Selective extraction of pentacyclic triterpenoids from Centella asiatica using aprotic ionic liquid-assisted techniques

Abstract

This study investigates imidazolium-based ionic liquids (ILs) as alternative solvents to improve extraction efficiency for the extraction of pentacyclic triterpenoids from Centella asiatica . Three ILs, [C₄mim]Cl, [C₄mim][CF₃SO₃], and [C₄mim][CH₃SO₃], were evaluated for the recovery of asiaticoside, madecassoside, asiatic acid, and madecassic acid. Key extraction parameters, including IL concentration, extraction time, temperature, and assisted extraction techniques were optimized to enhance recovery efficiency. HPLC-DAD enabled reliable separation, quantification, and validation of the four target compounds. Among the tested conditions, 1.2 M [C₄mim][CH₃SO₃] combined with microwave-assisted extraction at a controlled bulk (externally monitored) temperature of 25 °C for 60 min provided the highest triterpenoid yield. Computational analysis indicated a slightly stronger complexation energy for [C₄mim][CH₃SO₃] than for [C₄mim][CF₃SO₃], consistent with the observed experimental trend, although the energy difference was modest. Comparative evaluation of extraction techniques established a clear performance hierarchy: MAE > UAE > shaking. The superior performance of MAE is attributed to its ability to mitigate the intrinsic viscosity of the ILs, thereby enhancing mass transfer. While IL-based systems show potential for selective extraction, their overall sustainability requires further consideration, particularly regarding solvent recovery, recyclability, and downstream processing. Consequently, coupling structurally optimized ILs with accelerated extraction techniques provides an efficient and selective approach, with computational analysis offering supportive mechanistic insight for extracting functional triterpenoids for food and nutraceutical applications.