How to call an "Admin" role in an IF in C #?

I have created several roles for me to do an access control. So I want to know how to call the admin role so I can pass in an if, type example that I'll put below in my _layout:

  @if ("Aqui que eu preciso saber como chamar a role admin")
                {
                    <li>@Html.ActionLink("Início", "Index", "Home")</li>
                    <li>@Html.ActionLink("Sobre", "About", "Home")</li>
                    <li>@Html.ActionLink("Contato", "Contact", "Home")</li>
                }
                else
                {
                    <li>@Html.ActionLink("Sobre", "About", "Home")</li>
                }

Here's how I created the role in my startup file:

public partial class Startup
{
    public void Configuration(IAppBuilder app)
    {
        ConfigureAuth(app);
        createRolesandUsers();
    }


    // In this method we will create default User roles and Admin user for login  
    private void createRolesandUsers()
    {
        ApplicationDbContext context = new ApplicationDbContext();

        var roleManager = new RoleManager<IdentityRole>(new RoleStore<IdentityRole>(context));
        var UserManager = new UserManager<ApplicationUser>(new UserStore<ApplicationUser>(context));


        // In Startup iam creating first Admin Role and creating a default Admin User   
        if (!roleManager.RoleExists("Admin"))
        {

            // criando a role do usuario Admin 
            var role = new Microsoft.AspNet.Identity.EntityFramework.IdentityRole();
            role.Name = "Admin";
            roleManager.Create(role);

            //Aqui estou criando o usuario que terá o acesso completo                 

            var user = new ApplicationUser();
            user.UserName = "ebase";
            user.Email = "[email protected]";

            string userPWD = "123456";

            var chkUser = UserManager.Create(user, userPWD);

            //Add default User to Role Admin  
            if (chkUser.Succeeded)
            {
                var result1 = UserManager.AddToRole(user.Id, "Admin");

            }
        }