Preliminary extraction of tannins by 1‐butyl‐3‐methylimidazole bromide and its subsequent removal from Galla chinensis extract using macroporous resins

Abstract

In recent years, ionic liquids have become increasingly attractive as 'green solvents' used in the extraction of bioactive compounds from natural plant. However, the separation of ionic liquid from the target compounds was difficult, due to their low vapour pressure and high stabilities. In our study, ionic liquid-based ultrasonic and microwave-assisted extraction was used to obtain the crude tannins, then the macroporous resin adsorption technology was further employed to purify the tannins and remove the ionic liquid from crude extract. The results showed that XDA-6 had higher separation efficiency than other tested resins, and the equilibrium experimental data were well fitted to Langmuir isotherms. Dynamic adsorption and desorption were performed on XDA-6 packed in glass columns to optimise the separation process. The optimum conditions as follows: the ratio of column height to diameter bed was 1:8, flow rate 1 BV/h (bed volume per hour), 85% ethanol was used as eluant while the elution volume was 2 BV. Under the optimised conditions, the adsorption and desoption rate of tannins in XDA-6 were 94.81 and 91.63%, respectively. The content of tannins was increased from 70.24% in Galla chinensis extract to 85.12% with a recovery of 99.06%. The result of ultra-performance liquid chromatography (UPLC)-MS/MS analysis showed that [bmim]Br could be removed from extract.

Ionic liquid solutions as extractive solvents for value-added compounds from biomass

“…A similar process was demonstrated by Lu et al 74,135 for the recovery of tannins and by Bi et al 59 in the isolation of astaxanthin from shrimp waste using macroporous resins. Lu et al 74,135 used a polymer with high adsorption ability and polarity to selectively adsorb the target compound through electrostatic forces, hydrogen-bonding interactions, complexation and size sieving. 138,139 Bi et al 59 employed a molecularly imprinted polymer to take advantage on the cavity shape selectivity for the separation of the target component.…”

Proanthocyanidins and hydrolysable tannins: occurrence, dietary intake and pharmacological effects

“…is a shrub grown in Spain, Italy, Turkey and some Mediterranean Arab countries from which a powder is obtained that has long been used as a tanning agent. The main compounds are D‐glucose derivatives esterified with gallic acid, such as penta‐, hexa‐, hepta‐, octa‐, nona‐, deca‐, undeca‐ and dodeca‐galloyl‐D‐glucose (Lu et al, ). Ellagitannins are present in only a few fruits and nuts (especially pecans and walnuts) consumed in the Western diet, and dietary intake (most probably far below 5 mg·day −1 ) is mainly resulting from the consumption of red fruits (strawberries, raspberries and blackberries or beverages and jams made from these) (Okuda and Ito, ), see Table .…”

Enrichment of total steroidal saponins from the extracts ofTrillium tschonoskiiMaxim by macroporous resin and the simultaneous determination of eight steroidal saponins in the final product by HPLC

“…Macroporous resin is a most promising candidate material for the separation and enrichment of natural products from crude materials due to its excellent properties of having a large surface area and high mechanical strength . Macroporous adsorption resin has widely been used in the separation and enrichment of bioactive components from crude extracts of herbal raw materials . However, to date, no report has used macroporous resin to separate and enrich total steroidal saponins from Trillium tschonoskii Maxim extracts.…”