A compound or its pharmaceutically acceptable salt, wherein said compound corresponds in structure to Formula II wherein D and F are the same or different and are CH 2, CHD, CD 2; circle A is an aromatic or heteroaromatic ring system containing one ring or two fused rings; W is O or NR 7; X is -S 2 -; R 1 represents up to three substituent groups that themselves are the same or different, R 1a, R 1b, and R 1c, wherein each of those three groups, R 1a-c, is separately selected from the group consisting of H, C 1 -C 6 hydrocarbyl, C 1 -C 6 hydrocarbyloxy, C 1 -C 6 hydrocarbyl-oxycarbonyl, trifluoromethyl, trifluoromethoxy, C 1 -C 7 hydrocarboyl, hydroxy-, trifluoromethyl- or halogen-substituted C 1 -C 7 hydrocarboyl, C 1 -C 6 hydrocarbylsulfonyl, C 1 -C 6 hydrocarbyloxysulfonyl, halogen, nitro, phenyl, cyano, carboxyl, C 1 -C 7 hydrocarbyl carboxylate, carboxamide or sulfonamide wherein the amido nitrogen in either group has the formula NR 3 R 4 wherein R 3 and R 4 are the same or different and are H, C 1 -C 4 hydrocarbyl, or R 3 and R 4 together with the depicted nitrogen form a 5-7-membered ring that optionally contains 1 or 2 additional hetero atoms that independently are nitrogen, oxygen or sulfur, M Ar, where M is -CH 2 -, -O- or -N=N- and Ar is a single-ringed aryl or heteroaryl group, and NR 5 R 6 wherein R 5 and R 6 are the same or different and are H, C 1 -C 4 hydrocarbyl, C 1 -C 4 acyl, C 1 -C 4 hydrocarbylsulfonyl, or R 5 and R 6 together with the depicted nitrogen form a 5-7-membered ring that optionally contains 1 or 2 additional hetero atoms that independently are nitrogen, oxygen or sulfur; and R 2 is H or C 1 -C 6 hydrocarbyl, R 7 is H, C v h where each of v and h is 0, 1, 2 or 3 and v+h = 3, C q r -aliphatic C 1 -C 11 hydrocarbyl where each of q and r is 0, 1, or 2 and q+r = 0, 1 or 2, aliphatic C 1 -C 12 hydrocarbyl sulfonyl or aliphatic C 1 -C 12 hydrocarboyl. wherein D and F are the same or different and are CH 2, CHD, CD 2; circle A is an aromatic or heteroaromatic ring system containing one ring or two fused rings; W is O or NR 7; X is -S 2 -; R 1 represents up to three substituent groups that themselves are the same or different, R 1a, R 1b, and R 1c, wherein each of those three groups, R 1a-c, is separately selected from the group consisting of H, C 1 -C 6 hydrocarbyl, C 1 -C 6 hydrocarbyloxy, C 1 -C 6 hydrocarbyl-oxycarbonyl, trifluoromethyl, trifluoromethoxy, C 1 -C 7 hydrocarboyl, hydroxy-, trifluoromethyl- or halogen-substituted C 1 -C 7 hydrocarboyl, C 1 -C 6 hydrocarbylsulfonyl, C 1 -C 6 hydrocarbyloxysulfonyl, halogen, nitro, phenyl, cyano, carboxyl, C 1 -C 7 hydrocarbyl carboxylate, carboxamide or sulfonamide wherein the amido nitrogen in either group has the formula NR 3 R 4 wherein R 3 and R 4 are the same or different and are H, C 1 -C 4 hydrocarbyl, or R 3 and R 4 together with the depicted nitrogen form a 5-7-membered ring that optionally contains 1 or 2 additional hetero atoms that independently are nitrogen, oxygen or sulfur, M Ar, where M is -CH 2 -, -O- or -N=N- and Ar is a single-ringed aryl or heteroaryl group, and NR 5 R 6 wherein R 5 and R 6 are the same or different and are H, C 1 -C 4 hydrocarbyl, C 1 -C 4 acyl, C 1 -C 4 hydrocarbylsulfonyl, or R 5 and R 6 together with the depicted nitrogen form a 5-7-membered ring that optionally contains 1 or 2 additional hetero atoms that independently are nitrogen, oxygen or sulfur; and wherein each of those three groups, R 1a-c, is separately selected from the group consisting of H, C 1 -C 6 hydrocarbyl, C 1 -C 6 hydrocarbyloxy, C 1 -C 6 hydrocarbyl-oxycarbonyl, trifluoromethyl, trifluoromethoxy, C 1 -C 7 hydrocarboyl, hydroxy-, trifluoromethyl- or halogen-substituted C 1 -C 7 hydrocarboyl, C 1 -C 6 hydrocarbylsulfonyl, C 1 -C 6 hydrocarbyloxysulfonyl, halogen, nitro, phenyl, cyano, carboxyl, C 1 -C 7 hydrocarbyl carboxylate, carboxamide or sulfonamide wherein the amido nitrogen in either group has the formula NR 3 R 4 wherein R 3 and R 4 are the same or different and are H, C 1 -C 4 hydrocarbyl, or R 3 and R 4 together with the depicted nitrogen form a 5-7-membered ring that optionally contains 1 or 2 additional hetero atoms that independently are nitrogen, oxygen or sulfur, M Ar, where M is -CH 2 -, -O- or -N=N- and Ar is a single-ringed aryl or heteroaryl group, and NR 5 R 6 wherein R 5 and R 6 are the same or different and are H, C 1 -C 4 hydrocarbyl, C 1 -C 4 acyl, C 1 -C 4 hydrocarbylsulfonyl, or R 5 and R 6 together with the depicted nitrogen form a 5-7-membered ring that optionally contains 1 or 2 additional hetero atoms that independently are nitrogen, oxygen or sulfur; and R 2 is H or C 1 -C 6 hydrocarbyl, R 7 is H, C v h where each of v and h is 0, 1, 2 or 3 and v+h = 3, C q r -aliphatic C 1 -C 11 hydrocarbyl where each of q and r is 0, 1, or 2 and q+r = 0, 1 or 2, aliphatic C 1 -C 12 hydrocarbyl sulfonyl or aliphatic C 1 -C 12 hydrocarboyl.