Influence of seasonal variation on phenolic content and in vitro antioxidant activity of Secondatia floribunda A. DC. (Apocynaceae)

Analysis of Antioxidant Compounds in Vitex negundo Leaves Using Offline 2D-LC-ECD and LC-MS/MS

Vitex negundo has strong antioxidant activity, but its primary antioxidant components are not clear. In this study, the antioxidant components were screened by offline two-dimensional liquid chromatography coupled with electrochemical detection (2D-LC-ECD) and subsequently assessed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) identification, radical scavenging capacity, and molecular docking. Various fractions were isolated from Vitex negundo leaves, and 39 antioxidant components were screened and identified. All of the fractions containing the antioxidant components exhibited certain antioxidant activity. Correlation analysis revealed a strong correlation between the response of LC-ECD and the in vitro antioxidant activity of the fractions. Molecular docking demonstrated that components with high response to LC-ECD exhibited robust interaction with antioxidant-related target proteins. The main antioxidant components of Vitex negundo leaves were isoorientin, chlorogenic acid, agnuside, cynaroside, and scutellarin. The 2D-LC-ECD combined with LC-MS/MS was rapid and effective in screening the antioxidant components in Vitex negundo leaves and could also provide technical support for the discovery of antioxidant components with different polarities and contents in other medicinal and edible plants.

Novel strategy to the characterization and enhance the glycemic control properties of walnut-derived peptides via zinc chelation

This study aimed to utilize zinc coordination to promote the hypoglycemic and antioxidant properties of walnut-derived peptides, such as walnut protein hydrolysate (WPH) and Leu-Pro-Leu-Leu-Arg (LPLLR, LP5), of which LP5 was previously identified from WPH. The optimal conditions for the chelation were a peptide-to-zinc ratio of 6:1, pH of 9, duration of 50 min, and temperature of 50 °C. The WPH-Zn and LP5-Zn complexes increased the α-glucosidase inhibition, α-amylase inhibition, and antioxidant activity more than WPH and LP5 (p < 0.05). In particular, the antioxidant activity of WPH-Zn was superior to LP5-Zn. This is attributable to the WPH containing more aromatic amino acids, carboxylate groups and the imidazole groups, which implies its capacity to potentially coordinate with Zn2+ to form the WPH-Zn complex. Moreover, particle size, zeta potential, and scanning electron microscope indicated that the chelation of Zn2+ by peptides led to intramolecular and intermolecular folding and aggregation.

Influence of seasonality and habitat on chemical composition, cytotoxicity and antimicrobial properties of the Libidibia ferrea

Libidibia ferrea Mart, belonging to the Fabacee family, is a medicinal plant known for its biological properties and production of phenolic compounds. Previous studies reveal the biological activity of its phenolic constituents, making it very promising for the development of new medicines. Seasonality and geographic distribution of species can modify the production of secondary metabolites in Fabaceae species in terms of the preferentially activated metabolic pathways and, consequently, interfere with the medicinal properties of these species. Studying the influence of seasonality on the production of phenolic constituents is essential to establish conditions for "cultivation," species collection, standardization, production, and safety in traditional medicine. This unprecedented study proposed to evaluate the influence of seasonal variations and habitat on the production of phenolic compounds and biological properties of the ethanolic extracts of the stem bark from L. ferrea, whose specimens were collected from the Caatinga and the Atlantic Forest, biomes of Brazil. Antimicrobial activity was determined by broth microdilution. Cytotoxicity was evaluated through a colorimetric assay using MTT. ABTS and DPPH radical reduction methods estimated antioxidant capacities. Folin-Ciocalteu and AlCl3 spectrophotometric methods quantified total phenolics and flavonoids, respectively. In turn, radial diffusion quantified tannin content. PCA score plot and HCA dendogram were obtained by multivariate analysis of 1H NMR data. The cytotoxicity against C6 glioma cells was observed only for Atlantic Forest extracts (EC50 = 0.13-0.5 mg mL-1). These extracts also showed selectivity against Gram-positive bacteria Bacillus subtilis (ATCC 6633) [MICs 500-2000 μg mL-1], B. cereus CCT 0096) [MIC = 250 μg mL-1], Staphylococcus aureus (ATCC 6538) [MICs = 250-500 μg mL-1], S. epidermidis (ATCC 12228) [62.5-1000 μg mL-1], mainly to Staphylococcus sp. Caatinga extracts showed higher production of flavonoids and antioxidants in the summer [7.36 ± 0.19 μg QE mg-1 extract; IC50ABTS = 4.86 ± 0.05 μg mL-1], spring [5.96 ± 0.10 μg QE mg-1 extract; IC50ABTS = 5.96 ± 0.08 μg mL-1 ], winter [4.89 ± 0.25 μg QE mg-1 extract; IC50ABTS = 6.72 ± 0.08 μg mL-1 ]. Regarding habitat, two discriminating compound patterns in the studied biomes were revealed by NMR. The results indicated that the Caatinga biome offers better conditions for activating the production of phenolics [336.34 ± 18.1 μgGAE mg-1 extract], tannins [328.38 ± 30.19 μgTAE mg-1 extract] in the summer and flavonoids in winter, spring, and summer. The extracts that showed the best antioxidant activities were also those from the Caatinga. In turn, extracts from the Atlantic Forest are more promising for discovering antibacterial compounds against Staphylococcus sp and cytotoxic for C6 glioma cells. These findings corroborated the traditional use of L. ferrea bark powder for treating skin wounds and suggest the cytotoxic potential of these extracts for glioblastoma cell lines.

