Screening of minor bioactive compounds from herbal medicines by in silico docking and the trace peak exposure methods

Antidiabetic and Antigout Properties of the Ultrasound-Assisted Extraction of Total Biflavonoids from Selaginella doederleinii Revealed by In Vitro and In Silico Studies

In this study, the extraction, purification and metabolic enzyme inhibition potential of Selaginella doederleinii were investigated. In order to extract the total biflavonoids from S. doederleinii (SDTBs), the optimum extraction process was obtained by optimizing the ultrasonic extraction parameters using response-surface methodology. This resulted in a total biflavonoid content of 22.26 ± 0.35 mg/g. Purification of the S. doederleinii extract was carried out using octadecylsilane (ODS), and the transfer rate of the SDTBs was 82.12 ± 3.48% under the optimum purification conditions. We determined the effect of the SDTBs on α-glucosidase (AG), α-amylase and xanthine oxidase (XOD) and found that the SDTBs had an extremely potent inhibitory effect on AG, with an IC50 value of 57.46 μg/mL, which was much lower than that of the positive control. Meanwhile, they also showed significant inhibition of XOD and α-amylase, with IC50 values of 289.67 μg/mL and 50.85 μg/mL, respectively. In addition, molecular docking studies were carried out to understand the nature of the action of the biflavonoids on AG and XOD. The results showed that robustaflavone had the lowest binding energy to AG (-11.33 kcal/mol) and XOD (-10.21 kcal/mol), while, on the other hand, amentoflavone showed a good binding affinity to AG (-10.40 kcal/mol) and XOD (-9.962 kcal/mol). Moreover, molecular dynamics simulations verified the above results.

Characterization and discrimination of volatile organic compounds and α-glucosidase inhibitory activity of soybeans (Glycine max L.) during solid-state fermentation with Eurotium cristatum YL-1

In this study, the influence of solid-state fermentation (SSF) using probiotic Eurotium cristatum on the change of volatile organic compounds (VOCs) and α-glucosidase inhibition activity of soybeans was investigated. A total of 46 VOCs were characterized via headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS), the majority of which were aldehydes (17), alcohols (10), and ketones (7). SSF by E. cristatum drastically affected the flavor characteristics of soybeans, and the levels of unpleasant beany flavor components, such as hexanal-D, 1-octen-3-ol, 1-hexanol-D, 1-hexanol-M, heptanal-M, 1-pentanol, heptanal-D, and 2-pentyl furan were all substantially decreased by 50% after 15 days of SSF, while volatiles with floral, caramel, and desirable flavors such as pentanal-D, methylpropanal, 2-propanol, and propyl acetate drastically (p < 0.05) increased by 1.1-, 19.2-, 3.6-, and 2.6-fold, respectively. Key aroma-active compounds analysis revealed that 18 VOCs (ROAV, relative odor activity value ≥ 1) play a great role in shaping the flavor characteristics of the soybean samples. After 15 days of SSF, the ROAV values of methylpropanal, 2-propanol, and propyl acetate drastically (p < 0.05) increased to 8.48, 63.88, and 11.29, respectively, which greatly contributed to the desirable flavor characteristics of fermented soybeans. Furthermore, E. cristatum greatly improved the α-glucosidase inhibitory activity of soybean by 22.4% after 15 days fermentation, which was closely correlated with the accumulated phenolic compounds during SSF. Molecular docking showed that genistein and daidzein have high binding affinity for α-glucosidase active sites, primarily driven by hydrogen bonds and hydrophobic interactions. These results demonstrated that soybeans fermented with E. cristatum substantially improved the flavor characteristics and α-glucosidase inhibitory effect, and were greatly helpful to promote the application of soybeans in food products.

Identification of cyclooxygenase-II inhibitory saponins from fenugreek wastes: Insights from liquid chromatography-tandem mass spectrometry metabolomics, molecular networking, and molecular docking

INTRODUCTION

This research explores sustainable applications for waste generated from fenugreek (Trigonella foenum-graecum), a plant with both nutritional and medicinal uses. The study specifically targets waste components as potential sources of nutrients and bioactive compounds.

OBJECTIVES

The focus is to conduct detailed metabolic profiling of fenugreek waste, assess its anti-inflammatory properties by studying its cyclooxygenase (COX) inhibitory effect, and correlate this effect to the metabolite fingerprint.

MATERIALS AND METHODS

Ethanolic extracts of fenugreek fruit pericarp and a combination of leaves and stems were subjected to untargeted metabolic profiling using liquid chromatography-mass spectrometry integrated with online database searches and molecular networking as an effective dereplication strategy. The study also scrutinized the COX inhibitory capabilities of these extracts and saponin-rich fractions prepared therefrom. Molecular docking was employed to investigate the specific interactions between the identified saponins and COX enzymes.

