Phenolic Compounds Research Articles

Screening of phenolic compounds (flavonoids and phenolpropanoids) of Centaurea cyanus L. flowers by planar chromatography

Screening of phenolic compounds (flavonoids and phenolpropanoids) of Centaurea cyanus L. flowers by planar chromatography

Physicochemical, Textural, and Antioxidant Attributes of Yogurts Supplemented with Black Chokeberry: Fruit, Juice, and Pomace.

The fruit, juice, and pomace of black chokeberry (Aronia melanocarpa) are a rich source of phenolic compounds and can be used to obtain enriched dairy products. Chokeberry fruit, due to its astringent taste, is less favorable or even unacceptable to consumers and is usually processed into juice, resulting in large quantities of pomace, which is often discarded as waste. The aim of this study is to valorize chokeberry fruit, juice, and pomace by incorporating them in different percentages (1, 2, and 3%) into yogurt as functional ingredients. The physicochemical (total solids content, fat, protein, titratable acidity, pH, color), textural (hardness, adhesion, cohesiveness, springiness, gumminess, and chewiness), antioxidant (DPPH scavenging activity and total phenolic content), and sensory characteristics of supplemented yogurts were investigated. The results showed that the addition of chokeberry pomace in yogurt increased their total solids content (from 11.46 ± 0.18% for the plain yogurt sample to 13.71 ± 0.18% for the yogurt sample with 3% chokeberry pomace), while the addition of fruit and juice decreased the protein content of the yogurt samples (from 4.35 ± 0.11% for the plain yogurt sample to 3.69 ± 0.15% for the yogurt sample with 3% chokeberry fruit and to 3.84 ± 0.1% for the yogurt sample with 3% chokeberry juice). There was no statistically significant change in the fat content of all samples of chokeberry-supplemented yogurt compared to plain yogurt. The pH of the yogurt samples decreased with the increase in the percentage of chokeberry fruit, juice, and pomace added to the yogurt (from 4.50 for the plain yogurt samples to 4.35, 4.30, and 4.20 for the yogurt samples supplemented with 1, 2, and 3% black chokeberry pomace). Inhibition of DPPH radical formation was higher in the yogurt samples with chokeberry fruit (57.84 ± 0.05%, 73.57 ± 0.11%, and 75.38 ± 0.05% inhibition for the samples with 1, 2, and 3% fruit) and pomace (up to 64.8 ± 0.11% inhibition for the sample with 3%), while total phenolic content decreased (from 392.14 ± 2.06 to 104.45 ± 2.63 µg/g) as follows: yogurt with chokeberry pomace > yogurt with chokeberry fruit > yogurt with chokeberry juice. The yogurt samples with the highest acceptance scores were the samples with 3% and 2% black chokeberry fruit, while the lowest acceptance score was obtained for the yogurt sample with 3% black chokeberry pomace. Chokeberry fruit, juice, and pomace can improve the physicochemical, textural, and antioxidant characteristics of yogurt, emphasizing that the antioxidant effect of yogurt could be substantially improved by the addition of chokeberry pomace due to its high phenolic content, while incorporation into yogurt is another way to valorize this by-product.

Bio-waste of vegetable oil production as a source of natural phenols with antioxidant properties

Bio-waste of vegetable oil production as a source of natural phenols with antioxidant properties

Evaluation of phenolics in the analysis of virgin olive oil using near infrared spectroscopy

