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).

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.

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.