Rapid screening of potential α-amylase inhibitors from Rhodiola rosea by UPLC-DAD-TOF-MS/MS-based metabolomic method

Recent advances in methods of extraction, pre-concentration, purification, identification, and quantification of kaempferol

As a naturally widely-occurring dietary, cosmetic, and therapeutic flavonoid, kaempferol has gained much consideration for its nutritional and pharmaceutical properties in recent years. Although there have been performed a high number of studies associated with different aspects of kaempferol's analytical investigations, the lack of a comprehensive summary of the various methods and other plant sources that have been reported for this compound is being felt, especially for many biological applications. This study, aimed to provide a detailed compilation consisting of sources (plant species) and analytical information that was precisely related to the natural flavonoid (kaempferol). There is a trend in analytical research that supports the application of modern eco-friendly instruments and methods. In conclusion, ultrasound-assisted extraction (UAE) is the most general advanced method used widely today for the extraction of kaempferol. During recent years, there is an increasing tendency towards the identification of kaempferol by different methods.

Phenolic compounds from the aerial parts of Rhodiola rosea in Japan, and their antioxidant activity and chemical adaptation to alpine environment

Twelve flavonoids (1-12) including a new flavonol glycoside, hibiscetin 3-O-glucopyranoside-8-O-glucuronopyranoside, ten known galloylglucoses (13-22) and three known phenolic acids (23-25) were isolated from the aerial parts of Rhodiola rosea growing in Japan. Their chemical structures were elucidated by UV-vis spectra, LC-MS, HR-MS, acid hydrolysis, NMR, and/or HPLC, and TLC comparisons with authentic samples. Antioxidant activity of major 14 compounds was measured by H-ORAC method, and two flavonols, herbacetin 3-O-glucoside-8-O-glucuronide, and gossypetin 3-O-glucuronide-8-O-glucoside, showed the strongest activity. Moreover, chemical adaptation to severe alpine environment of R. rosea was discussed.

Hypoglycemic activity of immature persimmon (Diospyros kaki Thunb.) extracts and its inhibition mechanism for α-amylase and α-glucosidase

Persimmon tannins, particularly in immature persimmons, haven't yet received corresponding attention to research on therapy of diabetes mellitus in spite of high hypoglycemic activity. To accurately screening key hypoglycemic components, immature persimmon extracts were isolated and identified using enzyme affinity ultrafiltration and HRLC-ESI-MS/MS. Among them, Hederagenin (IC50 = 0.077 ± 0.003 mg/mL), Ursolic acid (IC50 = 0.001 ± 0.000 mg/mL) and Quercetin dehydrate (IC50 = 0.081 ± 0.001 mg/mL) exhibited the strongest inhibitory effect on α-amylase (HSA and PPA) and α-glucosidase, respectively. And their inhibition mechanisms were analyzed using multi-spectral analysis, atomic force microscope and molecular docking, indicating the bonding with starch digestion enzymes through hydrogen bonding and hydrophobic interaction, and generating the enzyme aggregation. In vivo starch-tolerance experiment further verified that these inhibitors could improve postprandial hyperglycemia (17.18 % ∼ 40.29 %), far more than acarbose. Suppressing, Hederagenin and Ursolic acid as triterpenoids appeared amazing potentiality to alleviate postprandial hyperglycemia, which suggested that IPE were comprehensive exploration values on prevention and treatment of hyperglycemia.

Assessment of metabolic, mineral, and cytotoxic profile in pineapple leaves of different commercial varieties: A new eco-friendly and inexpensive source of bioactive compounds

Pineapple is among the most produced and consumed fruits worldwide, and consequently, its agroindustrial production/processing generates high amounts of agricultural waste, which are routinely discarded. Thus, it is crucial to seek alternatives to reuse this agricultural waste that are in high availability. Therefore, this work aims to evaluate the chemical composition of a specific residue (leaves) of seven commercial varieties of pineapples, to attribute high added value uses, and to evaluate its potential as a source of secondary metabolites and minerals. Thereby, twenty-eight metabolites were annotated by UPLC-QTOF-MS^E, including amino acids, organic acids, and phenolic compounds. The following minerals were quantitatively assessed by ICP-OES: Zn (5.30-19.77 mg kg^-1), Cr, Cd, Mn (50.80-113.98 mg kg^-1), Cu (1.05-4.01 mg kg^-1), P (1030.77-6163.63 mg kg^-1) and Fe (9.06-70.17 mg kg^-1). In addition, Cr and Cd (toxic materials) present concentration levels below the limit of quantification of the analytical method (LOQ_Cr and LOQ_Cd = 0.02 mg kg^-1) for all samples. The multivariate analysis was conceived from the chemical profile, through the tools of PCA (principal component analysis) and HCA (hierarchical cluster analysis). The results show that pineapple leaves have similarities and differences concerning their chemical composition. In addition, the cytotoxicity assays of the extracts against tumor and non-tumor strains shows that the extracts were non-toxic. This fact can corroborate and enhance the prospection of new uses and applications of agroindustrial co-products from pineapple, enabling the evaluation and use in different types of industries, such as pharmacological, cosmetic, and food, in addition to the possibility of being a potential source of bioactive compounds.

