Simultaneous determination of 15 phenolic compounds and caffeine in teas and mate using RP-HPLC/UV detection: method development and optimization of extraction process

A robust method for quantifying 42 phenolic compounds by RP-HPLC/DAD: Columns performance and characterization of Brazilian Citrus peels

Reliable analytical methods are the basis for the elucidation of phenolic compounds in foods. This study aimed to optimize and validate a method for determining 42 phenolics using reverse-phase (RP) high-performance liquid chromatography (HPLC) coupled to diode-array-detector-DAD. The performance of two RP columns was evaluated. The 150x4.6 mm 3-μm column showed superior separation quality, whereas 35 of the 42 phenolics showed a separation resolution ≥1.5. The method's linearity, precision (coefficient variation< 3.09%), recovery (87.5-103.2%), specificity, limits of detection (0.04-0.25 mg/L), and quantification (0.06-0.25 mg/L) had acceptable ranges. Thirty phenolics were quantified in Citrus peels, mainly flavanones, flavanols, flavonols, and phenolic acids, highlighting the high values of hesperidin (535-35070 mg/kg) and naringin (26-36466 mg/kg). Lemon peels named 'Lisboa,' 'Thaiti,' 'Thaiti-2000', and 'Thaiti-2001' presented the main phenolics associated with antioxidant capacity. The presented method was robust for determining 42 phenolic compounds, offering a new approach for bioactive compound quantification in food matrices.

Caffeine-Legal Natural Stimulant with Open Research Perspective: Spectroscopic and Theoretical Characterization

Caffeine is an alkaloid with a purine structure and has been well known for centuries due to its presence in popular drinks-tea and coffee. However, the structural and spectroscopic parameters of this compound, as well as its chemical and biological activities, are still not fully known. In this study, for the first time, we report on the measured oxygen-17 NMR spectra of this stimulant. To support the assignment of our experimental NMR data, extensive quantum chemical calculations of NMR parameters, including nuclear magnetic shielding constants and indirect spin-spin coupling constants, were performed. In a theoretical study, using nine efficient density functionals (B3LYP, BLYP, BP86, CAM-B3LYP, LC-BLYP, M06, PBE0, TPSSh, wB97x), and in combination with a large and flexible correlation-consistent aug-cc-pVTZ basis set, the structure and NMR parameters were predicted for a free molecule of caffeine and in chloroform, DMSO and water. A polarized continuum model (PCM) was used to include a solvent effect. As a result, an optimal methodology was developed for predicting reliable NMR data, suitable for studies of known, as well as newly discovered, purines and similar alkaloids. The results of the current work could be used in future basic and applied studies, including NMR identification and intermolecular interactions of caffeine in various raw materials, like plants and food, as well as in the structural and spectroscopic characterization of new compounds with similar structures.

Optimization of Ultrasonic-Assisted Extraction of Phenolic Compounds and Antioxidant Activity from Araticum Peel Using Response Surface Methodology

The peel represents a significant portion of the araticum fruit (about 40%), which becomes waste after its consumption or processing. Previous studies have shown that the araticum peel is rich in phenolic compounds; however, little is known about the ideal conditions for recovering these compounds. Therefore, response surface methodology, using a central composite rotatable design, was employed to optimize the extraction process to maximize the total phenolic compounds (TPCs) and enhance the Trolox equivalent antioxidant capacity (TEAC) from araticum peel. The variables optimized were ethanol concentration (EC; 20-80%, v/v), extraction time (ET; 5-45 min), and solid-solvent ratio (SSR; 10-100 mg/mL). Additionally, condensed tannins, antioxidant capacity against synthetic free radicals (TEAC and FRAP) and reactive oxygen species (ROS), and the phenolic compounds profile, were evaluated. Optimum extraction conditions were 50% (v/v) ethanol concentration, 5 min of extraction time, and 10 mg/mL solid-solvent ratio. Under these conditions, experimental TPCs and TEAC values were 70.16 mg GAE/g dw and 667.22 µmol TE/g dw, respectively, comparable with predicted models (68.47 mg GAE/g dw for TPCs and 677.04 µmol TE/g dw for TEAC). A high condensed tannins content (76.49 mg CE/g dw) was also observed and 12 phenolic compounds were identified, predominantly flavonoids (97.77%), including procyanidin B2, epicatechin, and catechin as the major compounds. Moreover, a potent antioxidant activity was observed against synthetic free radicals and ROS, especially in scavenging peroxyl and hydroxyl radicals. From this study, we obtained the ideal conditions for recovering phenolic compounds from araticum peel using a simple, fast, sustainable, and effective method, offering a promising opportunity for the management of this plant byproduct.

Impact of coffee and its bioactive compounds on the risks of type 2 diabetes and its complications: A comprehensive review

BACKGROUND

Coffee beans have a long history of use as traditional medicine by various indigenous people. Recent focus has been given to the health benefits of coffee beans and its bioactive compounds. Research on the bioactivities, applications, and effects of processing methods on coffee beans' phytochemical composition and activities has been conducted extensively. The current review attempts to provide an update on the biological effects of coffee on type 2 diabetes (T2D) and its comorbidities.

METHODS

Comprehensive literature search was carried out on peer-reviewed published data on biological activities of coffee on in vitro, in vivo and epidemiological research results published from January 2015 to December 2022, using online databases such as PubMed, Google Scholar and ScienceDirect for our searches.

RESULTS

The main findings were: firstly, coffee may contribute to the prevention of oxidative stress and T2D-related illnesses such as cardiovascular disease, retinopathy, obesity, and metabolic syndrome; secondly, consuming up to 400 mg/day (1-4 cups per day) of coffee is associated with lower risks of T2D; thirdly, caffeine consumed between 0.5 and 4 h before a meal may inhibit acute metabolic rate; and finally, both caffeinated and decaffeinated coffee are associated with reducing the risks of T2D.

CONCLUSION

Available evidence indicates that long-term consumption of coffee is associated with decreased risk of T2D and its complications as well as decreased body weight. This has been attributed to the consumption of coffee with the abundance of bioactive chemicals.

