Optimization of extraction and hydrolysis of withanolides from Withania somnifera

Withania somnifera (L.) Dunal (Solanaceae) (sanskrit name: ashwaganda) is native to the southern and northern regions of India. The leaves, roots and fruits of this evergreen medium sized bush are widely used in the traditional ayurvedic medicine as emetic, adstringent, diuretic, or aphrodisiac. The plant is mainly used as adaptogenic which explains its botanically misleading name: Indian ginseng. The main active compounds of the W. somnifera are the so called withanolides, and their biologically active aglycones. The aim of our research was to develop an effective extraction and hydrolyzation method of W. somnifera to increase the yield of withanolide aglycone extraction. For extraction optimization, different solvents were applied (mixtures of CH₂Cl₂, MeOH, EtOH and H₂O) and the withanolide contents of the extracts, determined as withaferin A were tested by HPLC-DAD (Phenomenex Kinetex, RP C-18, 150 × 4.6 mm, 5 µm; gradient elution with H₂O – MeOH – EtOH). To analyze the effectiveness of hydrolization, different concentrations of sulphuric acid and acetic acid were applied and furthermore the impact of hydrolysis time was assessed. For withaferin A extraction, MeOH – H₂O 1:1 was the most effective solvent (20.44 mg/g plant material), while optimal hydrolysis can be carried out by using 1% H₂SO₄ for 90 min (0.95 mg/0.5 g dry matter).

Acknowledgements: This research was supported by the European Union and the State of Hungary, co-financed by the European Social Fund in the framework of TÁMOP 4.2.4. A/1 – 11 – 1-2012 – 0001 'National Excellence Program'. The publication of the experiments was supported by TÁMOP-4.1.1.C- 12/1/KONV-2012 – 0014 project. This project could be realized through support of the European Union co-financed by the European Social Foundation.

Keywords: Withania, withanolide, HPLC, hydrolysis, optimization

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