Inhibition of pancreatic lipase by coffee leaves-derived polyphenols: A mechanistic study.

The suppression of pancreatic lipase has been employed to mitigate obesity. This study explored the mechanism of coffee leaf extracts to inhibit pancreatic lipase. The ethyl acetate fraction derived from coffee leaves (EAC) exhibited the highest inhibitory capacity with a half-maximal inhibitory concentration (IC50) of 0.469 mg/mL and an inhibitor constant (Ki) of 0.185 mg/mL. This fraction was enriched with 3,5-dicaffeoylquinic acid (3,5-diCQA, 146.50 mg/g), epicatechin (87.51 mg/g), and isoquercetin (48.29 mg/g). EAC inhibited lipase in a reversible and competitive manner, and quenched its intrinsic fluorescence through a static mechanism. Molecular docking revealed that bioactive compounds in EAC bind to key amino acid residues (HIS-263, PHE-77, and SER-152) located within the active cavity of lipase. Catechin derivatives play a key role in the lipase inhibitory activity within EAC. Overall, our findings highlight the promising potential of coffee leaf extract as a functional ingredient for alleviating obesity through inhibition of lipase.

Identification of differential volatile and non-volatile compounds in coffee leaves prepared from different tea processing steps using HS-SPME/GC-MS and HPLC-Orbitrap-MS/MS and investigation of the binding mechanism of key phytochemicals with olfactory and taste receptors using molecular docking.

Tea processing steps affected the proximate composition, enzyme activity and bioactivity of coffee leaves; however, the effects of different tea processing steps on the volatiles, non-volatiles, color, and sensory characteristics of coffee leaves have yet been demonstrated. Here the dynamic changes of volatile and non-volatile compounds in different tea processing steps were investigated using HS-SPME/GC-MS and HPLC-Orbitrap-MS/MS, respectively. A total of 53 differential volatiles (alcohol, aldehyde, ester, hydrocarbon, ketone, oxygen heterocyclic compounds, phenol, and sulfur compounds) and 50 differential non-volatiles (xanthone, flavonoid, organic acid, amino acid, organic amine, alkaloid, aldehyde, and purine et al.) were identified in coffee leaves prepared from different processing steps. Kill-green, fermentation, and drying steps significantly influenced the volatiles; however, kill-green, rolling, and drying steps significantly affected the color of coffee leaves and their hot water infusion. The coffee leaf tea that was prepared without the kill-green process was found to have a more pleasant taste as compared to the tea that was prepared with the kill-green process. This can be attributed to the fact that the former contained lower levels of flavonoids, chlorogenic acid, and epicatechin, but had higher levels of floral, sweet, and rose-like aroma compounds. The binding interactions between the key differential volatile and non-volatile compounds and the olfactory and taste receptors were also investigated. The key differential volatiles, pentadecanal and methyl salicylate generate fresh and floral odors by activating olfactory receptors, OR5M3 and OR1G1, respectively. Epicatechin showed a high affinity to the bitter receptors, including T2R16, T2R14, and T2R46. Since the specific content of differential compounds in different samples varies greatly, the dose-effect and structure-function relationships of these key compounds and the molecular mechanism of the odor and taste of coffee leaf tea need to be further studied.

Investigation into the anti-inflammatory mechanism of coffee leaf extract in LPS-induced Caco-2/U937 co-culture model through cytokines and NMR-based untargeted metabolomics analyses.

In this study, lipopolysaccharide (LPS)-induced Caco-2/U937 co-culture was used to investigate the anti-inflammatory mechanism of coffee leaf extract (CLE). HPLC analysis found that 5-caffeoylquinic acid (5-CQA) and epicatechin were degraded by 96.66 % and 85.35 %, respectively after 24 h incubation, while rutin and trigonelline remained unchanged. The absorption efficiency of 4,5-dicaffeoylquinic acid (4,5-diCQA) and mangiferin were higher than the other phytochemicals, reaching 46.90 % and 37.65 %, respectively. CLE significantly inhibited TNF-α, IL-1ß, and IL-8 produced by LPS-induced U937 cells in the basolateral side as well as IL-8 produced by apical Caco-2 cells, thereby inhibiting the intestinal monolayer leakage evidenced by the increase of transepithelial electrical resistance (TEER) values. CLE ameliorated some of the LPS-induced impaired cellular immunometabolism, including amino acid and energy metabolisms. Our study indicated that CLE inhibited the pro-inflammatory cytokines and regulated the metabolites in the co-culture system, thus recovering the disrupted intestinal monolayer caused by inflammation.

Mangiferin: a review of dietary sources, absorption, metabolism, bioavailability, and safety.