Nontargeted metabolomic analysis of four different parts of Actinidia arguta by UPLC-Q-TOF-MSE

Actinidia arguta, an edible berry plant with high nutritional values, has been widely used in Asian countries as a food and traditional medicinal herb. The well-recognized health-promoting properties of A. arguta were associated with its bioactive components in its different botanical parts. To rapidly screen and identify chemical components and simultaneously determine the potential metabolites from different parts of A. arguta, UPLC-Q-TOF-MS^E coupled with UNIFI platform and multivariate statistical analysis approach was established in this study. As a result, a total of 107 components were identified from the four different parts of A. arguta, in which 31 characteristic chemical markers were discovered among them, including 12, 8, 6, and 5 compounds from the fruits, leaves, roots, and stems, respectively. These results suggested that the combination of UPLC-Q-TOF-MS^E and metabolomic analysis is a powerful method to rapidly screen characteristic markers for the quality control of A. arguta.

The therapeutic role of Jingchuan tablet on ischaemic cerebral stroke via the HIF-1α/EPO/VEGFA signalling pathway

CONTEXT

Jingchuan tablet (JCT) is a Chinese medicine prescription for treating ischaemic cerebral stroke (ICS). However, its relevant mechanisms remain unclear.

OBJECTIVE

To unravel the intrinsic mechanisms of JCT anti-ICS.

MATERIALS AND METHODS

'Hongjingtian', 'chuanxiong', 'yanhusuo', 'bingpian', 'cerebral infarction', 'cerebral ischemia' or 'stroke' were used as keywords, and then components, targets and underlying mechanisms of JCT anti-ICS were analysed in TCMSP, TTD, DrugBank, STRING and Metascape databases up to June 2020. Male Sprague-Dawley rats under permanent middle cerebral artery occlusion (pMCAO) model, randomly assigned as: model, sham, nimodipine (0.012 g/kg/d) and JCT (0.78, 1.56 and 3.12 g/kg/d) groups, received oral gavage administration for a week. Therapeutic effects were evaluated by detecting the proportion of cerebral infarction, neuronal apoptosis and neurological deficits. Bioactive components were detected by HPLC-MS. Molecular biology and computational docking were used to verify the underlying mechanisms.

RESULTS

Eighty-one components, 166 targets and HIF-1α/EPO/VEGFA pathway contributed to the anti-ICS effect of JCT. JCT treatment effectively reduced the proportion of cerebral infarction (33.13%), apoptosis rate (14.80%) and neurobehavioural score (2.00). JCT increased the protein levels of HIF-1α (0.84), EPO (0.64) and VEGFA (0.69), respectively (p < 0.05). Gallic acid, salidroside, chlorogenic acid, ethyl gallate, ferulic acid and tetrahydropalmatine detected by HPLC-MS showed good interaction and binding with HIF-1α/EPO/VEGFA.

CONCLUSIONS

Our study demonstrated the mechanisms of JCT anti-ICS associated with the activation of the HIF-1α/EPO/VEGFA pathway, which provided a pharmacological basis for expanding the clinical application and some scientific ideas for further research into the material basis JCT anti-ICS.

A supercritical fluid workflow for the quality assessment of herbal drugs and commercial preparations from Rhodiola rosea

INTRODUCTION

Preparations from the Rhodiola rosea are experiencing an increase in popularity: extracts of dried roots and rhizomes are used as adaptogen to treat stress, fatigue, and weakness. To meet high pharmaceutical standards, fast and reliable methods to assess phytochemical variations in respect of quality control are needed.