RESULTS

The analysis led to the annotation of 81 metabolites, among which saponins were predominant. The saponin-rich fraction of the fruit pericarp extract displayed the strongest COX-II inhibitory activity in the in vitro inhibition assay (IC50 value of 81.64 ± 3.98 μg/mL). The molecular docking study supported the selectivity of the identified saponins towards COX-II. The two major identified saponins, namely, proto-yamogenin 3-O-[deoxyhexosyl (1 → 2)] [hexosyl (1 → 4)] hexoside 26-O-hexoside and trigofenoside A, were predicted to have the highest affinity to the COX-II receptor site.

CONCLUSION

In the present study, we focused on the identification of COX-II inhibitory saponins in fenugreek waste through an integrated approach. The findings offer valuable insights into potential anti-inflammatory and cancer chemoprotective applications of fenugreek waste.

Flavonoids as dual-target inhibitors against α-glucosidase and α-amylase: a systematic review of in vitro studies

Diabetes mellitus remains a major global health issue, and great attention is directed at natural therapeutics. This systematic review aimed to assess the potential of flavonoids as antidiabetic agents by investigating their inhibitory effects on α-glucosidase and α-amylase, two key enzymes involved in starch digestion. Six scientific databases (PubMed, Virtual Health Library, EMBASE, SCOPUS, Web of Science, and WHO Global Index Medicus) were searched until August 21, 2022, for in vitro studies reporting IC50 values of purified flavonoids on α-amylase and α-glucosidase, along with corresponding data for acarbose as a positive control. A total of 339 eligible articles were analyzed, resulting in the retrieval of 1643 flavonoid structures. These structures were rigorously standardized and curated, yielding 974 unique compounds, among which 177 flavonoids exhibited inhibition of both α-glucosidase and α-amylase are presented. Quality assessment utilizing a modified CONSORT checklist and structure-activity relationship (SAR) analysis were performed, revealing crucial features for the simultaneous inhibition of flavonoids against both enzymes. Moreover, the review also addressed several limitations in the current research landscape and proposed potential solutions. The curated datasets are available online at https://github.com/MedChemUMP/FDIGA .

Target-guided isolation and purification of cyclooxygenase-2 inhibitors from Meconopsis integrifolia (Maxim.) Franch. by high-speed counter-current chromatography combined with ultrafiltration liquid chromatography

Meconopsis integrifolia (Maxim.) Franch. is used extensively in traditional Tibetan medicine for its potent anti-inflammatory properties. In this study, six cyclooxygenase-2 (COX-2) inhibitors were purified from M. integrifolia using high-speed counter-current chromatography guided by ultrafiltration liquid chromatography (ultrafiltration-LC). First, ultrafiltration-LC was performed to profile the COX-2 inhibitors in M. integrifolia. The reflux extraction conditions were further optimized using response surface methodology, and the results showed that the targeted COX-2 inhibitors could be well enriched under the optimized extraction conditions. Then the six target COX-2 inhibitors were separated by high-speed countercurrent chromatography with a solvent system composed of ethyl acetate/n-butanol/water (4:1:4, v/v/v. Finally, the six COX-2 inhibitors, including 21.2 mg of 8-hydroxyluteolin 7-sophoroside, 29.6 mg of 8-hydroxyluteolin 7-[6'''-acetylallosyl-(1→2)-glucoside], 42.5 mg of Sinocrassoside D3, 54.1 mg of Hypolaetin 7-[6'''-acetylallosyll-(l→2)-3''-acetylglucoside, 30.6 mg of Hypolaetin 7-[6'''-acetylallosyll-(l→2)-6''-acetylglucoside and 17.8 mg of Hypolaetin were obtained from 500 mg of sample. Their structures were elucidated by 1 H-NMR spectroscopy. This study reveals that ultrafiltration-LC combined with high-speed counter-current chromatography is a robust and efficient strategy for target-guided isolation and purification of bioactive molecules. It also enhances the scientific understanding of the anti-inflammatory properties of M. integrifolia but also paves the way for its further medicinal applications.

Syringetin Promotes Melanogenesis in B16F10 Cells

Syringetin, an active compound present in red grapes, jambolan fruits, Lysimachia congestiflora, and Vaccinium ashei, is a dimethyl myricetin derivative which contains free hydroxyl groups at the C-2' and C-4' positions in ring B. Recent studies have revealed that syringetin possesses multiple pharmacological properties, such as antitumor, hepatoprotective, antidiabetic, antioxidative, and cytoprotective activities. To date, there has been no attempt to test the action of syringetin on melanogenesis. In addition, the molecular mechanism for the melanogenic effects of syringetin remains largely unknown. In this study, we investigated the effect of syringetin on melanogenesis in a murine melanoma cell line from a C57BL/6J mouse, B16F10. Our results showed that syringetin markedly stimulated melanin production and tyrosinase activity in a concentration-dependent manner in B16F10 cells. We also found that syringetin increased MITF, tyrosinase, TRP-1, and TRP-2 protein expression. Moreover, syringetin inhibited ERK and PI3K/Akt phosphorylation by stimulating p38, JNK, PKA phosphorylation levels, subsequently stimulating MITF and TRP upregulation, resulting in the activation of melanin synthesis. Furthermore, we observed that syringetin activated phosphorylation of GSK3β and β-catenin and reduced the protein level of β-catenin, suggesting that syringetin stimulates melanogenesis through the GSK3β/β-catenin signal pathway. Finally, a primary skin irritation test was conducted on the upper backs of 31 healthy volunteers to determine the irritation or sensitization potential of syringetin for topical application. The results of the test indicated that syringetin did not cause any adverse effects on the skin. Taken together, our findings indicated that syringetin may be an effective pigmentation stimulator for use in cosmetics and in the medical treatment of hypopigmentation disorders.

