Ming-Bo Zhao

Characterization of seventy polymethoxylated flavonoids (PMFs) in the leaves of Murraya paniculata by on-line high-performance liquid chromatography coupled to photodiode array detection and electrospray tandem mass spectrometry

A sensitive HPLC-DAD-ESI-MS/MS method was established to screen and identify the polymethoxylated flavonoids (PMFs) in the leaves of Murraya paniculata (L.) Jack. 16 PMF standards were first to be analyzed in positive mode by the CID-MS/MS. For polymethoxylated flavones, the fragments of [M+H-n×15](+) produced by loss of one or more methyl radicals from the protonated molecule, as well as [M+H-16](+), [M+H-28](+), [M+H-29](+), [M+H-31](+), [M+H-33](+), [M+H-43](+), [M+H-44](+), [M+H-46](+) and [M+H-61](+) fragment ions were detected, which could be taken as their diagnostic characters. For polymethoxylated flavanones and chalcones, their [M+H](+) ions usually underwent RDA cleavage fragmentation of the C-ring prior to the similar loss of diagnostic fragment ions as polymethoxylated flavones, which could be adopted as a shortcut to distinguish them from ordinary flavones rapidly. For the PMF glycosides, the neutral loss of the similar fragments with polymethoxylated flavones from their [aglycone+H](+) could be adopted as a simple method to screen them out from complex mixture. Based on these characterizations of PMFs and the results of EIC-MS/MS experiment, 70 PMFs including 45 flavones, 17 flavanones or chalcones and 8 PMFs glycosides were screened out from the complex extract of the leaves of M. paniculata. Among them, 16 compounds were unambiguously identified by comparison with reference substances. The results indicated that the developed analysis method could be employed as a rapid, effective technique for structural characterization of PMFs.

Triterpene Saponins from Clematis chinensis and Their Potential Anti-inflammatory Activity

Seven new triterpene saponins, clematochinenosides A-G (1-7), together with 17 known saponins (8-24), were isolated from the roots and rhizomes of Clematis chinensis. Their structures were elucidated on the basis of spectroscopic evidence and hydrolysis products. Compounds 1, 3-7, and 20-24 showed inhibitory activities against COX-1 and COX-2 enzymes.

Application of high-performance liquid chromatography–mass spectrometry to detection of diuretics in human urine

A rapid, sensitive and reliable high-performance liquid chromatographic-mass spectrometric method for the detection of 25 diuretics in human urine has been developed. Atmosphere pressure chemical ionization (APCI) and electrospray ionization (ESI) modes were evaluated. A 2-ml volume of urine was extracted under basic conditions and separated on an Agilent Zorbax SB-C(18) column (150 x 2.1 mm, 5 microm). The mobile phase consisted of formic ammonium-formic acid buffer (pH 3.5) and acetonitrile. The effects of capillary temperature, sheath gas pressure and compositions of mobile phase on the sensitivity were studied. The recoveries of most of the diuretics were 75-95%. In the full scan mode, the limits of detection of the 25 diuretics were 0.25-25 ng/ml for APCI and 0.6-250 ng/ml for ESI. Under the optimal conditions, 14 diuretics from authentic urine samples were detected successfully by LC-APCI-MS. To obtain more fragmentation information on the chemical structure for positive confirmation, tandem mass analysis was also investigated.

Phenylethanoid glycosides with anti-inflammatory activities from the stems of Cistanche deserticola cultured in Tarim desert

Five new phenylethanoid glycosides, cistanosides J-N (1-5), together with 15 known ones (6-20) were isolated from the stems of Cistanche deserticola cultured in Tarim desert, China. Their structures were elucidated on the basis of extensive spectroscopic analysis (IR, HR-ESIMS, 1D- and 2D-NMR) and chemical degradation. All the compounds obtained were examined for their inhibitory effect on the lipopolysaccharide (LPS)-induced nitric oxide (NO) production in mouse microglial cells (BV-2 cells), and compounds 2 and 8 showed potent inhibition on the NO production with IC50 values of 14.94 μM and 14.32 μM, respectively.

Metabolism of Echinacoside, a Good Antioxidant, in Rats: Isolation and Identification of Its Biliary Metabolites

Echinacoside (ECH) is one of the major active phenylethanoid glycosides (PEGs) in famous traditional Chinese medicine, Herba Cistanches. Although it has various bioactivities, such as antioxidation, neuroprotection, and hepatoprotection, knowledge about its metabolic fate is scant. In the present study, eight phase II metabolites, 3,4-O-dimethyl-ECH-3-O-β-d-glucuronide (M1); 4,4-O-dimethyl-ECH-3-O-β-d-glucuronide (M2); 3,4-O-dimethyl-ECH-4-O-sulfate ester (M3); 4,4-O-dimethyl-ECH-3-O-sulfate ester (M4); 3,3-O-dimethyl-ECH (M5); 3,4-O-dimethyl-ECH (M6); 4,3-O-dimethyl-ECH (M7); and 4,4-O-dimethyl-ECH (M8), were isolated from rat bile sample after intravenous administration of ECH and identified by mass spectra and NMR spectroscopy, including 1H NMR, 13C NMR, nuclear Overhauser effect difference spectroscopy, and two-dimensional NMR (heteronuclear single quantum correlation, heteronuclear multiple-bond correlation spectroscopy, gradient-selected correlation spectroscopy, and nuclear Overhauser effect spectroscopy). Among them, M5 to M8 were O-di-methylated conjugates; M1 and M2 and M3 and M4 were O-dimethyl glucuronides and O-dimethyl sulfates, respectively. In the three types of metabolites of rat, the major metabolites were the methyl ethers and the glucuronides, whereas the sulfates were minor. The regioselectivity of conjugation for ECH and metabolic pathway of ECH were proposed, which gave insight into the mechanism of ECH for its bioactivities in vivo.

