Suppression of cardiomyocyte functions by ß-CTX isolated from the Thai king cobra (Ophiophagus hannah) venom via an alternative method

Beta-cardiotoxin (ß-CTX), the three-finger toxin isolated from king cobra (Ophiophagus hannah) venom, possesses ß-blocker activity as indicated by its negative chronotropy and its binding property to both ß-1 and ß-2 adrenergic receptors and has been proposed as a novel ß-blocker candidate. Previously, ß-CTX was isolated and purified by FPLC. Here, we present an alternative method to purify this toxin. In addition, we tested its cytotoxicity against different mammalian muscle cell types and determined the impact on cardiac function in isolated cardiac myocyte so as to provide insights into the pharmacological action of this protein. Methods: ß-CTX was isolated from the crude venom of the Thai king cobra using reverse-phased and cation exchange HPLC. In vitro cellular viability MTT assays were performed on mouse myoblast (C2C12), rat smooth muscle (A7r5), and rat cardiac myoblast (H9c2) cells. Cell shortening and calcium transient dynamics were recorded on isolated rat cardiac myocytes over a range of ß-CTX concentration. Results: Purified ß-CTX was recovered from crude venom (0.53% w/w). MTT assays revealed 50% cytotoxicity on A7r5 cells at 9.41 ± 1.14 µM (n = 3), but no cytotoxicity on C2C12 and H9c2 cells up to 114.09 µM. ß-CTX suppressed the extend of rat cardiac cell shortening in a dose-dependent manner; the half-maximal inhibition concentration was 95.97 ± 50.10 nM (n = 3). In addition, the rates of cell shortening and re-lengthening were decreased in ß-CTX treated myocytes concomitant with a prolongation of the intracellular calcium transient decay, indicating depression of cardiac contractility secondary to altered cardiac calcium homeostasis. Conclusion: We present an alternative purification method for ß-CTX from king cobra venom. We reveal cytotoxicity towards smooth muscle and depression of cardiac contractility by this protein. These data are useful to aid future development of pharmacological agents derived from ß-CTX.(AU)

Purification and antibacterial activities of an L-amino acid oxidase from king cobra (Ophiophagus hannah) venom

Some constituents of snake venom have been found to display a variety of biological activities. The antibacterial property of snake venom, in particular, has gathered increasing scientific interest due to antibiotic resistance. In the present study, king cobra venom was screened against three strains of Staphylococcus aureus [including methicillin-resistant Staphylococcus aureus (MRSA)], three other species of gram-positive bacteria and six gram-negative bacteria. King cobra venom was active against all the 12 bacteria tested, and was most effective against Staphylococcus spp. (S. aureus and S. epidermidis). Subsequently, an antibacterial protein from king cobra venom was purified by gel filtration, anion exchange and heparin chromatography. Mass spectrometry analysis confirmed that the protein was king cobra L-amino acid oxidase (Oh-LAAO). SDS-PAGE showed that the protein has an estimated molecular weight of 68 kDa and 70 kDa under reducing and non-reducing conditions, respectively. The minimum inhibitory concentrations (MIC) of Oh-LAAO for all the 12 bacteria were obtained using radial diffusion assay method. Oh-LAAO had the lowest MIC value of 7.5 µg/mL against S. aureus ATCC 25923 and ATCC 29213, MRSA ATCC 43300, and S. epidermidis ATCC 12228. Therefore, the LAAO enzyme from king cobra venom may be useful as an antimicrobial agent.(AU)

A preliminary study of egg yolk antibody for kingcobra venom antigens detection / 中国药理学通报

Aim To discuss whether specific Egg yolk antibody(IgY) can be used for snake venom antigens detection.Methods Chickens(white Leghorn) were immunized with detoxicated king cobra venom by formaldehyde.Egg yolk antibody were isolated from egg yolk,and labeled with horse radish peroxidase(HRP).Snake venom antigens samples,including king cobra venom,cobra venom,bungrarus fasciatus venom,bungrarus multicinctus venom,agkistrodon actus venom and Guangdong viper venom,were detected using ELISA,and sensitivity,precision and specificity were tested,respectively.Results At about 32 ?g?L~(-1),the king cobra antigens were detected using the method;Linear relation was better(r=0.963) when the concentration of kingcobra venom was within 32～750?g?L~(-1).The method had good specificity and no cross reactivity was observed among the reagents and agkistrodon acutus guenther venom and vipera russelli siamensis smith venom;little cross reactivity was shown with bungarus multicinctus blyth venom and bungarus fasciatus chmeider venom;cross reactivity was obvious with cobra venom;the average intra-assay coefficient of variation(CV) was 1%～3%,and the inter-assay CV was within 8%.Conclusions The study indicates that IgY can be good reagents for snake venom antigens detecton,and the study provides foundation for the development of the diagnosis kits of snakebites.

King cobra egg yolk antibody from the egg yolks of immunized hens / 中国药理学通报

Aim To develop King cobra antivenom from the egg yolks of immunized hens,and study dynamic expression of IgY in egg yolks.Methods chickens(white Leghorn) were immunized with detoxicated King cobra venom by formaldehyde ,Egg yolk antibody (IgY) was isotated by thiophilic interaction chromatography and identified by SDS-PAGE. Activity of IgY was evaluated by enzyme-linked immunoserbent assay(ELISA) and Double immuodiffusion. Protein was measured using folin-lowry method. Results Specific antivenom could be detected in the yolk laid by the hens 9 d after immunization, At the 60th day after primary immunization ,ELISA titers reached 1∶ 100 000,and 97.5 mg IgY?ml -1 yolk was obtained from thiophilic interaction chromatography. IgY was highly specific, No cross reactivity was observed among IgY and agkistrodon acutus venom and vipera venom ;Little cross reactivity was shown with cobra genus venoms.Conclusion King cobra IgY was obtained and purified from the egg yolks of immunized hens,The dynamic expression of IgY was manitered during the course of immunization,Further investigation is needed.

Effect of king cobra venom on α2 –macroglobulin and proteases in human blood plasma.

Normal human blood plasma showed hydrolytic activities on several synthetic substrates for proteases, the most effective being H-D-Ile-Pro-Arg-p-nitroanilide, H-D-Pro- Phe-Arg-p-nitroanilide and H-D-Val-Leu-Arg-p-nitroanilide. When plasma was preincubated for 12 h at 37°C, there was no significant alteration of the hydrolytic activities. On incubation for 12 h with king cobra venom (2 μg for 0·1 ml plasma), there was considerable decrease in the activities and complete abolition of the protease binding capacity of α2-macroglobulin. On chromatography on Sephadex G-200, α2-macroglobulin activity and bulk of the protease activity of normal plasma were eluted in the void volume region. A minor protease peak was eluted with a Ve/Vo value of 2·5. With venom treated plasma, there was no decrease with this peak. The major protease peak and α2-macroglobulin activity were drastically reduced. Chromatography on red Sepharose showed that all the a2- macroglobulin activity and bulk of the protease activity in normal plasma were bound to the column. In venom treated plasma there was marked reduction in the bound fraction. The data suggest that cobra venom proteases directly or through proteases generated in plasma in situ causes limited cleavage of α2-macroglobulin as well as α2– macroglobulin bound proteases, inactivating them.