Iv'e found that zippo fluid has worked etter for me than the naptha products from the hardware store. And Xylene also. I haven't worked with DCM.
Iv'e been considering a p. viritis extraction of my own. If I were to perform such extraction, my plan would be to brew the viritis leaves in water which had been acidified with vitamine c. And brew the leaves as if one were brewing aya. Then perform an acid to base extraction on the result with sodium carbonate and zippo fluid and / or xylene.