I don't know where you can get the kits, however, I think the method web have developed to determine superoxide dismutase activity may be useful to you. It is easy to use, the reagents are inexpensive, fast and adapts to different samples. You can check it out at:
Contact RANDOX they have special kits for every enzyme and they have also represents in almost every country and if they don't have one in Nigeria send them an email may be they can ensure the shipping.