A compound for use in the treatment or prophylaxis of viral infections such, for example, as chicken pox or shingles caused by the Varicella Zoster virus, said compound having the general formula (II): wherein X is O, S, NH or CH2, Y is O, S or NH, Z is O, S or CH2, R1 is C1-6 alkyl, preferably n-alkyl, e.g., n-pentyl or n-hexyl, and one of R2 and R3 is H, and the other of R3 and R2 is a neutral, non-polar amino acid moiety, or a pharmaceutically acceptable salt or hydrate thereof. Said neutral, non-polar amino acid moiety R2 or R3 may be: in which R4, R5, R6 and R7 are each independently H or C1-2 alkyl. In preferred embodiments, one of R2 or R3 is valine, leucine, isoleucine or alanine, particularly valine.本發明揭示一種用於治療或預防例如由水痘帶狀疱疹病毒(Varicella Zoster virus)導致之水痘或帶狀疱疹之病毒感染的化合物,該化合物具有通式(II):其中X為O、S、NH或CH2,Y為O、S或NH,Z為O、S或CH2,R1為C1-6烷基,較佳為正烷基,例如正戊基或正己基,及R2及R3之一者為H,且R3及R2之另一者為中性非極性胺基酸部分,或其醫藥學上可接受之鹽或水合物。該中性非極性胺基酸部分R2或R3可為:其中R4、R5、R6及R7各獨立為H或C1-2烷基。在較佳實施例中,R2或R3之一者為纈胺酸、白胺酸、異白胺酸或丙胺酸,尤其為纈胺酸。