Seasonal effect on phenolic content and antioxidant activity of young, mature and senescent leaves from Anredera cordifolia (Ten.) Steenis (Basellaceae)

Abstract Anredera cordifolia (Ten.) Steenis is a vine species native to Brazil that is considered an unconventional food plant and a medicinal species whose phenolic compounds exert antioxidant activity. Since the production of metabolites is determined by environmental factors and leaf maturity, it is important to track these changes in order to determine the best time to harvest. This study aimed to verify whether leaf phenology and seasonality cause variations in the amount of phenolic compounds and in the antioxidant activity of this species. The leaves were collected in different seasons between September 2018 and April 2019, and separated according to maturity: young, mature, and senescent. Daily atmospheric temperature and rainfall data were used to characterize the collection period. The total phenolic content (TPC), determined by Folin-Ciocalteu method, was significantly higher in the young leaves collected in winter, a season of lower temperatures. These leaves showed 54.4 mg of gallic acid equivalents per 100 g of dry matter (mg GAE 100 g-1DM). Other results averaged 25.6 mg GAE 100 g-1DM. The highest antioxidant activity, assessed via the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method, regardless of leaf phenology, was observed in leaves harvested in autumn (73.7%) and winter (71.1%), seasons with lower rainfall. Leaves harvested in summer and spring had lower antioxidant action rates (54.3 e 37.5%, respectively). There was no significant correlation between the total phenolic content and antioxidant activity. Thus, the phenolic composition of A. cordifolia, and consequently its activity on free radicals, varies seasonally in response to temperature and rainfall, and may or may not interact with the age of the leaves.

Chemical composition and antibacterial effects of Etlingera elatior (Jack) R.M. Smith against Staphylococcus aureus efflux pumps

Multidrug resistance is a significant health problem worldwide, with increasing mortality rates, especially in the last few years. In this context, a consistent effort has been made to discover new antibacterial agents, and evidence points to natural products as the most promising source of bioactive compounds. This research aimed to characterize the antibacterial effect of the essential oil of Etlingera elatior (EOEE) and its major constituents against efflux pump-carrying Staphylococcus aureus strains. The essential oil was extracted from fresh inflorescences by hydrodistillation. Chemical analysis was performed using gas chromatography coupled to mass spectrometry (GC-MS) and gas chromatography equipped with a flame ionization detector (GC-FID). The strains RN-4220, 1199B, IS-58, and 1199 of S. aureus were used to evaluate the antibacterial activity and the inhibition of efflux pumps. A total of 23 compounds were identified, including dodecanal and 1-dodecanol as major compounds. EOEE and dodecanal showed weak activity against the strains, while 1-dodecanol inhibited bacterial growth at low concentrations, indicating strong antibacterial activity. In addition, this compound potentiated the activity of norfloxacin against S. aureus 1199. In conclusion, 1-dodecanol was identified as the most effective compound of EOEE, showing significant potential to be used in antibacterial drug development.

