A compound of the formula I or the formula II: ** Formula ** where: X is (C1-C6) alkyl； Y is (C1-C6) alkyl； R1 is a saturated or unsaturated (C1-C20) alkyl chain optionally comprising one or more aryl or heteroaryl rings in the chain where (C1-C20) alkyl is optionally substituted with one or more halo, cyano, nitro, carboxy, trifluoromethyl , trifluoromethoxy, aryl, heteroaryl, NRmRn, or S (O) 2NRpRq, and where any aryl or heteroaryl is optionally substituted with one or more (C1-C6) alkyl, (C1-C6) alkoxy, (C1-C6) alkanoyl, (C1-C6) alkanoyloxy, (C1-C6) alkoxycarbonyl, halo, cyano, nitro, carboxy, trifluoromethyl, trifluoromethoxy, NRaRb or S (O) 2NRcRd； R2 is H or a saturated or unsaturated (C1-C20) alkyl chain optionally comprising one or more aryl or heteroaryl rings in the chain where (C1-C20) alkyl is optionally substituted with one or more halo, cyano, nitro, carboxy , trifluoromethyl, trifluoromethoxy, aryl, heteroaryl, NRmRn, or S (O) 2NRpRq, and where any aryl or heteroaryl is optionally substituted with one or more (C1-C6) alkyl, (C1-C6) alkoxy, (C1-C6) alkanoyl ), (C1-C6) alkanoyloxy, (C1-C6) alkoxycarbonyl, halo, cyano, nitro, carboxy, trifluoromethyl, trifluoromethoxy, NRaRb or S (O) 2NRcRd； each R3, R4, R5, and R6 is independently OH or (C1-C6) alkoxy； R7 is a saturated or unsaturated (C1-C20) alkyl chain optionally comprising one or more halo, cyano, nitro, carboxy, trifluoromethyl, trifluoromethoxy, aryl, heteroaryl, NRmRn or S (O) 2NRpRq, and where any aryl or heteroaryl is optionally substituted with one or more (C1-C6) alkyl, (C1-C6) alkoxy, (C1-C6) alkanoyl, (C1-C6) alkanoyloxy, (C1-C6) alkoxycarbonyl, halo, cyano, nitro, carboxy, trifluoromethyl , trifluoromethoxy, NRaRb, aryl, heteroaryl or S (O) 2NRcRd； R8 is a saturated or unsaturated (C1-C20) alkyl chain optionally comprising one or more aryl or heteroaryl rings in the chain where (C1-C20) alkyl is optionally substituted with one or more halo, cyano, nitro, carboxy, trifluoromethyl , trifluor
