Jiminua is a lady on the north side of Tai Bwo Wannai village. She runs Jiminua's Jungle Store, and helps people crafting nature runes by un-noting Pure essence at a cost of 2 coins per essence. To use this service, just Use the noted essence on her (not trade). She wears a cat training medal.
Interestingly, she sells cooked beef for more money than cooked bread, although the bread heals more. Her antipoison costs only 300 gp, which is much cheaper than the Grand Exchange price, so it's very cheap to get antipoison this way rather than from G.E. The stock is limited, though.