Tea (Camellia sinensis) cultivated in three agro-ecological regions of Bangladesh: Unveiling the variability of methylxanthine, bioactive phenolic compound, and antioxidant activity

Tea (Camellia sinensis) is a widely consumed beverage known for its numerous health benefits, largely attributed to its rich content of quality determining secondary metabolites such as methylxanthine compounds and bioactive phenolic compounds. The goal of this study was to find out variations of the levels of methylxanthines, bioactive phenolic compounds, and antioxidant activity in methanolic and hot water extracts of 129 tea samples grown in three different ecological regions of Bangladesh named Panchagar, Sylhet, and Chattogram. Methylxanthine and bioactive phenolic compounds were determined by using HPLC-DAD, and the antioxidant profile was analysed by UV-vis spectrophotometric methods for methanol and hot water extracts of tea leaves. The IC50 values showed the trend as Panchagar > Sylhet > Chattogram and Sylhet > Chattogram > Panchagar for water and methanol extract, respectively. The results revealed significant (p < 0.05) variations in the levels of methylxanthines content: Panchagar > Chattogram > Sylhet. Caffeine was significantly higher (103.02 ± 5.55 mg/g of dry extract) in the methanolic extract of tea leaves of Panchagar district and lower (53.33 ± 4.30 mg/g of dry extract) in the hot water extract of Sylhet district. Panchagar and Chattogram possessed significantly (p < 0.05) higher catechin content for methanol (57.01 ± 5.50 mg/g dry extract) and hot water (55.23 ± 4.11 mg/g dry extract) extracts, respectively. The utilization of canonical discriminant functions yielded highly favorable outcomes in the classification of tea from three distinct cultivation origins in Bangladesh, relying on their inherent features. This study demonstrated the potential effects of geographical variations on the bioactive compounds and antioxidant properties of tea, emphasizing the importance of regional differences in tea cultivation for optimizing its health benefits as well as dispersing tea cultivation across the country.

The black Vitis vinifera seed oil saponifiable fraction ameliorates hepatocellular carcinoma in vitro and in vivo via modulating apoptosis and ROS/NF-κB signaling

To date, no total curative therapy for hepatocellular carcinoma (HCC) is available. This study aimed to evaluate the anticancer effect of black Vitis vinifera (VV) seed oil saponifiable (Sap) fraction (BSap) using five different cancer cell lines. The apoptotic and anti-inflammatory impacts of BSap on the cell line with the highest cytotoxic effect were studied. Furthermore, its therapeutic effect on p-dimethylaminoazobenzene (p-DAB)-induced HCC in mice was investigated. The phenolic and vitamin content, as well as the antiradical activities of BSap, were assessed. BSap demonstrated a greater cytotoxic effect on HepG-2 cells (lowest IC50 and highest SI values) than did the other tested cell lines. BSap showed superior anticancer efficacy to 5-FU on all examined cancer cells, particularly HepG-2 cells, by inducing apoptosis and downregulating NF-κB. In HCC-bearing mice, BSap reduced hepatic lipid peroxidation and boosted GSH levels due to its potent antiradical activities and high reducing power. In addition, it had an apoptotic effect by upregulating p53 and BAX and downregulating Bcl-2 fold expression. Moreover, BSap lowered the fold expression of various crucial HCC-related genes: CD133, ALAD1α1, COX-2, ABCG1, AKT1, Gli, Notch1, and HIF1α. Liver function markers and histopathology showed significant improvements in HCC-bearing mice after BSap administration compared to 5-FU. In silico analysis revealed that the most abundant phenolic and fatty acid ingredients of BSap exhibited competitive inhibitory effects on valuable HCC-associated enzymes (NADPH oxidase, histone deacetylase 1, and sepiapterin reductase). Thus, BSap fraction may be a promising treatment of HCC.

Distribution profiles of phenolic compounds in a cultivar of wampee (Clausena lansium (Lour.) Skeels) fruits and in vitro anti-inflammatory activity

ETHNOPHARMACOLOGICAL RELEVANCE

The fruits of wampee (Clausena lansium (Lour.) Skeels), which contain significant amounts of phenolics, are frequently applied as traditional medications to prevent or relieve inflammatory symptoms. Green honey wampee (GHW) is a local cultivar specially cultivated in Lianjiang City, Guangdong Province.

AIM OF THE STUDY

This study aimed to investigate phenolic distribution profiles in the peels, seeds and pulp of GHW as well as elucidate the underlying molecular mechanisms of the effective compounds for anti-inflammatory activity.

MATERIALS AND METHOD

Phenolic compounds in the extract were identified through UPLC-MS/MS and their ability to alleviate inflammation was assessed using RAW 264.7 macrophages exposed to lipopolysaccharide.

RESULTS

Among the three parts of GHW fruits, the total phenolic contents followed a descending order of peels > pulp > seeds. Additionally, eighty-six phenols were tentatively determined from the three parts, of which flavonoids accounted for the highest proportion. Furthermore, the phenolic extract of peels, seeds and pulp exhibited potential anti-inflammatory activity through the suppression effect on different pro-inflammatory mediators (NO, IL-6 and TNF-α). Among the three principal phenolic compounds (rutin, quercitrin, isorhamnetin-3-O-neohesperidoside) detected in GHW fruits, quercitrin was proved to be a more important anti-inflammatory compound inhibiting the iNOS and TNF-α mRNA expressions through the suppression effect on the phosphorylation of IκBα and ERK, belonging to the NF-κB and MAPK signaling pathway respectively.

CONCLUSIONS

Not only wampee pulp but also its by-products like peels and seeds are able to be comprehensively utilized as immunomodulatory supplements for daily diets due to their rich phenolic contents.

Recent insights into catechins-rich Assam tea extract for photoaging and senescent ageing

Tea (Camellia spp.) is an important medicinal herb. C. sinensis var. sinensis is the most studied tea variety due to its more preferred flavor than C. sinensis var. assamica (Assam tea), the less economic importance with more bitter variety. A bitter taste highlights its potential as a candidate source for tea catechins, the health beneficial actives applicable for ageing treatment. Nonetheless, indicative data for tea on UV-induced and senescent ageing remain unclarified. Assam tea extract (ATE) was prepared and standardized in terms of TPC, TFC and TTC. EGCG was HPLC quantified as the prime ATE catechin. In vitro antioxidant activity of ATE was exhibited with ABTS, DPPH and FRAP assays. ATE's cellular antioxidant activity was indicated in HDFs at a stronger degree than ascorbic acid. The photoaging protection of ATE was evidenced in a coculture of HaCaT cells and HDFs. ATE markedly suppressed UV-induced IL-6, IL-8, MMP-1 and MMP-9 expressions. The proficiency of ATE targeting on senescent ageing was demonstrated in an ex vivo human skin model, where IL-6 and MMP-1 expressions were suppressed, whilst hyaluronic acid and collagen syntheses were promoted. ATE was chemically stabled as indicated by the catechin contents and color parameters following 6 months storage under conditions recommended for topical product. ATE enriched in catechins warrants its applicability as a new generation of photoaging protectant agent promising for the prevention and treatment for senescent ageing. The findings indicate the proficiency of ATE for innovative anti-ageing agent.

