An isomer, enantiomer, diastereoisomer or tautomer of a compound, represented by formula I:
wherein A, B, R
2
, R
3
, L, M
1
, M
2
, M
3
, M
4
, Y
1
, Y
0
, Z and Sp are as defined in claim
1
, or a salt thereof, as an inhibitor of HCV NS5B polymerase.