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Diethyl dithiolisophthalate exerts an antituberculous effect in mice comparable to that of isoniazid and streptomycin. It is effective when given in single doses, and against isoniazidresistant strains. It is most active when given subcutaneously either by injection or by absorption through the skin. Drug resistance has been demonstrated in mice, and isoniazid is active against such strains. The effects of this and other ethyl thiolesters are antagonized by their methyl analogues.

Two thiol esters, ethyl dithiolterephthalate (Compound 13,130) and ditophal (ethyl dithiolisophthalate; Etisul), have been tested for their antituberculosis activity in guinea-pigs. Compound 13,130 was active at a dose of 100 mg./Kg. twice daily by mouth in animals infected subcutaneously, but was inactive against an intracerebral infection at 50 mg./kg. Ditophal was active in the subcutaneously infected animals at 200 mg./kg. orally or 50 mg./kg. subcutaneously. Higher doses subcutaneously were irritant.

gamma-Globulin fractions isolated from guinea-pig serum by chromatography on diethylaminoethyl cellulose exhibited all the properties of kallikrein. From a range of amino acid esters tested, only esters of arginine and lysine were hydrolysed; the esterase and capillary permeability-increasing activities of different samples were correlated. Both esterase and permeability-increasing activities could be increased by the addition of certain albumin-rich fractions or of glass beads previously treated with guinea-pig serum.