Green Extraction Techniques for the Determination of Active Ingredients in Tea: Current State, Challenges, and Future Perspectives

In recent years, the scientific community has turned its attention to the further study and application of green chemistry as well as to sustainable development in reducing the consumption of raw materials, solvents, and energy. The application of green chemistry aims to ensure the protection of the environment and to also, consequently, improve the quality of human life. It offers several benefits, both socially and economically. In the last few decades, new alternative non-conventional green extraction methodologies have been developed for the purposes of the extraction of active ingredient compounds from various raw products. The main objective of this literature review is to present the current knowledge and future perspectives regarding the green extraction of tea species in respect of the isolation of safe active biomolecules, which can be used as commercially available products—both as dietary supplements and pharmaceutical formulations. More specifically, in this literature review, the intention is to investigate several different extraction techniques, such as ultrasonic-assisted extraction, ultrasonic-assisted extraction with DESs, the microwave assisted-extraction method, and the reflux method. These are presented in respect of their role in the isolation of bioactive molecules regarding different tea species. Furthermore, following the literature review conducted in this study, the commonly used green extraction methods were found to be the ultrasound-assisted method and the microwave-assisted method. In addition to these, the use of a green solvent, in regard to its role in the maximum extraction yield of active ingredients in various species of tea, was emphasized. Catechins, alkaloids (such as caffeine), gallic acid, and flavonoids were the main extracted bioactive molecules that were isolated from the several tea species. From this literature review, it can be demonstrated that green tea has been widely studied at a rate of 52% in respect of the included research studies, followed by black tea at 26%, as well as white tea and oolong tea at 11% each. Regarding the determination of the bioactive molecules, the most utilized analytical method was found in the combination of high-performance liquid chromatography (HPLC) with a photodiode array detector (PDA) and mass spectrophotometry (MS) at a usage rate of about 80%. This method was followed by the utilization of UPLC and GC at 12% and 8%, respectively. In the future, it will be necessary to study the combination of green extraction techniques with other industry strategies, such as an encapsulation at the micro and nano scale, for the purposes of preparing stable final products with antioxidant properties where, finally, they can be safely consumed by humans.

Inhibition of Aflatoxin B1 Synthesis in Aspergillus flavus by Mate (Ilex paraguariensis), Rosemary (Rosmarinus officinalis) and Green Tea (Camellia sinensis) Extracts: Relation with Extract Antioxidant Capacity and Fungal Oxidative Stress Response Modulation

Plant extracts may represent an ecofriendly alternative to chemical fungicides to limit aflatoxin B1 (AFB1) contamination of foods and feeds. Mate (Ilex paraguariensis), rosemary (Romarinus officinalis) and green tea (Camellia sinensis) are well known for their beneficial properties, which are mainly related to their richness in bioactive phenolic compounds. AFB1 production is inhibited, with varying efficiency, by acetone/water extracts from these three plants. At 0.45 µg dry matter (DM)/mL of culture medium, mate and green tea extracts were able to completely inhibit AFB1 production in Aspergillus flavus, and rosemary extract completely blocked AFB1 biosynthesis at 3.6 µg DM/mL of culture medium. The anti-AFB1 capacity of the extracts correlated strongly with their phenolic content, but, surprisingly, no such correlation was evident with their antioxidative ability, which is consistent with the ineffectiveness of these extracts against fungal catalase activity. Anti-AFB1 activity correlated more strongly with the radical scavenging capacity of the extracts. This is consistent with the modulation of SOD induced by mate and green tea in Aspergillus flavus. Finally, rutin, a phenolic compound present in the three plants tested in this work, was shown to inhibit AFB1 synthesis and may be responsible for the anti-mycotoxin effect reported herein.

Functional dairy products as a source of bioactive peptides and probiotics: current trends and future prospectives

Milk is an incredibly healthy food world-wide. However, the 'lactase deficient' individuals cannot digest milk's carbohydrate lactose. A large part of the world population is depriving of highly beneficial milk proteins like casein, lactoalbumin, lactoglobulin, etc. due to lactose intolerance. Production of functional foods and bioactive peptides from milk with natural antioxidants and the addition of probiotics could be the best alternative to extend the use of milk functionalities. Among different probiotics, the lactic acid bacteria (LAB) like Lactobacillus delbrueckii sub sp. bulgaricus, Streptococcus thermophilus and some species of Bifidobacteria and their metabolites (paraprobiotics and postbiotics) have been given more preference to add in milk-derived functional foods. These species are generally considered as heat-tolerant, highly proteolytic, and peptidolytic towards milk proteins and they liberate smaller molecules of bioactive peptides during fermentation and other processes that stimulate the enzyme lactase to help people in digestion of milk carbohydrate lactose. Moreover, the incorporation of natural antioxidants in yoghurt and other dairy products prevents the rancidity of milk fat. The level of bioactive peptides produced in milk-derived functional foods can be determined by capillary zone electrophoresis, mass spectrometry, fractionation, and other modern assessment techniques. Commercial production of functional probiotic products with bioactive peptides could significantly contribute to reduce milk spoilage, enhance health benefits as well as the growth of the agro-processing industry.

Ultrasound-Assisted Extraction of Total Saponins from Aralia taibaiensis: Process Optimization, Phytochemical Characterization, and Mechanism of α-Glucosidase Inhibition

Purpose

Aralia taibaiensis, a medicinal food plant, and total saponins from its root bark extract inhibit α-glucosidase activity, which is associated with type 2 diabetes; however, the inhibitory mechanism is unknown. Furthermore, a green extraction technique superior to conventional hot reflux extraction (HRE) is needed for the rapid and easy extraction of A. taibaiensis total saponins (TSAT) to exploit and utilize this resource. Our aim was to develop a green extraction method for obtaining TSAT and to investigate the mechanism by which TSAT inhibits α-glucosidase.

Materials and Methods

In this study, the ultrasound-assisted extraction (UAE) process was optimized using a Box–Behnken design, and the extraction mechanism was investigated using scanning electron microscopy (SEM). High-performance liquid chromatography (HPLC) was used for qualitative and quantitative analyses of TSAT. In vitro glycosylation assays, enzyme kinetics, fluorescence spectroscopy measurements, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR) and molecular docking techniques were used to investigate the mechanism by which the A. taibaiensis active ingredients inhibit α-glucosidase.

Results

The optimal parameters for the extraction yield were obtained as an ethanol concentration of 73%, ultrasound time of 34 min, ultrasound temperature of 61 °C and solid–liquid ratio of 16 g/mL, which were better than HRE. The SEM analysis showed that UAE effectively disrupted plant cells, thus increasing the TSAT yield. In vitro α-glucosidase inhibition experiments showed that both TSAT and its active ingredient, araloside A, inhibited α-glucosidase activity by binding to α-glucosidase, thereby changing the conformation and microenvironment of α-glucosidase to subsequently inhibit enzyme activity.

