Abstract

The thermal decomposition behavior of olive hydroxytyrosol (HT) was first studied using thermogravimetry (TG). Cracked chemical bond and evolved gas analysis during the thermal decomposition process of HT were also investigated using thermogravimetry coupled with infrared spectroscopy (TG-FTIR). Thermogravimetry-Differential thermogravimetry (TG-DTG) curves revealed that the thermal decomposition of HT began at 262.8 °C and ended at 409.7 °C with a main mass loss. It was demonstrated that a high heating rate (over 20 K·min−1) restrained the thermal decomposition of HT, resulting in an obvious thermal hysteresis. Furthermore, a thermal decomposition kinetics investigation of HT indicated that the non-isothermal decomposition mechanism was one-dimensional diffusion (D1), integral form g(x) = x2, and differential form f(x) = 1/(2x). The four combined approaches were employed to calculate the activation energy (E = 128.50 kJ·mol−1) and Arrhenius preexponential factor (ln A = 24.39 min−1). In addition, a tentative mechanism of HT thermal decomposition was further developed. The results provide a theoretical reference for the potential thermal stability of HT.

Highlights

  • Hydroxytyrosol (HT), 3,4-dihydroxy phenethyl alcohol, is an important active compound in olive oil and olive leaf [1,2]

  • Many works have reported on the HT chemical structure and derivatives [11,12], antitumor activity and mechanism [13], and pharmacokinetics [14] for anticancer drugs or cancer adjuvant therapy

  • Theoretical application is the description of three kinetic factors that are determined by experimental investigation, which can be used to describe the thermodynamic properties

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Summary

Introduction

Hydroxytyrosol (HT), 3,4-dihydroxy phenethyl alcohol, is an important active compound in olive oil and olive leaf [1,2]. As reported by Luo et al [15], HT has a strong biological instability on account of its multiple hydroxyl groups structure. This greatly affects the relevant preparations quality and clinical application effect due to low bioavailability. Thermal analysis is a promising technology that has been used to investigate the thermal stability and decomposition kinetics of drug compounds [16,17]. It is important to study the thermal decomposition kinetics of HT for new antitumor drug decomposition of HT for new antitumor thermal stability. Multiple heating rate chemical bond mechanism in the process of TG and TG-FTIR.

As shown in shown
TG-DTG
Nonisothermal Kinetics of HT
Friedman Method
The linear equation
Chemical Bond Change by TG-FTIR
Three-dimensional
Infrared spectra of of HT
O production increased
Methods
Theoretical
Kissinger Method
Flynn-Wall-Ozawa Method
Most Probable Reaction Mechanism and Mathematical Model
Calculation of ln A
Conclusions

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