Ultrasound-assisted solvent extraction boosts Houttuynia flavonoids

Ultrasound-assisted extraction with a deep eutectic solvent produced a flavonoid-rich extract from Houttuynia cordata that showed measurable antioxidant and antibacterial activity in laboratory tests. Researchers screened eight solvents and selected a mixture of choline chloride and lactic acid at a 1:1 ratio with 30% water for further optimization.

The study combined single-factor experiments with Box–Behnken response surface methodology to determine the conditions that maximized total flavonoid recovery. The fitted model had an R² value of 0.9942. The optimized protocol used a 1:30 g/mL solid-to-liquid ratio, 360 W ultrasonic power, a temperature of 40 °C and an extraction time of 50 minutes. Under these conditions, the reported maximum extraction yield was 4.67%.

The resulting extract displayed concentration-dependent scavenging activity in five antioxidant assays. It scavenged DPPH, hydroxyl, ABTS⁺, superoxide-anion and nitrite radicals, indicating activity against several laboratory measures of oxidative stress. These results characterize the extract’s chemical performance under the tested conditions; they do not establish benefits in people or in a living organism.

The extract also inhibited two bacteria in vitro. Against Staphylococcus aureus subsp. aureus, the minimum inhibitory concentration was 0.0187 g/mL and the inhibition zone measured 21.76 mm. Against Escherichia coli, the minimum inhibitory concentration was 0.0375 g/mL and the inhibition zone was 18.03 mm. The findings support antibacterial potential for the H. cordata flavonoid extract, but the experiments were conducted in vitro rather than in an animal or human clinical setting.

Overall, the research identifies a solvent system and ultrasound-assisted operating conditions that efficiently extract total flavonoids from H. cordata while retaining measurable antioxidant and antibacterial activity in laboratory assays. The work is presented in Scientific Reports as an open-access article. The publisher notes that the shared version is an early form of peer-reviewed, accepted research, may undergo further editing and will be replaced by the final Version of Record.

Subject of Research: Extraction and in vitro bioactivity of total flavonoids from Houttuynia cordata

Article Title: Ultrasound-assisted deep eutectic solvent extraction of total flavonoids from Houttuynia cordata Thunb. and their in vitro activity

Article References: Zhang, Y., Liu, M., & Meng, L. (2026). Ultrasound-assisted deep eutectic solvent extraction of total flavonoids from Houttuynia cordata Thunb. and their in vitro activity. Scientific Reports. https://doi.org/10.1038/s41598-026-76109-4

Image Credits: AI Generated

DOI: 10.1038/s41598-026-76109-4

Keywords: Houttuynia cordata, total flavonoids, deep eutectic solvents, ultrasound extraction, antioxidant activity, antibacterial activity, response surface methodology, laboratory assays, Ultrasound-assisted, deep, eutectic, solvent