Methisazone , antiviral action

Inhibition of adenovirus 11 by methisazone> t ame as a surprise however, the virus dose used was extremely small and it was found, by other test methodsthat methlsazone did not affect plaque formation of adenoviruses 1, 2, and 5 These same methods did reveal that methlsazone produced considerable toxicity in HeLa cells, the type of cell used in the original study. It is possible that the antiviral action observed was due to a toxic reaction not readily observed in the test system used. 

Methisazone 6.19) (l-methylisatin-3-thiosemicarbazone, Marboran ) inhibits the multiplication of vaccinia virus in experimental animals. The antiviral action is extraordinarily high. Mice infected intracerebrally with 1000 mean lethal doses (LD50) of vaccinia (cowpox) virus required only 0.5 mg/kg for protection, and only 10 mg/kg was needed for protection against variola major... 

Antiviral drugs. It is thought that methisazone (6.16) and its analogues owe their antiviral action (see Section 6.3b) to chelation in which the metal is held between the oxygen atom and the second nitrogen of the side-chain (O Sullivan and Sadler, 1961). 

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