Elucidating Flavonoid and Antioxidant Activity in Edible and Medicinal Herbs Woodwardia japonica (L.f.) Sm. Based on HPLC-ESI-TOF-MS and Artificial Neural Network Model: Response to Climatic Factors

Woodwardia japonica is a kind of great potential edible and medicinal fern. In a previous study, it was found that flavonoid and antioxidant activity of W. japonica from different sites were different. However, the cause of the differences has still been unclear, which has restricted the utilization of W. japonica. In this paper, flavonoid and antioxidant activity of W. japonica from nine different regions were determined with the method of a colorimetric assay with UV-VIS spectrophotometry and HPLC-ESI-TOF-MS, and the effects of climate factors on flavonoids and antioxidant activities were evaluated by mathematical modeling and statistical methods. The results showed: (1) total flavonoid content (TFC) of W. japonica from Wuyi Mountain (Jiangxi) was the highest, which might be related to the low temperature; (2) the differences of antioxidant activities of W. japonica might be related to precipitation; (3) five flavonols, two flavones and one isoflavone were tentatively identified in W. japonica; (4) flavonol and isoflavone might be affected by sunshine duration, and flavones were probably related to temperature. In conclusion, the effects of climate factors on flavonoids and antioxidants are significant, which would provide an important basis for further exploring the mechanism of climate affecting secondary metabolites.

A Comparative UHPLC-Q-Trap-MS/MS-Based Metabolomics Analysis to Distinguish Foeniculum vulgare Cultivars' Antioxidant Extracts

Among the environmental factors, seasonality is the one which most affects the metabolome of a plant. Depending on the harvest season, the plant may have a variable content of certain metabolites and thus may have different biological properties. Foeniculum vulgare is an annual plant whose cultivation creates large amounts of waste rich in bioactive compounds. The present investigation was performed with the aim of determining the amount of biologically active compounds in F. vulgare wastes obtained from varieties of different seasonality. Ten polyphenolic compounds were quantified in the little stems and leaves of Tiziano, Pegaso, and Preludio cultivars by ultra performance liquid chromatography (UPLC) hyphenated to QTRAP mass spectrometry by using the MRM (multiple reaction monitoring) method. The antioxidant activity of hydroalcoholic extracts was then evaluated using TEAC and DPPH spectrophotometric assays, followed by a multivariate statistical analysis to determine the correlation between metabolite expression and antioxidant activity. The Preludio variety, grown in summer, showed a higher content of bioactive compounds, which guarantees it a better antioxidant power; kaempferol 3-O-glucuronide, quercetin 3-O-glucuronide, and quercetin 3-O-glucoside are the polyphenolic compounds that could be mainly responsible for the antioxidant effect of fennel. The PLS chemometric model, which correlated quantitative data obtained by a sensitive and selective LC-ESI-QTrap-MS/MS analysis of antioxidant activity, resulted in a selective tool to detect the compounds responsible for the activity shown by the extracts in chemical tests.

Variation in flavonoid and antioxidant activities of Pyrrosia petiolosa (Christ) Ching from different geographic origins

Pyrrosia petiolosa (Christ) Ching has both medicinal and health benefits in China. The potential antioxidant activities of P. petiolosa, which are mainly attributed to its flavonoids, have attracted much attention in recent years. The present study aimed to determine the concentration of flavonoid components and evaluate the relative antioxidant activities of P. petiolosa from different geographic origins using a UPLC-MRM-MS-based metabolomics approach. In total, 97 flavonoid components were identified, and their concentrations in the samples from different geographic locations showed significant variation. Thirteen flavonoid components were identified as potential biomarkers for distinguishing between the two major regions, Guizhou (GZ) and Guangxi (GX). The GZ group showed higher total flavonoid content, free radical scavenging activities, and ferric reducing antioxidant power. The well positive correlations were found between the antioxidant capacities and some flavonoid markers. The ecogeographic factors, namely altitude and longitude, play a crucial role in the difference of antioxidant activities and flavonoids concentration. These results indicate that P. petiolosa is rich in flavonoid compounds and is a promising source of natural antioxidants, providing a basis for the quality control of P. petiolosa.

