Authors:Lihua Gu, Shansong Zheng, Tao Wu, Guixin Chou, and Zhengtao Wang
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 (r2 = 0.9939 for magnolol and r2 = 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.
Authors:Fei Zhao, Zhong Liu, Yixin Gu, Yuelian Yang, Di Xiao, Xiaoxia Tao, Fanliang Meng, Lihua He, and Jianzhong Zhang
Mycoplasma pneumoniae (M. pneumoniae) is one of the most important pathogens that cause respiratory tract infection in children and adults. In this study, we describe a rapid and sensitive colorimetric loop mediated isothermal amplification (LAMP) method to detect M. pneumoniae. The specificity and sensitivity of this assay were detected with 21 common respiratory pathogens and 39 M. pneumoniae DNA. The sensitivity of LAMP was 100% among 39 M. pneumoniae isolates and the specificity was 100% among 9 members of other Mycoplasma and 12 common respiratory pathogens. The lowest detectable limit (LDL) of this assay was 102 copies, which detected by a series of standard M. pneumoniae DNA. To evaluate the clinical applicability of the LAMP assay, a total of 80 clinical samples were examined by conventional PCR, real-time PCR and the LAMP assays, respectively. The positive rates were 15.0%, 32.5% and 26.3%, respectively. This colorimetric LAMP assay demonstrated a high level of sensitivity comparable with that of conventional PCR for the detection of M. pneumoniae. It is a valuable method for simple, cost-effective and rapid detection of M. pneumoniae in the rural areas and basic clinical of China.
Authors:Lihua Gu, Tong Tian, Li Xia, Guixin Chou, and Zhengtao Wang
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.