Characterization of metabolic profile of honokiol in rat feces using liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry and 13C stable isotope labeling

Honokiol and magnolol: A review of structure-activity relationships of their derivatives

Honokiol (HK) and magnolol (MAG) are typical representatives of neolignans possessing a wide range of biological activities and are employed as traditional medicines in Asia. In the past few decades, HK and MAG have been proven to be promising chemical scaffolds for the development of novel neolignan drugs. This review focuses on recent advances in the medicinal chemistry of HK and MAG derivatives, especially their structure-activity relationships. In addition, it also presents a comprehensive summary of the pharmacology, biosynthetic pathways, and metabolic characteristics of HK and MAG. This review can provide pharmaceutical chemists deeper insights into medicinal research on HK and MAG, and a reference for the rational design of HK and MAG derivatives.

Honokiol inhibits epithelial-mesenchymal transition and hepatic fibrosis via activation of Ecadherin/GSK3β/JNK and inhibition of AKT/ERK/p38/β-catenin/TMPRSS4 signaling axis

Though Honokiol was known to have anti-inflammatory, antioxidant, anticancer, antithrombotic, anti-viral, metabolic, antithrombotic, and neurotrophic activities, the underlying mechanisms of Honokiol on epithelial-mesenchymal transition (EMT) mediated liver fibrosis still remain elusive so far. Anti-EMT and antifibrotic effects of Honokiol were explored in murine AML-12 hepatocyte cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, wound healing assay, Western blotting and also in CCl4-induced liver injury mouse model by immunohistochemistry. Honokiol significantly suppressed transforming growth factor β1 (TGF-β1)-induced EMT and migration of AML-12 cells along with decreased EMT phenotypes such as loss of cell adhesion and formation of fibroblast like mesenchymal cells in TGF-β1-treated AML-12 cells. Consistently, Honokiol suppressed the expression of Snail and transmembrane protease serine 4 (TMPRSS4), but not p-Smad3, and activated E-cadherin in TGF-β1-treated AML-12 cells. Additionally, Honokiol reduced the expression of β-catenin, p-AKT, p-ERK, p-p38 and increased phosphorylation of glycogen synthase kinase 3 beta (GSK3β) and JNK in TGF-β1-treated AML-12 cells via TGF-β1/nonSmad pathway. Conversely, GSK3β inhibitor SB216763 reversed the ability of Honokiol to reduce Snail, β-catenin and migration and activate E-cadherin in TGF-β1-treated AML-12 cells. Also, Honokiol suppressed hepatic steatosis and necrosis by reducing the expression of TGF-β1 and α-SMA in liver tissues of CCl4 treated mice. These findings provide scientific evidence that Honokiol suppresses EMT and hepatic fibrosis via activation of E-cadherin/GSK3β/JNK and inhibition of AKT/ERK/p38/β-catenin/TMPRSS4 signaling axis.

Computational method for rapid screening of the metabolites of Pulsatilla chinensis in rats using UHPLC-Q-TOF/MS combined with mass spectrum-based orthogonal projection

Screening metabolites in vivo can be challenging due to the complexity of traditional Chinese medicine (TCM) and the ambiguous intracorporal process. To resolve this problem, we established the mass spectrum-based orthogonal projection (MSOP) method to differentiate prototype compounds from metabolites in vivo and applied it to the study of metabolites of Pulsatilla chinensis (PC). Initially, the validity and feasibility of the MSOP method were verified by using the ultra- high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) data of reference solution. Then, the MSOP method was applied to screen the metabolites of PC. A total of 63 metabolites were identified in vivo (urine, feces, bile, and plasma samples) and in vitro (intestinal bacteria biological sample). The results indicated that the main metabolic pathways of pentacyclic triterpenoids were demethylation, oxidation, dehydration, sulfation, and glucuronidation reactions. This study contributes to developing an integrated strategy based on chemometrics to characterize and classify the metabolism feature of pentacyclic triterpenoids of PC. This will support the scientific and rational application of PC in the clinic. The MSOP method based on the orthogonality of MS signals was used to differentiate the prototype compounds from metabolites in vivo. The method provides scientific and reliable support for fully understanding the metabolic fate of TCM.

