Anxiolytic Effect of Peptides from Sea Anemone Heteractis crispa, Modulators of TRPV1 and ASIC Channels.

A number of studies confirmed the involvement of transient receptor potential vanilloid (TRPV) and acid-sensing (ASIC) ion channels in the physiological processes associated with the development of anxiety disorders. This makes their ligands new potential anxiolytic agents. We examined the efficacy of two peptides from the sea anemone Heteractis crispa, Hcr 1b-2 and HCRG21, affecting ASIC1a and TRPV1 channels, respectively, in the open field and elevated plus maze tests. According to the obtained data, HCRG21 significantly decreases both the level of anxiety and stimulates the activity of animals at doses of 0.01-1 mg/kg, whereas Hcr 1b-2 has a weak anxiolytic effect only at a dose of 0.1 mg/kg. The pharmacodynamic study showed that the HCRG21 has an anxiolytic effect for 2 h, and its effectiveness is higher than that of the reference drug.

New Sea Anemone Toxin RTX-VI Selectively Modulates Voltage-Gated Sodium Channels.

A new neurotoxin RTX-VI that modulates the voltage-gated sodium channels (NaV) was isolated from the ethanolic extract of the sea anemone Heteractis crispa. Its amino acid sequence was determined using the combination of Edman degradation and tandem mass spectrometry. RTX-VI turned out to be an unusual natural analogue of the previously described sea anemone toxin RTX-III. The RTX-VI molecule consists of two disulfide-linked peptide chains and is devoid of Arg13, which is important for the selectivity and affinity of such peptides for the NaV channels. Electrophysiological screening of RTV-VI on NaV channel subtypes showed its selective interaction with the central nervous system (NaV1.2, NaV1.6) and insect (BgNaV1, VdNaV1) sodium channels.

Peptide Blocker of Ion Channel TRPV1 Exhibits a Long Analgesic Effect in the Heat Stimulation Model.

The ion channel TRPV1, which is one of the most important integrators of pain and inflammatory stimuli, is considered a promising therapeutic target in the treatment of pain conditions. In this work, we performed a comparative study of the analgesic effect in the "hot plate" test of recombinant analogues of Kunitz-type peptides from the sea anemone Heteractis crispa venom: APHC1-modulator of TRPV1 and HCRG21-a full blocker of TRPV1. As a result of biological tests, it was shown that the full blocker HCRG21, despite the higher value of 50% effective concentration of TRPV1 inhibition, had an equal analgesic ability with the APHC1 upon intramuscular administration and retained it for 13 h of observation. The analgesic effect of APHC1 at a dose of 0.1 mg/kg when administered intramuscularly developed very quickly in 5 min but lasted 3 h. The differences in the pharmacodynamic profile of the peptides are in good agreement with different mechanisms of binding to TRPV1.

Magnificamide Is a New Effective Mammalian α-Amylase Inhibitor.

Recombinant analogue of the sea anemone Heteractismagnifica peptide was obtained, and the kinetic parameters of its interaction with mammalian α-amylases were determined. Magnificamide inhibits α-amylases significantly stronger than the medical drug acarbose (PrecoseTM or GlucobayTM). Magnificamide is assumed to find application as a drug for prevention and treatment of metabolic disorders and type 2 diabetes mellitus.

New Targets of Kunitz-Type Peptide from Sea Anemone Heteractis magnifica.

The interaction of Kunitz-type peptide, HMIQ3c1, from the sea anemone Heteractis magnifica with several serine proteases, including inflammatory proteases, was investigated using the surface plasmon resonance approach. We showed that the recombinant analog of HMIQ3c1 forms sufficiently strong complexes with trypsin (KD = 1.07 × 10-9 М) and chymotrypsin (KD = 4.70 × 10-8 М). Analysis of thermodynamic parameters of HMIQ3c1/chymotrypsin revealed significant contribution of the entropic factor to the complex formation. The formation of specific complexes of HMIQ3c1 with the kallikrein (KD = 2.81 × 10-8 М) and neutrophil elastase (KD = 1.11 × 10-7 М) indicates its anti-inflammatory activity and makes prospects to use the peptide as a potential therapeutic agent.

[Anti-Inflammatory Activity of the Polypeptide of the Sea Anemone, Heteractis crispa].

The anti-inflammatory effect of the recombinant polypeptide HCGS 1.20, a Kunitz-type serine protease inhibitor of the sea anemone Heteractis crispa, was investigated. It was shown that the polypeptide inhibits the increase of the concentration of calcium ions in mouse bone marrow derived macrophages elicited by histamine, and reduces the content of NO in lipopolysaccharide stimulated macrophages. A presumable mechanism of anti-inflammatory action of the polypeptide was being discussed.

New Actinoporins from sea anemone Heteractis crispa: cloning and functional expression.

A new actinoporin Hct-S4 (molecular mass 19,414 ± 10 Da) belonging to the sphingomyelin-inhibited α-pore forming toxin (α-PFT) family was isolated from the tropical sea anemone Heteractis crispa (also called Radianthus macrodactylus) and purified by methods of protein chemistry. The N-terminal nucleotide sequence (encoding 20 amino acid residues) of actinoporin Hct-S4 was determined. Genes encoding 18 new isoforms of H. crispa actinoporins were cloned and sequenced. These genes form a multigene Hct-S family characterized by presence of N-terminal serine in the mature proteins. Highly conserved residues comprising the aromatic phosphorylcholine-binding site and significant structure-function changes in the N-terminal segment (10-27 amino acid residues) of actinoporins were established. Two expressed recombinant actinoporins (rHct-S5 and rHct-S6) were one order less hemolytically active than native actinoporins.

Proteinase inhibitors from the tropical sea anemone Radianthus macrodactylus: isolation and characteristic.

Two new serine proteinase inhibitors (RmIn I and RmIn II) from the tropical sea anemone Radianthus macrodactylus have been isolated and characterized. The purification procedure includes polychrome-1 hydrophobic chromatography, Superdex Peptide 10/30 FPLC, and Nucleosil C(18) reverse-phase HPLC. The molecular masses of RmIn I, RmIn II, and the complexes RmIn II/trypsin and RmIn I,II/alpha-chymotrypsin have been determined. The K(i) values of RmIn I and RmIn II for trypsin and alpha-chymotrypsin have been determined. The polypeptides RmIn I and RmIn II are shown to be nontoxic and to exhibit antihistamine activity. The N-terminal amino acid sequences of RmIn I (GICSEPIVVGPCKAG-) and RmIn II (GSTCLEPKVVGPCKA-) have been determined. A high homology of the amino acid sequences is demonstrated for the proteinase inhibitors produced by such evolutionarily distant species as coelenterates, reptiles, and mammals.