In vitro and in vivo antifilarial activity of ethynesulfonamides, epoxyethanesulfonamides and carboxamide analogues.

A series of 2-substituted trans-1,2-epoxyethanesulfonamides (1T), ethynesulfonamides (2), and their carboxamide analogues 3 (cis and trans) and 4 were evaluated for their antifilarial activity, first in vitro against the infective larvae of the filaria Molinema dessetae, then in vivo against the same filaria in Proechimys oris, its natural host. On the whole, compounds 2 displayed a high level of activity in vitro, while 4 showed a wider range and 3 were virtually inactive. The modest activity found within the series 1T was assumed to be due, in part, to the instability of the products under the conditions of the biological tests. Five new compounds within the series 1T, 2 and 4 showed a macrofilaricidal activity in vivo. There is no clear correlation between in vivo and in vitro data. It was observed, however, that within the series 2 and 4 all the compounds active in vivo were among the most potent compounds in vitro. Nevertheless, the in vitro model, although of limited value, could help in selecting compounds for further evaluation within a given series.