Thermal stability of propolis from Tucumán, Argentina

Propolis, the material used by bees to protect their hives, is a glue-like substance composed of plant resins, bee waxes and pollens. A large number of flavonoids have been identified in propolis and the content of flavonoids is considered as an important index for evaluating propolis quality. The aim of this work was to study temperature effects on propolis from Amaicha del Valle (Tucumán, Argentina) and some of the main active flavonoids. Thermal analysis was carried out by thermogravimetric (TGA) and thermodifferential analysis (DTA). The identification of compounds was carried out by different spectroscopic methods: Ultraviolet (UV), Infrared (IR), 1H Nuclear Magnetic Resonance (1H NMR) and Electronic Impact Mass Spectrometry (EIMS). The propolis from Amaicha del Valle and apigenin, chrysin and galangin were found to be stable from room temperature to 120ºC.