Patent ID: 8168647

Claim:
A compound having structure represented by the following formula 1 or physiologically acceptable salt thereof, wherein, “ ” represents a double bond or a single bond; R 1 is R 2 is —OR 7 ′ R 3 is wherein, R 5 , R 6 , R 7 and R 8 are independently hydrogen, C 1 -C 5 alkylcarboxyl, C 3 -C 8 cycloalkylcarbonyl, C 2 -C 4 unsatuated hydrocarbylcarbonyl, C 6 -C 12 arylcarbonyl, C 1 -C 5 alkyl, C 3 -C 8 cycloalkyl, C 2 -C 4 unsatuated hydrocarbyl or C 6 -C 12 aryl, R 4 is hydrogen or fluorine.