OBJECTIVE

The aim of this study was to extract and quantify seven characteristic secondary metabolites of R. rosea, namely p-tyrosol (1), rosin (2), rosiridin (3), salidroside (4), rosarin (5), rosavin (6), and tricin-5-O-β-d-glucopyranoside (7) in 24 herbal drugs and seven commercial preparations using a newly established supercritical fluid workflow.

METHODS

The developed protocol allowed for an exhaustive extraction of compounds 1-7 using 60% carbon dioxide (CO₂ ) and 40% methanol. The constituents were analysed on an ultra-high-performance supercritical fluid chromatography (UHPSFC) instrument using a charged surface hybrid fluoro-phenyl (CSH FP) column (3.0 mm × 100 mm, 1.7 μm; mobile phase: CO₂ and methanol).

RESULTS

The seven compounds were separated in a remarkably short time (< 3.5 minutes). For their quantitation, good results in terms of selectivity, linearity (R²  ≥ 0.99), precision (intraday ≤ 3.03%, interday ≤ 5.17%) and accuracy (recovery rates 96.6-102.4%) were achieved using selected ion recording on a Quadrupole Dalton (QDa) mass detector.

CONCLUSION

The quantitative analysis of the investigated herbal drugs showed a highly differing metabolite pattern which was also observed in the investigated commercial products. None of the commercial dietary products met the declared content of rosavins and salidroside. The developed and validated protocol offers a novel and reliable method to assess the quantitative composition of Rhodiola herbal drugs and preparations.

A comprehensive review of herbacetin: From chemistry to pharmacological activities

ETHNOPHARMACOLOGICAL RELEVANCE

Herbacetin is an active constituent of traditional Chinese medicines such as Ephedra sinica Stapf (MaHuang) and Sedum roseum (L.). Scop. (Hong JingTian). MaHuang was used to treat cough, asthma, fever, and edema for more than 5000 years, while Hong JingTian was used to treat depression, fatigue, cancers, and cardiovascular disease. Recent studies indicate that herbacetin and its glycosides play a critical role in the pharmacological activities of these herbs. However, currently, no comprehensive review on herbacetin has been published yet.

AIM OF THE STUDY

This review aimed to summarize information on the chemistry, natural sources, and pharmacokinetic features of herbacetin, with an emphasis on its pharmacological activities and possible mechanisms of action.

MATERIALS AND METHODS

A literature search was performed on the Web of Science, PubMed, and China Knowledge Resource Integrated databases (CNKI) using the search term "herbacetin" ("all fields") from 1935 to 2020. Information was also obtained from classic books of Chinese herbal medicine, Chinese pharmacopeia, and the database "The Plant List" (www.theplantlist.org). Studies have been analyzed and summarized in this review if they dealt with chemistry, taxonomy, pharmacokinetic, and pharmacological activity.

RESULTS

Herbacetin is distributed in various plants and can be extracted or synthesized. It showed diverse pharmacological activities including antioxidant, antiviral, anti-inflammatory, anticancer, antidiabetic, and anticholinesterase. It is thought to have great potential in cancer treatment, especially colon and skin cancers. However, the bioavailability of herbacetin is low and the toxicity of herbacetin has not been studied. Thus, more studies are required to solve these problems.

CONCLUSIONS

Herbacetin shows promising pharmacological activities against multiple diseases. Future research should focus on improving bioavailability, further studying its pharmacological mechanism, evaluating its toxicity and optimal dose, and performing the clinical assessment. We hope that the present review will serve as a guideline for future research on herbacetin.

Simultaneous Determination of 78 Compounds of Rhodiola rosea Extract by Supercritical CO2-Extraction and HPLC-ESI-MS/MS Spectrometry

