Complex sentence: Mostapha was the ADCC European Champion in 2005 and was the British Cage Rage Heavyweight Champion, before relinquishing his title to sign a four-fight deal with the UFC.
Split into simpler sentences: Mostapha was the ADCC European Champion in 2005. He has recently relinquished his British Cage Rage Heavyweight title and signed a four-fight deal with the UFC.