Isolation and identification of metabolites of bakuchiol in rats

Bakuchiol – a natural meroterpenoid: structure, isolation, synthesis and functionalization approaches

Bakuchiol is an emblematic meroterpene class of natural product extracted from Psoralea corylifolia. It has been reported to possess a broad range of biological and pharmacological properties and is considered as a leading biomolecule. It is highly desirable to devise an efficient approach to access bakuchiol and its chemical biology applications. In this review we provided structural features, isolation methods, various chemical routes and late-stage functionalization (LSF) approaches for bakuchiol and its derivatives. Moreover, this review encompasses the structure–activity relationships (SAR), value-added contributions and future perspectives of bakuchiol

The isolation methods, various chemical routes and late-stage functionalization approaches and structure–activity relationships of bakuchiol – a meroterpene class of natural product has been discussed in detail.

A new strategy for discovering effective substances and mechanisms of traditional Chinese medicine based on standardized drug containing plasma and the absorbed ingredients composition, a case study of Xian-Ling-Gu-Bao capsules

ETHNOPHARMACOLOGICAL RELEVANCE

The overall therapeutic effect of traditional Chinese medicine formulae (TCMF) was achieved by the interactions of multiple components with multiple targets. However, current pharmacology research strategies have struggled to identify effective substance groups and encountered challenges in elucidating the underlying mechanisms of TCMF.

AIM

In this study, a comprehensive strategy was proposed and applied to elucidate the interactions of the multiple components that underlie the functions of the famous TCMF: Xian-Ling-Gu-Bao (XLGB) capsule on bone metabolism in vivo and to elucidate the molecular mechanisms underlying the effects of XLGB on bone cells, especially on osteoblasts.

METHODS

The efficacy of XLGB in the protection against bones loss in ovariectomized (OVX) rats was confirmed by Micro-CT analysis. The anti-osteoporosis mechanism involved in the systemic regulatory actions of XLGB was elucidated by transcriptome sequencing analysis on bone marrow mesenchymal stem cells isolated from OVX rats. Moreover, the components absorbed in XLGB-treated plasma were characterized by mass spectrometry analysis, and subsequently, a standardized preparation process of drug-containing plasma was established. The synergistic osteogenic effect of the multiple components in plasma was investigated by a combination and then knockout of components using pre-osteoblast MC3T3-E1 cells. In order to decipher the underlying mechanism of XLGB, the targets of the absorbed components on bone were predicted by target prediction and network pharmacology analysis, then several interactions were validated by biochemical and cell-based assay.

RESULTS

A total of 18 genes, including HDC, CXCL1/2, TNF, IL6 and Il1b, were newly found to be the major target genes regulated by XLGB. Interestingly, we found that a combination of the three absorbed components, i.e. MSP, rather than their single form at the same concentration, stimulated the formation of calcified nodules in MC3T3-E1 cells, suggesting a synergistic effect of these components. Besides, target prediction and experimental validation confirmed the binding affinity of corylin and icaritin for estrogen receptor α and β, the inhibitory activity of isobavachin and isobavachalcone on glycogen synthase kinase-3β, and the inhibitory activity of isobavachalcone on cathepsin K. The cell-based assay further confirmed the result of the biochemical assay. A network that integrated absorbed components of XLGB-targets-perturbation genes-pathways against osteoporosis was established.

CONCLUSION

Our current study provides a new systemic strategy for discovering active ingredient groups of TCM formulae and understanding their underlying mechanisms.

Chemical constituents from the bioactive fraction of the seeds of Psoralea corylifolia and proliferation activities on osteoblastic-like UMR106 cells

A new flavonol named 5,4'-dihydroxy-6,7-[(1''S,2''R)-1''-hydroxy-2''-(1-hydroxy-1-methylethyl)-furano]flavonol (1), together with eight known compounds (2-9), were isolated from the seeds of Psoralea corylifolia. Their chemical structures were elucidated on the basis of spectroscopic analyses. In addition, all compounds were firstly studied for their proliferation effects on osteoblastic-like UMR 106 cells. Results showed that compounds 1, 2, 5 and 8 possessed significant promoting effects on cell proliferation and increased osteoblastic cell numbers by 26.3%, 34.6%, 20.5% and 21.1% at concentrations of 10^-8 M, 10^-8 M, 10^-10 M and 10^-10 M, respectively. These data indicated that flavonoids may be the main constituents accounting for the bone protective effects of the seeds of P. corylifolia.

