Determination of Three Main Chlorogenic Acids in Water Extracts of Coffee Leaves by Liquid Chromatography Coupled to an Electrochemical Detector

Stress-relieving properties of a polyherbal blend with Syzygium aromaticum L. and Coffea canephora Pierre ex A. Froehner: A review and bibliometric analysis

OBJECTIVE

Syzygium aromaticum and Coffea canephora are acknowledged for their outstanding antioxidant, anti-inflammatory, and nerve-stimulant properties, showcasing potential in brain protection. Therefore, this study aims to quantitatively review existing literature and assess the potential of using it to formulate a herbal tea blend for managing stress and anxiety.

METHODS

Data was retrieved from the Scopus database, and a bibliometric analysis was performed using VOSviewer software.

RESULTS

Following a screening process, a total of 121 articles were identified, with S. aromaticum yielding a higher number compared to C. canephora. A detailed exploration of each plant revealed active components such as eugenol, β-caryophyllene, α-humulene, caffeine, mangiferin, and chlorogenic acids, each exhibiting stimulatory effects alongside antioxidant and anti-inflammatory properties. The neuroprotective effects were attributed to the reduction of oxidative stress and inflammation, coupled with the stimulation of neurotransmitters and hormones like dopamine, serotonin, cortisol, and adrenaline.

CONCLUSIONS

The review showed that these plants positively affect mood and cognition by influencing the brain's pleasure system. This suggests the need for further research to combine these plant extracts for developing 'Tenang tea', a potential herbal blend for managing stress and anxiety.

High-speed countercurrent chromatography with offline detection by electrospray mass spectrometry and nuclear magnetic resonance detection as a tool to resolve complex mixtures: A practical approach using Coffea arabica leaf extract

INTRODUCTION

Many secondary metabolites isolated from plants have been described in the literature owing to their important biological properties and possible pharmacological applications. However, the identification of compounds present in complex plant extracts has remained a great scientific challenge, is often laborious, and requires a long research time with high financial cost.

OBJECTIVES

The aim of this study was to develop a method that allows the identification of secondary metabolites in plant extracts with a high degree of confidence in a short period of time.

MATERIAL AND METHODS

In this study, an ethanolic extract of Coffea arabica leaves was used to validate the proposed method. Countercurrent chromatography was chosen as the initial step for extraction fractionation using gradient elution. Resulting fractions presented a variation of compounds concentrations, allowing for statistical total correlation spectroscopy (STOCSY) calculations between liquid chromatography coupled with high-resolution tandem mass spectrometry (LC-HRMS/MS) and NMR across fractions.

RESULTS

The proposed method allowed the identification of 57 compounds. Of the annotated compounds, 20 were previously described in the literature for the species and 37 were reported for the first time. Among the inedited compounds, we identified flavonoids, alkaloids, phenolic acids, coumarins, and terpenes.

CONCLUSION

The proposed method presents itself as a valid alternative for the study of complex extracts in an effective, fast, and reliable way that can be reproduced in the study of other extracts.

Risk Assessment of Chlorogenic and Isochlorogenic Acids in Coffee By-Products

Chlorogenic and isochlorogenic acids are naturally occurring antioxidant dietary polyphenolic compounds found in high concentrations in plants, fruits, vegetables, coffee, and coffee by-products. The objective of this review was to assess the potential health risks associated with the oral consumption of coffee by-products containing chlorogenic and isochlorogenic acids, considering both acute and chronic exposure. An electronic literature search was conducted, revealing that 5-caffeoylquinic acid (5-CQA) and 3,5-dicaffeoylquinic acid (3,5-DCQA) are the major chlorogenic acids found in coffee by-products. Toxicological, pharmacokinetic, and clinical data from animal and human studies were available for the assessment, which indicated no significant evidence of toxic or adverse effects following acute oral exposure. The current state of knowledge suggests that long-term exposure to chlorogenic and isochlorogenic acids by daily consumption does not appear to pose a risk to human health when observed at doses within the normal range of dietary exposure. As a result, the intake of CQAs from coffee by-products can be considered reasonably safe.

Characterization of Extracts of Coffee Leaves (Coffea arabica L.) by Spectroscopic and Chromatographic/Spectrometric Techniques

Coffea arabica L. leaves represent a viable alternative to the canonical matrices used for preparation of beverages, such as tea leaves and grounded coffee beans. Coffee leaves infusions are rich in antioxidant phenolic compounds and have a lower concentration of caffeine. Due to increasing interest in this field, a complete study of the bioactive compounds as chlorogenic acids, xanthones and alkaloids is noteworthy. C. arabica leaves were subjected to ultrasound-assisted extraction, and the extracts were studied via nuclear magnetic resonance spectroscopy (NMR) and chromatographic techniques coupled with mass spectrometry (HPLC-MSn) to identify and quantify the secondary metabolites profile through an untargeted data dependent approach. A quantitative analysis was performed for the major components—chlorogenic acids, mangiferin, caffeine and trigonelline—via HPLC-MS in Single Ion Monitoring (SIM) mode. In total, 39 compounds were identified. The presence of these bioactive compounds proved the strong potential of C. arabica leaves as functional food and as an alternative to classic infused beverages.

