Fifteen new 3-allyl-5-substituted-3,4,5,6-tetrahydro-2H-1,3,5-
thiadiazine-2-thiones were synthesized by the reaction of allylamine
with carbon disulfide and potassium hydroxide, followed by
formaldehyde and appropriate primary amine such as alkyl,
aralkylamines, glycine, L-alanine or ethyl glycine ester. The title
compounds were tested, in vitro, for antimicrobial activity against
gram-positive bacteria (Bacillus cereus, Staphylococcus aureus,
Micrococcus leuteus), Gram-negative bacteria (Escherichia coli,
Serratia marcescens, Pseudomonas aeruginosa), and some fungi
(Aspergillus flavus, Aspergillus niger, candida albicans,
Geotrichum candidum, Scopulariopsis brevicaulis and Trichophyton
rubrum), using agar disc method. Quantitative structure
activity relationship study was performed using the log form of
MIC against Scopulariopsis brevicaulis fungi and some physicochemical
descriptors (MR, L, and Fr) of substituents at N-5 position. The log MIC were found to be negatively linearly correlated
with MR and L and positively linearly correlated with Fr.