Cloning, synthesis and target identification of a novel α-conotoxin Lt1.1 / 军事医学

Objective To discover novel conopeptides which are the antagonists of neuronal nicotinic acetylcholine receptors (nAChRs) in order to contribute to the development of novel analgesic drugs and neuropharmacological probes.Methods Based on the conserved untranslated region and intron of A-superfamily conotoxins,a novel α-conotoxin Lt1.1 was cloned from Conus litteratus.The peptide-resin was synthesized using the solid-phased method and was cleaved.The resulting linear peptide was oxidized by air to give the product containing disulfide bridges.The folding product was finally purified by HPLC.The disulfide bond connectivity was determined using the two-step oxidative folding methods.The cRNA of rat nAChRs was expressed on the membrane of Xenopus oocyte.Membrane currents were recorded using the two electrode voltage-clamp technique.Results A novel α-conotoxin designated as Lt1.1(GCCSHPACNVNNPDIC-NH2) was cloned and its disulfide connectivity was C1-C3,C2-C4.Lt1.1 selectively inhibited the α3β2 and α3β4 nAChRs with an IC50 of 166.76 and 190.00 nmol/L,respectively.Conclusion Lt1.1 is a novel 4/7 α-conotoxin that selectively targets α3β2 and α3β4 nAChRs.

Preparation of conotoxin GI antiserum and determination of neutralization activity / 军事医学

Objective To determine whether the antiserum produced by immunizing mice with conotoxin GI coupled with bovine serum albumin (BSA) could neutralize GI conotoxin.Methods The GI-BSA was prepared by glutaraldehyde-coupled method,and the mice were immunized with the GI-BSA to produce antiserum.The antibody neutralization assay was used to test the detoxication of the antiserum.Results The SDS-PAGE protein electrophoresis showed that the coupling reaction of GI hapten with BSA was successful.The two distinct protein bands of GI-BSA were more than 120×103.Each mouse was immunized four times with 99 μg every two weeks.After the fourth immunization,the serum neutralization titer was more than 1:64 000.After the intraperitoneal injection of the mixture of 100 or 200 μl of the antiserum and different doses of GI,75% of the mice survived in the group with 100 μl of the antiserum and 1× LD50 GI(16.3 μg/kg).The same percentage of mice also survived in the group of with 200 μl of serum and 25.8 μg/kg of GI.Conclusion The antiserum produced by immunizing mice with GI-BSA exhibits significant detoxication activity to conotoxin GI.

Screening of high antigenic fragments of Marburg virus GP protein and their immunogenicity / 军事医学

Objective To screen small fragments with high antigenicity in order to overcome the defects of the full-length Marburg virus GP as a vaccine antigen.Methods Based on the structure and function of GP sequence [amino acids(aa) 1-681], three small fragments,including GP1△(aa 25-239), GPM(aa 250-520) and GP2△(aa 436-648), were expressed by prokaryotic cells and immunized into mice, and the serum specific antibodies were detected after different immunization time.The proliferation of spleen lymphocytes and the concentration of cytokines of immunized mice were also measured.Results ELISA test results showed that high humoral immunity of GP2△ was produced as the full-length GP group did, and was higher than that of GP1△ and GPM (P<0.05).GP2△ immunization groups exhibited a higher SI value in mouse splenic lymphocytes stimulated by ConA than the mixed GP immunization groups did(P<0.05), but the effect was the opposite when mouse splenic lymphocytes were stimulated by the mixed GP.In addition, the amount of cytokines IL-2 and IFN-γ of mouse splenic lymphocytes in the GP2△ group was larger than that of the saline group (P<0.05), but smaller than that of the mixed GP group.Conclusion The fragment GP2△ can induce not only the high humoral immunity as GP does,but also moderate cellular immunity, which can be used for vaccine design.

Progress in toxicology and pharmacology of conotoxins / 中国药理学与毒理学杂志

Conotoxins are secreted by Conus snail,which are mainly composed of 12-40 amino acid residues and several disulfide bridges. Their diversities in sequences,disulfide bond connections and modified amino acids are different from those of peptide toxins and proteins secreted by terrestrial animals,and their targets include sodium,potassium,calcium ion channels and membrane receptors. Conotoxins have been categorized into more than 20 superfamilies,such as A,M,O,P,S,T,I,V, Y,J,D,C and L,which are characterized by consensus signal sequences and cysteine framework. According to pharmacological functions,these superfamilies are further classified into several pharma?cological families,such as α,μ,ω,κ,δ,ψ,σ,ρ,γ,conopressin and conantokins. This review briefly introduced the classifications and diversities of conotoxins,and summarized the progresses in the toxi?cology and pharmacology of conotoxins targeting calcium,sodium ion channel,nicotinic acetylcholine receptor and N-methyl-D-aspartic acid receptor. Some of the above conotoxins are highly poisonous,some have been developed as drugs or drug candidates,or have become powerful research tools for neuro?pharmacology. We hope this review will contribute to researches of toxins and related neuropharmacology.