Qualitative and Quantitative Analysis of the Major Bioactive Components of Juniperus chinensis L. Using LC-QTOF-MS and LC-MSMS and Investigation of Antibacterial Activity against Pathogenic Bacteria

Plants in the genus Juniperus have been reported to produce a variety of chemical components, such as coumarins, flavonoids, lignans, sterols, and terpenoids. Here, ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) and ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) were applied to qualitatively and quantitatively analyze the major bioactive components in an ethanolic crude extract from the leaves of Juniperus chinensis L., which grows naturally in Korea. In addition, the antibacterial activity of the crude extract against pathogenic bacteria was investigated. Using LC-QTOF-MS analysis, we identified ten compounds, of which six were confirmed to be flavonoid and lignan-based components as the major bioactive components, i.e., isoquercetin, quercetin-3-O-α-l-rhamnoside, hinokiflavone, amentoflavone, podocarpusflavone A, and matairesinoside. Among them, a quantitative analysis performed using LC-MS/MS revealed that the levels of quercetin-3-O-α-l-rhamnoside and amentoflavone in the crude extract were 203.78 and 69.84 mg/g, respectively. Furthermore, the crude extract exhibited potential antibacterial activity against 10 pathogenic bacteria, with the highest antibacterial activity detected against Bordetella pertussis. Thus, further studies of the leaf extract of J. chinensis L. must be carried out to correlate the compounds present in the extract with the antibacterial activity and elucidate the mechanisms of action of this extract against bacteria.

Screening of Potential α-Glucosidase Inhibitors from the Roots and Rhizomes of Panax Ginseng by Affinity Ultrafiltration Screening Coupled with UPLC-ESI-Orbitrap-MS Method

Panax ginseng was a traditional Chinese medicine with various pharmacological activities and one of its important activities was hypoglycemic activity; therefore, panax ginseng has been used in China as an adjuvant in the treatment of diabetes mellitus. In vivo and in vitro tests have revealed that ginsenosides, which are derived from the roots and rhizomes of panax ginseng have anti-diabetic effects and produce different hypoglycemic mechanisms by acting on some specific molecular targets, such as SGLT1, GLP-1, GLUTs, AMPK, and FOXO1. α-Glucosidase is another important hypoglycemic molecular target, and its inhibitors can inhibit the activity of α-Glucosidase so as to delay the absorption of dietary carbohydrates and finally reduce postprandial blood sugar. However, whether ginsenosides have the hypoglycemic mechanism of inhibiting α-Glucosidase activity, and which ginsenosides exactly attribute to the inhibitory effect as well as the inhibition degree are not clear, which needs to be addressed and systematically studied. To solve this problem, affinity ultrafiltration screening coupled with UPLC-ESI-Orbitrap-MS technology was used to systematically select α-Glucosidase inhibitors from panax ginseng. The ligands were selected through our established effective data process workflow based on systematically analyzing all compounds in the sample and control specimens. As a result, a total of 24 α-Glucosidase inhibitors were selected from panax ginseng, and it was the first time that ginsenosides were systematically studied for the inhibition of α-Glucosidase. Meanwhile, our study revealed that inhibiting α-Glucosidase activity probably was another important mechanism for ginsenosides treating diabetes mellitus. In addition, our established data process workflow can be used to select the active ligands from other natural products using affinity ultrafiltration screening.

The Spectrum of Pharmacological Actions of Syringetin and Its Natural Derivatives-A Summary Review

Mono- and poly-O-methylated flavonols and their glycoside derivatives belong to the group of natural plant polyphenols with a wide spectrum of pharmacological activities. These compounds are known for their antioxidant, antimutagenic, hepatoprotective, antidiabetic, and antilipogenic properties. Additionally, they inhibit carcinogenesis and cancer development. Having in mind the multidirectional biological activity of methylated flavonols, we would like to support further study on their health-promoting activities; in this review we summarized the most recent reports on syringetin and some of its structural analogues: laricitrin, ayanin, and isorhamnetin. Natural sources and biological potential of these substances were described based on the latest research papers.

