Tentative identification of new metabolites of epimedin C by liquid chromatography-mass spectrometry

Uncovering the key pharmacodynamic material basis and possible molecular mechanism of extract of Epimedium against liver cancer through a comprehensive investigation

ETHNOPHARMACOLOGICAL RELEVANCE

Liver cancer is a worldwide malignant tumor, and currently lacks effective treatments. Clinical studies have shown that epimedium (YYH) has therapeutic effects on liver cancer, and some of its prenylflavonoids have demonstrated anti-liver cancer activity through multiple mechanisms. However, there is still a need for systematic research to uncover the key pharmacodynamic material basis and mechanism of YYH.

AIM OF THE STUDY

This study aimed to screen the anti-cancer material basis of YYH via integrating spectrum-effect analysis with serum pharmacochemistry, and explore the multi-target mechanisms of YYH against liver cancer by combining network pharmacology with metabolomics.

MATERIALS AND METHODS

The anti-cancer effect of the extract of YYH (E-YYH) was first evaluated in mice with xenotransplantation H22 tumor cells burden and cultured hepatic cells. Then, the interaction between E-YYH compounds and the cytotoxic effects was revealed through spectrum-effect relationship analysis. And the cytotoxic effects of screened compounds were verified in hepatic cells. Next, UHPLC-Q-TOF-MS/MS was employed to identify the absorbed components of E-YYH in rat plasma to distinguish anti-cancer components. Subsequently, network pharmacology based on anti-cancer materials and metabolomics were used to discover the potential anti-tumor mechanisms of YYH. Key targets and biomarkers were identified and pathway enrichment analysis was performed.

RESULTS

The anti-cancer effect of E-YYH was verified through in vitro and in vivo experiments. Six anti-cancer compounds in plasma (icariin, baohuoside Ⅰ, epimedin C, 2″-O-rhamnosyl icariside Ⅱ, epimedin B and sagittatoside B) were screened out by spectrum-effect analysis. Forty-five liver-cancer-related targets were connected with these compounds. Among these targets, PTGS2, TNF, NOS3 and PPARG were considered to be the potential key targets preliminarily verified by molecular docking. Meanwhile, PI3K/AKT signaling pathway and arachidonic acid metabolism were found to be associated with E-YYH's efficacy in network pharmacology and metabolomics analysis.

CONCLUSIONS

Our research revealed the characteristics of multi-component, multi-target and multi-pathway mechanism of E-YYH. This study also provided an experimental basis and scientific evidence for the clinical application and rational development of YYH.

Systematically Engineered Fatty Acid Catabolite Pathway for the Production of (2S)-Naringenin in Saccharomyces cerevisiae

The (2S)-naringenin is an important natural flavonoid with several bioactive effects on human health. It is also a key precursor in the biosynthesis of other high value compounds. The production of (2S)-naringenin is significantly influenced by the acetyl-CoA available in the cytosol. In this study, we increased the acetyl-CoA supply via the β-oxidation of fatty acids in the peroxisomes of Saccharomyces cerevisiae. Several lipases from different sources and PEX11, FOX1, FOX2, and FOX3, the key genes of the fatty acid β-oxidation pathway, were overexpressed during the production of (2S)-naringenin in yeast. The level of acetyl-CoA was 0.205 nmol higher than that in the original strain and the production of (2S)-naringenin increased to 286.62 mg/g dry cell weight when PEX11 was overexpressed in S. cerevisiae strain L07. Remarkable (2S)-naringenin production (1129.44 mg/L) was achieved with fed-batch fermentation, with the highest titer reported in any microorganism. Our results demonstrated the use of fatty acid β-oxidation to increase the level of cytoplasmic acetyl-CoA and the production of its derivatives.

Promoter-Library-Based Pathway Optimization for Efficient (2S)-Naringenin Production from p-Coumaric Acid in Saccharomyces cerevisiae

Pathway optimization plays an important role in fine-tuning metabolic pathways. In most conditions, more than three genes are involved in the biosynthesis pathway of a specific target product. To improve the titer of products, rational regulation of a group of genes by a series of promoters with different strengths is essential. On the basis of a series of RNA-Seq data, a set of 66 native promoters was chosen to fine-tune gene expression in Saccharomyces cerevisiae. Promoter strength was characterized by measuring the fluorescence strength of the enhanced green fluorescent protein through fluorescence-activated cell sorting. The expressions of P_TDH1, P_PGK1, P_INO1, P_SED1, and P_CCW12 were stronger than that of P_TDH3, whereas those of another 15 promoters were stronger than that of P_TEF1. Then, 30 promoters were chosen to optimize the biosynthesis pathway of (2S)-naringenin from p-coumaric acid. With a high-throughput screening method, the highest titer of (2S)-naringenin in a 5 L bioreactor reached 1.21 g/L from p-coumaric acid, which is the highest titer according to the currently available reports.

