Improving the quality of Vernonia amygdalina extract by ultrasound-assisted extraction coupled with gas bubble flotation

Vernonia amygdalina is an herb commonly used in folk medicine; It possesses various compounds with therapeutic capabilities. Traditional extraction approaches applied to this plant may destroy its bioactive compounds and inherently contaminate them with toxic organic solvents. In this study, ultrasound-assisted extraction combined with gas-bubble flotation was applied to increase V. amygdalina extraction yield. The efficiency of water maceration was increased by 200%, without the drawbacks of the conventional extraction methods. The total phenolic content yield was 189 +/- 12.7 (mg GAE/g dry weight) with a condensation efficiency of 115 +/- 5.7%; and the total flavonoid content was 6.44 +/- 1.68 (mg QE/g dry weight). Additionally, the antioxidant activity of the condensed foam was enhanced up to 120%. Analysis of the extract by FTIR revealed the presence of extractable chemical families: sesquiterpene lactones, saponins and flavonoids, and that the chemical characteristics of the extract were also preserved due to mild extracting conditions. Overall, this method is effective for extracting bioactive compounds from herbs with appealing advantages: no thermal degradation, organic solvent free extraction, and low energy consumption. Practical Applications The utilization of ultrasound-assisted extraction and gas bubble flotation has been proven to be effective in condensing the aqueous extract of Vernonia amygdalina. Gas bubble flotation was shown to condense the herb extract by 120%, which is considered efficient given the simplicity and energy consumption of the process.