Phytochemical compounds extraction from Orthosiphon aristatus, Andrographis paniculata, Gynura segetum using hydrothermal method: experimental kinetics and modeling

Orthosiphon aristatus (O. aristatus), Andrographis paniculata (A. paniculata), and Gynura segetum (G. segetum) leaves were subjected as raw material to obtain phytochemical compounds using sub-critical water extraction (SWE) technique. In a semi-batch process, the extraction was performed for ∼150 min extraction time at 120 – 160°C and 3 – 10 MPa. The Fourier-transform infrared spectroscopy (FT–IR) spectrum depicted that the phenolic and flavonoid compounds were liberated from each medicinal plant leaves in the aforementioned-temperature range. The second-order kinetic and Weibull models also may properly represent and describe the extraction kinetics curves of each sample at these operating conditions (120 – 160°C and 3 – 10 MPa). The amounts of phenolic and flavonoid compounds could approach 284.73 mg of GAE/g of dried sample (140°C, 3 MPa) and 232.89 mg of CE/g of dried sample (140°C, 3 MPa), respectively.