Evaluation of antioxidant, antidiabetic and antiobesity potential of phenylpropanoids (PPs): Structure-activity relationship and insight into action mechanisms against dual digestive enzymes by comprehensive technologies.

Phenylpropanoids (PPs), a group of natural compounds characterized by one or more C6-C3 units, have exhibited considerable potential in addressing metabolic disease. However, the comprehensive investigation on the relationship of compound structures and involved activity, along with the action mechanisms on the drug target is absent. This study aimed to evaluate the antioxidant and inhibitory activities of 16 PPs against two digestive enzymes, including α-glucosidase and pancreatic lipase, explore the structure-activity relationships and elucidate the mechanisms underlying enzyme inhibition. The findings revealed the similarities in the rules governing antioxidant and enzyme inhibitory activities of PPs. Specifically, the introduction of hydroxyl groups generally exerted positive effects on the activities, while the further methoxylation and glycosylation were observed to be unfavorable. Among the studied PPs, esculetin exhibited the most potent antioxidant activity and dual enzymes inhibition potential, displaying IC50 values of 0.017 and 0.0428 mM for DPPH and ABTS radicals scavenging, as well as 1.36 and 6.67 mM for α-glucosidase and lipase inhibition, respectively. Quantification analysis indicated esculetin bound on both α-glucosidase and lipase successfully by a mixed-type mode. Further analyses by UV-Vis, FT-IR, fluorescence spectra, surface hydrophobicity, SEM, and molecular docking elucidated that esculetin could bind on the catalytic or non-catalytic sites of enzymes to form complex, impacting the normal spatial conformation for hydrolyzing the substrate, thus exhibiting the weakened activity. These results may shed light on the utilization value of natural PPs for the management of hyperglycemia and hyperlipemia, and afford the theoretical basis for designing drugs with stronger inhibition against the dual digestive enzymes based on esculetin.

Detection of the Adulteration of Dendrobium Huoshanense with Dendrobium Henanense by UV-Vis-Shortwave Near-Infrared Diffuse Reflectance Spectroscopy Combined with Chemometrics.

BACKGROUND: Dendrobium huoshanense (DHS) is a classic traditional Chinese medicine (TCM) with distinctive medicinal benefits and great economic worth; nevertheless, because of similar tastes and looks, it is simple to adulterate with less expensive substitutes (such as Dendrobium henanense [DHN]). OBJECTIVE: This work aimed to develop a reliable tool to detect and quantify the adulteration of DHS with DHN by using UV-Vis-shortwave near-infrared diffuse reflectance spectroscopy (UV-Vis-SWNIR DRS) combined with chemometrics. METHODS: Adulterated samples prepared in varying concentrations (0-100%, w/w) were analyzed with UV-Vis-SWNIR DRS methods. Partial least-square-discriminant analysis (PLS-DA) and partial least-squares (PLS) regression techniques were used for the differentiation of adulterated DHN from pure DHS and the prediction of adulteration levels. RESULTS: The PLS-DA classification models successfully differentiated adulterated and nonadulterated DHS with an over 100% correct classification rate. UV-Vis-SWNIR DRS data were also successfully used to predict adulteration levels with a high coefficient of determination for calibration (0.9924) and prediction (0.9906) models and low error values for calibration (3.863%) and prediction (5.067%). CONCLUSION: UV-Vis-SWNIR DRS, as a fast and environmentally friendly tool, has great potential for both the identification and quantification of adulteration practices involving herbal medicines and foods. HIGHLIGHTS: UV-Vis-SWNIR DRS combined with chemometrics can be applied to identify and quantify the adulteration of herbal medicines and foods.

Simultaneous determination of phenols in the four main original plants of the famous traditional Chinese medicine Shihu by pressurized capillary electrochromatography.