Progress in vaccine development of Marburg virus / 军事医学

Marburg virus (MARV) is a member of the Filoviridae family and belongs to a non-segmented, single-strand and negative-sense RNA virus.Since the first discovery of virus in 1967, infections have broken out 14 times, causing the infection of 588 people and 482 deaths.The mortality is up to 82%.Marburg virus results in multiple organ infections , severe hemorrhagic fever and death .Currently, there are no available licensed vaccines or post-exposure treatment , but the vaccines have proved effective in experimental animals .This review briefly summarizes the structure , infection mechanism and the progress in vaccines of this virus .

Stability of anticoagulant peptide Hirulog-S / 军事医学

Objective To study the stability of anticoagulant peptide Hirulog-S and its lyophilized product, and to provide data on the storage conditions and clinical applications.Methods RP-HPLC was used to determine the content and the related substances of Hirulog-S and its lyophilized powder with influence factor test, accelerated test and long-term storage test.Results Light, temperature and humidity had no significant effect on the stability of Hirulog-S and its lyophilized powder in the influence factor test.The content and related substances of Hirulog-S and its lyophilized powder did not significantly change in the accelerated test ( 40℃, RH75%) and 24-month long-term storage test at room temperature and 4℃.Conclusion Hirulog-S and its lyophilized product are very stable, even after being stored at room temperature for two years.

Synthesis of favipiravir / 国际药学研究杂志

Objective To design and investigate an effective synthetic route of the antivirus compound favipiravir(T-705) with a stable and high yield. Methods The commercial available diethyl aminomalonate hydrochloride was selected as the starting material. The product of aminolysis was cyclized with glyoxal to yield 3-hydroxy-2-pyraziamide, which was subjected to nitration with KNO3, chlorination and dehydration with POCl3 and fluorination with KF to afford 3, 6-difluoropyrazin-2-carbonnitrile. The difluorate product was further hydrolyzed and oxidized to give favipiravir. Results The target compound was efficiently prepared by the above synthetic route. Conclusion The reaction conditions are mild except the fluoro-substitution, in which all reagents should be dried completely. The synthetic procedure is simple, high-yield and suitable for scale preparation.

Cloning and synthesis of a new A-superfamily conotoxin Bt14.10 / 军事医学

Objective To clone a new conotoxin Bt14.10 from Conus betulinus derived from the South China Sea, synthesize the peptide , and to determine linkage of its disulfide bridges .Methods The genomic DNA was extracted from C.betulinus venom duct while the Bt14.10 sequence was cloned using primers designed based on the untranslated region and intron.The peptide was then synthesized using solid-phase method and folded into the target product whose disulfide bridge connection was further determined by two-step oxidative folding .Results A novel conotoxin designated as Bt 14.10 (CAHSVPGMHPCKCNNTC-NH2) was obtained,the disulfide connectivity of which was C1-C3,C2-C4.Conclusion Bt14.10 is a new A-superfamily conotoxin and has a distinct loop spacing pattern between cysteines in A-superfamily conotoxins.

Design,synthesis and activity evaluation of new anti-HIV-1 CXCR4 inhibitors / 军事医学

Objective To design and synthesize a series of new type four hydrogen quinoline-benzyl/benzimidazole amine derivatives as a potential new inhibitor targeting auxiliary receptor CXCR 4, and determine their inhibitory activities to HIV-1.Methods Based on HIV-1 receptor CXCR4 inhibitors containing three nitrogen structure-activity motif and CCR5 partial hydrophobic pharmacophore , a series of new compounds were designed , synthesized and characterized by 1 HNMR and MS.The inhibitory activities of these compounds were determined using HIV-1 IIIB virus.Results and Conclusion Ten target compounds are synthesized .Four hydrogen quinoline-benzimidazole amine derivatives exhibit good anti-HIV activity(IC50 8 μmol/L).