Phytochemical Quantification and the In Vitro Acetylcholinesterase Inhibitory Activity of Phellodendron chinense and Its Components.

The dried bark of Phellodendron chinense has been used as a traditional herbal medicine to remove damp heat, relieve consumptive fever, and cure dysentery and diarrhea. In the present study, we performed quantitative analyses of the two components of P. chinense , phellodendrine and berberine, using high-performance liquid chromatography. A 70% ethanol extract of P. chinense was prepared and the two components were separated on a C-18 analytical column using a gradient solvent system of acetonitrile and 0.1% ( v / v ) aqueous trifluoroacetic acid. The ultraviolet wavelength used for detection was 200 nm for phellodendrine and 226 nm for berberine. The analytical method established here showed high linearity (correlation coefficient, ≥0.9991). The amount of phellodendrine and berberine used was 22.255 ± 0.123 mg/g and 269.651 ± 1.257 mg/g, respectively. Moreover, we performed an in vitro acetylcholinesterase (AChE) activity assay and an amyloid-β aggregation test to examine the biological properties of phellodendrine and berberine as therapeutic drugs for Alzheimer's disease. Phellodendrine and berberine inhibited AChE activity in a dose-dependent manner (IC50 = 36.51 and 0.44 μM, respectively). In contrast, neither phellodendrine nor berberine had an effect on amyloid-β aggregation. The P. chinense extract and phellodendrine, but not berberine, exhibited antioxidant activity by increasing radical scavenging activity. Moreover, P. chinense demonstrated a neuroprotective effect in hydrogen peroxide-treated HT22 hippocampal cells. Overall, our findings suggest that P. chinense has potential as an anti-Alzheimer's agent via the suppression of the enzymatic activity of acetylcholinesterase and the stimulation of antioxidant activity.