I have not....I do have some 100% organic powdered spirulina that is as fine or finer then the supplements we give. I will start trying a every other or every third feeding with some dusted flies and see if I can see any results. I am sure it will take a couple weeks of supplementing before there is any results if there is any.....
I welcome the results of your "experiment". I'd love to find something that works with blues and greens. Not only for frogs but for fish too.
I don't think there is any supplement that would enhance blue or green - or if there is it's a well kept secret! The only thing I could suggest is change your lighting to focus on the blues and greens - I'm sure reef keepers could suggest some light temps etc.
D. auratus El Cope 
D. tinctorious Azureus 
D. tinctorious Inferalanis 
Dendrobates leucomelas 
Dendrobates tinctorious "Bakhuis" 
Dendrobates tinctorious "Cobalt" 
Dendrobates tinctorious "Powder Blue" 
Phyllobates bicolor 
Linear Mode
