Human UDP-glucuronosyltransferase 1As catalyze aristolochic acid D O-glucuronidation to form a lesser nephrotoxic glucuronide.

ETHNOPHARMACOLOGICAL RELEVANCE: Aristolochic acids (AAs) are naturally occurring nitro phenanthrene carboxylic acids primarily found in plants of the Aristolochiaceae family. Aristolochic acid D (AAD) is a major constituent in the roots and rhizomes of the Chinese herb Xixin (the roots and rhizomes of Asarum heterotropoides F. Schmidt), which is a key material for preparing a suite of marketed Chinese medicines. Structurally, AAD is nearly identical to the nephrotoxic aristolochic acid I (AAI), with an additional phenolic group at the C-6 site. Although the nephrotoxicity and metabolic pathways of AAI have been well-investigated, the metabolic pathway(s) of AAD in humans and the influence of AAD metabolism on its nephrotoxicity has not been investigated yet. AIM OF THE STUDY: To identify the major metabolites of AAD in human tissues and to characterize AAD O-glucuronidation kinetics in different enzyme sources, as well as to explore the influence of AAD O-glucuronidation on its nephrotoxicity. MATERIALS AND METHODS: The O-glucuronide of AAD was biosynthesized and its chemical structure was fully characterized by both 1H-NMR and 13C-NMR. Reaction phenotyping assays, chemical inhibition assays, and enzyme kinetics analyses were conducted to assess the crucial enzymes involved in AAD O-glucuronidation in humans. Docking simulations were performed to mimic the catalytic conformations of AAD in human UDP-glucuronosyltransferases (UGTs), while the predicted binding energies and distances between the deprotonated C-6 phenolic group of AAD and the glucuronyl moiety of UDPGA in each tested human UGT isoenzyme were measured. The mitochondrial membrane potentials (MMP) and reactive oxygen species (ROS) levels in HK-2 cells treated with either AAI, or AAD, or AAD O-glucuronide were tested, to elucidate the impact of O-glucuronidation on the nephrotoxicity of AAD. RESULTS: AAD could be rapidly metabolized in human liver and intestinal microsomes (HLM and HIM, respectively) to form a mono-glucuronide, which was purified and fully characterized as AAD-6-O-ß-D-glucuronide (AADG) by NMR. UGT1A1 was the predominant enzyme responsible for AAD-6-O-glucuronidation, while UGT1A9 contributed to a lesser extent. AAD-6-O-glucuronidation in HLM, HIM, UGT1A1 and UGT1A9 followed Michaelis-Menten kinetics, with the Km values of 4.27 µM, 9.05 µM, 3.87 µM, and 7.00 µM, respectively. Docking simulations suggested that AAD was accessible to the catalytic cavity of UGT1A1 or UGT1A9 and formed catalytic conformations. Further investigations showed that both AAI and AAD could trigger the elevated intracellular ROS levels and induce mitochondrial dysfunction and in HK-2 cells, but AADG was hardly to trigger ROS accumulation and mitochondrial dysfunction. CONCLUSION: Collectively, UGT1A-catalyzed AAD 6-O-glucuronidation represents a crucial detoxification pathway of this naturally occurring AAI analogs in humans, which is very different from that of AAI.

[Monoterpenoids from Paeoniae Radix Rubra based on UPLC-Q-TOF-MS].

The ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry(UPLC-Q-TOF-MS) was used to conduct the qualitative analysis of the monoterpene chemical components from Paeoniae Radix Rubra. Gradient elution was performed on C_(18) HD(2.1 mm×100 mm, 2.5 µm) column with a mobile phase of 0.1% formic acid(A) and acetonitrile(B). The flow rate was 0.4 mL·min~(-1) and the column temperature was 30 ℃. MS analysis was conducted in both positive and negative ionization modes using electrospray ionization(ESI) source. Qualitative Analysis 10.0 was used for data processing. The identification of chemical components was realized by the combination of standard compounds, fragmentation patterns, and mass spectra data reported in the literature. Forty-one monoterpenoids in Paeoniae Radix Rubra extract were identified. Among them, 8 compounds were reported in Paeoniae Radix Rubra for the first time and 1 was presumed to be the new compound 5″-O-methyl-galloylpaeoniflorin or its positional isomer. The method in this study realizes the rapid identification of monoterpenoids from Paeoniae Radix Rubra and provides a material and scientific basis for quality control and further study on the pharmaceutical effect of Paeoniae Radix Rubra.