Olive oil is an indispensable part of the diet in Mediterranean regions, and is appreciated worldwide for its sensory characteristics, combining a fine aroma and pleasant flavor with the high nutritional value of specific chemical compounds. However, making rapid measurements of phenolic compounds is a major challenge for the olive oil sector. The development of a new method based on near infrared (NIR) spectroscopy may be considered an important advance for the sector, as it is rapid, low-cost, non-contaminant and non-destructive. In this study, three different NIR instruments – one FT-NIR benchtop instrument (671.82–2702.70 nm) and two low-cost portable devices (900–1700 nm and 1350–2150 nm) – were used to analyze a collection of virgin olive oil samples from various Mediterranean regions. To predict both the individual and total concentration of phenols in the olive oil, four signal pretreatment methods and modified partial least squares regression analyses were employed to develop the predictive models. The results showed that the benchtop FT-NIR instrument performed better than the other portable instruments when measuring the phenolic compounds in virgin olive oil. The best models of hydroxytyrosol derivatives, tyrosol derivatives, total phenols and “EFSA phenols” showed R2cv values of 0.84, 0.85, 0.88 and 0.89, while the RPDcv values were 2.51, 2.61, 2.93 and 2.95, respectively. Meanwhile, for the portable NIR instruments, the prediction models for hydroxytyrosol derivatives, total phenols and “EFSA phenols” (the sum of the hydroxityrosol and tyrosol derivatives) showed R2cv values ranging between 0.75 and 0.81 and an RPDcv between 2 and 2.5. These results indicate the great potential of NIR, both with benchtop and portable devices, to detect phenolic compounds in virgin olive oil, which can guarantee the quality of virgin olive oil and thus aid progress in the olive oil industry. Moreover, this is the first published work to determine phenolic compounds in virgin olive oil using portable NIR instruments.

Pharmacological profile of Cymbopogan Citratus: A review

Cymbopogoncitratus is an aromatic plant of Gramineae family well-known as lemon grass. Cymbopogon is derived from Greek word “kymbe – pogon” which means boat-beard. The lemon-like scent could be ascribed to the existence of a cyclic monoterpene (citral). The herb is a perennial grass, native and distributed in Asia, Africa, South and North America. It contains considerable group of flavonoids, essential oils, phenolic compounds and other phytochemical constituents which possesses pharmacological activities such as anti-obesity, anti-carcinogenic, anti-bacterial, anti-fungal, anti-nociceptive, anti-oxidants anti-diarrheal, and anti-inflammatory properties which could enhance health.It has also been known to restrain platelet composition, cure diabetes, gastrointestinal infections, anxiety or depression, malaria and pneumonia. Industrially, they serve as additive, flavour, insecticides and preservative in beverages, baked foods and cuisines. The essential oil of the plant is used in aromatherapy. The compounds identified in Cymbopogoncitratus are mainly terpenes, alcohols, ketones, aldehyde and esters. Some of the reported phytoconstituents are essential oils that contain Citral ?, Citral ?, NerolGeraniol, Citronellal, Terpinolene, Geranyl acetate, Myrecene and TerpinolMethylheptenone. The plant also contains reported phytoconstituents such as flavonoids and phenolic compounds, which consist of luteolin, isoorientin 2’-O-rhamnoside, quercetin, kaempferol and apiginin. Studies indicate that Cymbopogoncitratus possesses various pharmacological activities such as anti-amoebic, antibacterial, antidiarrheal, antifilarial, antifungal and anti-inflammatory properties. Various other effects like antimalarial, antimutagenicity, antimycobacterial, antioxidants, hypoglycemic and neurobehaviorial have also been studied. These results are very encouraging and indicate that this herb should be studied more extensively to confirm these results and reveal other potential therapeutic effects.

A Versatile Ultra-High-Performance Liquid Chromatography-Full-Scan High-Resolution Mass Spectrometry Method to Quantify Wine Polyphenols.

Polyphenols are responsible for wine colour and astringency, and, as antioxidants, they also have beneficial health properties. In this work, we developed a robust full-scan high-resolution mass spectrometry method for the quantification of 90 phenolic compounds in wine samples (either red, rosé, or white wine), using a UHPLC-OrbitrapTM system. With this method, we could conduct a detailed analysis of phenolic compounds in red, rosé, and white wines with great selectivity due to sub-ppm mass accuracy. Moreover, accessing the full-scan spectrum enabled us to monitor all the other compounds detected in the sample, facilitating the adaptability of this method to new phenolic compounds if needed.

Metabolic differences in Zingiber officinale Roscoe by geographical origin determined via multiplatform metabolomics and method for simultaneous analysis of six phenolic compounds.

