Hughes and Barnett, along with reserve safety Forisse Hardin, will sit out because of undisclosed violations of team rules. Indiana has yet to announce which game the three players will miss.
Indiana also announced Thursday that wide receiver Jay McCants has been dismissed from the team for an unspecified rules violation, while safety Shaquille Jefferson and wide receiver Logan Young have left the program. Running back Matt Perez, tight end Paul Phillips, linebacker Ishmael Thomas and tight end Jordan Jackson will miss preseason camp because of injuries.
Hughes, a junior, led Indiana with 35 receptions for 536 yards and three touchdowns in 2011. Barnett, a junior, made nine starts last season and recorded 46 tackles, six pass breakups, a forced fumble and a fumble recovered and returned for a touchdown. Hardin started two games and had 17 tackles and an interception.
Indiana opened preseason practice Thursday.