Conclusion

The optimal extraction conditions identified here established a basis for future scale-up of ultrasound extraction parameters with the potential for obtaining maximum yields. In vitro enzyme inhibition experiments investigated the mechanism of the TSAT interaction with α-glucosidase and further explored whether araloside A may be the main contributor to the good inhibition of α-glucosidase activity by TSAT.

Near-infrared spectroscopy and machine learning-based technique to predict quality-related parameters in instant tea

The traditional method for analyzing the content of instant tea has disadvantages such as complicated operation and being time-consuming. In this study, a method for the rapid determination of instant tea components by near-infrared (NIR) spectroscopy was established and optimized. The NIR spectra of 118 instant tea samples were used to evaluate the modeling and prediction performance of a combination of binary particle swarm optimization (BPSO) with support vector regression (SVR), BPSO with partial least squares (PLS), and SVR and PLS without BPSO. Under optimal conditions, Rp for moisture, caffeine, tea polyphenols, and tea polysaccharides were 0.9678, 0.9757, 0.7569, and 0.8185, respectively. The values of SEP were less than 0.9302, and absolute values of Bias were less than 0.3667. These findings indicate that machine learning can be used to optimize the detection model of instant tea components based on NIR methods to improve prediction accuracy.

Amazonian Bacuri (Platonia insignis Mart.) Fruit Waste Valorisation Using Response Surface Methodology

Bacuri (Platonia insignis Mart) is a species from the Clusiaceae genus. Its fruit pulp is commonly used in South America in several food products, such as beverages, ice cream and candies. Only the pulp of the fruit is used, and the peels and seeds are considered waste from these industries. As a trioxygenated xanthone source, this species is of high interest for bioproduct development. This work evaluated the mesocarp and epicarp of bacuri fruits through different extraction methods and experimental conditions (pH, temperature and solvent) in order to determine the most effective method for converting this agro-industrial waste in a value-added bioproduct. Open-column procedures and HPLC and NMR experiments were performed to evaluate the chemical composition of the extracts, along with total phenols, total flavonoids and antioxidant activities (sequestration of the DPPH and ABTS radicals). A factorial design and response surface methodology were used. The best extraction conditions of substances with antioxidant properties were maceration at 50 °C with 100% ethanol as solvent for mesocarp extracts, and acidic sonication in 100% ethanol for epicarp extracts, with an excellent phenolic profile and antioxidant capacities. The main compounds isolated were the prenylated benzophenones garcinielliptone FC (epicarp) and 30-epi-cambogin (mesocarp). This is the first study analysing the performance of extraction methods within bacuri agro-industrial waste. Results demonstrated that shells and seeds of bacuri can be used as phenolic-rich bioproducts obtained by a simple extraction method, increasing the value chain of this fruit.

UV-Vis Spectrophotometry and UPLC–PDA Combined with Multivariate Calibration for Kappaphycus alvarezii (Doty) Doty ex Silva Standardization Based on Phenolic Compounds

The algae Kappaphycus alvarezii is considered an important raw material for industrial practices, producing high economic value of various derived products. However, the quality of this commodity, which can be indicated by the level of phenolic compounds, may vary due to growth factors, including cultivation sites. An analytical UV-Vis spectrophotometry method coupled with chemometrics was proposed to standardize the red alga based on the content of phenolic compounds. The correlation between the UV-Vis spectra and UPLC–PDA results, combined with a multivariate calibration of the K. alvarezii extracts, was analyzed. The extracts were prepared using an ultrasound-based technique and subsequently subjected to UV-Vis spectral measurements at 200–800 nm and UPLC–PDA at 260 and 330 nm. Chemometric techniques and partial least squares (PLS) were applied to the acquired data to build a reliable analysis of the phenolics in the K. alvarezii extracts. The result showed that the wavelength combination of 200–450 and 600–690 nm provided a valid method for quantitative analysis of the studied phenolics that belong to hydroxybenzoic acid, hydroxycinnamic acid, and flavonoid with a coefficient of regression (R2) > 0.96 in the calibration and validation models, along with an RMSEC and RMSEP value < 8%. The method was then employed to characterize the K. alvarezii samples from 13 different cultivation areas. Principal component analysis (PCA) generated principal components that produced a clear distribution among the samples of K. alvarezii based on phenolic compounds corresponding to the geographical origin.

Phenolic, Carotenoid and Saccharide Compositions of Vietnamese Camellia sinensis Teas and Herbal Teas

Tea (Camellia sinensis) and herbal tea have been recognized as rich sources of bioactive constituents with the ability to exert antioxidant actions. The aims of this study were to analyze phenolic, carotenoid and saccharide contents in a set of Vietnamese tea and herbal tea and compare the results with those of green and black teas marketed in the U.S. In total, 27 phenolics, six carotenoids and chlorophylls, and three saccharides were quantitatively identified. Catechins, quercetin glycosides and chlorogenic acid were the predominating phenolics in the teas, with the concentrations following the order: jasmine/green teas > oolong tea > black tea. Lutein was the dominant carotenoid in the teas and its concentrations were generally found to be higher in the jasmine and green teas than in the oolong and black teas. The study showed that the green teas originating in Vietnam had much higher levels of phenolics and carotenoids than their counterparts stemming from another country. The application of partial least squares discriminant analysis (PLS-DA) as a chemometric tool was able to differentiate phenolic profiles between methanolic extracts and tea infusions. Through principal component analysis (PCA), the similarities and dissimilarities among the jasmine, green, oolong, black teas and herbal teas were depicted.

Effect of an Antioxidant Based on Red Beetroot Extract on the Abiotic Stability of Polylactide and Polycaprolactone

This study investigated the effect of natural antioxidants inherent to beetroot (Beta vulgaris var. Vulgaris) on the ageing of environmentally friendly plastics. Certain properties were examined in this context, comprising thermal, mechanical, and morphological properties. A visual evaluation of relevant changes in the given polymers (polylactide and polycaprolactone) was conducted during an ageing test in a UV chamber (45 °C, 70% humidity) for 720 h. The films were prepared by a casting process, in which samples with the extract of beetroot were additionally incorporated in a common filler (bentonite), this serving as a carrier for the extract. The results showed the effect of the incorporated antioxidant, which was added to stabilize the biodegradable films. Its efficiency during the ageing test in the polymers tended to exceed or be comparable to that of the reference sample.

Evaluation of phenolic composition and antioxidant properties of different varieties of Chinese citrus

Citrus peels have health-promoting effects and are a rich source of antioxidant substances. This study evaluated the compositions of phenolic compounds and antioxidant activities in the peels of 52 citrus varieties with consistent planting time and management. The highest levels of total phenols (72.95 ± 37.60 mg/g DW) and total flavonoids (71.43 ± 37.64 mg/g DW) were found in mandarin. The highest phenolic acid content (18.78 ± 0.38 mg/g DW), dominated by protocatechuic acid, was found in kumquat. The antioxidant potency composite index was 6.23-94.56, suggesting mandarin varieties HJ, TWPG, TTPG, AY28, BZH and TCJC had the highest antioxidant activity. Statistics analysis indicated phenolic compounds and antioxidant activity were positively correlated. Principal component analysis and hierarchical cluster analysis suggested a strong relationship between phenolic compound composition and genetic background. This study indicated significant differences in the biological properties of various types of citrus peels; which are valuable for future utilization and research of citrus peels.