Lipid nanodiscs of poly(styrene-alt-maleic acid) to enhance plant antioxidant extraction

Plant antioxidants can be applied in the management of various human diseases. Despite these, extraction of these compounds still suffers from residual solvent impurities, low recovery yields, and the risks of undesirable chemical changes. Inspired by the protein–lipid interactions in the cell membranes, we proposed using poly(styrene-alt-maleic acid) (PSMA) to destabilize and associate with the bilayer lipids into the membrane-like nanodiscs. Such nanostructures could serve as protective reservoirs for the active compounds to reside with preserved bioactivities. This concept was demonstrated in the antioxidant extraction from robusta coffee leaves. Results indicated that aqueous PSMA extraction (no buffer agent) yielded products with the highest contents of phenolic acids (11.6 mg GAE·g−1) and flavonoids (9.6 mg CE·g−1). They also showed the highest antioxidant activity (IC50 = 3.7 µg·mL−1) compared to those obtained by typical sodium dodecyl sulfate and water extraction. This biomimetic approach could be considered for developing environmentally friendly extraction protocols in the future.

Evaluation of Antioxidants Using Electrochemical Sensors: A Bibliometric Analysis

The imbalance of oxidation and antioxidant systems in the biological system can lead to oxidative stress, which is closely related to the pathogenesis of many diseases. Substances with antioxidant capacity can effectively resist the harmful damage of oxidative stress. How to measure the antioxidant capacity of antioxidants has essential application value in medicine and food. Techniques such as DPPH radical scavenging have been developed to measure antioxidant capacity. However, these traditional analytical techniques take time and require large instruments. It is a more convenient method to evaluate the antioxidant capacity of antioxidants based on their electrochemical oxidation and reduction behaviors. This review summarizes the evaluation of antioxidants using electrochemical sensors by bibliometrics. The development of this topic was described, and the research priorities at different stages were discussed. The topic was investigated in 1999 and became popular after 2010 and has remained popular ever since. A total of 758 papers were published during this period. In the early stages, electrochemical techniques were used only as quantitative techniques and other analytical techniques. Subsequently, cyclic voltammetry was used to directly study the electrochemical behavior of different antioxidants and evaluate antioxidant capacity. With methodological innovations and assistance from materials science, advanced electrochemical sensors have been fabricated to serve this purpose. In this review, we also cluster the keywords to analyze different investigation directions under the topic. Through co-citation of papers, important papers were analyzed as were how they have influenced the topic. In addition, the author’s country distribution and category distribution were also interpreted in detail. In the end, we also proposed perspectives for the future development of this topic.

Lanthanide ternary mixed-ligand coordination polymers as fluorescent sensors for the sensitive and selective detection of chlorogenic acid

A series of lanthanide coordination polymers constructed from ternary mixed ligands were synthesized. The Eu-CP has fluorescence sensing properties for chlorogenic acid. The film loaded with Eu-CP can be used for visual fluorescence detection.

Coffee Leaves: An Upcoming Novel Food?

Unlike those of coffee beans, the healthy properties of coffee leaves have been overlooked for a long time, even if they are consumed as a beverage by local communities of several African countries. Due to the presence of xanthines, diterpenes, xanthones, and several other polyphenol derivatives as main secondary metabolites, coffee leaves might be useful to prevent many daily disorders. At the same time, as for all bioactive molecules, careless use of coffee leaf infusions may be unsafe due to their adverse effects, such as the excessive stimulant effects on the central nervous system or their interactions with other concomitantly administered drugs. Moreover, the presence of some toxic diterpene derivatives requires careful analytical controls on manufactured products made with coffee leaves. Accordingly, knowledge about the properties of coffee leaves needs to be increased to know if they might be considered a good source for producing new supplements. The purpose of the present review is to highlight the biosynthesis, metabolism, and distribution of the 4 main classes of secondary metabolites present in coffee leaves, their main pharmacological and toxicological aspects, and their main roles in planta. Differences in coffee leaf chemical composition depending on the coffee species will also be carefully considered.

