Per the source, Gunners boss Arsene Wenger is considering alternatives to chief target Valencia defender Shkodran Mustafi with Toprak and Fenerbahce defender Simon Kjaer among the alternatives.
Toprak has himself hinted that he could leave Bayer but did not confirm which clubs have shown an interest.
Toprak was quoted by Turkish-Football.com as saying: “It is not certain whether I will stay at Bayer Leverkusen, we still have a month and anything could happen until them.”
The North London based outfit could however, face competition for his signature.
The report claims that United scouted Toprak all season and that they were plotting a move for the experienced defender.
The Turkish international has 23 caps for his country and has made 171 appearances for Bayer since joining from Freiburg in 2011.
Wenger was heavily criticised following Arsenal’s 4-3 defeat at home to Liverpool in their opening game of the season, especially for not strengthening the defence and striker positions.
The Arsenal boss was short at options in defence with Mertesacker, Gabriel and Koscileny all out. Wenger was forced to play Rob Holding and Calum Chambers at the back as a result.