Coreosides A-D, C14-polyacetylene glycosides from the capitula of Coreopsis tinctoria and its anti-inflammatory activity against COX-2.

Four new C14-polyacetylene glycosides, namely coreosides A-D (1-4), were isolated from the capitula of Coreopsis tinctoria, a Snow chrysanthemum or Snow tea that is used as a folk tea for prevention of cardiovascular disease in southern Xinjiang, China. Coreosides A-D feature a long chain structure as its aglycon with two acetylenes on C-8 and C-10 and two olefinics on C-6 and C-12 sites, which construct a large conjugate system. The structures were elucidated on the basis of spectroscopic evidences and hydrolysis. Compounds 1-4 exhibited significant inhibition against cyclooxygenase-2 at the concentration of 1×10(-6) mol/L, with its IC50 values of 0.22-8.8×10(-2) μmol/L.

A series of strategies for solving the shortage of reference standards for multi-components determination of traditional Chinese medicine, Mahoniae Caulis as a case.

In order to solve the bottleneck of reference standards shortage for comprehensive quality control of traditional Chinese medicines (TCMs), a series of strategies, including one single reference standard to determine multi-compounds (SSDMC), quantitative analysis by standardized reference extract (QASRE), and quantitative nuclear magnetic resonance spectroscopy (qNMR) were proposed, and Mahoniae Caulis was selected as an example to develop and validate these methods for simultaneous determination of four alkaloids, columbamine, jatrorrhizine, palmatine, and berberine. Comprehensive comparisons among these methods and with the conventional external standard method (ESM) were carried out. The relative expanded uncertainty of measurement was firstly used to compare their credibility. The results showed that all these three new developed methods can accurately accomplish the quantification by using only one purified reference standard, but each of them has its own advantages and disadvantages as well as the specific application scope, which were also discussed in detail in this paper.

Exotines A and B, Two Heterodimers of Isopentenyl-Substituted Indole and Coumarin Derivatives from Murraya exotica

Exotines A and B (1 and 2), two heterodimers of isopentenyl-substituted indole and coumarin derivatives linked through a new fused heptacyclic ring system, were isolated from the roots of Murraya exotica. Their structures were established by comprehensive NMR and MS spectroscopic data analysis, and the absolute configurations were determined by single-crystal X-ray crystallographic analysis and ECD calculations. Compounds 1 and 2 showed inhibition of nitric oxide production in lipopolysaccharide-induced BV-2 microglial cells with IC50 values of 9.2 and 39.9 μM, respectively.

An Integrated Strategy for Global Qualitative and Quantitative Profiling of Traditional Chinese Medicine Formulas: Baoyuan Decoction as a Case

Clarification of the chemical composition of traditional Chinese medicine formulas (TCMFs) is a challenge due to the variety of structures and the complexity of plant matrices. Herein, an integrated strategy was developed by hyphenating ultra-performance liquid chromatography (UPLC), quadrupole time-of-flight (Q-TOF), hybrid triple quadrupole-linear ion trap mass spectrometry (Qtrap-MS), and the novel post-acquisition data processing software UNIFI to achieve automatic, rapid, accurate, and comprehensive qualitative and quantitative analysis of the chemical components in TCMFs. As a proof-of-concept, the chemical profiling of Baoyuan decoction (BYD), which is an ancient TCMF that is clinically used for the treatment of coronary heart disease that consists of Ginseng Radix et Rhizoma, Astragali Radix, Glycyrrhizae Radix et Rhizoma Praeparata Cum Melle, and Cinnamomi Cortex, was performed. As many as 236 compounds were plausibly or unambiguously identified, and 175 compounds were quantified or relatively quantified by the scheduled multiple reaction monitoring (sMRM) method. The findings demonstrate that the strategy integrating the rapidity of UNIFI software, the efficiency of UPLC, the accuracy of Q-TOF-MS, and the sensitivity and quantitation ability of Qtrap-MS provides a method for the efficient and comprehensive chemome characterization and quality control of complex TCMFs.

Deoxysappanone B, a homoisoflavone from the Chinese medicinal plant Caesalpinia sappan L., protects neurons from microglia-mediated inflammatory injuries via inhibition of IκB kinase (IKK)-NF-κB and p38/ERK MAPK pathways.

Caesalpinia sappan L. (Lignum Sappan) is a Chinese medicinal plant for treating ischemic cerebral apoplexy. Deoxysappanone B (DSB), a homoisoflavone compound isolated from C. sappan L. (Lignum Sappan), was studied for anti-neuroinflammatory and neuroprotective properties using lipopolysaccharide (LPS)-induced BV-2 microglia neuroinflammation model and LPS-induced microglia-neuron co-culture system. Our findings showed that DSB effectively inhibited BV-2 microglia-mediated neuroinflammatory mediators׳ release including NO, PGE₂, TNF-α, IL-6 and reactive oxygen species. Moreover, DSB markedly protected neurons against inflammatory microglia-mediated neurotoxicity in a microglia-neuron co-culture system. Mechanism study revealed that DSB blocked two major neuroinflammation-related signaling pathways including IKK-IκB-nuclear factor kappaB (NF-κB) and p38/ERK mitogen-activated protein kinase (MAPK) cascades, further leading to the inhibition of neuroinflammatory mediators׳ production. The present study provides evidence that the anti-neuroinflammatory and neuroprotective effect of DSB are due to the suppression of neuroinflammatory mediators׳ production as well as inflammation-induced neurotoxicity through regulation of multi-targets. Therefore, DSB may serve as a neuroprotective agent for the treatment of neuroinflammatory disorders and inflammation-related neuronal injury.