The Effect of Coffee Arabica Gayo Leaf Extract (Coffea arabica L.) on Increased PI3K Serum Levels in Type 2 Diabetic Rat

BACKGROUND: Coffee arabica gayo leaf extract (Coffea arabica L.) contains polyphenols (chlorogenic acid), flavonoids, saponins, tannins, and steroids which improved PI3K serum levels in rats type 2 diabetic rat. AIM: The purpose of the study was to determine the effect of Coffee Arabica Gayo Leaf Extract (C. arabica L.) on increased PI3K serum levels in type-2 diabetic rat (Rattus norvegicus). METHODS: Thirty-five male Wistar rats with type 2 diabetic induced a combination of feeding a high-fat diet for 5 weeks and intraperitoneal injection of low dose streptozotocin (30 mg/kg). The diabetic rats were randomly divided into seven groups which consist of group without type 2 diabetic, group without type 2 diabetic with dose 250 mg/kg/day Coffee Arabica Gayo Leaf Extract, group with type 2 diabetic without intervention, group with type 2 diabetic with metformin, and group with type 2 diabetic with Coffee Arabica Gayo Leaf Extract doses 150, 200, and 250 mg/kg/day. The extract was administered orally for 30 days. Subsequently, PI3K serum levels were measure by Sandwich Elisa. RESULTS: There were significantly higher PI3K serum levels in the treatment groups than in the control groups (p = 0.037) after giving Coffee Arabica Gayo Leaf Extract 200 mg/kg/day and 250 mg/kg/day to rats for 30 days. CONCLUSION: These data suggest that Coffee Arabica Gayo Leaf Extract can improve PI3K serum levels in a rat model type 2 diabetic.

Low-cost smartphone-controlled potentiostat based on Arduino for teaching electrochemistry fundamentals and applications

Accessibility to potentiostats is crucial for research development in electrochemistry, but their cost is the principal drawback for their massive use. With the aim to provide an affordable alternative for resource-constrained communities, we present a low-cost, portable electrochemical workstation that integrates an open-source potentiostat based on Arduino and a smartphone application. This graphical user interface allows easy control of electrochemical parameters and real-time visualization of the results. This potentiostat can perform the most used electrochemical techniques of cyclic and linear voltammetry and chronoamperometry, with an operating range of ±225 μA and ±1.50 V, and results that are comparable with those obtained with commercial potentiostats. Three applications reported here demonstrate the capacity and the good performance of this low-cost potentiostat as a teaching tool: identification of redox pairs, electrochemical characterization of pencil graphite electrodes, and detection of heavy metals using an electrodeposited film of bismuth on the pencil graphite electrode. Furthermore, detailed schemes of the device and its software are entirely available, expecting to provide an open-source potentiostat easy to replicate to further support education in electrochemical fundamentals and instrumentation.

Comparison of Batch and Continuous Wet-Processing of Coffee: Changes in the Main Compounds in Beans, By-Products and Wastewater

Many technical challenges still need to be overcome to improve the quality of the green coffee beans. In this work, the wet Arabica coffee processing in batch and continuous modus were investigated. Coffee beans samples as well as by-products and wastewaters collected at different production steps were analyzed in terms of their content in total phenols, antioxidant capacity, caffeine content, organic acids, reducing sugars, free amino group and protein content. The results showed that 40% of caffeine was removed with pulp. Green coffee beans showed highest concentration of organic acids and sucrose (4.96 ± 0.25 and 5.07 ± 0.39 g/100 g DW for the batch and continuous processing). Batch green coffee beans contained higher amount of phenols. 5-caffeoylquinic Acid (5-CQA) was the main constituent (67.1 and 66.0% for the batch and continuous processing, respectively). Protein content was 15 and 13% in the green coffee bean in batch and continuous processing, respectively. A decrease of 50 to 64% for free amino groups during processing was observed resulting in final amounts of 0.8 to 1.4% in the processed beans. Finally, the batch processing still revealed by-products and wastewater with high nutrient content encouraging a better concept for valorization.

Determination of Phenolic Compounds, Procyanidins, and Antioxidant Activity in Processed Coffea arabica L. Leaves

The effects of dry processing and maturity on antioxidant activity, total phenolic content, total procyanidins, and identity of phenolic compounds in coffee leaves were evaluated. Fresh coffee leaves were tray-dried at 40 °C for 8 h before total phenolic content, total procyanidins, and antioxidant activity were analyzed. The drying process significantly (p < 0.05) improved the release of total phenolic content and total procyanidins compared with the fresh leaves. The results showed that the young leaves exposed to drying processes had the highest total phenolic content, total procyanidins, and DPPH radical scavenging activity. Therefore, the effect of different drying temperatures (30, 40, and 50 °C) in the young leaves were further analyzed. The results indicated that DPPH radical scavenging activity, total phenolic content, and total procyanidins were increasingly generated when exposed to an increase in drying temperatures, whereby the highest bioactivity was evident at 50 °C. The DPPH radical scavenging activity of the coffee leaf teas was significantly correlated with total phenolic content and total procyanidins. Identification of Coffea arabica L. bioactive compounds by LC-MS showed the presence of catechin or epicatechin, mangiferin or isomangiferin, procyanidin B, caffeoylquinic acids (CQA), caffeine, quercetin-3-O-glucoside, procyanidin C, rutin, and 3,4-diCQA. Coffea arabica L. leaf tea was confirmed to be a potential functional food rich in phenolic compounds with strong antioxidant activity.