Quality Assessment of Wild and Cultivated Green Tea from Different Regions of China

Natural products have always enjoyed great popularity among consumers. Wild tea is an interesting alternative to tea from intensive plantations. The term "wild tea" is applied to many different varieties of tea, the most desirable and valued of which are native or indigenous tea plants. Special pro-health properties of wild tea are attributed to the natural conditions in which it grows. However, there are no complex studies that describe quality and health indicators of wild tea. The aim of this research was to evaluate the quality of wild and cultivated green tea from different regions of China: Wuzhishan, Baisha, Kunlushan, and Pu'Er. The assessment was carried out by verifying the concentration of selected chemical components in tea and relating it to the health risks they may pose, as well as to the nutritional requirements of adults. Wild tea was characterized by higher micronutrient concentration. The analyzed teas can constitute a valuable source of Mn in the diet. A higher concentration of nitrates and oxalates in cultivated tea can be associated with fertilizer use. The analyzed cultivated tea was a better source of antioxidants with a higher concentration of caffeine. There were no indications of health risks for wild or cultivated teas.

Cost-Effective Simultaneous Separation and Quantification of Phenolics in Green and Processed Tea Using HPLC–UV–ESI Single-Quadrupole MS Detector and Python Script

Phenolic composition of green tea (Camellia sinensis) varies according to manufacturing processes that result in deglycosylation of glycosylated phenolics and condensation, epimerization, and degalloylation of flavan-3-ols (catechins). Ambiguous phenolic assignments based on UV absorbance alone can occur when the chromatographic peaks overlapped slightly. We established an improved method using an HPLC–UV coupled with a single-quadrupole MS detector (MS1) that can reject false UV peaks after checking the preceding MS1 peaks. Adjusted UV data coded by the Python algorithm were deployed to compare tea phenolics. Performance validation of the MS1 and UV analysis methods for 19 phenolics revealed a sensitivity of 0.17 and 0.47 pmol/injection, limit of detection of 15 and 33 μg/L, limit of quantification of 50 and 110 μg/L, intra-day precision of 5% and 1% relative standard deviation, and trueness of 83–135% and 97–100%, respectively. Our results suggest that the HPLC–UV–MS1 method, which is a low operational cost method, potentially provides the precise phenolic composition of teas.

Rapid visualized characterization of phenolic taste compounds in tea extract by high-performance thin-layer chromatography coupled to desorption electrospray ionization mass spectrometry

Phenolic compounds are the important taste source of tea infusion. In this paper, the phenolic compounds in tea extracts were separated by high-performance thin-layer chromatography (HPTLC), and then in-situ determined by desorption electrospray ionization mass spectrometry (DESI-MS). Total 44 phenolic compounds in tea extracts were accurately confirmed by NIST library as well as reference substances. The clustering results of heat-map can better reflect the differences of phenolic compounds in different categories and subcategories of teas. Besides, the contents of hydrolyzable tannins, including galloylglucose, digalloylglucose, trigalloyglucose and strictinin, were positively correlated with the grades of green tea. The method validation and quantification results of exemplified five phenolic compounds in teas were also obtained, and LODs, LOQs and recoveries were ranging between 1.5-15.9 μg/mL, 5.1-53.1 μg/mL, and 79%-117.6%, respectively. Moreover, HPTLC-DESI-MS can save tenfold analytical time compared to HPLC-MS. Therefore, HPTLC-DESI-MS was a rapid, efficient characterization method of phenolic compounds in tea extracts.

Intelligent evaluation of taste constituents and polyphenols-to-amino acids ratio in matcha tea powder using near infrared spectroscopy

Matcha tea is rich in taste and bioactive constituents, quality evaluation of matcha tea is important to ensure flavor and efficacy. Near-infrared spectroscopy (NIR) in combination with variable selection algorithms was proposed as a fast and non-destructive method for the quality evaluation of matcha tea. Total polyphenols (TP), free amino acids (FAA), and polyphenols-to-amino acids ratio (TP/FAA) were assessed as the taste quality indicators. Successive projections algorithm (SPA), genetic algorithm (GA), and simulated annealing (SA) were subsequently developed from the synergy interval partial least squares (SiPLS). The overall results revealed that SiPLS-SPA and SiPLS-SA models combined with NIR exhibited higher predictive capabilities for the effective determination of TP, FAA and TP/FAA with correlation coefficient in the prediction set (R_p) of R_p > 0.97, R_p > 0.98 and R_p > 0.98 respectively. Therefore, this simple and efficient technique could be practically exploited for tea quality control assessment.

Determination of 4 psychoactive substances in tea using ultra high performance liquid chromatography combined with the quadrupole time-of-flight mass spectrometry

In this study, a method for the qualification and quantification of 4 psychoactive substances in tea using ultra high performance liquid chromatography coupled with the quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) has been developed. Tea samples were extracted by a 50% (v/v) methanol-water solution, and then separated by an ACQUITY UPLC BEH Shield RP18 column using a binary solvent system by gradient elution. The analytes were determined by Q-TOF/MS in TOFMS and information-dependent acquisition (IDA)-MS/MS mode. The results showed that the mass accuracy error of the 4 psychoactive substances were lower than 5.0 × 10-6, and a good linear relationship was observed in the range of 0.5-500 μg L-1 and correlation coefficient was higher than 0.9990. The LOD was in the range of 0.005-0.020 mg kg-1 and the LOQ was in the range of 0.010-0.040 mg kg-1. The recovery of the method was in range of 80.14-93.25% with spike levels of 0.010-0.400 mg kg-1, and relative standard deviations were lower than 10%. The method was simple, specific and reliable. It has been successfully used for the detection of 4 psychoactive substances in tea samples.

