Separation, UPLC-QTOF-MS/MS analysis, and antioxidant activity of hydrolyzable tannins from water caltrop (Trapa quadrispinosa) pericarps

Chitosan/water caltrop pericarp extract reinforced active edible film and its efficacy as strawberry coating for prolonging shelf life

This study focuses on developing and characterizing active and sustainable packaging films made from chitosan (CS), enriched with a novel bioactive extract sourced from water caltrop (Trapa bispinosa Roxb.) pericarp (WCPE). In this study, chitosan (1 % w/v) based biocomposite films were produced using varying concentrations of bioactive extracts (0,5,10,15 and 20 % w/w of CS) from water caltrop pericarp, obtained through ultrasound-assisted extraction. WCPE extract possess excellent antioxidant (89 ± 1.41 %), higher phenolics (120.48 ± 4.67 mg GAE g-1) and antimicrobial property. Similarly, developed biocomposite demonstrated superior UV barrier (OP600nm ∼4.30), lower swelling (21.43 ± 2.61 %), lower moisture content (17.15 ± 1.82 %), minimum water vapor permeability (1.28 ± 0.06 g m-1 day-1 Pa-1 (×10-10)), excellent antioxidant capacity (60.41 ± 1.52 % for DPPH and 70.80 ± 2.36 % for ABTS), greater phenolics content (168 ± 4.16 mg GAE/100 g) and good antimicrobial property. Additionally, all formulated coating solutions demonstrated biocompatibility (>85 % cell viability) with BHK-21 fibroblast cells. Finally, the CS-WCPE20 solution was evaluated for its practical use as an edible coating to preserve strawberry, under storage conditions of 20 ± 5 °C and 75 ± 5 % relative humidity. Developed coating successfully preserved quality attribute such as lower weight loss (∼17 %), higher texture (∼2.18 N), optimum TSS (∼8.44 % Brix), maximum antioxidant quality (∼50 % DPPH scavenging activity) and higher color and visual attribute upto 8 days at ambient temperature. Thus, the optimized formulation demonstrates significant potential for use as an active and intelligent packaging solution, effectively extending the shelf life of fruits and vegetables.

Comprehensive phytochemical profiling of Phyllanthus emblica L. flowers on UHPLC/MS quadrupole time of flight, HPTLC, HPLC, and NMR analytical platforms reveals functional metabolites with potent anti-inflammatory effects in human (THP-1) macrophages

INTRODUCTION

Phyllanthus emblica L., renowned for its pharmacological benefits found in its fruits and leaves, has received considerable attention. However, there is a notable lack of research on its flowers, specifically on metabolite profiling and pharmacological activity.

OBJECTIVE

The present study aims to delineate the phytochemical constituents of hydromethanolic extract of P. emblica flowers by ultra-high-performance liquid chromatography coupled with quadrupole time of flight mass spectrometry (UHPLC-QToF-MS), high-performance thin layer chromatography (HPTLC), high-performance liquid chromatography (HPLC), infrared and nuclear magnetic resonance spectroscopic methods and subsequent evaluation of its anti-inflammatory potential.

MATERIALS AND METHODS

The identification and characterization of phytochemicals in P. emblica flowers was performed by UHPLC/MS-QToF in both positive and negative ionization modes. Additionally, marker compounds present in flower extract were analyzed using HPTLC, HPLC, FT-IR, and NMR methods. The anti-inflammatory potential was evaluated in lipopolysaccharide-stimulated THP-1 macrophages by evaluating inflammatory biomarkers.

RESULTS

UHPLC/MS-QToF analysis facilitated the identification of 51 compounds from P. emblica flowers including gallic acid derivatives, flavonoid glycosides, and tannins based on their fragmentation patterns and previous literature reports. Notably, the study also identified spermidine compounds for the first time in this species. Optimization of HPTLC and HPLC methods marked the presence of corilagin as major compound followed by FT-IR and NMR spectral methods. Moreover, treatment with hydromethanolic extract of P. emblica flowers resulted in decreased levels of proinflammatory cytokines, TNF-α, IL-1β, and IL-6, alongside modulation of nuclear factor-κB activity in lipopolysaccharide-induced THP-1 macrophages.