A rapid pressurized capillary electrochromatography (pCEC) method has been established for the simultaneous analysis of 11 phenols in the four main original plants of the famous traditional Chinese medicine (TCM) Shihu. The effects of wavelength, mobile phase, flow rate, pH value, concentration of buffer, and applied voltage were systematically studied. The investigated 11 phenols could be isolated in 35 min on a reversed-phase EP-100-20/45-3-C18 capillary column using the established method. To apply the established pCEC method, all phenols except tristin (11) were detected in the four Dendrobium plants. A total of 10 components were detected in D. huoshanense, 6 components in D. nobile, 3 components in D. chrysotoxum, and 4 components in D. fimbriatum. The consistent evaluation revealed that the similarities among the four original plants of Shihu were 38.2-86.0% based on the 11 polyphenols and 92.5-97.7% based on the pCEC fingerprints. These further suggested that the components of the four original plants of TCM Shihu might be significantly different. Further investigation should be conducted to confirm and evaluate if the four species could be used as the same medicine with the same amount according to Chinese Pharmacopoeia (ChP).

Simultaneous Quantification of 11 Phenolic Compounds and Consistency Evaluation in Four Dendrobium Species Used as Ingredients of the Traditional Chinese Medicine Shihu.

The interchangeable use of different herbs to prepare the same formulation is a common practice in Traditional Chinese Medicine (TCM). However, this practice would require the component herbs to share similar compositions, at least in terms of the bioactive agents, to ensure they can replace each other in drug preparation. In this study, we developed an effective and comprehensive high-performance liquid chromatography-diode array detector (HPLC-DAD) method for simultaneous analysis of 11 phenolic compounds in the methanol extracts of Dendrobium huoshanense, Dendrobium nobile (D. nobile), Dendrobium chrysotoxum (D. chrysotoxum), and Dendrobium fimbriatum (D. fimbriatum), which have been identified as interchangeable ingredients for the same TCM preparation "Shihu" in the Chinese pharmacopeia (ChP). The consistency of the four Dendrobium species was evaluated on the basis of the presence of the 11 investigated compounds and the HPLC fingerprints of the methanol extracts of the plants. When gradient elution was performed with a solvent system of acetonitrile and water on a Zorbax Eclipse XDB-C18 (150 mm × 4.6 mm, 5 µm) with monitoring at 220 nm, all 11 investigated compounds were isolated at the baseline. The established HPLC method showed excellent linearity (all analytical curves showed relative coefficients [R2] > 0.999), sensitivity, precision (relative standard deviation [RSD] < 2%), and accuracy (recovery, 90.65-99.17%). These findings confirmed that the method we constructed was reliable. Quantification analysis showed significant differences in the contents of the investigated polyphenols in the four Dendrobium species. Evaluations of consistency revealed that the similarities among the four species were 0.299-0.906 in assessments based on the 11 polyphenols and 0.685-0.968 in assessments based on HPLC fingerprints. Thus, the components of the four Dendrobium species may be significantly different, and more experiments are required to determine whether they can be used interchangeably in the same amounts for preparing the formulation according to ChP.

Simultaneous analysis of 20 free amino acids by a single marker combined with an HPLC fingerprint evaluation of Dendrobium huoshanense.

A phenylhexyl isothiocyanate (PITC) precolumn derivatization quantitative analysis of multicomponents by a single marker (QAMS) strategy for the simultaneous analysis of 20 free amino acids (FAA) in Dendrobium huoshanense is proposed. The method was validated by the linearity, limit of detection (LDO), and limit of quantitation (LOQ), recovery, precision, and stability. The results showed that when applying the established method, the LOQ of the FFAs was lower than 1 ng/ml except threonine (1.32 ng) and cysteine (1.16 ng). The QAMS investigation revealed that, using any one of the 20 FAAs as the reference internal standard, no significant differences were observed between the external standard method and the QAMS method for the quantification of FAAs in D. huoshanense by PITC precolumn derivatization [The relative standard deviation (RSD, %) by QAMS and ESM were all below 5%]. HPLC fingerprint investigation combined with similar analysis (the similarity values for S1-S25 were >0.875) and quality fluctuation analysis showed that the cultivation environment might have a great effect on the accumulation of FAAs in D. huoshanense. Overall, our study showed that we might increase the accuracy and scope of the simultaneous quantification of multicomponents using the QAMS technique by being derivatized with a strong UV absorbing group, and QAMS combined with chromatographic fingerprinting can be considered good quality criteria for the quality control of D. huoshanense and may provide analytical technical support for research on Maillard Reaction during the further processing of D. huoshanense.