Isolation of bioactive components with soluble epoxide hydrolase inhibitory activity from Stachys sieboldii MiQ. by ultrasonic-assisted extraction optimized using response surface methodology

Stachys sieboldii MiQ (SSM) is an important food and medicinal herb in Korea, used to improve memory of patients with senile dementia and cardiovascular diseases. However, little information on bioactive components from SSM or standardized extraction methods for these components is available. This study isolated and purified major components from SSM for the first time, and assessed their ability to inhibit soluble epoxide hydrolase (sEH). The results showed that acteoside is the most potent inhibitor of sEH, with an IC₅₀ of 33.5 ± 0.5 μM. Additional active components, including harpagide, tryptophan, and 8-acetate-harpagide, along with acteoside, were tentatively identified using high-performance liquid chromatography photodiode array tandem mass spectrometry (HPLC-PDA-MS/MS) and quantified using an ultraviolet detector at 210 nm. Further, an ultrasonic-assisted extraction technique for extraction of four bioactive compounds in SSM was developed and optimized using response surface methodology (RSM). The optimal extraction conditions were: extraction time, 30.46 minutes; extraction temperature, 67.95 °C, and methanol concentration 53.85%. The prediction model of RSM was validated with laboratory experiments. The similarity between predicted and actual values was 97.84%. The extraction method is thus a rapid, environment-friendly, energy-saving method can be applied to extract bioactive components from SSM in large quantities.

Emerging techniques for determining the quality and safety of tea products: A review

Spectroscopic techniques, electrochemical methods, nanozymes, computer vision, and modified chromatographic techniques are the emerging techniques for determining the quality and safety parameters (e.g., physical, chemical, microbiological, and classified parameters, as well as inorganic and organic contaminants) of tea products (such as fresh tea leaves, commercial tea, tea beverage, tea powder, and tea bakery products) effectively. By simplifying the sample preparation, speeding up the detection process, reducing the interference of other substances contained in the sample, and improving the sensitivity and accuracy of the current standard techniques, the abovementioned emerging techniques achieve rapid, cost-effective, and nondestructive or slightly destructive determination of tea products, with some of them providing real-time detection results. Applying these emerging techniques in the whole industry of tea product processing, right from the picking of fresh tea leaves, fermentation of tea leaves, to the sensory evaluation of commercial tea, as well as developing portable devices for real-time and on-site determination of classified and safety parameters (e.g., the geographical origin, grade, and content of contaminants) will not only eliminate the strong dependence on professionals but also help mechanize the production of tea products, which deserves further research. Conducting a review on the application of spectroscopic techniques, electrochemical methods, nanozymes, computer vision, and modifications of chromatographic techniques for quality and safety determination of tea products may serve as guide for other types of foods and beverages, offering potential techniques for their detection and evaluation, which would promote the development of the food industry.

An Online Tea Fixation State Monitoring Algorithm Based on Image Energy Attention Mechanism and Supervised Clustering (IEAMSC)

This study aimed at the shortcomings of existing fixation algorithms that are image-based only, and an effective tea fixation state monitoring algorithm was proposed. An adaptive filtering algorithm was used to automatically filter the ineffective information. Using the energy extractor, the complete energy information of each fixation image was extracted. The image energy attention mechanism was used to identify the prominent features, and based on these, the energy data was mapped to generate the data points as the training data. The cluster idea was adopted, and the training data feed the features trainer. The trend center data of the tea processing energy clustering was generated from different color channels. The corresponding decision function was designed which is based on the distance of the cluster center. The fixation degree of each monitoring image set was measured by the decision function. The Euclidean distance of the energy clustering center of the three channels with the same fixation time progressively approached. The triangle formed by these three points had a trend of gradually shrinking, which was first discovered by us. The detection results showed high accuracy compared with the common classification algorithms. It indicates that the algorithm proposed has positive guiding and reference significance.

Advances and Prospects of Phenolic Acids Production, Biorefinery and Analysis

Biotechnological production of phenolic acids is attracting increased interest due to their superior antioxidant activity, as well as other antimicrobial, dietary, and health benefits. As secondary metabolites, primarily found in plants and fungi, they are effective free radical scavengers due to the phenolic group available in their structure. Therefore, phenolic acids are widely utilised by pharmaceutical, food, cosmetic, and chemical industries. A demand for phenolic acids is mostly satisfied by utilising chemically synthesised compounds, with only a low quantity obtained from natural sources. As an alternative to chemical synthesis, environmentally friendly bio-based technologies are necessary for development in large-scale production. One of the most promising sustainable technologies is the utilisation of microbial cell factories for biosynthesis of phenolic acids. In this paper, we perform a systematic comparison of the best known natural sources of phenolic acids. The advances and prospects in the development of microbial cell factories for biosynthesis of these bioactive compounds are discussed in more detail. A special consideration is given to the modern production methods and analytics of phenolic acids.

Evaluation of carbohydrates and quality parameters in six types of commercial teas by targeted statistical analysis

The content of low molecular weight carbohydrates (LMWC) of six types of tea produced from the leaves of Camellia sinensis were analyzed by hydrophilic interaction chromatography (HILIC) coupled to mass spectrometry. Quantities of sucrose, glucose, fructose, myo-inositol, maltose, mannitol, raffinose, galactinol, and stachyose were determined in samples of white, yellow, green, black, oolong, and dark tea. Sucrose was the most abundant carbohydrate in all types of tea. The concentration of all measured carbohydrates except mannitol was lowest in dark tea samples. Correlation analyses using quantitative data of LMWCs, antioxidant activity, and color parameters were performed on black tea samples to evaluate the interaction of different quality parameters. Carbohydrates depletion was observed during tea processing with formation of Amadori compounds with theanine.

Phenolic Profiling of 12 Strawberry Cultivars Using Different Spectroscopic Methods

Phenolic compounds of 12 strawberry cultivars were profiled using spectrophotometry, spectrofluorometry, and high-performance liquid chromatography-mass spectrometry, coupled with multivariate regression analysis. Total phenolic content, total anthocyanin content, and total antioxidant capacity (TPC, TACY, and TAC, respectively) and concentrations of individual phenolics were evaluated, and the multivariate statistic was employed to identify the most promising cultivars based on their phenolic content. According to the principal component analysis, TAC was strongly correlated with the TPC (0.81), pointing out its importance in overall antioxidant activity. 'Joly', 'Laetitia', and 'Asia' cultivars were distinguished from others as the richest in concerning identified anthocyanins, almost all flavonoids and phenolic acids. Multivariate curve resolution with alternating least squares indicated the presence of two main types of fluorophores assigned to anthocyanins and phenolics, in which emission spectral ratios also showed the highest values in the referred cultivars. These cultivars could be recommended to consumers in terms of the health functionality of fruit.

