Stability of guayulins from Parthenium argentatum, A. Gray during post-harvesting storage for industrial exploitation

Abstract

Abstract Background Guayulins comprise a family of sesquiterpene compounds with potential industrial applications that are extracted from the resinous fraction of the guayule plant (Parthenium argentatum, A. Gray). If a whole industry is to be developed around guayulins, not only their activity should be assessed, but also their stability because the quality of the final products is likely influenced by the time that elapses from harvesting to processing. Thus, the aim of the present study was to evaluate the stability of guayulin compounds from harvested guayule stems or extracted resin after storage at different temperatures to find in which form, stems or resin, is the storage better. Results Results showed that, once extracted, the resin could be stored at 20-25 °C for 3 months or more without significant losses of guayulin content. In the case of harvested stems, however, the findings were more complex, with guayulins A and B degrading over time and guayulins C and D showing enrichment. In addition, analysis of the thermal and thermo-oxidative degradation of the resin and guayulins showed that while guayulins A and B showed a maximum decomposition rate around 280 °C, guayulins C and D decomposed at 245 °C. Such thermal differences might be attributed to the observed oxidation of guayulin A and B standards into guayulin C and D, respectively. Conclusion These findings provide, for the first time, information on the stability of guayulins after harvesting and resin extraction, which could help to the development of an integral industrial process from harvesting to commercializing. Graphical Abstract