Design, Synthesis, and Biological Evaluation of Membrane-Active Bakuchiol Derivatives as Effective Broad-Spectrum Antibacterial Agents

Infections caused by drug-resistant bacteria seriously endanger human health and global public health. Therefore, it is urgent to discover and develop novel antimicrobial agents to combat multidrug-resistant bacteria. In this study, we designed and synthesized a series of new membrane-active bakuchiol derivatives by biomimicking the structure and function of cationic antibacterial peptides. The most promising compound 28 displayed potent antibacterial activity against both Gram-positive bacteria (minimum inhibitory concentration, MIC = 1.56-3.125 μg/mL) and Gram-negative bacteria (MIC = 3.125 μg/mL), very weak hemolytic activity, and low cytotoxicity. Compound 28 had rapid bactericidal properties and avoided bacterial resistance. More importantly, compound 28 showed strong in vivo antibacterial efficacy against Staphylococcus aureus and Pseudomonas aeruginosa in murine corneal infection models. This design strategy is expected to provide an effective solution to the antibiotic crisis.

New compounds from the seeds of Psoralea corylifolia with their protein tyrosine phosphatase 1B inhibitory activity

Two new flavonoids, 5,4'-dihydroxy-6,7-furanbavachalcone (1), 1″-methoxy-6,7-furanflavanone (2), together with five known compounds (3-7), were isolated from the seeds of Psoralea corylifolia. Their structures were elucidated by IR, UV, NMR, HRESMS experiments, and comparison of their NMR data with previously reported data. All compounds were evaluated for in vitro inhibitory activity against PTP1B. Additionally, the isolated compounds (1-6) displayed moderate inhibitory effects against PTP1B with IC₅₀ values ranging from 10.3 ± 0.9 to 25.1 ± 1.6 μM.

Two new isoflavones from the seeds of Psoralea corylifolia with diacylglycerol acyltransferase inhibitory activity

Two new compounds 7-hydroxy-4'-methoxy-3'-(7''-hydroxy-3'',7''-dimethyl-octa-2'',5''-dienyl)-isoflavone (1) and 7-hydroxy-4'-methoxy-3'-(6''-hydroxy-3'',7''-dimethyl-octa-2'',7''-dienyl)-isoflavone (2), together with five known compounds (3-7), were isolated from EtOAc-soluble extract of the seeds of Psoralea corylifolia. Their structures were elucidated on the basis of detailed spectroscopic and physico-chemical analyses. All the isolates were evaluated for in vitro inhibitory activity against diacylglycerol acyltransferase (DGAT). And compounds 1-7 displayed significant inhibitory activity on DGAT1 with IC₅₀ values ranging from 51.2 ± 1.1 to 116.4 ± 1.3 μM.

A new bioactive coumestan from the seeds of Psoralea corylifolia

A new coumestan named bavacoumestan D (1), together with five known compounds (2-6), was isolated from EtOAc-soluble extract of seeds of Psoralea corylifolia. Their structures were elucidated on the basis of spectroscopic and physico-chemical analyses. All compounds were evaluated for in vitro inhibitory activity against DGAT1, DGAT2 and α-glucosidase. Among them, compounds 1-2, 5-6 showed potential inhibitory activity on DGAT1 with IC₅₀ values ranging from 52.3 ± 1.3 to 81.0 ± 1.0 μM. Compounds 1-3, 6 displayed the significant inhibitory activity on α-glucosidase with IC₅₀ values ranging from 31.2 to 89.1 μM.[Formula: see text].

Anticolon Cancer Potential of (2Z)-2-[(4′-Hydroxyphenyl) Methylene]-6-Methoxy-7-Prenyl-3(2H)-Benzofurane, a New Aurone From Psoralea corylifolia

A new aurone, (2 Z)-2-[(4′-hydroxyphenyl) methylene]-6-methoxy-7-prenyl-3(2 H)-benzofurane (1), together with 6 known compounds (2-7), was isolated from the EtOAc-soluble extract of the seeds of Psoralea corylifolia. Their structures were elucidated on the basis of spectroscopic methods. All compounds were evaluated for in vitro inhibitory activity against a human colon cancer cell line (SW620). Compounds 1 to 3 showed moderate cytotoxicity against the SW620 cells with IC50 values ranging from 24.31 to 28.72 μM. Among these compounds, 1 showed higher cytotoxicity against SW620 cells with an IC50 value of 24.31 μM.

A new benzophenone with biological activities from metabolites of butyrolactone I in rat faeces

Butyrolactone I, one of the major secondary metabolites of fungus Aspergillus terreus, is a selective cdc2 kinase inhibitor. In the present study, the metabolism of butyrolactone I in male Wistar rats was investigated by characterising metabolites excreted into faeces. Following an oral dose of 40 mg/kg butyrolactone I, two phase I metabolites were isolated from the faeces of rat. The new structure was identified on the spectroscopic data analysis. The new compound V1 and known compound V2 were tested for their cytotoxicity, antimicrobial and antioxidant activity. V1 and V2 showed significant free radical scavenging ability. V2 also showed strong inhibitory activity against Staphylococcus aureus.

