Ionic liquid based ultrasonic-assisted extraction of forskolin from Coleus forskohlii roots

•Extraction of forskolin from Coleus forskohlii roots using ionic liquids.•Tetramethyl guanidium lactate (TMGL) showed maximum extraction of forskolin.•Ultrasonic-assisted extraction enhanced the extraction of forskolin in TMGL.•The technique requires only 4 h as compared to 12 h in conventional Soxhlet extraction.

Ionic liquid based ultrasonic-assisted extraction (ILUAE) was successfully applied to extract forskolin (FSK) from Coleus forskohlii roots. Six ionic liquids with different cations and anions were initially investigated in this work from which tetramethyl guanidium lactate (TMGL) was selected for further studies using ultrasound-assisted extraction. Parameters of ultrasound extraction such as ultrasonic power, duty cycle and extraction time were optimized to get maximum extraction of FSK. The maximum extraction yield of 0.508 ± 0.006% (w/w) corresponding to an extraction efficiency of 87.4 ± 1.04% of FSK was obtained under the optimized conditions. ILUAE offered shorter extraction time (4 h) as compared to Soxhlet extraction (12 h) which indicated it to be a rapid, efficient, simple and green approach for extracting FSK from Coleus forskohlii roots.