Broad spectrum anti-RNA virus activities of titanium and vanadium substituted polyoxotungstates.

Seven polyoxotungstates substituted with vanadium or titanium atoms were examined for their activity against Flaviviridae (Dengue fever virus, DFV), Orthomyxoviridae (influenza virus type A, fluV-A), Paramyxoviridae (respiratory syncytial virus, RSV, parainfluenza virus type 2, PfluV-2 and canine distemper virus, CDV) and Lentiviridae (human immunodeficiency virus type 1, HIV-1) families. Among the seven polyoxotungstates examined, PM-43 [K(5)[SiVW(11)O(40)]], PM-47 [K(7)[BVW(11)O(40)]], and PM-1001 [K(10)Na(VO)(3)(SbW(9)O(33))(2)]26H(2)O contained vanadium. PM-1002 had the same core structure of (VO)(3)(SbW(9)O(33))(2) as PM-1001; however, three V atoms of PM-1001 consisted of two V(IV) and one V(V) and those of PM-1002 consisted of three V(IV). On the other hand, PM-518 [[Et(2)NH(2)](7)[PTi(2)W(10)O(40)]], PM-520 [Pri(2)NH(2)](5)[PTiW(11)O(40)] and PM-523 [PriNH(3)](6)H[PTi(2)W(10)O(38)(O(2))(2)]H(2)O all contained titanium. All compounds showed broad spectrum antiviral activity against all viruses examined except for PMs-43, -518 and -523 which did not exhibit inhibitory activity at >/=50 microM against PfluV-2, CDV and DFV, respectively. All compounds were inhibitory against HIV replication at an EC(50) of less than 2.0 microM. Among them, PMs-1001 and -1002 showed the most potent inhibition. The compounds were not toxic for MDCK, HEp-2 and Vero cells at a concentration of 200 microM. For the exponentially growing MT-4 cells, the vanadium containing polyoxometalates (PMs-43, 47, 1001, 1002) showed toxicity at concentrations between 41 and 47 microM. On the other hand, titanium containing polyoxometalates (PMs-518, -520, -523) were not toxic at 100 microM. The mechanism of anti-HIV action of PM-1001 was analyzed: it affected the binding of HIV to the cell membrane and syncytium formation between HIV-infected and uninfected cells.