Anti-diabetic compounds from the seeds of Psoralea corylifolia

A new aurone named (2Z)-2-[(4'-hydroxyphenyl) methylene]-6-hydroxy-7-prenyl-3(2H)-benzofurane (1), two new flavonoids named (2S)-7-methoxy-6-(2-hydroxy-3-methylbut-3-en-1-yl)-2-(4-hydroxyphenyl)chroman-4-one (2), (2S)-4'-hydroxyl-7-hydroxymethylene-6-(2″,3″-epoxy-3″-methylbutyl)flavanone (3), and a new coumestan named bavacoumestan E (4), together with eleven known compounds (5-15), were isolated from the seeds of Psoralea corylifolia. The chemical structures were elucidated by spectroscopic and physico-chemical analyses. All isolates were evaluated for in vitro inhibitory activity against DGAT, PTP1B and α-glucosidase. Compounds 1, 2 and 3 showed potential inhibitory activities on DGAT1 with IC₅₀ values of 35.2 ± 1.3, 51.3 ± 1.1 and 43.4 ± 0.7 μM, respectively. Compounds 6 and 8 displayed the significant inhibitory activities on α-glucosidase with IC₅₀ value of 28.0 and 23.0 μM, respectively.

A New Aurone and Other Constituents From the Seeds of Psoralea corylifolia With Their Diacylglycerol Acyltransferase Inhibitory Activity

A new aurone (1), together with 5 known compounds (2-6), were isolated from EtOAc-soluble extract of the seeds of Psoralea corylifolia. Their structures were elucidated on the basis of spectroscopic methods. All compounds were evaluated for in vitro inhibitory activity against diacylglycerol acyltransferase (DGAT). Among them, compound 1 showed selective inhibitory activity on DGAT1 with IC50 value of 54.9 ± 1.4 µM.

A New Flavanone from Seeds of Psoralea corylifolia with α-Glucosidase Inhibitory Activity

A new flavanone (2 S)-7,4'-hydroxyl-6-(2″,3″-epoxy-3″-methylbutyl)flavanone (1), together with five known compounds (2–6) were isolated from EtOAc-soluble extract of seeds of Psoralea corylifolia. Their structures were elucidated on the basis of spectroscopic and physico-chemical analyses. All compounds were evaluated for in vitro inhibitory activity against α-glucosidase. Among them, new compound 1 was found to exhibit inhibitory activity on α-glucosidase with IC50 value of 29.2 μM.

Metabolic detoxification of bakuchiol is mediated by oxidation of CYP 450s in liver microsomes

Bakuchiol, one of bioactive compounds isolated from the dried ripe fruits of Psoralea corylifolia L., possesses a variety of pharmacological activities. In this study, the metabolites of bakuchiol in rat liver microsomes as well as their cytotoxicities were studied. A total of eight metabolites were isolated and identified as 14-carboxylbakuchiol (M1), 14,15-dihydroxybakuchiol (M2), 12,13-dihydroxybakuchiol (M3), 15-hydroxybakuchiol (M4), 14-hydroxybakuchiol (M5), bakuchiol hydrate (M6), 15-hydroxybakuchiol acetate (M7), and 14-hydroxybakuchiol acetate (M8). All the metabolites are new compounds except for M3. The main type of biotransformation is oxidation reaction, including hydroxylation, epoxidation and carboxylation. Cytotoxicities of bakuchiol and its metabolites against human kidney-2 (HK-2) cell line were evaluated. The median inhibition concentration (IC₅₀) values of bakuchiol, M4, M6 and M8 were (29.48 ± 0.22) μM, (67.51 ± 6.80) μM, (90.23 ± 3.89) μM, and (86.62 ± 6.08) μM, respectively, and the IC₅₀ values of M1, M2, M3, M5, and M7 were all in excess of 100 μM. To further verify the metabolic reliability, the metabolits of bakuchiol in vivo and the metabolic species variations in human and rat liver microsomes were studied using UPLC-MS/MS method. This study provides valuable information for further investigation of metabolism and toxicity of bakuchiol in vivo.

Characterization of human UDP-glucuronosyltransferases responsible for glucuronidation and inhibition of norbakuchinic acid, a primary metabolite of hepatotoxicity and nephrotoxicity component bakuchiol inPsoralea corylifolia L

Norbakuchinic acid (NBKA) is the most abundant metabolite of bakuchiol (a hepatotoxicity and nephrotoxicity component inPsoralea corylifoliaL.) in plasma and urine.