OK, I had a problem here when converting bio2rdf.org irefindex data into nanopublication using sparql here: 

in a database, if the item you are looking for has multiple types, but you only need one of those types in your converted data, what you can do is to use a sparql filter function with regex

1. the proper sparql filter syntax is as follows: 

select ?s where{  ?s ?p ?o .  filter ( #your statements here for filter ) #it's brackets () not curly parenthesis {} }

2. the proper regex to match those items that you don't want 

^.*?(?
     

^.*?(?