Subcritical water extraction (SWE) applied to analyses the bioactives from ashwagandha (W. somnifera) at varying temperature (100-200 °C) and extraction time (10-30 min). The effect of temperature and time has been investigated in terms of extraction yield (EY), total phenolic content (TPC), cytotoxicity, antioxidant, and enzyme inhibitory activities. The withanosides and withanolides responsible for various biological effects were quantified using high performance liquid chromatography (HPLC). The HPLC analysis revealed Withanoside V, Withanoside IV, 12-Deoxywithastramonolide, Withanolide A, and Withaferin A as a principle bioactive compounds in SWE, with high in concentration compared to microwave-assisted extraction (MAE), Soxhlet extraction (SE) and maceration (MC). For SWE the highest EY (65.6%; 200 °C for 30 min), TPC (82.5 mg GAE/g DE), antioxidant activity (DPPH: 80.3%, FRAP: 60.5% and ABTS: 78.9), and potent enzyme inhibitory effects were observed. The SWE and Withaferin A showed significant reduction in cell viability of cervical cancer (HeLa) cells, with IC50 values 10 mg/ml and 8.5 μM/ml, respectively but no cytotoxic effect for normal cells (MDCK). Thus, SWE can provide effective extraction for ashwagandha withanosides and withanolides compared MAE, SE and MC to conventional methods, which could be used for extraction of pharmacologically active fractions with therapeutic applications.
Keywords: Antioxidant activity; Ashwagandha; Enzyme inhibition; Subcritical water extraction; W. somnifera; Withanosides.
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