Ginger, which is the rhizome of Zingiber officinale Roscoe, is widely distributed and consumed. The taste and aroma of ginger differ depending on its geographical origin. To distinguish the origin of ginger, ginger extracts from Korea, Peru, and China were analyzed using ultra-performance liquid chromatography (UPLC) coupled to quadrupole time-of-flight mass spectrometry and nuclear magnetic resonance spectroscopy for metabolomics. Korean ginger contained more 10-gingerol, and Peruvian ginger contained more 6-gingerol and 8-gingerol. Several amino acids negatively correlated with gingerols, suggesting that amino acids are related to the biosynthesis of gingerols. Sugars, which are the main energy source, positively correlated with gingerols. Organic acids and gingerols were also positively correlated, indicating that both organic acids and gingerols are used for adaptation to the environment surrounding the root. We confirmed the features of the primary and secondary metabolites by verifying the correlation between metabolites and differences in metabolites according to ginger origin. We additionally optimized a simultaneous UPLC analytical method of marker compounds for the simple and rapid quality control of ginger. This method exhibits excellent linearity, sensitivity, and reproducibility. Using metabolomics, differences in origin were observed, and a low-end equipment analysis method for quality control can be used in the ginger industry.

Ultrasound-assisted Co-extraction and characterization of saponin-rich Co-extracts from fenugreek seeds (Trigonella foenum-graecum L.) and quinoa husk (Chenopodium quinoa Willd.) and their hydrolysates

The co-extraction of steroidal and triterpenoid saponins, followed by hydrolysis to produce sapogenin-rich extracts, offers an efficient strategy to enhance the multi-bioactive potential of extracts. The resulting chemical composition modifications, including the presence of other co-extracted or co-hydrolyzed compounds, must also be considered. In this study, ultrasound-assisted co-extraction of fenugreek seeds and quinoa husk using methanol and 50% aqueous methanol was conducted to obtain extracts and co-extracts with varying proportions of steroidal and triterpenoid saponins, in ratios of 0:100, 25:75, 50:50, 75:25, and 100:0, respectively. Aqueous methanol produced the highest extraction yields (15–25%) and saponin contents (40–70%) in the extracts and co-extracts. The conversion by microwave-assisted acid hydrolysis of saponins to sapogenins was more efficient for triterpenoid saponins, leading to a higher triterpenoid sapogenin content in all co-extracts, accounting for over 70% of the total sapogenins. The co-extracts also contained other bioactive compounds, such as phenolic compounds (3–4 g/100 g), with their content being favored by the presence of fenugreek. Hydrolysis altered the overall composition of the saponin-rich co-extracts, enriching the resulting hydrolyzed products in both types of sapogenins, along with fatty acids, carbonyls, non-protein nitrogen compounds and organic acids, while reducing monoglycerides, removing carbohydrates and significantly modifying the phenolic profile by eliminating many original phenolic compounds and generating new ones. Therefore, co-extraction and post-extraction hydrolysis of fenugreek and quinoa allowed the combination of triterpenoid and steroidal saponins or sapogenins into single products, along with other specific compounds from both sources.

Multidimensional Exploration of Wood Extractives: A Review of Compositional Analysis, Decay Resistance, Light Stability, and Staining Applications

Extractives, which naturally evolve as fundamental defense mechanisms in wood against environmental stresses, hold an essential place in the field of wood conservation science. Despite their low content in woody substrates, extractives are chemically complex and can be extracted accurately by solvents with different polarities, covering key components such as aliphatic, terpenoid, and phenolic compounds. The application of solvent extraction allows for the effective recovery of these extracts from forestry waste, thereby creating new opportunities for their reuse in wood modification and enhancing the economic value and potential applications of forestry waste. In the wood industry, extractives not only act as efficient preservatives and photo-stabilizers, significantly improving the decay resistance and photodegradation resistance of wood, but also serve as ideal dyes for fast-growing wood due to their abundant natural colors, which lend the product a distinct aesthetic appeal. The aim of this paper is to provide a comprehensive review of the origin and distribution characteristics of wood extractives and to examine the impact of solvent selection on extraction efficiency. At the same time, the mechanism of extractives in enhancing wood decay resistance and slowing down photodegradation is deeply analyzed. In addition, specific examples are presented to illustrate their wide utilization in the wood industry. This is intended to provide references for research and practice in related fields.