Pharmacokinetics and metabolites of glycosides and lignans of the stem bark of Magnolia officinalis in functional dyspepsia and normal rats using LC-MS/MS

The stem bark of Magnolia officinalis is a traditional Chinese medicine for the treatment of abdominal distention and functional dyspepsia. The pharmacokinetics of three glycosides (magnoloside A, magnoloside B, and syringin) and two lignans (honokiol and magnolol) in both of normal and functional dyspepsia rats were firstly investigated by ultra-performance liquid chromatography-triple quadrupole mass spectrometry method and the influences of the coexisting compounds on the pharmacokinetic parameters of honokiol and magnolol were also studied. It was found that all of the five target compounds were quickly absorbed and eliminated in both of normal and functional dyspepsia rats, while, their residence time was significantly decreased in pathological states except magnoloside A. The coexisting compounds in the stem bark of M. officinalis significantly reduced absorption and increased elimination of honokiol in vivo. It's worth noticing that the volume of distribution of lignan was quite lower than that of glycoside. Moreover, the metabolic profiling of magnoloside A, honokiol, and magnolol in vivo was analyzed by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry method, from which three prototypes were identified and thirty five metabolites were putatively characterized, and eighteen unknown metabolites were reasonably characterized for the first time. The results indicated that sulfation and glucuronidation were the main metabolic pathways of honokiol and magnolol. This article is protected by copyright. All rights reserved.

Biphenyl-type neolignans from stem bark of Magnolia officinalis with potential anti-tumor activity

Six new biphenyl-type neolignans (1-6), and eighteen known compounds (7-24) were isolated from the EtOH extract of Magnolia officinalis. Their structures were determined by 1D and 2D NMR, and by HRMS. The anti-tumor activities of the isolated compounds were evaluated on HepG2, HCT-116, H1975 and HUVEC cell lines. Among the isolated compounds, nine compounds (3, 5, 7, 8, 12, 14, 20, 22, and 24) showed moderate cytotoxicities, and compound 23 showed the best cytotoxicity with IC₅₀ value lower than 10 μM.

Determination of the chemical components and phospholipids of velvet antler using UPLC/QTOF-MS coupled with UNIFI software

Velvet antler, which exhibits immune and growth enhancing effects, is commonly used in a variety of Asian health care products, but its complex components remain unknown. The current study analyzed extracts using ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry in the MSE mode. Automated detection and data filtering were performed using UNIFI software and peaks were compared with a proprietary scientific library (Traditional Medicine Library; TML). The results obtained using different data processing parameters (including 3D peak detection, target by mass and fragment identification) were evaluated against 87 compounds comprising 1 lignan, 30 terpenoids (including 20 triterpenes), 39 steroids, 8 alkaloids, 4 organic acids and 5 esters in the TML. Using a screening method with a mass accuracy cutoff of ±2 mDa, a retention time cutoff of ±0.2 min, a minimum response threshold of 1,000 counts and an average of 10 false detects per sample analysis, 16 phospholipids were identified in the extracts of velvet antler, three of which were quantified. The results demonstrated that there was 1.07±0.02 µg/g of 1-myristoyl-sn-glycero-3-phosphocholine, 7.05±0.52 ng/g of 1,2-dimyristoyl-sn-glycero-3-phosphocholine and 18.81±0.55 ng/g of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine in velvet antler. The current study successfully identified certain components of velvet antler. Furthermore, the results may provide an experimental basis for further pharmacological and clinical study.

Discovery and synthesis of novel magnolol derivatives with potent anticancer activity in non-small cell lung cancer