Simultaneous determination of 16 important biologically active phytohormones in Dendrobium huoshanese by pressurized capillary electrochromatography.

A rapid pressurized capillary electrochromatography (pCEC) method has been successfully developed for the simultaneous determination of 16 phytohormones in Dendrobium huoshanense. Effects of wavelength, mobile phase, the flow rate, pH value, concentration of buffer and applied voltage were investigated, respectively. The results showed that the 16 phytohormones could be baseline-separated rapidly in less than 21 min on a reversed-phase EP-100-20/45-3-C18 capillary column (total length of 45 cm, effective length of 20 cm, diameter of 100 µm, ODS packing inside for 3 µm) with ACN/5.0 mM ammonium acetate (containing 0.05% formic acid, pH = 3) as the mobile phase using gradient elution mode as follows: 0.1-10.0 min 40%ACN,10-15.0 min 70%ACN, 15.0-20 min 80% ACN, 20-21.0 min 80% ACN at a flow rate of 0.12 mL/min, applied voltage of -5 kV and a UV detection wavelength of 210 nm. The method validation howed that the established method is precise and stability, and the RSDs of intra- and inter-day precision based retention time and peak area were all below 5%. Employed the established method, in our experimental conditions, total 6 endogenous hormones including IAA, IBA, NAA, GA, ABA, t-Z were detected in D. huoshense. However, a relative larger amount of exogenous hormone 2,4-D (25.3 ~ 4.2 µg/kg) and 6-BA (79.5 ~ 35.4 µg/kg) were detected in 1 ~ 4 year old cultivated D. huoshense, suggesting there were still a certain amount of exogenous hormone residue in tissue-cultured D. huoshanese though they had been transplanted to field cultivation from the test-tube plantlets for several years.

Rapid Detection of Adulteration in Dendrobium huoshanense Using NIR Spectroscopy Coupled with Chemometric Methods.

BACKGROUND: Dendrobium huoshanense (DHS) is a typical traditional Chinese medicine with unique medical and high economic values; however, it may easily be adulterated with cheaper alternatives (e.g. Dendrobium henanese, DHN), because of their similar appearances and tastes. OBJECTIVE: In this study, adulteration of DHN in DHS was detected by near infrared (NIR) spectroscopy combined with chemometric methods. METHODS: By performing partial least squares (PLS) analysis, PLS multivariate methods including partial least-squares discriminant analysis (PLS-DA), and partial least-squares regressions (PLSR) were applied to the obtained spectral data to build models. The PLS-DA model was employed to differentiate between pure DHS samples and those adulterated with DHN. RESULTS: The R2 value obtained for the PLS-DA model was 0.4898 with an RMSEP error of 0.1554, resulting in a 100% accuracy of validation sample sets. Similarly, a PLSR model was also developed to quantify the amount of DHN adulterant in DHS samples. Experimental results indicated that the good performance of the multiplicative scattering correction (MSC) model is the better model showing a prediction performance of RMSEP of 2.38 and R2 of 0.9946. CONCLUSIONS: These results suggest that the combination of NIR spectroscopy and chemometric method provides a fast, simple and reliable method for detecting adulteration of DHS. HIGHLIGHTS: The method of classification allowed identification of both authentic and adulterated DHS samples. Comparison of six different techniques for spectra preprocessing to improve quantitative model performance was obtained with MSC derivative spectra. The method can detect most of the current DHS adulterations in the Chinese market.