Thymol screening, phenolic contents, antioxidant and antibacterial activities of Iranian populations of Trachyspermum ammi (L.) Sprague (Apiaceae)

The seeds of Trachyspermum ammi were gathered at the ripening stage from different regions of Iran and grouped into 14 populations (P1-P14) accordingly. The essential oil (EO) extraction yielded in the 3.16–5% range. EOs were analyzed by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC–MS) and 11 constituents were identified. Thymol (59.92–96.4%), p-cymene (0.55–21.15%), γ-terpinene (0.23–17.78%), and carvacrol (0.41–2.77%) were the major constituents. The highest contents of thymol and carvacrol were found in the Ghayen population (P2). Also, P2 and P8 (Estahban) had the highest value of total phenol (TPC) 43.2 mg gallic acid equivalent (GAE)/g DW, and total flavonoids (TFC) 8.03 mg quercetin equivalent (QE)/g DW, respectively. P1 (Kalat) had the highest total coumarin (TCC) value (0.26 mg coumarin equivalent CE/g DW). Based on EO constituents, principal component analysis (PCA) and cluster analysis classified populations into two chemotypes of thymol/p-cymene/γ-terpinene and thymol/carvacrol. The highest positive correlation coefficient was between α-terpinene and limonene (0.96), while the highest negative correlation was between thymol and p-cymene (–0.984). The antioxidant activities of extracts and EOs were evaluated by phosphomolybdenum (total antioxidant capacity; TAC), diphenylpicrylhydrazyl (DPPH IC₅₀), and ferric ion reducing antioxidant power (FRAP) assays. Also, the antimicrobial activity of EOs was studied against Escherichia coli and Staphylococcus aureus. P8 with high thymol, EO content (%v/w), TFC, and antibacterial and antioxidant activities is recommended but further studies are needed to confirm the chemotype introduction.

The Influence of Different Extraction Techniques on the Chemical Profile and Biological Properties of Oroxylum indicum: Multifunctional Aspects for Potential Pharmaceutical Applications

Oroxylum indicum (L.) Kurz (Bignoniaceae), a traditional Chinese herbal medicine, possesses various biological activities including antioxidant, anti-inflammatory, antibacterial, and anticancer. In order to guide the practical application of O. indicum in the pharmaceutical, food, and cosmetic industries, we evaluated the effects of five different extraction techniques (maceration extraction (ME), oxhlet extraction (SOXE), ultrasound-assisted extraction (UAE), tissue-smashing extraction (TSE), and accelerated-solvent extraction (ASE)) with 70% ethanol as the solvent on the phytochemical properties and biological potential. The UHPLC-DAD Orbitrap Elite MS technique was applied to characterize the main flavonoids in the extracts. Simultaneously, the antioxidant and enzyme inhibitory activities of the tested extracts were analyzed. SOXE extract showed the highest total phenolic content (TPC, 50.99 ± 1.78 mg GAE/g extract), while ASE extract displayed the highest total flavonoid content (TFC, 34.92 ± 0.38 mg RE/g extract), which displayed significant correlation with antioxidant activity. The extract obtained using UAE was the most potent inhibitor of tyrosinase (IC50: 16.57 ± 0.53 mg·mL-1), while SOXE extract showed the highest activity against α-glucosidase (IC50: 1.23 ± 0.09 mg·mL-1), succeeded by UAE, ME, ASE, and TSE extract. In addition, multivariate analysis suggested that different extraction techniques could significantly affect the phytochemical properties and biological activities of O. indicum. To sum up, O. indicum displayed expected biological potential and the data collected in this study could provide an experimental basis for further investigation in practical applications.

Phenolic Contents and Antioxidant Activity of Citrullus colocynthis Fruits, Growing in the Hot Arid Desert of the UAE, Influenced by the Fruit Parts, Accessions, and Seasons of Fruit Collection

Citrullus colocynthis (Cucurbitaceae) is an important medicinal plant traditionally used in the United Arab Emirates (UAE). In a recent study, it has been reported that different individuals of the same population of C. colocynthis, growing in the hot arid desert of the UAE, exhibited variations in their fruit size, color, and stripe pattern. In addition, these plants differed genetically, and their seeds showed variation in size, color, and germination behavior (hereinafter, these individuals are referred to as accessions). In the present study, the total phenolic content (TPC) and antioxidant activity of different fruit parts (rinds, pulps, and seeds) of three different accessions with significant genetic variations, from a single C. colocynthis population, were assessed in response to different seasonal environments. Green fruits were collected in summer and winter from three accessions growing in the botanic garden of the University of Sharjah, UAE. Methanolic extracts from different fruit parts were prepared. The TPC was qualitatively determined by a Folin–Ciocalteu assay, while the antioxidant capacity was analyzed using the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging ability. The metabolic profiling of the antioxidant metabolites was determined using a gas chromatograph coupled to mass spectrometry (GC–MS), associated with a literature search. The results showed that the TPC and the DPPH free radical scavenging activity varied between seasons, accessions, and fruit parts. The highest phenolics were in rinds, but the highest antioxidant activities were in seeds during the summer, reflecting the role of these compounds in protecting the developed seeds from harsh environmental conditions. The metabolomic analysis revealed the presence of 28 metabolites with significant antioxidant activities relevant to fruit parts and season. Collectively, the formation of phenolics and antioxidant activity in different fruit parts is environmentally and genetically dependent.