The plant Rhodiola rosea L. of family Crassulaceae was extracted using the supercritical CO₂-extraction method. Several experimental conditions were investigated in the pressure range of 200–500 bar, with the used volume of cosolvent ethanol in the amount of 1% in the liquid phase at a temperature in the range of 31–70°C. The most effective extraction conditions are pressure 350 bar and temperature 60°C. The extracts were analyzed by HPLC with MS/MS identification. 78 target analytes were isolated from Rhodiola rosea (Russia) using a series of column chromatography and mass spectrometry experiments. The results of the analysis showed a spectrum of the main active ingredients Rh. rosea: salidroside, rhodiolosides (B and C), rhodiosin, luteolin, catechin, quercetin, quercitrin, herbacetin, sacranoside A, vimalin, and others. In addition to the reported metabolites, 29 metabolites were newly annotated in Rh. rosea. There were flavonols: dihydroquercetin, acacetin, mearnsetin, and taxifolin-O-pentoside; flavones: apigenin-O-hexoside derivative, tricetin trimethyl ether 7-O-hexosyl-hexoside, tricin 7-O-glucoronyl-O-hexoside, tricin O-pentoside, and tricin-O-dihexoside; flavanones: eriodictyol-7-O-glucoside; flavan-3-ols: gallocatechin, hydroxycinnamic acid caffeoylmalic acid, and di-O-caffeoylquinic acid; coumarins: esculetin; esculin: fraxin; and lignans: hinokinin, pinoresinol, L-ascorbic acid, glucaric acid, palmitic acid, and linolenic acid. The results of supercritical CO₂-extraction from roots and rhizomes of Rh. rosea, in particular, indicate that the extract contained all biologically active components of the plant, as well as inert mixtures of extracted compositions.

Anti-Allergic, Anti-Inflammatory and Anti-Hyperglycemic Activity of Chasmanthe aethiopica Leaf Extract and Its Profiling Using LC/MS and GLC/MS

This study aims to comprehensively explore the phytoconstituents as well as investigate the different biological activities of Chasmanthe aethiopica (Iridaceae) for the first time. Metabolic profiling of the leaf methanol extract of C. aethiopica (CAL) was carried out using HPLC-PDA-ESI-MS/MS. Twenty-nine compounds were annotated belonging to various phytochemical classes including organic acids, cinnamic acid derivatives, flavonoids, isoflavonoids, and fatty acids. Myricetin-3-O-rhamnoside was the major compound identified. GLC/MS analysis of the n-hexane fraction (CAL-A) resulted in the identification of 45 compounds with palmitic acid (16.08%) and methyl hexadecanoic acid ester (11.91%) representing the major constituents. CAL-A exhibited a potent anti-allergic activity as evidenced by its potent inhibition of β-hexosaminidase release triggered by A23187 and IgE by 72.7% and 48.7%, respectively. Results were comparable to that of dexamethasone (10 nM) in the A23187 degranulation assay showing 80.7% inhibition for β-hexosaminidase release. Both the n-hexane (CAL-A) and dichloromethane (CAL-B) fractions exhibited potent anti-inflammatory activity manifested by the significant inhibition of superoxide anion generation and prohibition of elastase release. CAL showed anti-hyperglycemic activity in vivo using streptozotocin-induced diabetic rat model by reducing fasting blood glucose levels (FBG) by 53.44% as compared with STZ-treated rats along with a substantial increase in serum insulin by 22.22%. Molecular modeling studies indicated that dicaffeoylquinic acid showed the highest fitting with free binding energies (∆G) of -47.24 and -60.50 Kcal/mol for human α-amylase and α-glucosidase, respectively confirming its anti-hyperglycemic activity. Thus, C. aethiopica leaf extract could serve as an effective antioxidant natural remedy combating inflammation, allergy, and hyperglycemia.

Screening and identifying of α-amylase inhibitors from medicine food homology plants: Insights from computational analysis and experimental studies

There is a growing interest in screening α-amylase inhibitors from natural products for application in the development of new antidiabetic drugs or functional foods. In this study, a structure-based virtual screening was applied to rapidly identify the α-amylase inhibitors from medicine food homology (MFH) plants. Similarity search, docking & scoring were used for further filter small molecules. As a result, 21 corresponding potential α-amylase inhibitors from MFH plants were obtained. And, six polyphenol compounds (curcumin, procyanidins, epicatechin gallate (ECG), epigallocatechin gallate (EGCG), hesperidin, and puerarin) were highlighted for further verification after a thorough assessment of the classification of hit molecules as well as docking scores. The results of the enzyme inhibition test showed that ECG, EGCG, and procyanidins had the better binding ability of α-amylase among these six polyphenols. The Ki values of ECG, EGCG, and procyanidins on α-amylase were 0.70, 1.68, and 0.24, respectively. The CD spectra results indicated that the three polyphenols can cause conformational changes in α-amylase. PRACTICAL APPLICATIONS: A structure-based virtual screening method for rapid identifying α-amylase inhibitors from MFH plants was developed successfully in this study. These findings suggested that natural polyphenols such as ECG, EGCG, and procyanidins may be a potential inhibitor of α-amylase which could be used as a nutrient supplement for the prevention of diabetes mellitus or can be further used in the development of hypoglycemic drugs. At the same time, it can provide theoretical guidance for the better utilization and development of medicine food homology plants containing these potential α-amylase inhibitors. Moreover, this work may provide ideas and references for the screening of other target protein inhibitors.