[Purification and cytotoxicity of glycoprotein isolated from Dendrobium huoshanense].

Dendrobium huoshanense is a rare traditional Chinese medicinal herb, and the anti-tumor activity of its polysaccharides is a research hotspot in traditional Chinese medicine resources domain. This study aims to explore the material basis for the anti-tumor activity of polysaccharide. D. huoshanense was used as raw material in the experiment, and the different protein components were obtained through low salt solution extraction and ammonium sulfate fractional precipitation. Then glycoprotein components were determined by SDS-PAGE electrophoresis staining, and were further isolated and purified by DEAE ion column and Sephadex gel column. At the same time, MTT assay was used in detecting the cytotoxicity of different products on HepG2 cells in vitro. As a result, three kinds of glycoprotein components RG1, RG2, RG3 with relative molecular mass of 22.5, 19.8, 15.6 kDa were gained, and the IC50 of three compounds on human liver cancer cell HepG2 was 534.23 mg•L⁻¹, meanwhile IC50 of single glycoprotein component RG1, RG2 was 432.96, 413.91 mg•L⁻¹ respectively, and glycoprotein component RG3 had no cytotoxicity on HepG2 cells. All in all, the experiment results suggested that two kinds of glycoproteins components with relative molecular mass of 22.5, 19.8 kDa may be one of the material basis for anti-tumor activity of D. huoshanense polysaccharide, and they had a synergistic effect.

A comparative study of three tissue-cultured Dendrobium species and their wild correspondences by headspace gas chromatography-mass spectrometry combined with chemometric methods.

Plant tissue culture technique is widely used in the conservation and utilization of rare and endangered medicinal plants and it is crucial for tissue culture stocks to obtain the ability to produce similar bioactive components as their wild correspondences. In this paper, a headspace gas chromatography-mass spectrometry method combined with chemometric methods was applied to analyze and evaluate the volatile compounds in tissue-cultured and wild Dendrobium huoshanense Cheng and Tang, Dendrobium officinale Kimura et Migo and Dendrobium moniliforme (Linn.) Sw. In total, 63 volatile compounds were separated, with 53 being identified from the three Dendrobium spp. SAMPLES: Different provenances of Dendrobiums had characteristic chemicals and showed remarkable quantity discrepancy of common compositions. The similarity evaluation disclosed that the accumulation of volatile compounds in Dendrobium samples might be affected by their provenance. Principal component analysis showed that the first three components explained 85.9% of data variance, demonstrating a good discrimination between samples. Gas chromatography-mass spectrometry techniques, combined with chemometrics, might be an effective strategy for identifying the species and their provenance, especially in the assessment of tissue-cultured Dendrobium quality for use in raw herbal medicines.

[Study on Monosaccharide Compositions of Polysaccharide in Dendrobium Stems of Different Resources by PMP-HPCE].

OBJECTIVE: To establish a PMP-HPCE method for comparing the monosaccharides of polysaccharide in tissue-cultured and wild Dedrobium huoshanese and Dedrobium moniliforme as well as wild Dedrobium henanese, in order to investigate the similarities of their bioactive components. METHODS: The PMP-monosaccharides of polysaccharide from the five investigated Dedrobium samples were separated by HPCE on a fused silica capillary column(100 cm x 50 µm) at 25 °C with 350 mmol/L BAS (adjusted to pH 10 with 1.0 mol/L NaOH) as running buffer for 34 min. The applied voltage was 20 kV and the detection wavelength was set at 250 nm. RESULTS: Total six monosaccharides including xylose, glucose, mannose, galactose, galacturonic acid and ribose were detected in the five Dendrobiurms samples and the similarity coefficients between the ten batches of the same Dendrobium species were all above 0. 98,while remarkable dissimilarity were exhibited among species and different resources. CONCLUSION: PMP-HPCE technique combined with chemometrics is simple, convenient, precise, reproducible and proved to be an effective strategy for identifying the species and origins, especially in the quality assessment of Dendrobium stems.