Toxic Potential of Cerrado Plants on Different Organisms

Cerrado has many compounds that have been used as biopesticides, herbicides, medicines, and others due to their highly toxic potential. Thus, this review aims to present information about the toxicity of Cerrado plants. For this purpose, a review was performed using PubMed, Science Direct, and Web Of Science databases. After applying exclusion criteria, 187 articles published in the last 20 years were selected and analyzed. Detailed information about the extract preparation, part of the plant used, dose/concentration tested, model system, and employed assay was provided for different toxic activities described in the literature, namely cytotoxic, genotoxic, mutagenic, antibacterial, antifungal, antiviral, insecticidal, antiparasitic, and molluscicidal activities. In addition, the steps to execute research on plant toxicity and the more common methods employed were discussed. This review synthesized and organized the available research on the toxic effects of Cerrado plants, which could contribute to the future design of new environmentally safe products.

Metabolite characterization of fifteen by-products of the coffee production chain: From farm to factory

Approximately 11.4 million tonnes of solid by-products and an increased amount of waste water will be generated during the 2020/21 coffee harvest. There are currently no truly value-adding uses for these potentially environmentally threatening species. This work presents the most wide-ranging chemical investigation of coffee by-products collected from farms to factories, including eight never previously investigated. Twenty compounds were found for the first time in coffee by-products including the bioactive neomangiferin, kaempferol-3-O-rutinoside, lup-20(29)-en-3-one and 3,4-dimethoxy cinnamic acid. Five by-products generated inside a factory showed caffeine (53.0-17.0 mg.g^-1) and/or chlorogenic acid (72.9-10.1 mg.g^-1) content comparable to coffee beans, while mature leaf from plant pruning presented not only high contents of both compounds (16.4 and 38.9 mg.g-1, respectively), but also of mangiferin (19.4 mg.g-1) besides a variety of flavonoids. Such by-products are a source of a range of bioactive compounds and could be explored with potential economic and certainly environmental benefits.

Influence of Plant Origins and Seasonal Variations on Nutritive Values, Phenolics and Antioxidant Activities of Adenia viridiflora Craib., an Endangered Species from Thailand

Adenia viridiflora Craib. is an indigenous plant found in Thailand, Cambodia and Vietnam that has become threatened owing to lack of knowledge about its agricultural management. This plant is now rare in the wild and was registered in the Plant Genetic Conservation Project under the initiation of Her Royal Highness Princess Maha Chakri Sirindhorn (RSPG) to promote sustainable conservation and optimally beneficial utilization. A. viridiflora has a long history of utilization as a nutrient-rich source with medicinal properties but scientific evidence of the veracity of these claims is limited. Here, the nutritional compositions, phenolic contents and antioxidant activities of different plant parts (young shoots and old leaves) of A. viridiflora were investigated using plants collected from four areas of Thailand as Kamphaeng Phet (KP), Muang Nakhon Ratchasima (MN), Pakchong Nakhon Ratchasima (PN) and Uthai Thani (UT) at different harvesting periods (March-April, May–June and July–August). Results indicated that young shoots provided higher energy, protein, fat, dietary fiber, phosphorus, sodium, and zinc than old leaves. By contrast, nutrients such as total sugar, vitamin C, carotenoids, potassium, calcium, magnesium, and iron contents were higher in old leaves that also exhibited higher phenolic contents and most antioxidant activities than young shoots. Generally, most nutrients, phenolic contents, and antioxidant activities exhibited no clear trend among different plant origins. The harvesting period of July–August provided a suitable climate for biosynthesis of most nutrients, while high phenolics were mainly found in samples harvested in March–April. No clear trend was observed in the prevalence of antioxidant activities that varied according to assay techniques.