Screening and characterization estrogen receptor ligands from Arnebia euchroma (Royle) Johnst. via affinity ultrafiltration LC-MS and molecular docking

Arnebiae Radix (dried root of Arnebia euchroma (Royle) Johnst.) is a traditional Chinese medicine (TCM) used to treat macular eruptions, measles, sore throat, carbuncles, burns, skin ulcers, and inflammations. The Arnebiae Radix extract can exert anti-breast cancer effects through various mechanisms of action. This study aimed to rapidly screen potential estrogen receptor (estrogen receptor α and estrogen receptor β) ligands from the Arnebiae Radix extract. In this study, an analytical method based on affinity ultrafiltration coupled with UHPLC-Q-Exactive Orbitrap mass spectrometry was established for rapidly screening and identifying estrogen receptor ligands. Then, bindings of the components to the active site of estrogen receptor (estrogen receptor α and estrogen receptor β) were investigated via molecular docking. Moreover, surface plasmon resonance (SPR) experiments with six compounds were performed to verify the affinity. As a result, a total of 21 ligands were screened from Arnebiae Radix using affinity ultrafiltration. Among them, 14 and 10 compounds from Arnebiae Radix showed affinity with estrogen receptor α and estrogen receptor β, respectively. All of those ligands could have a good affinity for the multiple amino acid residues of the estrogen receptor based on molecular docking. In addition, six compounds display the great affinity by SPR. The method established in the study could be used to rapidly screen estrogen receptor ligands in Traditional Chinese medicine. The results demonstrated that the affinity ultrafiltration-UHPLC-Q-Exactive Orbitrap mass spectrometry method not only aids in the interpretation of the potential bioactive components and possible mechanisms of action of Arnebiae Radix but also provides a further effective basis for the quality control of this valuable herb medicine.

Ginkgo biloba leaf extract EGb 761® as a paragon of the product by process concept

It is an often-neglected fact that extracts derived from the very same plant can differ significantly in their phytochemical composition, and thus also in their pharmacokinetic and pharmacodynamic properties which are the basis for their clinical efficacy and safety. The Ginkgo biloba L. [Ginkgoaceae] special extract EGb 761® is one of the best-studied plant extracts in the world. In the present review, using that extract as a paradigm, we describe insights how climate, the harvest region, processing of the plant material, the drying process, the extraction solvents, and the details of the subsequent process steps substantially impact the quality and uniformity of the final extract. We highlight the importance of regulating active constituent levels and consistent reduction of undesired substances in herbal extracts. This is accomplished by a controlled production process and corresponding analytical specifications. In conclusion, since extracts derived from the same plant can have very different phytochemical compositions, results from pharmacological, toxicological and clinical studies gained with one specific extract cannot be extrapolated to other extracts that were generated using different production processes. We propose that the heterogenous nature of extracts should be meticulously considered when evaluating the efficacy and safety of plant-derived remedies.

Bio-Oriented Synthesis of Novel (S)-Flurbiprofen Clubbed Hydrazone Schiff’s Bases for Diabetic Management: In Vitro and In Silico Studies

A new series of (S)-flurbiprofen derivatives 4a–4p and 5a–5n were synthesized with different aromatic or aliphatic aldehydes and ketones to produce Schiff’s bases and their structures were confirmed through HR-ESI-MS, ¹H, and ¹³C-NMR spectroscopy. The α-glucosidase inhibitory activities of the newly synthesized compounds were scrutinized, in which six compounds 5k, 4h, 5h, 4d, 4b, and 5i showed potent inhibition in the range of 0.93 to 10.26 µM, respectively, whereas fifteen compounds 4c, 4g, 4i, 4j, 4l, 4m, 4o, 4p, 5c, 5d, 5j, 5l, 5m, 5n and 1 exhibited significant inhibitory activity with IC₅₀ in range of = 11.42 to 48.39 µM. In addition, compounds 5g, 5f, 4k, 4n, and 4f displayed moderate-to-low activities. The modes of binding of all the active compounds were determined through the molecular docking approach, which revealed that two residues, specifically Glu277 and His351 are important in the stabilization of the active compounds in the active site of α-glucosidase. Furthermore, these compounds block the active site with high binding energies (−7.51 to −3.36 kcal/mol) thereby inhibiting the function of the enzyme.

Characterization of Tyrosinase Inhibitors in Dryopteris crassirhizoma Rhizome Using a Combination of High-Speed Counter-Current Chromatography, Affinity-Based Ultrafiltration, and Liquid Chromatography-Tandem Mass Spectrometry

Dryopteris crassirhizoma rhizome (DCR) inhibits melanin production in B16F10 melanoma cells and tyrosinase activity. The melanin content and tyrosinase activity of DCR-treated zebrafish embryos were determined to evaluate the in vivo inhibitory effect of DCR on melanogenesis. Moreover, an off-line hyphenated method combining the high-speed counter-current chromatography, affinity-based ultrafiltration, and liquid chromatography-tandem mass spectrometry was used to identify and characterize the DCR compounds with tyrosinase inhibitory activity. Our results indicated that DCR significantly decreased the melanin content and tyrosinase activity in zebrafish embryos in a dose-dependent manner; moreover, 22 compounds in DCR presented tyrosinase inhibitory activity. In silico molecular docking prediction data indicated that the 22 compounds in DCR can form stable conformations in the active site pocket of tyrosinase.

