Novel bicyclic compound, optical isomer thereof or pharmaceutically acceptable salt thereof, use thereof, and preparation method therefor

A compound represented by the following Chemical Formula 1, an optical isomer thereof, or a pharmaceutically acceptable salt thereof:

• in Chemical Formula 1 above,
• R1, R2, R3, R4, R5 and R6 are the same as or different from each other, and are each independently a hydrogen atom or hydroxyl (—OH);
• R7 is a substituted or unsubstituted C1-6 alkyl, a substituted or unsubstituted C2-6 alkene, a substituted or unsubstituted C3-8 heterocycloalkyl containing at least one oxygen atom (O) as a heteroatom, or a substituted or unsubstituted C3-8 heterocycloalkene containing at least one oxygen atom (O) as a heteroatom (wherein at least one H of the substituted C1-6 alkyl, the substituted C2-6 alkene, the substituted C3-8 heterocycloalkyl, or the substituted C3-8 heterocycloalkene may each independently be substituted with hydroxyl (—OH), a halogen atom, C1-6 alkyl or oxo (═O));
• n is an integer of either 0 or 1;
• 10 when n is 0, X1 and X2 are the same as or different from each other, and are each independently a hydrogen atom or hydroxyl (—OH);
• and
• when n is 1, X1 and X2 are each independently a single bond, and X3 is —O—.