Phytochemicals and bioactive analysis of different sweet tea (Lithocarpus litseifolius [Hance] Chun) varieties

This paper aims to investigate the constituent phytochemicals and biological activities of six Lithocarpus litseifolius (Hance) Chun (L. litseifolius) cultivars. Processed by UPLC-MS/MS and untargeted metabolomics analysis software (MS-DIAL and MS-FINDER), components of different L. litseifolius cultivars were analyzed qualitatively and quantitatively. By conducting a comprehensive analysis of spectra, MS/MS fragmentation, and retention time, 40 compounds (including 6 phenolic glycosides and 34 flavonoids) were identified rapidly and accurately. Moreover, the total phenolic content (TPC), total flavonoid content (TFC), antioxidant, antimicrobial effects, and pheochromocytoma (PC12) cell viability of different L. litseifolius varieties were evaluated. Purple small leaf (PSL) was found to be the most superior variety with the highest antioxidant activities (8.27, 10.09, and 10.80 mg TE/g for DPPH, ABTS, and FRAP assays, respectively), broad-spectrum antimicrobial activity, and lowest cell cytotoxicity. The results showed that these bioactivities were closely related to phytochemicals among the six cultivars. PRACTICAL APPLICATIONS: L. litseifolius is well known as an important folk drink in the Southern China folklore for its specific efficacy in preventing diabetes. However, there is still a paucity of information on L. litseifolius, as other active components and bioactivities of it remain to be investigated. The wide range of flavonoids discovered in L. litseifolius provides abundant natural health-promoting agents for further applications in medicine and functional food.

Oxidative stability of spray dried matcha-tuna oil powders

Matcha-tuna oil and matcha-maltodextrin-tuna oil emulsions (25% oil, dry basis), formulated to have protein: carbohydrate ratios of 1:1.1, 1:2, 1:3 and 1:4, were spray dried. Confocal laser scanning microscopy showed effective emulsification of oil in all emulsions. All powders had low surface fat (2.9-4.2%). The addition of maltodextrin enhanced the bulk density and flowability of powders. Water sorption isotherms indicated that addition of maltodextrin increased water uptake of powders. The oxidative stability of the powders under accelerated conditions in an Oxipres® was highest for the matcha-tuna oil powder. Increasing amounts of added maltodextrin decreased oxidative stability. A comparison of levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in neat oil and tuna oil powders over 12 weeks at 40 °C, demonstrated that % remaining EPA and DHA were higher for all spray dried powders compared to neat oil. There was a significant correlation (p < 0.01) between the amount of the loss of tea catechins and % remaining EPA and DHA after 12 weeks at 40 °C, suggesting that the catechins had a major role in protecting the tuna oil against oxidation. This study has demonstrated the potential of using a whole biomass (matcha) as the single encapsulant for protection and delivery of omega-3 oils.

Solvent and temperature effect of accelerated solvent extraction (ASE) coupled with ultra-high-pressure liquid chromatography (UHPLC-PDA) for the determination of methyl xanthines in commercial tea and coffee

BACKGROUND

Methyl xanthines (MX), known for its psychostimulant effect, occurs mostly in tea and coffee samples. However most of the market available products does not mention the proper amount and quality of MX present where, its consumption in high amount may pose health risks.

AIM OF THE STUDY

To develop and validate a fast, efficient and reliable method of MX extraction along with a sensitive, rapid and precise method for simultaneous analysis of MX i.e. Theobromine (TB), Theophylline (TH) and Caffeine (C), with application in commercial tea and coffee samples.

MATERIALS AND METHODS

Accelerated Solvent Extraction (ASE) was utilized for the first time to extract MX, whereas UHPLC-DAD was applied in order to quantify MX.

RESULTS

ASE resulted a high extract yield (940.22 ± 192.28 mg/g) with optimized conditions of temperature (100 °C) and solvent (MeOH). UHPLC-DAD showed retention time (min) of 1.51 (TB), 1.81 (TH), 2.30 (C) with r² values (0.980-0.988). Average MX (μg/mL) was as; TB (14.73 ± 20.9), TH (32.05 ± 55.5), C (121.87 ± 32.3). The method application in commercial samples showed a high extract yield with MX concentration (mg/g) as; TB (0.13-0.38), TH (0-0.55), C (7.14-11.20). Temperature and solvent variation showed important correlation with samples in terms of extraction yield.

CONCLUSION

ASE-UHPLC/DAD revealed a fast and sensitive method of MX extraction, quantification and quality determination in market available tea and coffee samples.

Rapid and Sensitive Determination of Methylxanthines in Commercial Brands of Tea Using Ultra-High-Performance Liquid Chromatography-Mass Spectrometry

Recently, chromatographic techniques have the potential to be greener in order to reduce the environmental impact. In this work, a new simple, sensitive, efficient, and green analytical method based on UHPLC-MS has been developed for a quick determination of methylxanthines including caffeine, theobromine, and theophylline in tea. Under the optimum conditions, a baseline separation has been achieved within 30 seconds, using isocratic elution consisting of 90% water and only 10% acetonitrile at 0.5 mL/min flow rate (3 mL acetonitrile per hour). The mass spectrometer was operated with the SIR mode in ESI⁺. The developed method was found to be linear in the range of 0.03–5 μg/mL, with correlation coefficients greater than 0.9995 for the three compounds. The respective values of LOD were found to be 0.025, 0.015, and 0.01 μg/mL for caffeine, theobromine, and theophylline, respectively. The proposed assay was applied to 30 commercial tea samples of different brands. Both caffeine and theobromine were found in all tea samples with maximum concentration in sample no. 15, corresponding to 32.6 and 2.72 mg/g of caffeine and theobromine, respectively. On the contrary, theophylline was not detected at all in most samples. When compared with all previous studies that dealt with the same compounds in different matrices, the developed method was found to be the fastest, allowing high-throughput analyses with more than 100 samples/h. The results prove that the method is suitable for routine analysis of methylxanthines and to distinguish the quality of tea samples of various brands.

Polyphenol extract from superheated steam processed tea waste attenuates the oxidative damage in vivo and in vitro

In this study, tea polyphenols (TPs) was first extracted from tea waste by superheated steam (SS) pretreated ultrasonic-assisted hydrothermal extraction (UAH). The optimized strategy presented extracts with the extraction yield up to 21.19% with a significantly higher antioxidant ability, compared with the one without SS pretreatment. Further investigation proved that the SS suppressed the polyphenol oxidase activity of the TPs extract. The ability to scavenge the free radicals were compared in mouse liver mitochondria. Mitochondrial swelling, mitochondrial membrane potential (MMP), cardiolipin peroxidation, and respiratory chain complex (RCC) I-V activities were also evaluated as the index of the mitochondrial oxidative damage. The study supports evidence that the TPs extract exhibited significant protection against oxidative damage on mitochondrial. Furthermore, the effect of TPs on antioxidant ability in zebrafish embryo was evaluated. After TPs pretreatment for 1 day, zebrafish embryos showed a significantly higher survival rate as well as heart rate when facing the oxidative stress. PRACTICAL APPLICATIONS: Polyphenols from tea leaves have been viewed as an antioxidant additive in food, mainly due to the ability of scavenging free radicals and reactive oxygen species. The results of this study suggest that the SS pretreatment could be used as an efficient method to extract TPs from the tea waste for the prevention of oxidative damage in the mouse liver mitochondria and zebrafish embryos.