Preparation and identification of isoquinoline alkaloids with ATP citrate lyase inhibitory activity from Dactylicapnos scandens.

Three new isoquinoline alkaloids including a morphine derivative (1), two aporphine alkaloids (2-3), together with five known alkaloids (4-8) were obtained from the extract of Dactylicapnos scandens (D.Don) Hutch. (D. scandens). Their structures and absolute configurations were elucidated by extensive spectroscopic data analysis including HRESIMS, NMR and electronic circular dichroism (ECD) and ECD calculation. Compounds 1-8 were evaluated for ATP Citrate Lyase (ACLY) inhibitory activity through an enzymatic assay. Among them, 2 and 3 showed the high ACLY inhibitory activity with an IC50 value of 10.48 ± 1.59 and 10.89 ± 4.89 µM.

Structurally diverse isoquinoline and amide alkaloids with dopamine D2 receptor antagonism from Corydalis bungeana.

Four new isoquinoline alkaloids including a benzophenanthridine alkaloid (1), a morphine derivative (2), a narceine-type alkaloid (3) and a simple isoquinoline alkaloid (4), a new amide alkaloid (5) and a new phthalic acid derivative (6), together with eleven known alkaloids (7-17) were obtained from the whole herbs extract of Corydalis bungeana Turcz. Their structures and absolute configurations were elucidated by extensive spectroscopic data analysis including HRESIMS, NMR and electronic circular dichroism (ECD) and ECD calculation. Compounds 1-17 were evaluated for dopamine D2 receptor activity in CHO-D2 cells. Among them, 16 showed the highest antagonistic activity on the D2 receptor with an IC50 value of 2.04 ± 0.01 µM. Compounds 14 and 15 exhibited moderate antagonism with IC50 values of 13.66 ± 2.28 and 31.72 ± 2.52 µM, respectively.

Comprehensive profiling and characterization of the absorbed components and metabolites in mice serum and tissues following oral administration of Qing-Fei-Pai-Du decoction by UHPLC-Q-Exactive-Orbitrap HRMS.

Qing-Fei-Pai-Du decoction (QFPDD) is a Chinese medicine compound formula recommended for combating corona virus disease 2019 (COVID-19) by National Health Commission of the People's Republic of China. The latest clinical study showed that early treatment with QFPDD was associated with favorable outcomes for patient recovery, viral shedding, hospital stay, and course of the disease. However, the effective constituents of QFPDD remain unclear. In this study, an UHPLC-Q-Orbitrap HRMS based method was developed to identify the chemical constituents in QFPDD and the absorbed prototypes as well as the metabolites in mice serum and tissues following oral administration of QFPDD. A total of 405 chemicals, including 40 kinds of alkaloids, 162 kinds of flavonoids, 44 kinds of organic acids, 71 kinds of triterpene saponins and 88 kinds of other compounds in the water extract of QFPDD were tentatively identified via comparison with the retention times and MS/MS spectra of the standards or refereed by literature. With the help of the standards and in vitro metabolites, 195 chemical components (including 104 prototypes and 91 metabolites) were identified in mice serum after oral administration of QFPDD. In addition, 165, 177, 112, 120, 44, 53 constituents were identified in the lung, liver, heart, kidney, brain, and spleen of QFPDD-treated mice, respectively. These findings provided key information and guidance for further investigation on the pharmacologically active substances and clinical applications of QFPDD.

Inhibition of drug-metabolizing enzymes by Qingfei Paidu decoction: Implication of herb-drug interactions in COVID-19 pharmacotherapy.

Corona Virus Disease 2019 (COVID-19) has spread all over the world and brings significantly negative effects on human health. To fight against COVID-19 in a more efficient way, drug-drug or drug-herb combinations are frequently used in clinical settings. The concomitant use of multiple medications may trigger clinically relevant drug/herb-drug interactions. This study aims to assay the inhibitory potentials of Qingfei Paidu decoction (QPD, a Chinese medicine compound formula recommended for combating COVID-19 in China) against human drug-metabolizing enzymes and to assess the pharmacokinetic interactions in vivo. The results demonstrated that QPD dose-dependently inhibited CYPs1A, 2A6, 2C8, 2C9, 2C19, 2D6 and 2E1 but inhibited CYP3A in a time- and NADPH-dependent manner. In vivo test showed that QPD prolonged the half-life of lopinavir (a CYP3A substrate-drug) by 1.40-fold and increased the AUC of lopinavir by 2.04-fold, when QPD (6 g/kg) was co-administrated with lopinavir (160 mg/kg) to rats. Further investigation revealed that Fructus Aurantii Immaturus (Zhishi) in QPD caused significant loss of CYP3A activity in NADPH-generating system. Collectively, our findings revealed that QPD potently inactivated CYP3A and significantly modulated the pharmacokinetics of CYP3A substrate-drugs, which would be very helpful for the patients and clinicians to avoid potential drug-interaction risks in COVID-19 treatment.

