(4R,4aS,6S,6aR,11bS)-6-Carboxy-3-(cyclopropylmethyl)-1,2,3,4,4a,5,6,6a-octahydro-4a,6,8-trihydroxy-3-methyl-4,11-methanobenzofuro[3',2':2,3]cyclopenta[1,2-c]pyridinium, Inner Salt