Simple quantitative analytical methods for the determination of alkaloids from medicinal and edible plant foods using a homemade chromatographic monolithic column

A polymer-based chromatographic monolithic column was prepared via in-situ radical polymerization using tetrahydrofurfuryl methacrylate as the monomer. The homemade column was used for the separation and quantitative analysis of alkaloids, including piperine from Piper longum (fruit of Piper longum Linn.) and pepper (fruit of Piper nigrum L.), hydroxy-α-sanshool, and hydroxy-γ-sanshool from zanthoxylum (fruit of Zanthoxylum bungeanum Maxim), as well as caffeine from Wuyi rock tea. The chromatographic fractions were identified by mass spectrometry. Single factor test and orthogonal test were both carried out to optimize the extraction conditions. The method validation indicated that the accuracy represented by spiked recovery ranged in 98.89%-102.06%, the correlation coefficients in 0.99986-0.99999. These results show that the prepared monolithic column can be successfully used to quantitatively analyse alkaloids from the real medicinal and edible plant foods with reversed-phase mechanism, which can avoid the long analytical time using traditional packed C18 column. The present method is a simple, and inexpensive method for quantitatively analysing alkaloids from medicinal and edible plant foods, exhibiting good specificity and durability.

Optimization of ultrasound-assisted extraction of poly-phenols from Ajuga ciliata Bunge and evaluation of antioxidant activities in vitro

Effective extraction of natural antioxidants from cheap plant sources is still a problem. In this paper, an excellent method of ultrasound-assisted extraction of phenolic compounds from Ajuga ciliata Bunge was studied. The effects of four factors including ethanol volume fraction, ultrasonic time, ultrasonic temperature and material liquid ratio were discussed. After single factor experiments had been investigated, a 4-factor, 3-level Box-Behnken design experiment was used to obtain the model optimum conditions, which are shown as follows: ethanol volume fraction of 41%, liquid-solid ratio of 35:1 mL/g, ultrasonic temperature of 60 °C and ultrasonic time of 50 min. Under these conditions, the experimental productivity is 3.552 mg/g. The spectra of Fourier infrared and energy dispersive X-ray suggest that phenolic compounds exist in the extracts. Besides, free radical scavenging potentials of superoxide anion, hydroxyl and DPPH were measured to evaluate their antioxidant properties. This study proves that the ultrasonic-assisted extraction technique can extract phenolic compounds with antioxidant capacity from Ajuga ciliata Bunge.

Ultrasound-Assisted Extraction of Total Flavonoids from Pteris cretica L.: Process Optimization, HPLC Analysis, and Evaluation of Antioxidant Activity

In the present work, the ultrasonic-assisted extraction (UAE) of total flavonoids (TF) from Pteris cretica L. was optimized by response surface methodology (RSM) on the basis of a single-factor experiment. The optimized UAE parameters were as follows: Ethanol concentration 56.74%, extraction time 45.94 min, extraction temperature 74.27 °C, and liquid/solid ratio 33.69 mL/g. Under the optimized conditions, the total flavonoids yield (TFY) was 4.71 ± 0.04%, which was higher than that obtained by heat reflux extraction (HRE). The extracts were further analyzed by HPLC, and five major flavonoids, including rutin, quercitrin, luteolin, apigenin, and luteolin-7-O-glucoside, were identified and quantified. Furthermore, the results of the antioxidant test showed that the TF extract obtained under optimized UAE conditions exhibited good 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS⁺•), nitric oxide radical (NO•) scavenging activities, and ferrous ion (Fe²⁺) chelating capacity, with IC₅₀ values of 74.49, 82.92, 89.12, and 713.41 µg/mL, respectively. Results indicated that the UAE technique developed in this work was an efficient, rapid, and simple approach for the extraction of flavonoids with antioxidant activity from P. cretica.

A high-throughput screening method for improved R-2-(4-hydroxyphenoxy)propionic acid biosynthesis

R-2-(4-hydroxyphenoxy)propionic acid (R-HPPA) is a key intermediate of the enantiomerically pure phenoxypropionic acid herbicides. R-HPPA could be biosynthesized through selective introduction of a hydroxyl group (-OH) into the substrate R-2-phenoxypropionic acid (R-PPA) at C-4 position, facilitated by microorganisms with hydroxylases. In this study, an efficient high-throughput screening method for improved R-HPPA biosynthesis through microbial hydroxylation was developed. As a hydroxylated aromatic product, R-HPPA could be oxidized by oxidant potassium dichromate to form brown-colored quinone-type compound. The concentration of R-HPPA can be quantified according to the absorbance of the colored compound at a suitable wavelength of 570 nm; and the R-HPPA biosynthetic capability of microorganism strains could also be rapidly evaluated. After optimization of the assay conditions, the high-throughput screening method was successfully used in identification of Beauveria bassiana mutants with enhanced R-HPPA biosynthesis capacity. A positive mutant C-7 with high tolerance to 20 g/L R-PPA was rapidly selected from 1920 mutants. The biomass and R-HPPA titer were 12.5- and 38.19-fold higher compared with the original strain at 20 g/L R-PPA. This high-throughput screening method developed in this work could also be a potential tool for screening strains producing other important phenolic compounds.

Enzyme-assisted extraction of polyphenols from green yerba mate

Abstract The enzyme-assisted extraction of bioactive compounds from plants has been studied as an alternative green technology and the carbohydrases have been candidates to improve the extraction process of numerous such compounds from plants. Polyphenols are secondary plant metabolites, generally involved in the defense against different types of stress and yerba mate (Ilex paraguariensis A. St.-Hil., Aquifoliaceae) is a natural source of these antioxidant compounds. The aim of this work was to evaluate the enzyme-assisted extraction of polyphenols from green yerba mate employing response surface methodology (RSM), in order to determine the best extraction conditions. The independent variables were temperature (33.2 to 66.8 °C), enzyme concentration (0 to 336 FGBU/100g), reaction time (19 to 221 minutes) and pH (2.82 to 6.18). The use of carbohydrases increased the extraction of polyphenols from about 38.67% to 52.08%. The present results showed that all the independent variables were significant at the linear level and that temperature and pH were not significant at the quadratic level. The interactions of temperature and pH; enzyme and reaction time; and enzyme and pH were significant. The regression model presented a determination coefficient (R2) close to 0.85 and a fitted value close to 0.45. Considering the results of this study and their industrial viability, the best conditions for the extraction of polyphenols from green yerba mate are a temperature of 50.0 °C, enzyme concentration of 168 FGB/100 g, reaction time of 120 minutes and pH value of 4.50. This study was the first RSM-based report of the optimization of the enzyme-assisted extraction of total phenolic compounds from green yerba mate.