Synthesis And Bioactivity Of Novel 1, 3, 4-oxadiazole Derivatives Derived From Gallic Acid

1, 3, 4-oxadiazole derivatives have received increasing interests in the agrochemical and pharmaceutical fields because of their unique and diverse potential biological properties such as insecticidal, antibacterial, anticancer and anti-inflammatory activities.Gallic acid is separated from the plant nutgall which is widely planted in Guizhou province. Recently the synthesis and bioactivity of gallic acid derivatives have attracted more and more attention. Compounds based on gallic acid such as isoflavone derivatives with good antimicrobial activity were reported.In order to find green pesticides and anticancer agents, fifteen new 1, 3, 4-oxadiazole compounds containing 3, 4, 5-trimethoxyphenyl moieties have been synthesized from gallic acid by five steps: etherification, esterification, hydrazidation, hydrazone formation and cyclization. The reaction conditions have been optimized.The structures of the fifteen new compounds were confirmed by elemental analyses, IR, ¹H NMR and ¹³C NMR spectra. The crystal structure of compound 5i was determined by X-ray diffraction analysis.The preliminary bioassay tests showed that some compounds exhibited weak antifungal activity in vitro.The anticancer activities in vitro of title compounds were evaluated against PC3, BGC823 and Bcap37 cells by MTT method. Highest inhibiting activity was achieved when R=2,4-dimethoxy (5m), with an inhibition rate of 92.0% at the concentration of 5 μM. Compound 51 (R=3, 5-dichloro) could inhibit PC3 cells proliferation of 93.9% at the concentration of 5 uM.