Hong Ngoc Thuy Pham
University of Newcastle, Australia
Title: Optimization of ultrasound-assisted extraction of total phenolic compounds and antioxidant activity from Helicteres hirsuta Lour.
Biography
Biography: Hong Ngoc Thuy Pham
Abstract
Helicteres hirsuta Lour. (H. hirsuta L.) is wildly distributed in Southeast Asian countries and has been used as a traditional medicine for the treatment of various ailments such as malaria and diabetes. This study aimed to optimize ultrasound-assisted extraction conditions for retaining maximum yield of bioactive compounds and antioxidant capacity from H. hirsuta L. Response surface methodology (RSM) with central composite design (CCD) was employed to design experiments for assessing the effect of ultrasonic temperature (40 – 60 ºC), ultrasonic time (15 – 35 min), ultrasonic power (60 – 100% or 150 – 250W), sample-to-solvent ratio (1 – 6 g/100 mL) and methanol concentration (0 – 50 %) on the yields of total phenolic content, total flavonoid content and antioxidant activity of H. hirsuta L. extract. The results showed that ultrasonic temperature, sample-to-solvent ratio and methanol concentration had a significant influence on the extraction efficiency of phenolics, flavonoids and antioxidant capacity. The optimal extraction conditions were ultrasonic temperature of 60 ºC, ultrasonic time of 25 min, ultrasonic power of 150W, sample-to-solvent ratio of 3:100 g/mL, with the solvent being 40% (v/v) methanol. The actual values obtained under these conditions were 15.97 mg GAE/g of phenolics, 16.42 mg CE/g of flavonoids, and 13.34 g/100 g of extractable solids. The highest values of the antioxidant assays (DPPH, ABTS and FRAP) were also observed under these conditions, with the exception of CUPRAC (obtaining 87% maximum value). These optimal extraction conditions can be applied to produce powdered crude extract for further isolation and purification of individual bioactive compounds for their potential use in the nutraceutical and pharmaceutical industries.