Response surface methodology optimised solvothermal system enables an efficient extraction of echinacoside and oleuropein from Syringa pubescens Turcz

INTRODUCTION

Syringa pubescens Turcz. was reported to be abundant in the Funiu Mountains of Henan Province and can be used to treat hepatitis and cirrhosis. In order to develop and utilise the resource, a fast and simple technique to extract bioactive compounds is needed.

OBJECTIVES

Our aims were to provide an extraction technique of glycosides from S. pubescens and study the antioxidant activity of this material.

METHODS

Box-Behnken design (BBD) was employed with three factors at three levels. The process parameters such as ethanol concentration (X₁ ), temperature (X₂ ), and solvent-solid ratio (X₃ ) could significantly influence efficiency and yield of target compounds. High-performance liquid chromatography (HPLC) was used to determine the content of glycosides. DPPH (α,α-diphenyl-β-picrylhydrazyl), ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and reducing power were used to evaluate the antioxidant activity of S. pubescens extract.

RESULTS

The optimal parameters for the maximal extraction yield were obtained with ethanol concentration of 68%, temperature of 89°C, solvent-solid ratio of 46 mL/g, and time of 20 min. The S. pubescens extract showed strong antioxidant properties in vitro.

CONCLUSION

The findings indicated the potential application of solvothermal extraction method to extract bioactive compounds from S. pubescens Turcz. Furthermore, the S. pubescens extract could be used as an important resource of antioxidant activity.

Phenological and Geographical Effects on Phenolic and Triterpenoid Content in Vaccinium vitis-idaea L. Leaves

Lingonberry leaves have been proposed as a potential raw material for nutraceutical products and functional food due to the richness of phenolic and triterpenic compounds. However, contents of these bioactive compounds tend to vary greatly with physiological, climatic, and edaphic conditions, resulting in lingonberry leaves’ nutritional-pharmaceutical quality changes. In this context, we examined the effects of seasonal and geographical factors on phenolic and triterpenoid contents in lingonberry leaves. Quantitative and qualitative differences between samples were determined using validated HPLC-PDA methods. A total of 43 bioactive compounds were found at a detectable level throughout the year in young and old lingonberry leaves, with the highest contents of most compounds observed in samples collected in autumn–first half of spring. This suggests the potential to exploit the continuous biosynthesis for a longer harvesting season. Considerable variations in phytochemical profiles of lingonberry leaves, obtained from 28 locations in Lithuania, were found. Correlation analyses revealed significant negative correlations between contents of particular constituents and sunshine duration, temperature, and precipitation, and positive correlation with air humidity, longitudes, and altitudes of collecting locations and macronutrients in soil. These results suggest that harsh weather is favorable for most identified compounds and it may be possible to achieve appropriate accumulation of secondary metabolites by adjusting edaphic conditions. Taken together, the accumulation of phenolics and triterpenoids in lingonberry leaves highly depends on phenological and geographical factors and the influence of both variables differ for the particular compounds due to different metabolic processes in response to stresses.

Seasonal variation of verbascoside as a principal phenolic compound linked with antioxidant potentials of Clerodendrum glandulosum Lindl. leaves

This study reports the influence of seasonality on the accumulation of verbascoside as a principal phenolic compound in Clerodendrum glandulosum Lindl. leaves along with possible alteration of antioxidant potentials. Leaves were collected during winter (December 2018), spring (February 2019), summer (May 2019), monsoon (July 2019), autumn (October 2019), and extracted with 95% aqueous methanol by cold maceration. The total phenolic content and antioxidant capacities (DPPH, ABTS and FRAP) were estimated by spectrophotometric technique, and verbascoside content was estimated by HPLC-PDA. Results indicate that the leaves collected during summer and winter both exhibited the highest total phenolic content verbascoside accumulation and antioxidant potentials which are significantly different (p < 0.05) than other seasons. Correlation studies further demonstrated that the total polyphenol and verbascoside contents were directly proportional to the antioxidant potentials. Thus, the study concludes that winter and summer are the best seasons for collecting leaves from this plant to obtain maximum antioxidant potential.