Target protein-oriented isolation of Hes1 dimer inhibitors using protein based methods

Natural products isolation using protein based methods is an attractive for obtaining bioactive compounds. To discover neural stem cell (NSC) differentiation activators, we isolated eight inhibitors of Hes1 dimer formation from Psidium guajava using the Hes1-Hes1 interaction fluorescent plate assay and one inhibitor from Terminalia chebula using the Hes1-immobilized beads method. Of the isolated compounds, gallic acid (8) and 4-O-(4”-O-galloyl-α-L-rhamnopyranosyl)ellagic acid (11) showed potent Hes1 dimer formation inhibitory activity, with IC₅₀ values of 10.3 and 2.53 μM, respectively. Compound 11 accelerated the differentiation activity of C17.2 NSC cells dose dependently, increasing the number of neurons with a 125% increase (5 μM) compared to the control.

Understanding glycaemic control and current approaches for screening antidiabetic natural products from evidence-based medicinal plants

Type 2 Diabetes Mellitus has reached epidemic proportions as a result of over-nutrition and increasingly sedentary lifestyles. Current therapies, although effective, are not without limitations. These limitations, the alarming increase in the prevalence of diabetes, and the soaring cost of managing diabetes and its complications underscores an urgent need for safer, more efficient and affordable alternative treatments. Over 1200 plant species are reported in ethnomedicine for treating diabetes and these represents an important and promising source for the identification of novel antidiabetic compounds. Evaluating medicinal plants for desirable bioactivity goes hand-in-hand with methods in analytical biochemistry for separating and identifying lead compounds. This review aims to provide a comprehensive summary of current methods used in antidiabetic plant research to form a useful resource for researchers beginning in the field. The review summarises the current understanding of blood glucose regulation and the general mechanisms of action of current antidiabetic medications, and combines knowledge on common experimental approaches for screening plant extracts for antidiabetic activity and currently available analytical methods and technologies for the separation and identification of bioactive natural products. Common in vivo animal models, in vitro models, in silico methods and biochemical assays used for testing the antidiabetic effects of plants are discussed with a particular emphasis on in vitro methods such as cell-based bioassays for screening insulin secretagogues and insulinomimetics. Enzyme inhibition assays and molecular docking are also highlighted. The role of metabolomics, metabolite profiling, and dereplication of data for the high-throughput discovery of novel antidiabetic agents is reviewed. Finally, this review also summarises sample preparation techniques such as liquid-liquid extraction, solid phase extraction, and supercritical fluid extraction, and the critical function of nuclear magnetic resonance and high resolution liquid chromatography-mass spectrometry for the dereplication, putative identification and structure elucidation of natural compounds from evidence-based medicinal plants.

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.

Quickly Screening for Potential α-Glucosidase Inhibitors from Guava Leaves Tea by Bioaffinity Ultrafiltration Coupled with HPLC-ESI-TOF/MS Method

Guava leaves tea (GLT) has a potential antihyperglycemic effect. Nevertheless, it is unclear which compound plays a key role in reducing blood sugar. In this study, GLT extract (IC₅₀ = 19.37 ± 0.21 μg/mL) exhibited a stronger inhibitory potency against α-glucosidase than did acarbose (positive control) at IC₅₀ = 178.52 ± 1.37 μg/mL. To rapidly identify the specific α-glucosidase inhibitor components from GLT, an approach based on bioaffinity ultrafiltration combined with high performance liquid chromatography coupled to electrospray ionization-time-of-flight-mass spectrometry (BAUF-HPLC-ESI-TOF/MS) was developed. Under the optimal bioaffinity ultrafiltration conditions, 11 corresponding potential α-glucosidase inhibitors with high affinity degrees (ADs) were screened and identified from the GLT extract. Quercetin (IC₅₀ = 4.51 ± 0.71 μg/mL) and procyanidin B3 (IC₅₀ = 28.67 ± 5.81 μg/mL) were determined to be primarily responsible for the antihyperglycemic effect, which further verified the established screening method. Moreover, structure-activity relationships were discussed. In conclusion, the BAUF-HPLC-ESI-TOF/MS method could be applied to determine the potential α-glucosidase inhibitors from complex natural products quickly.