Mangiferin is a potential candidate for use in nutraceutical and functional food applications due to its numerous bioactivities. However, the low bioavailability of mangiferin is a major limitation for establishing efficacy for use. This review describes current information on known food sources and factors that influence mangiferin contents, absorption, and metabolism features, and recent progress that has come from research efforts to increase the bioavailability of mangiferin. We also list patents that targeted to enhance mangiferin bioavailability. Mangifera indica L. is the major dietary source for mangiferin, a xanthone that varies widely in different parts of the plant and is influenced by many factors that involve plant propagation and post-harvest processing. Mangiferin absorption occurs mostly in the small intestine by passive diffusion with varying absorption capacities in different segments of the gastrointestinal tract. Recent research has led to the development of novel technologies to encapsulate mangiferin in nano/microparticle carrier systems as well as generate mangiferin derivatives to improve solubility and bioavailability. Preclinical studies reported that mangiferin < 2000 mg/kg is generally nontoxic. The safety and the increase in bioavailability are key limiting factors for developing successful applications for mangiferin as a nutritional dietary supplement or nutraceutical.Supplemental data for this article is available online at.

Zinc oxide nanoparticles synthesized using coffee leaf extract assisted with ultrasound as nanocarriers for mangiferin.

Plant extracts have been widely used to green synthesize zinc oxide nanoparticles (ZnO NPs); however, how the combination of ultrasound and coffee leaf extract (CLE) affects the structure characteristics and the yield of ZnO NPs remains unknown. In this study, we used CLE to green synthesize ZnO NPs with the help of ultrasound. The highest yield (43.59 ± 0.13%) of ZnO NPs was obtained under the optimal processing conditions of pH = 8.0, mass ratio of coffee leaves to C4H6O4Zn•2H2O = 1.71, ultrasound time = 10 min, ultrasound frequency = 28/40 kHz, ultrasound power = 180 W, and synthesis temperature = 30 °C. The as-synthesized ZnO NPs were characterized by UV-Vis, SEM, EDX, TEM, FTIR, XRD, and zeta potential analyses. SEM and TEM analyses revealed that ZnO NPs synthesized using ultrasound-assisted method were spherical with an average particle size of 8.29 ± 1.38 nm, which was smaller than ZnO NPs synthesized without ultrasound treatment (10.48 ± 1.57 nm) and the chemically synthesized ZnO NPs (17.15 ± 2.84 nm). HPLC analysis showed that the phenolic compounds in coffee leaves, especially 5-CQA, were the main reductants and chelating agents for ZnO NPs synthesis. The synthesized ZnO NPs were used to load mangiferin, which was control released under pH 7.4 over 132 h. Our study provides an easy and eco-friendly method using CLE assisted with ultrasound for green synthesis of ZnO NPs which can be used as nanocarriers to control release of mangiferin.

Ultrasound-assisted green synthesis of gold nanoparticles using citrus peel extract and their enhanced anti-inflammatory activity.

Ultrasound and plant extract are two green approaches that have been used to synthesize gold nanoparticles (AuNPs); however, how the combination of ultrasound and citrus peel extract (CPE) affects the structure characteristics and the bioactivity of AuNPs remains unknown. Here we investigated the effects of ultrasound conditions on the particle size, stability, yield, phenolic encapsulation efficacy, and the anti-inflammatory activity of AuNPs. The results showed that temperature was positively correlated to the particle size and the anti-inflammatory activity of synthesized AuNPs. Increasing the power intensity significantly decreased the particle size, while increased the change of total phenolic content (ΔTPC) in the reaction mixture. The increase of ΔTPC caused the enhanced anti-inflammatory activity of AuNPs. The AuNPs synthesized with or without ultrasound treatment were characterized using UV-Vis, DLS, SEM, TEM, EDS, XRD, and FT-IR. The result verified the formation of negatively charged, spherical, stable, and monodispersed AuNPs. AuNPs synthesized with ultrasound (AuNPs-U) has smaller particle size (13.65 nm vs 16.80 nm), greater yield and anti-inflammatory activity (IC50, 82.91 vs 157.71 µg/mL) than its non-ultrasound counterpart (AuNPs-NU). HPLC analysis showed that hesperidin was the key reductant for the synthesis of AuNPs. AuNPs-U also inhibited the mRNA and protein expression of iNOS and COX-2 in the LPS-induced Raw 264.7 cells. Our research elucidates the relationship between the reaction conditions and the structure characteristics and the anti-inflammatory activity of AuNPs synthesized using CPE with the help of ultrasound, thereafter, provides a feasible and economic way to synthesize AuNPs that can be used to ameliorate inflammation.