Identification and characterization of naturally occurring inhibitors against human carboxylesterase 2 in White Mulberry Root-bark.

White Mulberry Root-bark (WMR) is an edible Chinese herbal used for the treatment of inflammation, nephritis and asthma. This study aimed to investigate the inhibitory effects of ethanol extract from WMR against human carboxylesterase 2 (hCE2), as well as to identity and character natural hCE2 inhibitors in this herbal. Our results demonstrated that the ethanol extract of WMR displayed potent inhibitory effects against hCE2, while three major bioactive constitutes in WMR were identified on the basis of LC fingerprinting combined with activity-based screening of LC fractions. Three bioactive compounds including SD, KG and SC were efficiently identified by comparison of LC retention times, UV and MS spectral data, with the help of authentic standards. The inhibition potentials and inhibition types of these natural compounds against hCE2 were further investigated in human liver microsomes. The results demonstrated that these bioactive compounds are potent non-competitive inhibitors against hCE2, with the Ki values ranging from 0.76µM to 1.09µM. All these findings suggested that three abundant natural compounds in WMR displayed potent inhibitory effects against hCE2, which could be used as lead compounds to develop more potent hCE2 inhibitors for the alleviation of hCE2-mediated severe delayed-onset diarrhea.

Neuroprotective effect of schizandrin A on oxygen and glucose deprivation/reperfusion-induced cell injury in primary culture of rat cortical neurons

Brain ischemia appears to be associated with innate immunity. Recent reports showed that C3a and C5a, as potent targets, might protect against ischemia induced cell death. In traditional Chinese medicine, the fruit of Schizandra chinesis Baill (Fructus schizandrae) has been widely used as a tonic. In the present study, we sought to evaluate the neuroprotective effects of schizandrin A, a composition of S. chinesis Baill, against oxygen and glucose deprivation followed by reperfusion (OGD/R)-induced cell death in primary culture of rat cortical neurons, and to test whether C3a and C5a affected cortical neuron recovery from ischemic injury after schizandrin A treatment. The results showed that schizandrin A significantly reduced cell apoptosis and necrosis, increased cell survival, and decreased intracellular calcium concentration ([Ca2+]i) and lactate dehydrogenase (LDH) release in primary culture of rat cortical neurons after OGD/R. Mechanism studies suggested that the modulation of extracellular-regulated kinase (ERK), c-Jun NH2-terminal kinases (JNK), and p38, as well as caspase-3 activity played an important role on the progress of neuronal apoptosis. C5aR participated in the neuroprotective effect of schizandrin A in primary culture of rat cortical neurons after OGD/R. Our findings suggested that schizandrin A might act as a candidate therapeutic target drug used for brain ischemia and related diseases

Neuroprotective effect of schizandrin A on oxygen and glucose deprivation/reperfusion-induced cell injury in primary culture of rat cortical neurons.

Brain ischemia appears to be associated with innate immunity. Recent reports showed that C3a and C5a, as potent targets, might protect against ischemia induced cell death. In traditional Chinese medicine, the fruit of Schizandra chinesis Baill (Fructus schizandrae) has been widely used as a tonic. In the present study, we sought to evaluate the neuroprotective effects of schizandrin A, a composition of S. chinesis Baill, against oxygen and glucose deprivation followed by reperfusion (OGD/R)-induced cell death in primary culture of rat cortical neurons, and to test whether C3a and C5a affected cortical neuron recovery from ischemic injury after schizandrin A treatment. The results showed that schizandrin A significantly reduced cell apoptosis and necrosis, increased cell survival, and decreased intracellular calcium concentration ([Ca(2+)]i) and lactate dehydrogenase (LDH) release in primary culture of rat cortical neurons after OGD/R. Mechanism studies suggested that the modulation of extracellular-regulated kinase (ERK), c-Jun NH2-terminal kinases (JNK), and p38, as well as caspase-3 activity played an important role on the progress of neuronal apoptosis. C5aR participated in the neuroprotective effect of schizandrin A in primary culture of rat cortical neurons after OGD/R. Our findings suggested that schizandrin A might act as a candidate therapeutic target drug used for brain ischemia and related diseases.

