Do you want something like this?

if (/\b(API|APIN|UWI)\s*\./) {
    do_something if $1 eq 'API';
    do_another   if $1 eq 'APIN';
    do_else      if $1 eq 'UWI'; 
}
[download]

All in brackets is remembered for future use. Text matched in first () is stored in variable $1.