Ocimum gratissimum mediated green synthesised iron oxide nanoparticles as a plausible nanofertilizer for peanut plant (Arachis hypogaea)

Exploring the potential of iron/iron oxide nanoparticles (IONPs) to act as fertilizer is an area of immense interest. This paper reports the green synthesis of IONPs using aqueous extract of Ocimum gratissimum leaves and its characterization with XRD, HRTEM and FTIR. This environmentally benign route avoids hazardous and toxic chemicals commonly employed in nanoparticle synthesis. The IONPs formed (Fe2O3) are stabilized by the phenolic and aromatic compounds found in the aqueous extract of Ocimum gratissimum and are of small crystallite size (5–30 nm). Peanut seedlings treated with these IONPs exhibited a superior growth performance at lower application rates (100 mg L−1), as evidenced by better growth parameters, which also corroborated with gibberellic acid accumulation in a dose-dependent manner. The differential activity of green synthesized IONPs, highlighted in this study, compared to already reported chemically synthesized IONPs, reveals their functional superiority.

Alteration in certain growth, biochemical, and anatomical indices of grapevine (Vitis vinifera) in response to the foliar application of auxin under water deficit.

Drought-induced stress represents one of the most economically detrimental natural phenomena impacting grapevine (Vitis vinifera ) development, yield, and fruit characteristics. Also, auxin is one of the most important plant growth regulators that can reduce damage caused by stress in plants. In this study, the impact of exogenously sprayed auxin (0, 50, and 200mgL-1 ) on growth, biochemical, and anatomical parameters was investigated in two grapevine varieties (cvs. 'Rashe' and 'Fakhri') under water deficit. According to our findings, water deficit led to a notable decrease in growth, protein content, and anatomical parameters; but significantly enhanced electrolyte leakage. Grapevines exposed to water deficit exhibited substantial increases in total phenolic compounds and antioxidant activity. Applying 50mgL-1 napthalene acetic acid (NAA) reduced the effects of water deficit in both grapevine cultivars by decreasing electrolyte leakage (15% in 'Rashe' and 20% in 'Fakhri'), and accumulating protein content (22% 'Rashe' and 32% 'Fakhri'), total phenolic compounds (33%'Rashe' and 40% 'Fakhri'), and antioxidant capacity (11% 'Rashe' and 39% 'Fakhri'); anantomical parameters were also improved. However, application of 200mgL-1 NAA had adverse effects on growth and biochemical traits of grapevines, with a more pronounced impact on root growth and anatomical parameters compared to other NAA concentrations. In conclusion, the application of 50mgL-1 NAA enhanced grapevine growth, enabling them to better thrive under water deficit.

OPTIMIZATION OF THE SYNERGISTIC ANTIOXIDANT EFFECT OF SELECTED PHENOLIC COMPOUNDS (GALLIC ACID, ROSMARINIC ACID and CAFFEIC ACID) AND INVESTIGATION OF THEIR ABILITY TO PREVENT FORMATION OF DNA BASE DAMAGE

Considering the areas of use of phenolic compounds, it is important to determine the concentrations at which they show synergistic and antagonistic interactions for their integration into various systems and their correct use. In this study, the synergistic interaction concentration of rosmarinic acid, gallic acid, and caffeic acid was determined by Folin–Ciocalteu and FRAP methods. The central composite design–response surface methodology was used to determine the optimum concentration for synergistic interaction. As a result of the optimization, caffeic acid, rosmarinic acid, and gallic acid showed synergistic interaction at 7.87 μM, 6.75 μM and 9.42 μM concentrations for Folin–Ciocalteu method; 8.03 μM, 9.34 μM and 6.00 μM concentration for FRAP method respectively. The capacity of phenolic compounds to prevent the formation of DNA base damage products was evaluated by GC–MS/MS. As a result, the synergistic concentration of three phenolics reduces the DNA damage products at 37.17% (FOLIN) and 40.17% (FRAP).

