Extraction of bioactive compounds from Withania somnifera using hydrothermal technique

Abstract

The present study was undertaken to evaluate bio-active compounds present in the Ashwagandha (Withania somnifera) root extracts. The hydrothermal extraction process was used to access the extraction yields using different solvents (ethanol and water) from 2 gm dried root powders. Four different samples were prepared by hand milling for 15 mins, 30 mins, 45 mins and 60 mins labeled as sample 1 to sample 4 respectively. The extraction involved high- temperature (100 °C) and high-pressure to effectively extract selected phytochemicals using the same solvent amount (50 ml) and extraction time (2 h) for all four samples. The average size of the powder particles was confirmed to be between 3 mm and 500 mm using an optical microscope equipped with a digital imaging camera. All the extracts were studied through Ultraviolet–Visible (UV–vis) spectroscopy and Fourier Transform Infra-Red (FTIR) spectroscopy. Strong absorption peaks in the UV–vis spectra of all the extracts around 280 nm and 320 nm confirmed the presence of flavonoid and other phenolic compounds. However, the relative variation of absorption peak showed that extracts in ethanol possess higher yield of flavonoids. The FTIR spectra of the extracts confirmed the observations of the optical spectroscopy. It was found that extract in water contains only small amounts of these bioactive molecules. It can be concluded from the current study that different solvents can be used to selectively extract a range of bioactive nuclei from the Withania somnifera roots.