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Objective To develop an HPLC-UV-DPPH method to compare anti-oxidants of Rehmanniae Radix and Rehmanniae Radix Praeparata sample from different manufactories and to provide an effective method for the processing and quality control of traditional Chinese medicine. Methods HPLC in HPLC-UV-DPPH system was performed on Aglient Extend C18 (250 mm × 4.6 mm, 5 μm) column with gradient elution of acetonitrile-0.1% acetic acid at the flow rate of 1.0 mL/min, and the detection wavelength was at 334 nm. The column temperature was 30 ℃. Flow rate of DPPH solution is 0.5 mL/min, and detection wavelength was set at 517 nm. The total activities of the samples and the contribution rate of each component to the total activity were evaluated by the “quantity-effect” research idea, and verbascoside was regarded as a positive reference. The main anti-oxidants in original and processed herbs were identified by HPLC-FT-MS and were compared. Results The detection of HPLC-UV-DPPH method showed that there were nine anti-oxidants in Rehmanniae Radix extract, while 13 anti-oxidants were found in Rehmanniae Radix Praeparata. There were eight common anti-oxidants in the two herbs. The anti-oxidants were obviously different before and after Rehmanniae Radix processed. The activities of the antioxidants in different samples were markedly different. Anti-oxidants with higher contributions were mussaenosidic acid, echinacoside, jionoside A1/A2, verbascoside, and isoverbascoside, respectively. Conclusion The HPLC-UV-DPPH method is stable, sensitive, reproducible, and suitable for rapid screening of anti-oxidants and quality evaluation of Rehmanniae Radix and Rehmannia Radix Praeparata.
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The metabolites were detected in feces and urine of rats orally administrated alkaloids of Piper longum by using high performance liquid chromatography coupled with a Fourier Transform ion cyclotron resonance mass spectrometer (HPLC-FT-MS). According to the mass spectrometric data and reported literature, the structures of metabolites were identified. Several metabolites were analyzed and belonged to piperine, piperanine, piperlonguminine, Δα,β-dihydropiperlonguminine and pellitorine, respectively. The metabolites of alkaloids from P. longum alkaloids were produced through Ⅰ phase and Ⅱ phase metabolism reaction, and were excreted with urination and defecation. The approach provided a rapid method for characterizing the metabolites of P. longum alkaloids and gave the truly active structures and the action mechanism of their neuroprotective effects.