Lactic acid-based deep eutectic solvent: An efficient green media for the selective extraction of steroidal saponins from Trillium govanianum

Natural deep eutectic solvents have a high solvation and food-grade characteristics, which make them a preffered choice for extracting bioactives to develop nutraceutical and cosmetic formulations. This research aimed to investigate the systematic effects of several NADESs on the ultrasonic-assisted extraction of steroidal saponins from the rhizomes of Trillium govanianum Wall. ex D.Don, which is utilized in traditional Ayurvedic medicine. After screening of fifteen different NADESs, choline chloride: lactic acid (1:1) (NADES 1) was found most effective eutectic solvent for the extraction of steroidal saponins performed by the three-round micro-extraction (1 mL). Compared with hydro-ethanolic solvent-based extraction, lactic acid-derived NADESs showed higher extractability of steroidal saponins. The extraction efficiency of bioactive steroidal saponins e.g. borassoside E and protodioscin was also enhanced with NADES 1. The effects of extraction variables such as S:L ratio, working duration, and temperature on the extraction of steroidal saponins by NADES 1 was also studied and optimized. Furthermore, optimized parameters were validated by performing 100 mL NADES 1-based extraction to recover phytomolecules and NADES 1 by using Diaion HP20 resin column chromatography. As a proof of concept, this study suggested that lactic acid-derived NADESs are effective media for the extraction of steroidal saponins from biomass. The cytocompatibility assay of NADESs with NRK-52E and IEC-6 cells revealed the safe nature of NADESs to normal animal cells. The steroidal saponins-enriched extract obtained with NADES 1 has shown promising antagonistic effects on acetylcholinesterase activity.

Automated summary

Natural deep eutectic solvents, such as lactic acid-derived NADESs, have shown high solvation and food-grade characteristics, making them a preferred choice for extracting bioactive compounds. This study focused on investigating the effects of different NADESs on the extraction of steroidal saponins from Trillium govanianum Wall. ex D.Don. It was found that choline chloride: lactic acid (1:1) was the most effective eutectic solvent for the extraction, resulting in higher extractability of steroidal saponins compared to hydro-ethanolic solvent-based extraction. The optimized parameters were validated, and the cytocompatibility of NADESs with animal cells was also evaluated.