Extracellular cyclophilin inhibitor and use thereof

An extracellular cyclophilin inhibitor having a structure shown in Formula (I), or a pharmaceutically acceptable salt thereof:

• wherein,
• R1 is —CH═CHR1′ or —CH2CH2R1′;
• wherein, R1′ is selected from alkyl, carboxyl, —(CH2)n—COOH, acetamino, —(CH2)n—NH(C═O)CH3, phenyl, or phenyl with one or more substitution of —COOCH3 and/or one or more substitution of —CH2NH(C═O)CH3, wherein n is an integer of 1-6;
• R2 is H, SR2′, CH2SR2′, or CH2OR2′;
• wherein, R2′ is selected from alkyl, carboxyl, —(CH2)m—COOH, hydroxy, —(CH2)m—OH, acetamino, —(CH2)m—NH(C═O)CH3, phenyl, or phenyl with one or more substitution of —COOCH3 and/or one or more substitution of —CH2NH(C═O)CH3, wherein m is an integer of 1-6;
• and
• the linker is selected from —(CH2)x—NH(C═O)—(CH2)y— or —(CH2)x—NH(C═O)—(CH2CH2O)y—;
• wherein, x is an integer of 1-4, and y is an integer of 1-6.