Abstract
(1) The anti-tubercular activity of the thiosemicarbazone of nicotinaldehyde in the intravenous infection of mice with M. tuberculosis as described by Levaditi was confirmed. (2) The thiosemicarbazone of isonicotinaldehyde was found as active as the thiosemicarbazone of nicotinaldehyde and the effect of both compounds was comparable to that of Tibione. Picolinaldehyde thiosemicarbazone was ineffective. (3) The thiosemicarbazones of nicotinaldehyde and isonicotinaldehyde also were found appreciably active in the therapeutically more resistant bronchogenic type of tuberculosis of mice produced by intranasal infection. Under these experimental conditions the compounds appeared superior to Tibione.