Turkey's heavyweight boxing champion Sinan Şamil Sam, who was known as "Bull of the Bosporus," has died of liver failure in Istanbul, his brother announced Friday.Sam was only 41 years old.His brother, Alparslan Sam, told reporters that the boxing champ had been suffering from liver problems for five years. He passed away early in the morning at the Marmara University Pendik Training Research Hospital in Istanbul.He will be buried in Ankara on Saturday."We are at the point where words fail. I am too sad," his brother said.Sinan Şamil Sam was born in the German city of Frankfurt in 1974. He bagged several boxing championship titles during his career. In 1992, he was crowned the Junior World Champion; he was the European Champion in 1993 and in 1999 he became the Amateur World Boxing Champion. He also won the world intercontinental heavyweight boxing champion title in 2004.In his career, he had won 31 matches out of his 35 fights; 16 of his victories ended in knockouts. Sam, first entered intensive care after he was hospitalized for liver failure five years ago in December 2010 due to excessive alcohol consumption. He was hospitalized in 2010 in Ankara after vomiting blood and was rushed to the 29 Mayıs Hospital and since then, the former world champ had been battling an alcohol addiction that had left him in need of a liver transplant.