If you can grab the small center piece (red arrow) to unscrew it and you don?t have to get to the nut part (blue arrow) a pair of vice grips might work.
The small center just turns and can't be unscrewed. But, I was able to break it off of the female hose end.
I'm using some larger channel locks and sprayed it with wd40. Might try heating it a little and see if I can start a fire.