CONCLUSION

Chromatographic techniques in conjunction with spectral methods found robust prevalence in the identification of signature phytometabolites present in P. emblica flowers, which sets the basis for its anti-inflammatory potentials. The studies established a foundation for further exploration of potential applications of P. emblica flowers across various domains.

Phytochemical analysis and hepatotoxicity assessment of braised Polygoni Multiflori Radix (Wen-He-Shou-Wu)

Polygoni Multiflori Radix (PMR) is a medicinal herb commonly used in China and Eastern Asia. Recently, the discovery of hepatotoxicity in PMR has received considerable attention from scientists. Processing is a traditional Chinese medicine technique used for the effective reduction of toxicity. One uncommon technique is the braising method-also known as 'Wen-Fa' in Chinese-which is used to prepare tonics or poisonous medications. Braised PMR (BPMR)-also known as 'Wen-He-Shou-Wu'-is one of the processed products of the braising method. However, the non-volatile components of BPMR have not been identified and examined in detail, and therefore, the hepatotoxic advantage of BPMR remains unknown. In this study, we compared the microscopic characteristics of different samples in powder form using scanning electron microscopy (SEM), investigated the non-volatile components, assessed the effects of different processed PMR products on the liver, and compared the differences between BPMR and PMR Praeparata recorded in the Chinese Pharmacopoeia (2020 edition). We found that the hepatotoxicity of BPMR was dramatically decreased, which may be related to an increase in polysaccharide content and a decrease in toxic substances. The present study provides an important foundation for future investigations of the processing mechanisms of BPMR.

Hydrolyzable tannins are incorporated into the endocarp during sclerification of the water caltrop Trapa natans

The water caltrop (Trapa natans) develops unique woody fruits with unusually large seeds among aquatic plants. During fruit development, the inner fruit wall (endocarp) sclerifies and forms a protective layer for the seed. Endocarp sclerification also occurs in many land plants with large seeds; however, in T. natans, the processes of fruit formation, endocarp hardening, and seed storage take place entirely underwater. To identify potential chemical and structural adaptations for the aquatic environment, we investigated the cell-wall composition in the endocarp at a young developmental stage, as well as at fruit maturity. Our work shows that hydrolyzable tannins-specifically gallotannins-flood the endocarp tissue during secondary wall formation and are integrated into cell walls along with lignin during maturation. Within the secondary walls of mature tissue, we identified unusually strong spectroscopic features of ester linkages, suggesting that the gallotannins and their derivatives are cross-linked to other wall components via ester bonds, leading to unique cell-wall properties. The synthesis of large amounts of water-soluble, defensive aromatic metabolites during secondary wall formation might be a fast way to defend seeds within the insufficiently lignified endocarp of T. natans.

Discriminating geographical origins and determining active substances of water caltrop shells through near-infrared spectroscopy and chemometrics

Near-infrared spectroscopy (NIRS) combined with chemometric methods were used to discriminate the geographical origins of the water caltrop shells from different regions of China. Two active substances, the total phenolic content (TPC) and total flavonoid content (TFC) in the water caltrop shells were determined through the technique as well. Principal component analysis (PCA) combined with linear discriminant analysis (LDA) was adopted to build the geographical discriminant model. Quantitative analysis models of TPC and TFC were built using partial least squares (PLS) regression. 1st derivative and randomization test (RT) methods were used to optimize the quantitative analysis models. It was found that the geographical discriminant model can correctly recognize the water caltrop shells from different regions of China with a total accuracy of 93.33%. The values of TPC and TFC obtained by the optimized models and the standard method are close. The coefficient of determination (R2) and the ratio of prediction to deviation for the two substances were 0.91, 0.89 and 3.02, 3.02, respectively. The results demonstrated the feasibility of NIRS combined with chemometric methods for the geographical discrimination of water caltrop shells and the quantitative analysis of TPC and TFC in water caltrop shells.