Efficient Biosynthesis of (2S)-Naringenin from p-Coumaric Acid in Saccharomyces cerevisiae

(2S)-Naringenin, a (2S)-flavanone, is widely used in the food, chemical, and pharmaceutical industries because of its diverse physiological activities. The production of (2S)-naringenin in microorganisms provides an ideal source that reduces the cost of the flavonoid. To achieve efficient production of (2S)-naringenin in Saccharomyces cerevisiae (S. cerevisiae), we constructed a biosynthetic pathway from p-coumaric acid, a cost-effective and more efficient precursor. The (2S)-naringenin synthesis pathway genes were integrated into the yeast genome to obtain a (2S)-naringenin production strain. After gene dosage experiments, the genes negatively regulating the shikimate pathway and inefficient chalcone synthase activity were verified as factors limiting (2S)-naringenin biosynthesis. With fed-batch process optimization of the engineered strain, the titer of (2S)-naringenin reached 648.63 mg/L from 2.5 g/L p-coumaric acid. Our results indicate that the constitutive production of (2S)-naringenin from p-coumaric acid in S. cerevisiae is highly promising.

Metabolic profile of danshen in rats by HPLC-LTQ-Orbitrap mass spectrometry

Danshen, the dried root of Salvia miltiorrhiza Bunge (Lamiaceae), is one of the traditional Chinese medicines (TCMs) most commonly used for the treatment of cardiovascular and cerebrovascular diseases. However, little is known about the chemical and metabolic profiles of danshen in vitro or in vivo. In particular, more information is needed in relation to the 50% ethanol extracts usually used in danshen formulations such as Fufang Xueshuantong Capsules and Fufang Danshen tablets. High-performance liquid chromatography coupled with a linear ion trap-Orbitrap mass spectrometer (HPLC-LTQ-Orbitrap) provides a sensitive and accurate method for analyzing the composition of samples. This method was used to determine the in vitro and in vivo chemical and metabolic profiles of danshen. Sixty-nine components of danshen extract and 118 components of danshen in rat plasma, urine, feces, and bile were unambiguously or tentatively identified. These results not only revealed the material composition of danshen, but also provided a comprehensive research approach for the identification of multi-constituents in TCMs.

Pharmacokinetics and metabolism study of veratramine in mice after oral administration using LC-MS/MS

A simple and sensitive high-performance liquid chromatography coupled with hybrid triple quadrupole-linear ion trap mass spectrometry (Q-trap-MS) method was developed and validated for the determination of veratramine, the major bioactive and neurotoxic component in Veratrum nigrum L. Veratramine and the internal standard (IS) were separated with a Waters Symmetry C18 column and eluted with a gradient mobile phase system containing acetonitrile and 0.1% aqueous formic acid. The analysis was performed by using positive electrospray ionization mode with multiple reaction monitoring (MRM). Transition ions of m/z 410.2 → 295.2 for veratramine and m/z 426.1 → 113.8 for the IS were monitored. The method was validated with a good linearity in the range of 1-1000 ng/mL and lower limit of quantification of 1 ng/mL. The precision (CV) of intra- and inter-day ranged from 3.92 to 7.29%, while the accuracy (bias) intra- and inter-day were between -4.78 and 1.65%. The recovery, stability and matrix effect were within the acceptable ranges. Five metabolites of veratramine, including four hydroxylated and one sulfated metabolites, were tentatively identified using predictive MRM-information dependent acquisition-enhanced product ion mode (predictive MRM-IDA-EPI). The developed method was successfully applied to the pharmacokinetic and metabolic study of veratramine in mice after oral administration of veratramine. Copyright © 2016 John Wiley & Sons, Ltd.

Chemical Constituents, Quality Control, and Bioactivity of Epimedii Folium (Yinyanghuo)

Epimedii Folium (Yinyanghuo in Chinese) is one of the most commonly used traditional Chinese medicines. Its main active components are flavonoids, which exhibit multiple biological activities, such as promotion of bone formation and sexual function, protection of the nervous system, and prevention of cardiovascular diseases. Flavonoids also show anti-inflammatory and anticancer effects. Various effective methods, including genetic and chemical approaches, have been developed for the quality control of Yinyanghuo. In this review, the studies conducted in the last decade about the chemical constituents, quality control, and bioactivity of Yinyanghuo are summarized and discussed.