EGFR T790 M accounts for 50% to 60% of cases of non-small-cell lung carcinoma (NSCLC) resistance to the first-generation EGFR tyrosine kinase inhibitors (TKIs). Hence, identifying novel compounds with activity against TKIs resistant is of great value. In this study, twenty honokiol and magnolol derivatives were isolated from the EtOH extract of Magnolia officinalis and the antiproliferative activity was evaluated on HCC827 (19del EGFR mutation), H1975 (L858 R/T790 M EGFR mutation), and H460 (KRAS mutation) cell lines. Among the isolated compounds, piperitylmagnolol (a 3-substituted magnolol derivative) showed the best antiproliferative activity against those three cell lines with the IC₅₀ values of 15.85, 15.60 and 18.60 μM, respectively, which provided a direction for the structural modification of magnolol. Further structural modification led to the synthesis of thirty-one magnolol derivatives, and compounds A13, C1, and C2 exhibited significant and broad-spectrum antiproliferative activity with the IC₅₀ values ranging from 4.81 to 13.54 μM, which were approximately 4- and 8-fold more potent than those of honokiol and magnolol, respectively. Moreover, their aqueous solubility was remarkably improved with 12-, 400- and 10⁵ fold greater than those of honokiol and magnolol. Anti-tumor mechanism research revealed that these three compounds were able to induce cell cycle arrest at G0/G1 phase, cause efficient apoptosis in H1975 cells, and also prevent the migration of HUVECs in a dose-dependent manner through Cdk2, Cdk4, Cyclin E, and Cyclin D1 inhibition as well as up-regulation of cleaved-PARP and cleaved-caspase 3 levels. In in vivo antitumor activity, C2 (10, 30 and 100 mg/kg, po) dose-dependently inhibited the tumor growth in H1975 xenograft model with the tumor inhibition rate of 46.3%, 59.3% and 61.2% respectively, suggesting that C2 is a potential oral anticancer agent deserving further investigation.

Identification, characterization and HPLC quantification of formulation-related impurities of honokiol, an antitumor natural drug candidate in clinical trials

Natural products and their derivatives have historically been invaluable as a source of therapeutic agents. Honokiol, as a well-known natural product in Chinese herbal medicine Houpu, is finally being studied in a Phase I clinical trial (CTR20170822) in patients with Advanced Non-Small Cell Lung Cancer (NSCLS) in China this year. During the honokiol liposome formulation process, five major impurities were present in the range of 0.05-0.1% based on the HPLC analysis. These five major impurities were obtained from the forced degradation product of honokiol through countercurrent chromatography and prep-HPLC. The structure were elucidated with ¹H NMR, ¹³C NMR, 2D NMR and MS spectral data. The proposed HPLC method was validated for specificity, linearity (concentration range 0.01-1.62, 0.003-0.96, 0.05-7.98, 0.04-6.52, 0.03-5.18 μg/ml for impurities I-V respectively, R2 > 0.9988), accuracy (99.11-100.67%), precision (CV < 1.6%), and sensitivity (LOD 3.3, 0.1, 16.7, 13.3, 10.0 ng/ml for impurities I-V respectively). The validated method was employed in the further study of the honokiol drug substance.

Detection of 191 Taxifolin Metabolites and Their Distribution in Rats Using HPLC-ESI-IT-TOF-MS(n)

Taxifolin is a ubiquitous bioactive constituent of foods and herbs. To thoroughly explore its metabolism in vivo, an HPLC-ESI-IT-TOF-MSⁿ method combined with specific metabolite detection strategy was used to detect and identify the metabolites of taxifolin in rats. Of the 191 metabolites tentatively identified, 154 were new metabolites, 69 were new compounds and 32 were dimers. This is the first report of the in vivo biotransformation of a single compound into more than 100 metabolites. Furthermore, acetylamination and pyroglutamic acid conjugation were identified as new metabolic reactions. Seventeen metabolites were found to have various taxifolin-related bioactivities. The potential targets of taxifolin and 63 metabolites were predicted using PharmMapper, with results showing that more than 60 metabolites have the same five targets. Metabolites with the same fragment pattern may have the same pharmacophore. Thus these metabolites may exert the same pharmacological effects as taxifolin through an additive effect on the same drug targets. This observation indicates that taxifolin is bioactive not only in the parent form, but also through its metabolites. These findings enhance understanding of the metabolism and effective forms of taxifolin and may provide further insight of the beneficial effects of taxifolin and its derivatives.

Comparative metabolism of honokiol in mouse, rat, dog, monkey, and human hepatocytes

Honokiol has antitumor, antioxidative, anti-inflammatory, and antithrombotic effects. Here we aimed to identify the metabolic profile of honokiol in mouse, rat, dog, monkey, and human hepatocytes and to characterize the enzymes responsible for the glucuronidation and sulfation of honokiol. Honokiol had a high hepatic extraction ratio in all five species, indicating that it was extensively metabolized. A total of 32 metabolites, including 17 common and 15 different metabolites, produced via glucuronidation, sulfation, and oxidation of honokiol allyl groups were tentatively identified using liquid chromatography-high resolution quadrupole Orbitrap mass spectrometry. Glucuronidation of honokiol to M8 (honokiol-4-glucuronide) and M9 (honokiol-2'-glucuronide) was the predominant metabolic pathway in hepatocytes of all five species; however, interspecies differences between 4- and 2'-glucuronidation of honokiol were observed. UGT1A1, 1A8, 1A9, 2B15, and 2B17 played major roles in M8 formation, whereas UGT1A7 and 1A9 played major roles in M9 formation. Human cDNA-expressed SULT1C4 played a major role in M10 formation (honokiol-2'-sulfate), whereas SULT1A1*1, 1A1*2, and 1A2 played major roles in M11 formation (honokiol-4-sulfate). In conclusion, honokiol metabolism showed interspecies differences.

