MessageBox_Message_Cleanup_BizTalkMsgBoxDb
MessageBox_Parts_Cleanup_BizTalkMsgBoxDb
PurgeSubscriptionsJob_BizTalkMsgBoxDb
MessageBox_DeadProcesses_Cleanup_BizTalkMsgBoxDb
TrackedMessages_Copy_BizTalkMsgBoxDb
TrackingSpool_Cleanup_BizTalkMsgBoxDb
Run the above jobs in SQL Server which will release the unused memory.