In situ net fishing of α-glucosidase inhibitors from evening primrose (Oenothera biennis) defatted seeds by combination of LC-MS/MS, molecular networking, affinity-based ultrafiltration, and molecular docking

Defatted seeds of evening primrose (DSEP), the by-product of evening primrose oil manufacture, exhibit potential α-glucosidase inhibitory activity; however, presently they are routinely discarded as waste. In this study, an in situ net fishing strategy was proposed for rapid recognition of α-glucosidase inhibitors from DSEP. Firstly, the DSEP extraction method was optimized employing a response surface methodology for the recovery of α-glucosidase inhibitors, just like "finding a good fishery before net fishing". Then, molecular networks of DSEP were generated by GNPS-based molecular networking after LC-MS/MS analysis, just like "casting tight nets in the fishery". Subsequently, affinity-based ultrafiltration was carried out for fishing the "hit" together with its structural analogues according to the molecular networks, just like "hauling the specific net fishing". Finally, molecular docking analysis was performed to rapidly verify α-glucosidase inhibitory activities of the potential bioactive components and predict their inhibition mechanisms. In the results, DSEP displayed significant inhibitory effects against yeast and rat intestinal α-glucosidase, and the results of an oral starch tolerance test suggested that DSEP showed postprandial blood-glucose-lowering activity. Moreover, 1-galloyl-glucose, gallic acid, methyl gallate, 1,6-digalloyl-β-D-glucose, and 1,3,6-trigalloylglucose were rapidly identified as potential α-glucosidase inhibitors present in DSEP.

Is Our Natural Food Our Homeostasis? Array of a Thousand Effect-Directed Profiles of 68 Herbs and Spices

The beneficial effects of plant-rich diets and traditional medicines are increasingly recognized in the treatment of civilization diseases due to the abundance and diversity of bioactive substances therein. However, the important active portion of natural food or plant-based medicine is presently not under control. Hence, a paradigm shift from quality control based on marker compounds to effect-directed profiling is postulated. We investigated 68 powdered plant extracts (botanicals) which are added to food products in food industry. Among them are many plants that are used as traditional medicines, herbs and spices. A generic strategy was developed to evaluate the bioactivity profile of each botanical as completely as possible and to straightforwardly assign the most potent bioactive compounds. It is an 8-dimensional hyphenation of normal-phase high-performance thin-layer chromatography with multi-imaging by ultraviolet, visible and fluorescence light detection as well as effect-directed assay and heart-cut of the bioactive zone to orthogonal reversed-phase high-performance liquid chromato-graphy-photodiode array detection-heated electrospray ionization mass spectrometry. In the non-target, effect-directed screening via 16 different on-surface assays, we tentatively assigned more than 60 important bioactive compounds in the studied botanicals. These were antibacterials, estrogens, antiestrogens, androgens, and antiandrogens, as well as acetylcholinesterase, butyrylcholinesterase, α-amylase, α-glucosidase, β-glucosidase, β-glucuronidase, and tyrosinase inhibitors, which were on-surface heart-cut eluted from the bioautogram or enzyme inhibition autogram to the next dimension for further targeted characterization. This biological-physicochemical hyphenation is able to detect and control active mechanisms of traditional medicines or botanicals as well as the essentials of plant-based food. The array of 1,292 profiles (68 samples × 19 detections) showed the versatile bioactivity potential of natural food. It reveals how efficiently and powerful our natural food contributes to our homeostasis.

Towards multi-target antidiabetic agents: In vitro and in vivo evaluation of 3,5-disubstituted indolin-2-one derivatives as novel α-glucosidase inhibitors

Type 2 diabetes mellitus is a chronic progressive disease that usually requires polypharmacological treatment approaches. Previously we have described a series of 2-oxindole derivatives as GSK3β inhibitors with in vivo antihyperglycemic activity. α-Glucosidase is another antidiabetic target that prevents postprandial hyperglycemia and corresponding hyperinsulinemic response. Herein we report a study of 3,5-disubstituted indolin-2-one derivatives as potent α-glucosidase inhibitors. These inhibitors were identified via efficient synthesis, in vitro screening, and biological evaluation. The most active compound 5f inhibits yeast α-glucosidase with IC₅₀ of 6.78 µM and prevents postprandial hyperglycemia in rats after maltose and sucrose challenge at 5.0 mg/kg dose. Two lead glucosidase inhibitors, 5f and 5m, are also GSK3β inhibitors with submicromolar potency. Hence, structure-activity studies elucidate foundation for development of dual GSK3β/α-glucosidase inhibitors for treatment of type 2 diabetes.