Biphenyl-Type Neolignan Derivatives from the Twigs of Magnolia denudata and Their Anti-Inflammatory Activity

Two new biphenyl-type neolignan derivatives, 2-[2-(hydroxymethyl)-1-benzofuran-5-yl]-4-(prop-2-en-1-yl)phenol (1) and 2'-ethoxy-5,5'-di(prop-2-en-1-yl)biphenyl-2-ol (2), were isolated from the twigs of Magnolia denudata, together with six known compounds (3-8). The structures of 1 and 2 were determined through extensive 1D- and 2D-NMR and mass-spectrometric analyses. Magnolol (6) and honokiol (7) exhibited potent inhibition (IC50 values=4.4±0.2 and 0.71±0.13 μg/ml, resp.) of O$\rm{{_{2}^{{^\cdot} -}}}$ generation by human nutrophils in response to N-formyl-L-methionyl-L-leucyl-L-phenylalanine/cytochalasin B (fMLP/CB). In addition, 2-[2-(hydroxymethyl)-1-benzofuran-5-yl]-4-(prop-2-en-1-yl)phenol (1), 2'-ethoxy-5,5'-di(prop-2-en-1-yl)biphenyl-2-ol (2), magnolol (6), and vanillic acid (8) inhibited fMLP/CB-induced elastase release with IC50 values=6.4±1.5, 2.4±0.4, 1.5±0.2, and 4.8±0.5 μg/ml, respectively.

13C stable isotope labeling followed by ultra-high performance liquid chromatography/quadrupole time-of-flight tandem mass spectrometry (UHPLC/Q-TOF MS) was applied to identify the metabolites of honokiol in rat small intestines

Honokiol, as a pharmacological active small-molecule, has received significant attention for its strong pharmacological effects without remarkable toxicity.

Effect of honokiol on the induction of drug-metabolizing enzymes in human hepatocytes

Honokiol, 2-(4-hydroxy-3-prop-2-enyl-phenyl)-4-prop-2-enyl-phenol, an active component of Magnolia officinalis and Magnolia grandiflora, exerts various pharmacological activities such as antitumorigenic, antioxidative, anti-inflammatory, neurotrophic, and antithrombotic effects. To investigate whether honokiol acts as a perpetrator in drug interactions, messenger ribonucleic acid (mRNA) levels of phase I and II drug-metabolizing enzymes, including cytochrome P450 (CYP), UDP-glucuronosyltransferase (UGT), and sulfotransferase 2A1 (SULT2A1), were analyzed by real-time reverse transcription polymerase chain reaction following 48-hour honokiol exposure in three independent cryopreserved human hepatocyte cultures. Honokiol treatment at the highest concentration tested (50 μM) increased the CYP2B6 mRNA level and CYP2B6-catalyzed bupropion hydroxylase activity more than two-fold in three different hepatocyte cultures, indicating that honokiol induces CYP2B6 at higher concentrations. However, honokiol treatment (0.5–50 μM) did not significantly alter the mRNA levels of phase I enzymes (CYP1A2, CYP3A4, CYP2C8, CYP2C9, and CYP2C19) or phase II enzymes (UGT1A1, UGT1A4, UGT1A9, UGT2B7, and SULT2A1) in cryopreserved human hepatocyte cultures. CYP1A2-catalyzed phenacetin O-deethylase and CYP3A4-catalyzed midazolam 1′-hydroxylase activities were not affected by 48-hour honokiol treatment in cryopreserved human hepatocytes. These results indicate that honokiol is a weak CYP2B6 inducer and is unlikely to increase the metabolism of concomitant CYP2B6 substrates and cause pharmacokinetic-based drug interactions in humans.