Microwave-assisted extraction of total bioactive saponin fraction from Gymnema sylvestre with reference to gymnemagenin: a potential biomarker.
OBJECTIVE
To develop a fast and ecofriendly microwave assisted extraction (MAE) technique for the effective and exhaustive extraction of gymnemagenin as an indicative biomarker for the quality control of Gymnema sylvestre.


METHODS
Several extraction parameters such as microwave power, extraction time, solvent composition, pre-leaching time, loading ratio and extraction cycle were studied for the determination of the optimum extraction condition. Scanning electron micrographs were obtained to elucidate the mechanism of extraction.


RESULTS
The final optimum extraction conditions as obtained from the study were: 40% microwave power, 6 min irradiation time, 85% v/v methanol as the extraction solvent, 15 min pre-leaching time and 25 : 1 (mL/g) as the solvent-to-material loading ratio. The proposed extraction technique produced a maximum yield of 4.3% w/w gymnemagenin in 6 min which was 1.3, 2.5 and 1.95 times more efficient than 6 h of heat reflux, 24 h of maceration and stirring extraction, respectively. A synergistic heat and mass transfer theory was also proposed to support the extraction mechanism.


CONCLUSIONS
Comparison with conventional extraction methods revealed that MAE could save considerable amounts of time and energy, whilst the reduction of volume of organic solvent consumed provides an ecofriendly feature.
Mandal
Vivekananda
V
Division of Pharmacognosy, Department of Pharmaceutical Technology, Jadavpur University, Kolkata, 700032, India.
Dewanjee
Saikat
S
Mandal
Subhash C
SC
D000470:Alkaloids / Q000302:isolation & purification*; D015415:Biomarkers; D002855:Chromatography, Thin Layer; D031104:Gymnema sylvestre / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D008872:Microwaves; D012503:Saponins / Q000302:isolation & purification*
D000470:Alkaloids; D015415:Biomarkers; D012503:Saponins; C517988:gymnemagenin