Supercritical carbon dioxide extraction of curcuma longa l. rhizome and acute toxicity evaluation of the extract / Siti Hafsah Mohd Shah

This study was carried out due to the increase in demand of herbal extracts as health supplement, which may contribute to hepatotoxicity if consumed in high amount regularly. Usage of solvent for extraction in conventional extraction methods will also lead to the presence of residues which can be harmful with regular consumption. Therefore, in this study, green extraction method of supercritical carbon dioxide (SC-CO2) extraction and ultrasonic assisted extraction (UAE) used to extract bioactive compounds from turmeric. The properties of the extracts obtained were compared based on the percentage yield, curcuminoids content, flavour profile, total phenolic content, colour and heavy metal constituents. Turmeric extracted using SC-CO2 (temperature of 40°C and pressure of 3263 psi) produced 5.62% extraction yield (%, dry weight basis), 0.0082% concentration of curcuminoids, 11.91 mg Gallic Acid Equivalent per 100 g of total phenolic content, flavour profile (turmerone and curlone), lighter in colour (L = 39.25) and more yellowish (b* = 19.67), higher than UAE extract (temperature of 40°C and frequency of 40 kHz). The content of heavy metals in SC-CO2 extract namely Zn, Pb, Cd, Fe, Mn, Cr, Ca, Cu and Al were 0.77, 0.052, 0.016, 0.20, 0.081, 0.052, 1.80, 0.056 and 0.22 mg/100 g, respectively, which significantly (p<0.05) lower than those contents in the UAE extract. Due to the quality of extract that it produced, SC-CO2 extraction method was selected for the optimisation study using Response Surface Methodology (RSM). The optimum extraction condition obtained was at 90°C and 4807 psi, which had resulted in 7.54% yield with desirability value of 1.0. The SC-CO2 extract also contained 0.023 mg/100 g curcuminoids. Acute toxicity study was also conducted to evaluate any toxicity symptoms to the rats when given high dosage of the turmeric extract. There was no mortality or signs of abnormality on body weight of experimental rats, water and food intake, no alteration in the haematological and biochemical values, as well as the histological parameters at the dosage of 2000 mg/kg of body weight. The study was significance in term of producing turmeric extract using non-conventional extraction method with establishment of optimised SC-CO2 method and evaluation of safe consumption of the extract at higher dosage (2000 mg/kg b. wt.).