A strategy to discover selective α-glucosidase/acetylcholinesterase inhibitors from five function-similar citrus herbs through LC-Q-TOF-MS, bioassay and virtual screening

The lack of direct connection between traditional herbal medicines and multiple biological targets is a bottleneck in herbal research and quality evaluation. To solve this problem, a strategy for the discovery of active ingredients from function-similar herbal medicines based on multiple biological targets was proposed in this article. The technical route includes chromatographic separation, mass spectrometry analysis, enzymatic activity detection, pharmacophore analysis and molecular docking. Five citrus herbs of Citri Reticulatae Pericarpium (CRP), Citri Exocarpium Rubrum (CER), Citri Grandis Exocarpium (CGE), Aurantii Fructus Immaturus (AFI) and Aurantii Fructus (AF) were used as the research objects. A total of 136 chemical components were identified from above five herbs based on LC-Q-TOF-MS/MS and database matching. The extracts of the five herbs showed obvious inhibitory effects on α-glucosidase and acetylcholinesterase in a concentration-dependent manner. Interestingly, the different types of components in the herbs exhibited selectivity for different targets: flavanone glycosides are effective on α-glucosidase but ineffective on acetylcholinesterase; polymethoxyflavonoids are effective on acetylcholinesterase but ineffective on α-glucosidase. Furthermore, we found for the first time that the components in citrus herbs exhibit opposite structure-activity relationships on the above two targets. For example, the methoxy group can enhance the activity of compounds on acetylcholinesterase but weaken the activity of compounds on α-glucosidase. The selective action is a supplement to the "multi-components, multi-targets" system of herbal medicines. Pharmacophore analysis and molecular docking were applied to explore the interaction between active ingredients and biological targets from the perspective of ligands and receptors, respectively. By combining the above multiple technologies, a strong connection among herbal medicines, chemical components and multiple biological targets was established. This work not only helps to understand the similar function of citrus herbs for the treatment of diabetes and Alzheimer's disease, but also provides selective lead compounds for the development of related drugs. This strategy is also helpful to improve the quality evaluation of citrus herbs from the perspective of biological activity.

Comprehensive off-line CCC × LC-DAD-MS separation of Cyclopia pubescens Eckl. & Zeyh. phenolic compounds and structural elucidation of isolated compounds

INTRODUCTION

The minor phenolic constituents of Cyclopia pubescens Eckl. & Zeyh. are unknown and one dimensional (1D) liquid chromatography (LC) is unable to provide sufficient separation.

METHODOLOGY

A two-dimensional (2D) LC method incorporating normal-phasehigh performance countercurrent chromatography (NP-HPCCC) in the first dimension (¹ D) and reversed-phase ultra-high-performance liquid chromatography (RP-UHPLC) as the second dimension (² D) was developed. The analytical HPCCC method was subsequently scaled up to semi-preparative mode and fractions pooled based on phenolic sub-groups. The phenolic compounds in selected fractions were subsequently isolated using RP-HPLC on a C₁₈ column. Isolated compounds were identified by nuclear magnetic resonance (NMR) spectroscopy. The absolute configurations of compounds were determined by optical rotation and electronic circular dichroism spectra. Sugars were identified by gas chromatography-mass spectrometry (GC-MS) analysis.

RESULTS

The comprehensive off-line 2D CCC × LC method gave a good spread of the phenolic compounds. Orthogonality calculated using both the convex hull and conditional entropy methods were 81%. High-resolution mass spectrometric fragmentation spectra obtained from a quadrupole-time-of-flight instrument and ultraviolet-visible (UV-vis) spectral data were used to (tentatively) identify 32 phenolic compounds from the analytical CCC fractions. Of the seven isolated compounds, (2S)-5-O-[α-l-rhamnopyranosyl-(1 → 2)-β-d-glucopyranosyl]eriodictyol (3) and (2S)-5-O-[α-l-rhamnopyranosyl-(1 → 2)-β-d-glucopyranosyl]-5,7,3',4'-tetrahydroxyflavan (4) were newly identified in all plants. The other isolated compounds were identified as (2S)-5-O-[α-l-rhamnopyranosyl-(1 → 2)-β-d-glucopyranosyl]naringenin (1), R-neo-eriocitrin (2), 3-O-α-l-arabinopyranosyl-3,4-dihydroxybenzoic acid (5), 4-O-β-d-glucopyranosyl-Z-4-hydroxycinnamic acid (6) and 4-(4'-O-β-d-glucopyranosyl-4'-hydroxy-3'-methoxyphenyl)-2-butanone (7).

CONCLUSIONS

Among the 32 compounds (tentatively) identified, only six were previously identified in Cyclopia pubescens using 1D LC. Most of the isolated compounds were also identified for the first time in Cyclopia spp., improving the knowledge of the minor phenolic compounds of this genus.

