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  • Author or Editor: Guixin Chou x
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A simple and accurate high-performance thin-layer chromatography (HPTLC)-bioautographic method was developed for the quantitative analysis of magnolol and honokiol in the herbal medicine Magnoliae officinalis Cortex. The samples were separated on a silica gel HPTLC plate with a mixture solution of toluene-methanol (10:1, v/v) as the mobile phase. Spots were visualized by dipping in 2,2-diphenyl-1-picrylhydrazyl radical (DPPH*) reagent and measured at a wavelength of 550 nm in a reflection mode, scanning after derivatization for 40 min. The method had excellent linearity (r 2 = 0.9939 for magnolol and r 2 = 0.9989 for honokiol, respectively) in the concentration range of 0.16–0.97 mg spot−1 for both analytes. The recoveries were 94.5–105.9% for magnolol and 86.6–103.4% for honokiol, respectively. The established HPTLC-bioautographic method was evaluated comprehensively in quantitative and antioxidant activity analysis of magnolol and honokiol in Magnoliae officinalis Cortex and various plants.

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Summary

A thin-layer chromatography (TLC)–bioautography–mass spectrometry (MS) method coupled with a liquid chromatography–MS-controlled autopurification system was developed and applied for screening and isolating natural dipeptidyl peptidase IV (DPP IV) inhibitor from plant extracts. An unknown constituent with potential DPP IV inhibitory activity from bulbs of Fritillaria cirrhosa was discovered using TLC–bioautography, followed by using a TLC interface with mass spectrometry to obtain m/z of the target compound, and the purification of the compound was directly achieved with a mass-directed autopurification system for 40 runs of injection. Finally, 2.1 mg of the compound was obtained and identified as peimisine by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The half maximal inhibitory concentration (IC50) of DPP IV inhibitory activity was determined at 80.5 µm comparing to 58.0 µm of the standard DPP IV inhibitor diprotin A by a spectrophotometric method.

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