Adenosine analog and its use in regulating the circadian clock

A composition comprising an adenosine analogue compound of Formula I or a pharmaceutically acceptable salt thereof and pentostatin,

• wherein:
• R1 is H;
• R2 is H, OH, O-Biotin, OAc, OTBS, F, Cl, Br, or I;
• R3 is OH, O-Biotin, OAc, or OTBS;
• or R2 and R3 are independently absent or ═O;
• R4 and R5 are independently H, OH, F, Cl, Br, I, ═O, O-Biotin or N3;
• or R2/R3 and R4/R5 form expoxy ethane together with the carbons they are connected to;
• R6 and R7 are independently H, CH2—OH, CH2—N3, CH2—O-Biotin, CH2—AcO, CH2—OTBS, CO2Me, triphosphorylated methylene, 1,2-bishydroxyethane, tetrabutylammonium monophosphate, 1-hydroxyprop-2-yn-1-yl, or diazacymene;
• R8 is H, NH—CH3, F, Cl, Br, I, —O—CH3, or deuterium;
• R10 is H, —CH3, F, Cl, Br, I, NH2, NH—CH3, NH—NH2, ═O, NHBn, Biotinamide, m-hydroxyaniline, amino-cyclopropane, amino-cyclobutane, amino-cyclopentane, amino-cyclohexane, OMe or octamide;
• and
• R12 is H, NH2, F, Cl, Br, I, OMe, or 4-formamide-substituted pyrazole,
• wherein the adenosine analogue compound does not include adenosine itself.