Bioactivity of natural biflavonoids in metabolism-related disease and cancer therapies

Natural biflavonoids, such as amentoflavone, bilobetin, ginkgetin, isoginkgetin, taiwaniaflavone, morelloflavone, delicaflavone, hinokiflavone, and other derivatives (~ 40 biflavonoids), are isolated from Selaginella sp., Ginkgo biloba, Garcinia sp., and several other species of plants. They are able to exert therapeutic benefits by regulating several proteins/enzymes (PPAR-γ, CCAAT/enhancer-binding protein α [C/EBPα], STAT5, pancreatic lipase, PTP1B, fatty acid synthase, α-glucosidase [AG]) and insulin signaling pathways (via PI3K-AKT), which are linked to metabolism, cell growth, and cell survival mechanisms. Deregulated insulin signaling can cause complications of obesity and diabetes, which can lead to cognitive disorders such as Alzheimer's, Parkinson's, and dementia; therefore, the therapeutic benefits of these biflavones in these areas are highlighted. Since biflavonoids have shown potential to regulate metabolism, growth- and survival-related protein/enzymes, their relation to tumor growth and metastasis of cancer associated with angiogenesis are highlighted. The translational role of biflavones in cancer with respect to the inhibition of metabolism-related processes/pathways, enzymes, or proteins, such as STAT3/SHP-1/PTEN, kinesins, tissue kallikreins, aromatase, estrogen, protein modifiers, antioxidant, autophagy, and apoptosis induction mechanisms, are discussed. Finally, considering their observed bioactivity potential, oral bioavailability studies of biflavones and related clinical trials are outlined.

Ligand fishing based on bioaffinity ultrafiltration for screening xanthine oxidase inhibitors from citrus plants

Citrus plants are valuable medicinal plants with abundant flavonoids content in the parts of fruits and peels, which exhibit potential hypouricemic effect. In the present study, a ligand fishing assay was performed based on bio-affinity ultrafiltration for rapidly screening and identifying xanthine oxidase inhibitors from citrus plants. Under the optimal experimental conditions, five potential ligands were fished out when xanthine oxidase acted as the targeted protein. Subsequently, the chemical structures of all five compounds were identified by quadrupole time-of-flight mass spectrometry. Among them, hesperidin and naringin were confirmed as high-efficiency xanthine oxidase inhibitors. The half maximal inhibitory concentration values of hesperidin and naringin were 0.15 and 1.82 μM, respectively. Compared with the clinical antigout drug, allopurinol (half maximal inhibitory concentration = 8.03 μM), lower half maximal inhibitory concentration values indicated higher enzyme inhibitory activity. The Lineweaver-Burk plots indicated that the two compounds inhibited xanthine oxidase in a noncompetitive manner. The results demonstrate that the bioaffinity ultrafiltration method is a powerful tool for screening out xanthine oxidase inhibitors from natural products.

Comparatively Evaluating the Role of Herb Pairs Containing Angelicae Sinensis Radix in Xin-Sheng-Hua Granule by Withdrawal Analysis

The present study aims to investigate the roles of herb pairs containing Angelicae Sinensis Radix (Danggui) in Xin-Sheng-Hua Granule (XSHG) on hemolytic and aplastic anemia (HAA) mice. HAA model mice were induced by acetyl phenylhydrazine and cyclophosphamide; then the samples of XSHG and its decomposed recipes (DY, DC, DT, DH, DJ, and DZ) were orally administrated to these mice. Indicators of peripheral blood routine, organ index, and ATPase activities were tested. Moreover, the main effective components in these samples were also analyzed by UHPLC-TQ-MS/MS. Clear separation between the control and model groups from score plot of principal component analysis (PCA) was easily seen, indicating that HAA model was successfully conducted. Afterwards, relative distance calculation method between dose groups and control group from PCA score plot was adopted to evaluate the integrated effects of hematinic function of different samples. And the orders of hematinic effects were as follows: XHSG > DJ > DT > DZ > DH > DC > DY. Further analysis of these samples by UHPLC-TQ-MS/MS revealed that XSHG underwent complicated changes when herb pairs containing Danggui were excluded from XSHG, respectively. Compared with XSHG, the vast majority of active compounds in sample DY (formula minus herb pair Danggui-Yimucao) decreased significantly, which could partly explain why herb pair Danggui-Yimucao made great contribution to XSHG. These findings showed that withdrawal analysis method is a valuable tool to analyze the impacts of herb pairs containing Danggui on XSHG, which could lay foundation to reveal the compatibility rules of this formula.

Screening and identification of potential tyrosinase inhibitors from Semen Oroxyli extract by ultrafiltration LC-MS and in silico molecular docking

There is an increasing interest in screening and developing natural tyrosinase inhibitors widely applied in medicinal and cosmetic products, as well as in the food industry. In this study, an approach by ultrafiltration LC-MS and molecular docking was used to screen and identify tyrosinase inhibitors from Semen Oroxyli extract. The samples were first incubated with the tyrosinase to select the optimal binding conditions including tyrosinase concentration, incubation time and the molecular weight of ultrafiltration membrane. By comparison of the chromatographic profiles of the extracts after ultrafiltration with activated and inactivated tyrosinase, the potential inhibitors were obtained and then identified by LC-MS. The relative binding affinities of the potential inhibitors were also calculated based on the decrease of peak areas of those. As a result, seven compounds were fished out as tyrosinase inhibitors by this assay. Among them, oroxin A and baicalein showed higher tyrosinase inhibitory than resveratrol as positive drug, and their binding mode with enzyme was further verified via the molecular docking analysis. The test results showed that the proposed method was a simple, rapid, effective, and reliable method for the discovery of natural bioactive compounds, and it can be extended to screen other bioactive compounds from traditional Chinese medicines.