Enrichment of shortcrust pastry cookies with bee products: polyphenol profile, in vitro bioactive potential, heat-induced compounds content, colour parameters and sensory changes

Bee products, including bee pollen (BP) and bee bread (BB) are natural sources that contain a diverse range of bioactive compounds. The objective of this study was to investigate the potential of BP and BB to enhance the functional properties of shortcrust pastry cookies. The impact on BP and BB on the colour parameters, polyphenolic compounds content, heat-induced compounds content (acrylamide, furfural, 5-hydroxymethylfurfural (HMF)), antioxidant properties, and inhibitory effects against advanced glycation end products (AGEs) formation and acetylcholinesterase (AChE) activity was examine by enriching cookies with 3 and 10% of BP or BB. The incorporation of BP or BB resulted in a notable darkening of the cookies. The spectroscopic and chromatographic analyses revealed that the cookies enriched with bee products exhibited an elevated content of phenolic compounds. The antioxidant activity (AA) of the enriched cookies exhibited an average increase of 2- to 3-fold in the ABTS test and 2-fold in the DPPH test. All cookies exhibited inhibitory potential against AGEs formation, witch inhibitory rates ranging from 10.64 to 46.22% in the BSA-GLU model and 1.75–19.33% in BSA-MGO model. The cookies enriched with 10% BP were characterised by to the highest level of AChE activity inhibition (13.72%). The incorporation of BB and BP resulted in elevated concentration of acrylamide, furfural, and HMF. Our findings suggest that bee products may serve as a valuable addition to food ingredients, significantly enhancing the functional properties of shortcrust pastry cookies. However, further investigation is necessary to address the increased level of heat-induced compounds.

Molecular insights into genistein-NSAID hybrids—synthesis, characterisation and DFT study

AbstractGenistein (GEN) is one of the pharmaceutically valuable phenolic compounds, which belongs to the isoflavone group of flavonoids and is a natural phytohormone found mainly in soybeans and red clover. It affects estrogen receptors, functioning as a selective estrogen receptor modulator (SERM) with anti-inflammatory and antioxidant activity. The presence of reactive phenolic groups in genistein provides an opportunity to expand its structure by introducing components responsible for anti-inflammatory properties. Such an innovative combination of a compound with anticancer and antioxidant potential with an anti-inflammatory compound (NSAID) may lead to interesting new derivatives with dual mechanisms of biological action. The synthesis and characterisation of genistein-NSAID hybrid compounds (ibuprofen, ketoprofen, naproxen, flurbiprofen) was conducted, together with a comprehensive structural and quantum chemistry DFT (density functional theory) computational analysis allowing the description of 1H-NMR and 13C-NMR spectroscopic properties of the starting compounds and the resulting hybrids. The study resulted in the formation of seven hybrid GEN-NSAID derivatives. In the case of ibuprofen, ketoprofen and flurbiprofen, a mixture of isomeric hybrid GEN-4’-NSAID and GEN-7-NSAID derivatives was obtained, whereas, for naproxen, only GEN-4’-NSAID was formed. The structural characteristics of the resulting compounds were determined using MS, IR, 1H-NMR and 13C-NMR spectroscopic methods. The most accurate DFT computational methods for predicting 1H-NMR and 13C-NMR spectra were also established with statistical parameters to assess their accuracy.

Stability of phenolic antioxidants in coffee leaf beverage during pasteurization

Coffee leaf beverage is prepared from pasteurized Robusta coffee leaves. This work aimed to study the stability of phenolic antioxidants in coffee leaf beverages during pasteurization. Robusta coffee leaves were dried using the smoking method. They contained 6.82 g gallic acid equivalents (GAE)/100 g of total phenolic compounds and 71.15% antioxidant activity. Dried coffee leaves were brewed and pasteurized under different conditions: two different temperatures (70°C and 90°C), two duration of times (15 mins and 30 mins) and two different pH conditions (adjusted and non-adjusted). The total phenolic content and antioxidant activity of pasteurized beverages ranged between 0.48-0.61 g GAE/L and 14.72-18.58%, respectively. Caffeoylquinic acids were stable during pasteurization at 90°C for 30 mins without pH adjustment. Our results indicate that pasteurized coffee leaf beverages may be a potent source of phenolic antioxidants.