Investigating the chemical profile of Rheum lhasaense and its main ingredient of piceatannol-3'-O-β-D-glucopyranoside on ameliorating cognitive impairment

Rheum lhasaense A. J. Li et P. K. Hsiao, a stout herb plant from the Polygonaceae, is a typical Tibetan folk herb with heat-clearing and detoxifying effects, but does not have the typical laxative effect compared with other rhubarb plants. Nevertheless, its chemical composition and pharmacological activities still lack in-depth research. The present study endeavored to analyze the possible phytochemical constituents in R. lhasaense and explore the main compound piceatannol-3'-O-β-D-glucopyranoside (PG) effect on cognitive impairment and its underlying mechanism. The chemical profile of R. lhasaense discovered 46 compounds, including 27 stilbenoids and 13 gallotannins using UPLC-Q-TOF-MS/MS. The UPLC determined the contents of 6 main stilbenoids, among which the content of PG was the highest, up to 61.06 mg/g. Moreover, behavioral tests showed that PG (40 mg/kg and 160 mg/kg) administration markedly ameliorated memory impairments of scopolamine-induced mice. Biochemical parameters showed that PG treatment alleviated the levels of Ach, AchE, and inflammatory factors while elevating the levels of antioxidants in mice. In addition, network pharmacology was performed to reveal PG exert an mild cognitive impairment effect by participating in neurodegenerative disease pathways, proliferation and apoptosis-, and inflammation-related pathways. Eventually, the results of molecular docking and the qRT-PCR revealed that PG down-regulated the mRNA expressions of MMP3, MMP9 and BACE1 in cognitive impairment mice brain tissue. In conclusion, our results demonstrated that PG mitigated scopolamine-induced cognitive dysfunction in mice by targeting the BACE1-MMP3/9 pathway, and PG might be a promising mild AD drug candidate.

Investigation on Antioxidant Activity and Different Metabolites of Mulberry (Morus spp.) Leaves Depending on the Harvest Months by UPLC-Q-TOF-MS with Multivariate Tools

The changes in active components in mulberry leaves harvested in different months and their antioxidant activities were investigated. Ultra-high-performance liquid chromatography-tandem quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) with multivariate statistical tools was used to investigate the chemical constituents in the extracts of mulberry leaves. The results indicated that mulberry leaves were rich in phenolic acids, flavonoids, organic acids, and fatty acid derivatives. In addition, 25 different compounds were identified in the different batches of mulberry leaves. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity was measured to evaluate the in vitro antioxidant activities of mulberry leaves. Among the four batches, batch A, harvested in December, exhibited the strongest DPPH radical-scavenging activity, while batch B, harvested in March, showed the weakest activity. This was related to the total phenolic content in the mulberry leaves of each batch. The optimal harvest time of mulberry leaves greatly influences the bioactivity and bioavailability of the plant.

Water Caltrop (Trapa quadrispinosa Roxb.) Husk Improves Oxidative Stress and Postprandial Blood Glucose in Diabetes: Phenolic Profiles, Antioxidant Activities and α-Glycosidase Inhibition of Different Fractions with In Vitro and In Silico Analyses

The aim of this study was to investigate the phenolic profiles, antioxidant activities and α-glycosidase inhibitory activities of three different phenolic fractions from water caltrop (Trapa quadrispinosa Roxb.) husk and to further explore the predominant compounds and their mechanisms on α-glycosidase inhibition by virtual screening and molecular dynamics. A total of 29 substances were identified and quantified in this study. Tannins were the main constituents of water caltrop husk extract. All of the free phenolic (FP), esterified phenolic (EP) and insoluble-bound phenolic (BP) fractions exhibited good antioxidant activities, and the BP had the highest radical scavenging ability with IC50 values of 0.82 ± 0.12 μg/mL (ABTS) and 1.15 ± 0.02 μg/mL (DPPH), respectively (p < 0.05). However, compared with the EP and BP, the FP showed the strongest inhibition towards the α-glycosidase and the IC50 value of FP was 1.43 ± 0.12 μg/mL. The 1,2,6-trigalloylglucose and α-glycosidase complex had better root mean square deviations (RMSD) stability via molecular dynamics simulation study. Results obtained from this study may provide a good potential natural resource for the improvement of oxidative stress injury and blood glucose control in diabetes mellitus, which could expand the use of water caltrop husk and improve its economic value.

