Microwave-assisted extraction optimization of Sabah snake grass (Clinacanthus nutans Lindau) herbal infusion and evaluation of antioxidant and acetylcholinesterase inhibition activity in vitro
Clinacanthus nutans is a great medicinal herb with high polyphenols content and had been used in its infusion form to treat illness. In this paper, microwave-assisted extraction of C. nutans tea infusion was investigated by using central composite design combined with response surface methodology. The influence factors of microwave power (80 - 800 W); brewing time duration (0 – 240 s) and extraction time duration (60 s – 300 s) on total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (DPPH) and acetylcholinesterase inhibition activity (AChE) were investigated. The optimum extraction conditions were determined as follows: microwave power X1, 560 W; brewing duration, X2, 60 s and extraction time, X3, 240 s. Under this optimal extraction conditions, the responses were as followed: Total phenolic content (251.58±10.98 mg GAE/L); Total flavonoid content (102.21±5.16 mg RE/L); DPPH (62.22±0.03%) and acetylcholinesterase inhibition activity (AChE) of 24.77±0.12%. Results demonstrated that MAE could be used to extract bioactive constituents having antioxidant and anti-acetylcholinesterase properties that may benefit in Alzheimer’s disease.