The Ultimate Fighter: Brazil 2 welterweight winner Leonardo Santos has retired from MMA following a decision defeat to Jared Gordon at UFC 278 on Aug. 20, he announced Thursday night on social media. Santos leaves the sport on a three-fight skid to Grant Dawson, Clay Guida and Gordon, bringing his professional record to 18-6-1. At one point during his UFC run, Santos was unbeaten in eight consecutive bouts against the likes of Kevin Lee and Anthony Rocco Martin. “A topic that felt so distance for me is now present in my life,” Santos wrote in Portuguese. “One of the toughest…