Effect of in vitro gastro-intestinal digestion on the phenolic composition and antioxidant capacity of Burdock roots at different harvest time

The current study aimed to evaluate how the harvest time affects the phenolic composition in Burdock root flours (BRF) and how these phenolics are influenced by the gastro-intestinal digestive environment. Burdock roots were harvested in 2020 in Jiangsu Province in June (B1), July (B2) and August (B3). The main phenolic, 5-O-caffeoylquinic acid (5-CQA) decreased after in vitro digestion from 1.14 to 0.22 mg/g (B1 < B2 < B3). Total phenolic content of BRF was 61% lower after in vitro digestion whereas 5-CQA bioaccessibility remained at about 60%. Twelve other phenolic compounds were tentatively identified after in vitro digestion. An average reduction in antioxidant capacity of 27% and 10% was observed for DPPH and ABTS, respectively. In conclusion, data demonstrated that phenolic composition, bioaccessibility and antioxidant capacity of Burdock roots harvested at different times were subject to the influence of in vitro gastrointestinal digestion.

Effects of enzymatic hydrolysis on the structural, rheological, and functional properties of mulberry leaf polysaccharide

Effects of enzymatic hydrolysis on the structural, rheological, and functional properties of mulberry leaf polysaccharide (MLP) were characterized in this study. The enzymatic hydrolysis of MLP raised the carbonyl, carboxyl, and hydroxyl groups from 7.21 ± 0.86 to 10.08 ± 0.28 CO/100 Glu, 9.40 ± 0.13 to 17.55 ± 0.34 COOH/100 Glu, and 5.71 ± 0.33 to 8.14 ± 0.24 OH/100 Glu, respectively. Meanwhile, an increase in thixotropic performance and structure-recovery capacities were observed in hydrolyzed MLP, while the molecular weight, surface tension, apparent viscosity, and thermal stability were decreased. An improved antioxidant activity of MLP was also achieved after the enzymatic degradation. Moreover, the hydrolyzed MLP showed greater ability to promote the growths of Bifidobacterium bifidum, Bifidobacterium adolescentis, Lactobacillus rhamnosus, and Lactobacillus acidophilus and the production of acetic acid, butyric acid, and lactic acid. The results demonstrate that enzymatic modification is a useful approach for polysaccharide processing.

Seasonal Variations of Polyphenols Content, Sun Protection Factor and Antioxidant Activity of Two Lamiaceae Species

Secondary metabolite production by plants is influenced by external environmental factors that can change depending on the seasons, which makes it important to know how the plant, through its metabolism, is able to adapt to these variations. Mentha x villosa and Plectranthus amboinicus present in their chemical composition polyphenols, and through previous studies, it has been seen that these two species present promising in vitro photoprotective activity. The aim of this study was to evaluate seasonal alterations in photoprotective and antioxidant activities and the influence of factors such as precipitation levels and sun radiation incidence. Thus, polyphenol quantification, cromatographics (HPLC-DAD) and multivariate (PCA) analyses of extracts of the two species through twelve months were done. It was observed that the best months for photoprotective and antioxidant activities were September for M. villosa and July for P. amboinicus (SPF = 14.79). It was possible to conclude that solar radiation more clearly influences the production of phenolics and the increase of SPF in M. villosa, in addition to favoring the antioxidant activity of the two species, while precipitation seems to have no influence.

Chemical Composition, Antioxidant and Enzyme Inhibitory Properties of Different Extracts Obtained from Spent Coffee Ground and Coffee Silverskin

In a world where an eco-friendlier approach is becoming more and more necessary, it is essential to reduce waste production and to reuse residues of the company’s supply chain. Coffee silverskin (CS) and spent coffee ground (SCG), two by-products of coffee production, are important sources of bioactive compounds and, for this, some authors have proposed their reuse in the nutraceutical, food, and cosmetic sector. However, their potential enzyme inhibitory properties have been poorly investigated. Hence, the objective of the current work was to study the enzymatic inhibitory activities against acetylcholinesterase, butyrylcholinesterase, α-amylase, α-glucosidase, and tyrosinase of different extracts of CS and SCG. Before these in vitro bioassays, the phytochemical composition of each extract was investigated via colorimetric assays and HPLC-MS/MS analysis. In addition, the antioxidant activities were evaluated by different chemical approaches. SCG extracts contained a higher content of bioactive compounds, notably the SCG EtOH:H₂O extract was the richest in caffeine and possessed the highest antioxidant activities. The hydroalcoholic and methanolic extracts were shown to be the most active against all tested enzymes, while the water extracts displayed lower activity. Our results showed a weak correlation between bioactive compounds and enzyme inhibitory effects, proving inhibitory activities likely due to non-phenolic molecules such as alkaloids and terpenoids. Obtained findings could be a starting point to develop novel nutraceuticals from CS and SCG.