Reversed-phase chromatographic separation and downstream precipitation of lupane- and oleanane-type triterpenoids: Experiments and modeling based on the method of moments

abstract

The reversed-phase chromatographic separation of two triterpenic acids (TTAs), betulinic and oleanolic acids, using a triacontyl (C30) stationary phase was addressed in this work. Methanol, water, acetonitrile, ethanol, isopropanol, ethyl acetate, acetone and mixtures thereof were tested, and the best mobile phase to conduct the separation was found to be methanol/acetonitrile 50/50 (%, v/v) at 23 degrees C, taking into account parameters like selectivity, resolution and TTAs solubility. The method of moments was used to determine the equilibrium constants of isotherms, the axial dispersion coefficients and the global linear driving force coefficients of pure betulinic and pure oleanolic acids. These parameters were then successfully validated by modeling unary and binary breakthrough curves. Simulated moving bed calculations showed that betulinic and oleanolic acids can be both obtained with purity of 99.2 % and productivity of 56.2 kg/(m(adsorbent)(3) day) using the packing material of an Acclaim C30 column with a 1-1-1-1 configuration with columns of 7.5 cm long. Finally, in order to recover the two TTAs from the SMB extract and raffinate streams, water was envisioned as a precipitation agent. Accordingly, the solubility of each TTA was measured in methanol/acetonitrile 70/30, 50/50, and 30/70 (%, v/v) modified with water. The obtained results showed that adding 65 % (%, v/v) of water it is possible to precipitate 98 % of the dissolved TTAs in all the tested methanol/acetonitrile mixtures.

keywords

POROUS GRAPHITIC CARBON; SUPERCRITICAL-FLUID EXTRACTION; MOVING-BED CHROMATOGRAPHY; OLEANOLIC ACID; STATIONARY PHASES; BETULINIC ACID; URSOLIC ACID; PENTACYCLIC TRITERPENOIDS; RAPID ANALYSIS; OPTIMIZATION

subject category

Engineering, Chemical

authors

Azenha, IS; Aniceto, JPS; Ribeiro, DP; Mendes, A; Silva, CM

Groups

G4 - Renewable Materials and Circular Economy

Projects

CICECO - Aveiro Institute of Materials (UIDB/50011/2020)

CICECO - Aveiro Institute of Materials (UIDP/50011/2020)

acknowledgements

This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology/MCTES, and the Multibiorefinery project (POCI01-0145-FEDER-016403). I.S. Azenha acknowledges a PhD grant from Fundacao para Ciencia e a Tecnologia (Portugal) (grant number SFRH/BD/126509/2016) and financial support of Project POCI-01-0145-FEDER-006939 (Laboratory for Process Engineering, Environment, Biotechnology and Energy -LEPABE funded by FEDER funds through COMPETE2020 -Programa Operacional Competitividade e Internacionalizacao (POCI). The authors would also like to thank Monica Valega (University of Aveiro) for the continuous support with the HPLC setup.