A strategy for screening bioactive components from natural products based on two-dimensional cell membrane chromatography and component-knockout approach

Cell membrane chromatography (CMC) is a bioaffinity chromatographic method used to screen active compounds from natural products. However, since the receptor capacity of CMC column is limited, high content/affinity compounds may cause column overloading and thus lead to ignorance of other positive candidates. For avoiding this effect and comprehensively discovering bioactive components, a strategy based on two-dimensional CMC and component-knockout approach was proposed. As an illustrative case study, red yeast rice (RYR), a rice product with good myocardial protective effect in clinical studies, was selected as the model experimental sample. For discovering its potential cardioprotective compounds, a CMC model with H9c2 rat cardiac myoblasts (H9c2/CMC) with good selectivity, stability and reproducibility was established. By using two-dimensional H9c2/CMC-HPLC coupled with QTOF MS system, three components were firstly screened out. After knocking out high content/affinity compound, another four bioactive compounds were then found. By this two-round screening, column overloading caused by high concentration or infinity compounds was avoided, and trace compounds were enriched. As a result, one pigment and six monacolins from RYR were fished out. The results indicate the proposed strategy might be used to discover active compounds from complex matrix.

Rapid identification of urokinase plasminogen activator inhibitors from Traditional Chinese Medicines based on ultrafiltration, LC-MS and in silico docking

The urokinase plasminogen activator (uPA) is regarded as the crucial trigger for plasmin generation, which is involved in several diseases especially for neoplasm metastasis. In this study, an efficient approach integrating ultrafiltration, LC/MS, bioassay and in silico docking, was proposed for rapidly detecting uPA ligands from Traditional Chinese Medicines (TCMs). Forty-two TCMs were initially assessed, and as illustrative case studies, Galla Chinensis and Sanguisorbae Radix, which appeared significant inhibitory activities on uPA, were chosen to develpe and verify the strategy. A total of seven uPA ligands were successfully detected and identified. Two of them, pentagalloylglucose and 28-O-β-d-glucopyranosyl pomolic acid, were demonstrated to be potential inhibitors, with IC50 at 1.639 μM and 37.82 μM repectively. Furthermore, a combinatorial compound library screening combined with in silico docking assay, was revealed that ursolic acid (IC50 = 2.623 μM) was also speculated to be a potent parent structure for inhibition of uPA. This approach offers a multidimensional perspective to discover uPA-binding leading compounds from TCMs or other complex mixtures, which would provide an efficient route for drug discovery.

Current advances in screening for bioactive components from medicinal plants by affinity ultrafiltration mass spectrometry

INTRODUCTION

Medicinal plants have played an important role in maintaining human health for thousands of years. However, the interactions between the active components in medicinal plants and some certain biological targets during a disease are still unclear in most cases.

OBJECTIVE

To conduct the high-throughput screening for small active molecules that can interact with biological targets, which is of great theoretical significance and practical value.

METHODOLOGY

The ultrafiltration mass spectrometry (UF-LC/MS) is a powerful bio-analytical method by combining affinity ultrafiltration and liquid chromatography-mass spectrometry (LC/MS), which could rapidly screen and identify small active molecules that bind to biological targets of interest at the same time. Compared with other analytical methods, affinity UF-LC/MS has the characteristics of fast, sensitive and high throughput, and is especially suitable for the complicated extracts of medicinal plants.

RESULTS

In this review, the basic principle, characteristics and some most recent challenges in UF-LC/MS have been demonstrated. Meanwhile, the progress and applications of affinity UF-LC/MS in the discovery of the active components from natural medicinal plants and the interactions between small molecules and biological target proteins are also briefly summarised. In addition, the future directions for UF-LC/MS are also prospected.

CONCLUSION

Affinity UF-LC/MS is a powerful tool in studies on the interactions between small active molecules and biological protein targets, especially in the high-throughput screening of active components from the natural medicinal plants.

Pharmaceutical applications of affinity-ultrafiltration mass spectrometry: Recent advances and future prospects

The immunoaffinity of protein with ligand is broadly involved in many bioanalytical methods. Affinity-ultrafiltration mass spectrometry (AUF-MS), a platform based on interaction of protein-ligand affinity, has been developed to fish out interesting molecules from complex matrixes. Here we reviewed the basics of AUF-MS and its recent applications to pharmaceutical field, i.e. target-oriented discovery of lead compounds from combinatorial libraries and natural product extracts, and determination of free drug concentration in biosamples. Selected practical examples were highlighted to illustrate the advances of AUF-MS in pharmaceutical fields. The future prospects were also presented.