Place drumsticks in a large ziplock bag. In a large bowl stir together juice concentrate, soy sauce, ginger, salt, garlic, and cayenne pepper.
RESERVE 1/2 CUP MARINADE FOR SAUCE.
Pour the remaining marinade in the ziplock with the chicken. Seal bag; and turn to coat chicken. Marinate in the refrigerator for 4-24 hours, turning bag occasionally.
Preheat oven to 375 degrees. Drain chicken and discard marinade. Arrange chicken in a large baking pan. Bake for 20 minutes.
Meanwhile, in a small bowl stir together the 1/2 cup reserved marinade and the brown sugar.
Brush both sides of chicken with some of the sauce. Bake for 20 more minutes more minutes brushing once more with the remaining sauce. Sprinkle with green onions and sesame seeds, if desired.