[Effects of effective components compatibility of aqueous extracts of Salviae Miltiorrhizae and Rhizoma Chuanxiong on rat myocardial ischemia/reperfusion injury].

OBJECTIVE: To observe effects of effective components compatibility of aqueous extracts of Salviae Miltiorrhizae and Rhizoma Chuanxiong on myocardial ischemia/reperfusion (I/R) injury in rat. METHODS: Sprague-Dawley (SD) rats were randomly divided into sham group, model group, Guanxinning injection group and effective components of aqueous extracts from Salviae Miltiorrhizae and Rhizoma Chuanxiong salvianolic low dose group and high dose group, with 10 rats in each group. The myocardial I/R injury model was reproduced by ligation of the left anterior descending artery, and the experimental drugs were injected intravenously via femoral vein at 10 minutes after ligation. 2.88 g/kg Guanxinning injection was given in Guanxinning group, and 2.43 g/kg or 4.86 g/kg effective components of aqueous extracts of Salviae Miltiorrhizae and Rhizoma Chuanxiong salvianolic was given in low dose group and high dose group, respectively, and equal volume of normal saline was given in sham group and model group. The anesthetic rats were sacrificed 40 minutes after ischemia and 120 minutes of reperfusion. Blood samples were collected before rats were sacrificed. The contents of serum troponin T (cTnT) and MB isoenzyme of creatine kinase (CK-MB) were determined, 6-keto-prostaglandin F(1 alpha) (6-keto-PGF(1 alpha)), thromboxane B(2) (TXB(2)) and platelet aggregation rate in blood plasma were assessed, and the degree of myocardial infarction in rats was determined. RESULTS: The myocardial infarction size in combined Salviae Miltiorrhizae and Rhizoma Chuanxiong low dose group and high dose group [(23.0+/-3.8)%, (20.8+/-4.7)%] were lower significantly than that in model group [(29.1+/-3.2)%, P<0.05 and P<0.01], the contents of serum cTnT [(0.78+/-0.29) mg/L, (0.76+/-0.29) mg/L] and CK-MB [(891.5+/-252.5) U/L, (759.5+/-191.3) U/L] were lower significantly than those in model group [(1.04+/-0.14) mg/L, (1 268.2+/-256.5) U/L, all P<0.05]. The level of 6-keto-PGF(1 alpha) was higher significantly in high dose of the combination group than that in model group [(206.7+/-35.6) ng/L vs. (138.6+/-28.9) ng/L, P<0.05], and platelet aggregation rate was inhibited significantly [(49.4+/-9.3)% vs. (77.1+/-16.7)%, P<0.05]. CONCLUSION: Effective components compatibility of aqueous extracts from Salviae Miltiorrhizae and Rhizoma Chuanxiong may reduce significantly the size of myocardial infarct and blood content of myocardial enzyme CK-MB and cTnT, and increase the ratio of 6-keto-PGF(1 alpha)/TXB(2), thus reducing myocardial I/R injury.

Three novel terpenoids from the rhizomes of Curcuma longa.

Investigation of the EtOH extract of the rhizomes of Curcuma longa led to the isolation of two new sesquiterpenes, 2-methoxy-5-hydroxybisabola-3,10-diene-9-one (1) and 2,8-epoxy-5-hydroxybisabola-3,10-diene-9-one (2), one new monoterpene, 2-(2,5-dihydroxy-4-methylcyclohex-3-enyl)propanoic acid (3), together with five known sesquiterpenes (4-8). Among the known compounds, bisacurone A (5) and 4-methylene-5-hydroxybisabola-2,10-diene-9-one (6) were isolated from C. longa and genus Curcuma for the first time, respectively. Their structures were established on the basis of various spectroscopic analyses including HR-ESI-MS, 1D and 2D NMR, IR spectra, and by comparison of their spectral data with those of related compounds.

Qualitative and quantitative analysis in quality control of traditional Chinese medicines.