Pharmacological effects and pharmacokinetic properties of icariin, the major bioactive component in Herba Epimedii

Herba Epimedii is an important medicinal plant which has been used in various traditional Chinese formulations for thousands of years as well as in modern proprietary traditional Chinese medicine products. It has extensive clinical indications, especially for the treatment of sexual dysfunction and osteoporosis. There have been more than 260 chemical moieties identified in the genus Epimedium most of which belong to flavonoids. Icariin is the most abundant constituent in Herba Epimedii. Icariin is pharmacologically bioactive and demonstrates extensive therapeutic capacities such as osteoprotective effect, neuroprotective effect, cardiovascular protective effect, anti-cancer effect, anti-inflammation effect, immunoprotective effect and reproductive function. Particularly, the significant osteogenic effect of icariin made it a promising drug candidate in bone tissue engineering. The current review paper aims to summarize the literatures reporting the pharmacological effects of icariin. The pharmacokinetic properties of bioactive ingredients in Herba Epimedii have also been discussed.

Metabolic profile of Yi-Xin-Shu capsule in rat by ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry analysis

In this study, the metabolite profiles of YXS in different biofluids of rats were investigated.

Metabolic profiling of isomeric aglycones central-icaritin (c-IT) and icaritin (IT) in osteoporotic rats by UPLC-QTOF-MS

The isomers, although of similarly chemical structures, have different pharmacological activities due to their metabolic processes in vivo. Central-icaritin (c-IT) and icaritin (IT) are isomers and major bioactive aglycones of the Herba Epimedii. In this study, we found that the anti-osteoporotic effect of c-IT was stronger than IT on bone structural changes in osteoporotic rats evaluated by Micro-μCT with the parameters of bone mineral density (BMD), bone mineral content (BMC), tissue mineral content (TMC), and tissue mineral density (TMD). c-IT treatment significantly increased the bone microarchitecture, compared with IT (p < 0.05). In order to explain their differences in anti-osteoporosis, the metabolic profiling and pathways of c-IT and IT in the plasma, bile, urine, and faeces of ovariectomized (OVX) rats were investigated by ultra-performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC-QTOF-MS) after oral administration of c-IT or IT (80 mg/kg). Finally, 59 metabolites of c-IT and 43 metabolites of IT were identified by elucidating their corresponding quasimolecular ions and fragment ions. IT could be quickly absorbed into blood and reached a maximum plasma concentration, and then be rapidly conversed to its glucuronidation metabolites, most of which were excreted out by urine. Interestingly, the absorbed and conjugated speeds of c-IT were slower than IT. The metabolic processes of c-IT existed enterohepatic circulation, which decreased the metabolism and excretion rate of c-IT, and prolonged the anti-osteoporosis effect. Our findings provided evidence on the difference on metabolic profiles of c-IT and IT in osteoporotic rats, which might shed new lights on improving anti-osteoporotic effects of IT and c-IT.

Metabolic characterization of (±)-praeruptorin A in vitro and in vivo by high performance liquid chromatography coupled with hybrid triple quadrupole-linear ion trap mass spectrometry and time-of-flight mass spectrometry

(±)-Praeruptorin A (PA) is the major bioactive component in Peucedani Radix (Chinese name: Qian-hu), and exhibits dramatically anti-hypertensive effect typically through acting as a calcium channel blocker. The current study aims on the characterization of the metabolic profiles of PA in vitro and in vivo using high performance liquid chromatography (HPLC) coupled with hybrid triple quadrupole-linear ion trap mass spectrometry (Q-trap-MS) and time-of-flight mass spectrometry (TOF-MS). A total of 12 phase I metabolites (M1-12) in rat liver microsomes (RLMs), 9 phase I metabolites (M1-3, M5-6 and M9-12) in human liver microsomes (HLMs), 2 hydrolyzed products in rat plasma (M11 and M12), none metabolite in human plasma, none metabolite in rat intestinal bacteria, 7 metabolites (M1, M4-7, M13 and M15) in PA-treated rat urine and 6 metabolites (M1, M4-7 and M15) in PA-treated feces were detected and tentatively identified using predictive multiple reaction monitoring-information dependent acquisition-enhanced product ion (predictive MRM-IDA-EPI) mode in combination with enhanced mass spectrum-information dependent acquisition-enhanced product ion (EMS-IDA-EPI) mode in the mass spectrometer domain, respectively, while TOF-MS was adopted to confirm the identification. Further, 2 glucuronidated metabolites (M13-14) in RLMs and none metabolite in HLMs of cis-khellactone (CKL), which was the main actual form of PA in vivo, were generated, while its sulfated product was not observed in either rat liver S9 fractions (RS9) or human liver S9 fractions (HS9). Oxidation, hydrolysis, intra-molecular acyl migration and glucuronidation were demonstrated to be the predominant metabolic types for PA in vitro and in vivo. Judging from the decrement of peak areas, PA was metabolized quickly in both RLMs and HLMs, indicating extensively hepatic first-pass elimination. Taken together, the metabolic fates of (±)-praeruptorin A in vitro and in vivo were elucidated in current study, and Q-trap-MS coupled with LightSight™ software can be adopted as a useful tool for quick detection and identification of metabolites in complex biological matrices.