Extraction of Phorbol Esters (PEs) from Pinion cake using computationally-designed polymers as adsorbents for Solid Phase Extraction

Computational modelling is a technology which could be used to develop bespoke specific adsorbents capable of recognising particular value-added compounds from complex plant matrices giving a step further to the creation of innovative biorefinery techniques. Jatropha curcas and its waste (pinion cake) have a large amount of metabolites, and it is known that some toxic compounds such as phorbol esters (PEs) prevent this waste from being used as fertiliser or balanced feed for animals. The extracted PEs could potentially be used as biological pesticides and as precursor molecules for the development of drugs. PEs is a large group of diterpenes where Phorbol 12-myristate-13-acetate (PMA) is one of the most employed for research purposes. Hence, it was used as a template for the design of a rationally designed polymer (RDP) specific for PEs using commercial modelling software Sybyl 7.3 (Tripos, USA) which selected the functional monomers with the highest affinity towards PMA. According to the simulation, six polymers were prepared, tested and screened with PMA’s model solution in methanol. UV-vis spectroscopy technique was used for the quantification and identification of the components extracted from samples. An SPE method was developed for the PMA stock solution using the HEM-DVB-based polymer as sorbent which demonstrated the highest binding capacity towards PMA. Subsequently, the pinion cake was subjected to Soxhlet extraction employing methanol to get the biomolecules from the biomass. The SPE method was optimised and tested employing the samples from biomass’ crude extract. The results show that the binding capacity of the RDP for PMA is 0.71 mg g-1 while for an analogous PE (in the crude extract) the binding capacity was 0.12 mg g-1. These results suggest that the performance of RDP can be improved by a deeper study of the physical-chemical properties and morphology of this sorbent; making it suitable for purification of PEs from pinion cake biomass.