Yes I can see it on their web site.

http://www.tiendaleon.com.ar/home/em..._hacemos_2.asp
"Luggage Deposit Service: if you are a Manuel Tienda León's passenger and you want to leave your baggage with us during the day, until your room is free or your flight departure schedule approaches, you will be able to do so in our central Terminal located on 1299 E. Madero Av. Your baggage will be labeled and kept in the safest way until the last regular bus departure time, then is when our personnel will ask you to present the corresponding label."