Separation techniques with high efficiency and sensitive detection have been widely used for quality control of traditional Chinese medicines (TCMs). High-performance liquid chromatography, gas chromatography, and capillary electrophoresis are commonly used to separate various components in TCMs. Ultraviolet detection, fluorescence detection, evaporative light-scattering detection, mass spectrometry and nuclear magnetic resonance can be applied to separation techniques for qualitative and quantitative analysis of TCMs. The development of quality control for TCMs based on quantitative and qualitative analysis from 2000 to 2007 are reviewed; the fingerprint technique is also discussed due to its broad application in the quality control of TCMs. Prospects for further research based on our primary results are also discussed.

Fingerprint analysis of Ligusticum chuanxiong using hydrophilic interaction chromatography and reversed-phase liquid chromatography.

Fingerprint analysis is considered one of the most powerful approaches to quality control in traditional Chinese medicines (TCMs). In this study, a binary chromatographic fingerprint analysis was developed using hydrophilic interaction chromatography (HILIC) and reversed-phase liquid chromatography (RPLC) to gain more chemical information about polar compounds and weakly polar compounds. This method was used to construct a chromatographic fingerprint of Ligusticum chuanxiong. The two chromatographic methods demonstrated good precision, reproducibility, and stability, with relative standard deviations of <2% for retention time and 7% for peak area for both HILIC and RPLC separations. Data from the analysis of 14 samples by HILIC and RPLC were processed with similarity analysis, with correlation coefficients and congruence coefficients. This binary fingerprint analysis, using two chromatographic modes, is a powerful tool for characterizing the quality of samples, and can be used for the comprehensive quality control of TCMs.

Characterization of polymethoxylated flavones in Fructus aurantii by off-line two-dimensional liquid chromatography/electrospray ionization-ion trap mass spectrometry.

Off-line two-dimensional reversed-phase liquid chromatography (2D-RPLC) coupled to electrospray ionization-ion trap mass spectrometry (ESI-ITMS) was operated in positive mode (PI) to characterize polymethoxylated flavonoids (PMFs) in botanical sample. The fragments of [M+H-nx15](+) produced by loss of one or more methyl group from the protonated molecules, as well as [M+H-14](+), [M+H-29](+), [M+H-33](+), [M+H-43](+), [M+H-46](+) and [M+H-61](+) fragments formed the multiple MS (MS(n)) "fingerprint" of PMFs. 42 target compounds were tentatively identified from the extract of Fructus aurantii (F. aurantii) based on this "fingerprint". Experimental outcomes indicated that the application of 2D separation method can reduce the matrix suppression of analytes caused by the coelution with interferential components and the column overloading of interferential components. 42 versus 23 target compounds were detected through 2D versus 1D method, which confirm the superiority of 2D coupled to MS in elimination of matrix effects.

Structural characterization of iridoid glucosides by ultra-performance liquid chromatography/electrospray ionization quadrupole time-of-flight tandem mass spectrometry.

The mass spectral fragmentation behavior of ten iridoid glucosides (IGs) has been studied using electrospray ionization (ESI), collision-induced dissociation (CID), and quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS). In the negative ESI mass spectra, the deprotonated [M-H](-) ion was observed for all of the ten IGs except gardoside methyl ester, while the formate adduct [M+HCOO](-) ion appeared to be favored by the presence of a methyl ester or a lactone group in the C-4 position when formic acid was added to the mobile phase. The CID MS/MS spectra of the [M-H](-) ions have been used for structural elucidation. Ring cleavages of the aglycone moiety have been observed in the MS/MS spectra, corresponding to (1,4)F(-), (2,6)F(-), (2,7)F(-), and (2,7)F(0) (-) ions, based on accurate mass measurements and the elemental compositions of the product ions. These characteristic ions gave valuable information on the basic structural skeletons. Furthermore, on the basis of the relative abundances of the fragment ions (1,4)F(-) and (2,7)F(-), different sub-classes, such as cyclopentane-type and 7,8-cyclopentene-type IGs, can be differentiated. Ring cleavage of the sugar moieties was also observed, yielding useful information for their characterization. In addition, the neutral losses, such as H(2)O, CO(2), CH(3)OH, CH(3)COOH, and glucosidic units, have proved useful for confirming the presence of functional substituents in the structures of the IGs. Based on the fragmentation patterns of these standard IGs, twelve IGs have been characterized in an extract of Hedyotis diffusa Willd. by means of ultra-performance liquid chromatography/Q-TOF MS/MS, of which six have been unambiguously identified and the other six have been tentatively identified.

