@caitp - in this case the escaped character `&#42; is being manually added to the source to prevent it from breaking the ngdoc comment.  Since these are always in a code block, the marked markdown processor is escaping them to `&amp;#42;`.  This processor runs right at the end of the processing after all the rendering has been done and converts them back to `*` characters.
As far as I am aware this is the only character sequence that needs to be manually de-escaped in since all other sequences don't break the comment.