Synthesis And Biological Activity Of 1,2,4-triazole Compounds Containing Decyl Esters

1,2,4-Triazole and its derivatives are acknowledged to possess extensive bioactivities including antimicrobial, antiviral, antitumor and regulating plants growth. Particularly, many substituted 1,2,4-triazole derivatives were proved to be a very promising class of antimicrobial compounds such as commercial fungicide Triadimefon, Triadimenol, Diniconazole, Tebuconazole and Propiconazole, which are used very often in agricultural disease control. Meanwhile, compounds containing oxime ester moiety are also reported as potent antimicrobial, insecticidal and antiviral agents and this structure is used often in structural modification and improvement of lead compounds. In this paper, oxime ester moiety was introduced into 1,2,4-triazole according to the principle of superposition of bioactive substructures by the formation of thioether and the structures of newly synthesized compounds have been characterized by 1H NMR, 13 C NMR, IR and MS. The title compounds were also evaluated for their antimicrobial activities in vitro against three bacteria and six fungi. Meanwhile, their antiviral activity were tested against tobacco mosaic virus.In the synthesis of compounds, the key intermediates 4-amino-5-substituted-1,2,4-triazol-3-thiols were obtained by reactions of esterification, hydrazinolysis, cyclization and ring transformation starting with the substituted carboxylic acid; Another key intermediates substituted ketone O-(2-chloroacetyl) oxime were prepared by reactions of oximation and esterification starting with the substituted ketone; A series of 32 novel 1,2,4-triazole derivatives containing oxime ester moiety were synthesized by reacting 4-amino-5-substituted-1,2,4-triazol-3-thiols with substituted ketone O-(2-chloroacetyl) oxime. All the title compounds were characterized by 1H NMR, 13 C NMR, IR and MS.In the antimicrobial bioassay, the turbidimeter test and the mycelial growth rate method were employed respectively for bioactivity evaluation of the title compounds against three phytopathogenic bacteria and six phytopathogenic fungi in vitro. The results of the antibacterial bioassay showed that most of the title compounds demonstrated good activity against X. citri, R. solanacearum and X. oryzae compared with the commercial antibacterial agents Thiodiazole-copper and Bismerthiazol at the concentration of 200 ?g/mL. Especially, six compounds showed excellent activity against bacterium X. oryzae with EC50 values of 15.15-24.84 ?g/mL; The results of the antifungal bioassay showed that most of the tested compounds were capable of inhibiting the growth of these fungi, namely, G. zeae, F. oxysporum, C. mandshurica, P. infestans, P. sasakii, S. sclerotiorum.In the test of antiviral activities, the half-leaf method was employed for bioactivity evaluation of some title compounds against TMV. The results showed that this series of compounds had low bioactivities against TMV, among which VII-5 showed good curative activity closing to Ningnanmycin at the concentration of 50 ?g/mL.