Selectivity Tuning by Natural Deep Eutectic Solvents (NADESs) for Extraction of Bioactive Compounds from Cytinus hypocistis—Studies of Antioxidative, Enzyme-Inhibitive Properties and LC-MS Profiles

In the present study, the extracts of Cytinus hypocistis (L.) L using both traditional solvents (hexane, ethyl acetate, dichloromethane, ethanol, ethanol/water, and water) and natural deep eutectic solvents (NADESs) were investigated in terms of their total polyphenolic contents and antioxidant and enzyme-inhibitive properties. The extracts were found to possess total phenolic and total flavonoid contents in the ranges of 26.47–186.13 mg GAE/g and 0.68–12.55 mg RE/g, respectively. Higher total phenolic contents were obtained for NADES extracts. Compositional differences were reported in relation to antioxidant potential studied by several assays (DPPH: 70.19–939.35 mg TE/g, ABTS: 172.56–4026.50 mg TE/g; CUPRAC: 97.41–1730.38 mg TE/g, FRAP: 84.11–1534.85 mg TE/g). Application of NADESs (choline chloride—urea 1:2, a so-called Reline) allowed one to obtain the highest number of extracts having antioxidant potential in the radical scavenging and reducing assays. NADES-B (protonated by HCl L-proline-xylitol 5:1) was the only extractant from the studied solvents that isolated a specific fraction without chelating activity. Reline extract exhibited the highest acetylcholinesterase inhibition compared to NADES-B and NADES-C (protonated by H2SO4 L-proline-xylitol 5:1) extracts, which showed no inhibition. The NADES extracts were observed to have higher tyrosinase inhibitory properties compared to extracts obtained by traditional organic solvents. Furthermore, the NADES extracts were relatively better inhibitors of the diabetic enzymes. These findings provided an interesting comparison in terms of total polyphenolic content yields, antioxidant and enzyme inhibitory properties (cholinesterase, amylase, glucosidase, and tyrosinase) between traditional solvent extracts and NADES extracts, used as an alternative. While the organic solvents showed better antioxidant activity, the NADES extracts were found to have some other improved properties, such as higher total phenolic content and enzyme-inhibiting properties, suggesting functional prospects for their use in phytonutrient extraction and fractionation. The obtained results could also be used to give a broad overview of the different biological potentials of C. hypocistis.

By-Products of Agri-Food Industry as Tannin-Rich Sources: A Review of Tannins' Biological Activities and Their Potential for Valorization

During recent decades, consumers have been continuously moving towards the substitution of synthetic ingredients of the food industry by natural products, obtained from vegetal, animal or microbial sources. Additionally, a circular economy has been proposed as the most efficient production system since it allows for reducing and reutilizing different wastes. Current agriculture is responsible for producing high quantities of organic agricultural waste (e.g., discarded fruits and vegetables, peels, leaves, seeds or forestall residues), that usually ends up underutilized and accumulated, causing environmental problems. Interestingly, these agri-food by-products are potential sources of valuable bioactive molecules such as tannins. Tannins are phenolic compounds, secondary metabolites of plants widespread in terrestrial and aquatic natural environments. As they can be found in plenty of plants and herbs, they have been traditionally used for medicinal and other purposes, such as the leather industry. This fact is explained by the fact that they exert plenty of different biological activities and, thus, they entail a great potential to be used in the food, nutraceutical and pharmaceutical industry. Consequently, this review article is directed towards the description of the biological activities exerted by tannins as they could be further extracted from by-products of the agri-food industry to produce high-added-value products.