in mice and can interact with the hNav1.7 subtype of the voltage-gated sodium channel (VGSC). Scorpion venom is rich in bioactive proteins, but most of their functions are unknown to us. This study has increased our knowledge of these novel disulfide-bridged peptides (DBPs) and their biological activities., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Residue 54 has been shown to be important for bioactivity in several toxins. However, its role in the antinociceptive activity of toxins has not been evaluated yet. In this study, site-directed mutagenesis and mouse acetic acid writhing test were used to investigate the role of Ser54 in the antinociceptive activity of BmK9 neurotoxin from the Buthus martensii Karsch scorpion. Detailed mutagenesis analysis revealed that substitution of Ser54 by various polar amino acids produced no significant change in the antinociceptive activity, while all substitutions of nonpolar amino acid for Ser54 led to a significant loss of antinociceptive activity. Following the conformational analysis, it was suggested that Ser54 in BmK9 plays a functional role in the antinociceptive activity, the residue exerts its effect by means of a side-chain hydrogen bond., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The genomic DNA sequence encoding an antitumor-analgesic peptide was amplified from the genome of Chinese scorpion Buthus martensii Karsch (BmKAGAP), then cloned and sequenced. An intron, with a high A + T content (61.6%), splits a glycine codon near the end of the precursor signal peptide and the consensus GT/AG splice junction was identified in the BmKAGAP gene. Using PCR amplification, we confirmed the identity of our cloned cDNA, and found that the BmKAGAP gene contained an intron of 506 bp in length, which was almost identical to that of the characterized scorpion sodium channel ligands in size, consensus junctions, putative branch point and A + T content. This is the first report of using a statistical method for Chinese scorpion B. martensii Karsch genomic sequence analysis, involving the extraction of some putative transcription regulatory factors. Moreover, it establishes a theoretical foundation for studying the relationship between scorpion evolution, gene expression and protein function., (Copyright 2010 Elsevier Ltd. All rights reserved.)

The scorpion Buthus martensii Karsch (BmK) has been one of the indispensable materials in Chinese traditional medicine for thousands of years. In this work, an analgesic peptide was purified through four continuous chromatographic steps. The mouse twisting test was used to identify the target peptides in every separation step. The molecular weight, isoelectric point, and N-terminal residues of the purified peptide were determined. Based on the N-terminal sequence, the cDNA was also cloned by rapid amplification of cDNA ends from the cDNA pool of scorpion glands. This peptide was identical to BmK AS, an agonist of rabbit skeletal muscle ryanodine receptors. Preliminary pharmacodynamics revealed the following: the dose-effect curve plotted by the mouse twisting test showed an ED(50) of 1.42 mg/kg; and the time-effect curves plotted by a hot plate procedure showed a similar effect to the painkiller morphine. We report a purification procedure that yields substantial amounts of natural BmK AS having high activity. BmK AS has the potential to become a new analgesic medicine.

Elucidating structural determinants in the functional regions of toxins can provide useful knowledge for designing novel analgesic peptides. A series of 100 ns MD simulations were performed on the scorpion toxin BmK AGAP in native and disulphide bond broken states. The comparison of disulphide bond broken states with the native state showed the α-helix was found to be the key to the analgesic activity. Furthermore, our results revealed disulphide bonds have considerable influence on the functionally important essential modes of motions and the correlations between the motions of the Core domain and the C-terminal region which are involved in the analgesic activity. Therefore, we can conclude that disulphide bonds have a crucial role in modulating the function via adjusting the dynamics of scorpion toxin BmK AGAP molecule. [ABSTRACT FROM PUBLISHER]

Scorpion toxins are invaluable source of therapeutic leads and pharmacological tools which produce influence on the voltage gated sodium channels. In the previous study, our group has reported BmK AGP-SYPU1 (64 amino acids), one scorpion toxin with both potential α-type and β-type scorpion characteristics and analgesic activity in vivo , act as an activator to hNa v 1.4 and hNa v 1.5. Additionally, conserved aromatic amino acids Tyr5 and Tyr42 played important roles in bioactivity of BmK AGP-SYPU1 on hNa v 1.4 and hNa v 1.5. However, the anti-nonceptitor mechanisms of BmK AGP-SYPU1 referred in vivo have not been clarified yet. The roles of Tyr5 and Tyr42 have still kept unclear in the interaction of BmK AGP-SYPU1 with other VGSCs. In this study, in order to give a deep insight into the relationship of structure and function, the effects of BmK AGP-SYPU1 and its two mutants (Y5F and Y42F) on hNa v 1.7, which has emerged as a key molecule involved in pain processing, were examined by using Na + -specialized fluorescent dye and the whole-cell patch clamp. The data showed that BmK AGP-SYPU1 also displayed as an activator to hNa v 1.7 with the potential characteristic of α-type and β-type scorpion toxin. Both Tyr5 and Tyr42 were the key amino acids to the functional properties of BmK AGP-SYPU1 when interacting with hNa v 1.7, and the Tyr42 was involved in the preferences of the toxin to distinct action sites of hNa v 1.7. On the whole, these data provided more information about the structure of BmK AGP-SYPU1 related to its function upon hNa v 1.7, and may bring some clues for engineering scorpion toxins to achieve high bioactivity with lower side effects. [ABSTRACT FROM AUTHOR]

A previous study showed that antitumor-analgesic peptide (AGAP), a novel recombinant polypeptide, which had been expressed in Escherichia coli , exhibits analgesic and antitumor effects in mice. In the present study, we investigated the underlying analgesic mechanism of AGAP. The effect of AGAP on voltage-gated calcium channels (VGCCs) was assessed in acutely isolated rat dorsal root ganglia (DRG) neurons using the whole-cell patch clamp technique. The results showed that AGAP potently inhibited VGCCs, especially high-voltage activated (HVA) calcium channels. AGAP inhibited HVA and T-type calcium currents in a dose-dependent manner, but had no significant effect on their dynamic functions in rat small-diameter DRG neurons. AGAP inhibited N- and L-type calcium currents at 78.2% and 57.3%, respectively. Thus, the present study demonstrates that AGAP affects calcium currents through the inhibition of N-, L- and T-type channels in DRG neurons, explaining the potential mechanisms of antinociception. [ABSTRACT FROM AUTHOR]