Characterization of C-glycosyl quinochalcones in Carthamus tinctorius L. by ultraperformance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry.

C-Glycosyl quinochalcones are unique components in Carthamus tinctorius L. The reported C-glycosyl quinochalcones have the same quinochalcone skeleton with a hydroxyl group at the 5'-position and a glucose linked to this position with a carbon-carbon bond. In this study, the standard hydroxysafflor yellow A and water-extracted fraction of Carthamus tinctorius L. were analyzed by ultraperformance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UPLC/Q-TOFMS) in both positive and negative ion modes. The fragmentation pathways of C-glycosyl quinochalcones were interpreted and validated by accurate mass measurement. Their fragmentation showed a special cleavage at the C-C bond except for the typical internal cleavage at the sugar moiety of other C-glycosyl flavonoids. In positive ion mode, cleavage of the 5'-glucose produced an [M+H-162](+) ion by a neutral loss, while cleavage of the 5'-glucose in negative ion mode led to an [M-H-163](-.) ion by radical cleavage. The cleavage from the carbonyl group produced fragment ions containing an A or a B ring. The fragment ions containing an A ring were common product ions of seven compounds in both ion modes, and fragment ions containing the B ring were used to judge the different substituent groups at the 3'-position. The fragmentation patterns of seven structurally related C-glycosyl quinochalcones were analyzed systematically and the formation of the fragment ions in two modes is explained in detail in this report. UPLC/Q-TOFMS is an effective tool for characterizing a complex sample, which gives higher resolution separation and generates accurate mass measurement of the product ions.

Polymethoxylated flavones metabolites in rat plasma after the consumption of Fructus aurantii extract: analysis by liquid chromatography/electrospray ion trap mass spectrometry.

A LC with full scan MS(n) method was developed in order to investigate the in vivo absorption and biotransformation of polymethoxylated flavones (PMFs) by analysis of plasma samples from rats after ingestion of Fructus aurantii extract. Four parent compounds and six metabolites with intact flavonoid structures were tentatively identified. The metabolites were either glucuronides of parent compounds or glucuronides of demethylated products of parent compounds.

Systematic screening and characterization of flavonoid glycosides in Carthamus tinctorius L. by liquid chromatography/UV diode-array detection/electrospray ionization tandem mass spectrometry.

The traditional Chinese medicine (TCM) is a complex system, which always consists of numerous compounds with significant difference in the content and physical and chemical properties. In this paper, a screening method based on target molecular weights was developed to characterize the flavonoid glycosides in the flower of Carthamus tinctorius L. The screening tables of aglycone and glycan were designed, respectively, in order to select and combine freely. The multiple reaction monitoring (MRM) scan mode with higher sensitivity and selectivity was adopted in the screening, which benefit the characterization for the minor components. Seventy-seven flavonoid glycosides were screened out finally, and their structures were characterized by tandem mass spectrometric method in both positive and negative ion modes. The glycosylation mode, aglycone, sequence and/or the interglycosidic linkages of the glycan portion and glycosylation position were elucidated by the fragmentation rule in the MS. Numerous compounds screened out with this method showed the structure variety in secondary plant metabolites, and the purposeful screening systemically and subsequent structure characterization offered more information about the chemical constitutions of TCM.

Simultaneous characterization of isoflavonoids and astragalosides in two Astragalus species by high-performance liquid chromatography coupled with atmospheric pressure chemical ionization tandem mass spectrometry.

A method was developed for the simultaneous identification of astragalosides (AGs) and isoflavonoids (IFs) in the roots of Astragalus membranaceus and Astragalus mongholicus by HPLC coupled with atmospheric pressure chemical ionization MS/MS (HPLC-APCI-MS/MS). Diagnostic fragment ions of AGs and different group of IFs were obtained with one AG and eight IF standards analyzed by CID-MS, which were adopted as characteristic MS/MS fingerprints for further identification of these compounds in the two Astragalus species by using HPLC-APCI-MS/MS. A total of 20 IFs and 10 AGs were identified or tentatively identified. Among them, six IFs were detected in A. membranaceus for the first time and five IFs were firstly identified in A. mongholicus. The results indicate that HPLC-APCI-MS/MS is a powerful tool for the simultaneous characterization of IFs and AGs in complex matrix.