In vitro and in vivo investigations on the antiviral activity of a series of mixed-valence rare earth borotungstate heteropoly blues.

A series of mixed-valence rare earth borotungsto-heteropoly blues, K15H2[Ln(BW9W2O39)2].28H2O (Ln2, Ln=La, Ce, Pr, Nd, Sm, Eu, Gd), have been prepared and characterized by IR, UV, XPS, ESR and electrochemistry. The cytotoxicity and antiviral activity of these rare earth borotungstate heteropoly blues were investigated against influenza A(FluVA) strain (A/H1N1/Jingfang/1/91 and A/H3N2/Jingfang/30/95) and influenza virus B(FluVB) (B/Hufang/1/87) in MDCK cells. The results show that K15H2[Pr(BW9W2O39)2].28H2O (Pr2) exhibits the highest antiviral activity against FluVA with EC50 of less than 4.0 microg/ml (A/H1N1/Jingfang/1/91) and 6.0 microg/ml (A/H3N2/Jingfang/30/95), respectively, and has the lowest toxicity with CC50 of more than 480 microg/ml against MDCK cells. Additionally, both K15H2[Pr(BW9W2O39)2].28H2O (Pr2) and K15H2[Eu(BW9W2O39)2].28H2O (Eu2) showed excellent antiviral activities against FluVB by inhibiting FluVB replication at an EC50 of less than 8.0 microg/ml. Furthermore, investigation on in vivo antiviral activity of Pr2 against FluVA(FM1) in mice by giving the dosage either orally (p.o.) or intraperitoneally (i.p.), indicates that Pr2 exhibits higher inhibitory activity than that of positive control, virazole, and that it's more effective when administered by i.p.