Innovative active bio-based food packaging material with Cannabis sativa L. seeds extract as an agent to reduce food waste

In the present study, ethanolic extracts from the extract of unshelled seeds of Cannabis sativa L. were used to produce films in order not to generate additional waste, taking into view a circular economy. Combinations of apple pectin and citrus pectin in a ratio of 80:20 were used. Film samples containing 0.5, 1.0 and 2.5 [wt%] of the extract were extruded. Antimicrobial, mechanical and barrier properties of the obtained films were tested. Samples with 0.5 [wt%] showed a WVTR of 16.98 [g/m2d]. The water vapour barrier properties of the films decreased with an increase in the amount of extract used. As the amount of extract increased, the transparency of the films decreased linearly to 12.84 [%] (0.5 [wt%]), 4.90 [%] (1.0 [wt%]) and 4.99 [%] (2.5 [wt%]). It was observed that the brightness of the samples decreased with increasing concentration, due to the presence of higher levels of phenolic compounds. Tests carried out showed that the prepared films exhibited inhibitory activity against all micrograms tested. All prepared films had antibacterial activity against the Salmonella typhimurium strain. Similarly, in the case of L. monocytogenes.

Chemical Survey and Antifungal Efficacy of Sargassum muticum's Alkaloids and Phenolic-Rich Fraction Against Airborne Toxigenic and Nosocomial Opportunistic Molds Isolates.

The Atlantic coastline of El-Jadida, Morocco, is renowned for its plentiful algae, especially brown seaweed, which is rich in active compounds known for their antifungal properties. This valuable resource offers an exciting opportunity to tackle the numerous challenges posed by invasive fungal infections, allergies, mycotoxin-related food poisoning, and drug-resistant strains. Underscoring the urgent need to explore alternative, sustainable, and environmentally friendly antifungal agents derived from algae. This study aimed to evaluate the antifungal activity of total alkaloids and phenolic-rich fractions derived from seven species of Pheophyceae: Sargassum muticum, Sargassum vulgare, Bifurcaria bifurcata, Cystoseira tamariscifolia, Cystoseira humilis, Laminaria ochroleuca, and Fucus spiralis against four fungi: airborne toxigenic isolates of Aspergillus westerdijkiae and Chaetomium globosum as well as nosocomial opportunistic isolates of Aspergillus nidulans and Scopulariopsis brevicaulis. The study also aimed to identify the most effective alga and its specific active compounds through LC-MS and GC-MS analysis. The invasive Sargassum muticum was chosen as the most potent alga in inhibiting the growth of mycelium. For the first time, the alkaloids palmatine and jatrorrhizine, along with caulerpin, have been identified. The chloroform fraction revealed the prevalence of phenolic compounds including, phenolic acids, flavonoids, and phlorotannins. The lowest minimum inhibitory concentrations (MICs), with a maximum fungal load of 108 colony-forming unit (CFU), recorded ranged from 3.12 to 6.25μg/mL by the phenolic-rich fraction against airborne toxigenic isolates, and from 100 to 200μg/mL against nosocomial opportunistic isolates by the total alkaloids. In comparison, the positive control, ketoconazole, showed higher MICs and resistance against A. nidulans. The valorization of Sargassum muticum is proposed as a green strategy to preserve the ecological balance, combat antifungal resistance, and address public health challenges.

Valorization of Pineapple Core Waste for Sequential Extraction of Phenolic Compounds and Carotenoids: Optimization Through Ultrasound-Assisted Method and Box–Behnken Design

AbstractIn this study, a pioneering cascade method involving ultrasound-assisted extraction (UAE) and Box–Behnken Design (BBD) was optimized to valorize pineapple core waste by the sequential extraction of, firstly phenolic compounds and, secondly, carotenoids. The effectiveness of the extraction was evaluated based on total polyphenol content (TPC) and antioxidant activity using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and ferric reducing antioxidant power (FRAP) assays. Characterization of the carotenoids was performed using high-performance liquid chromatography with a diode array detector (HPLC–DAD). The initial characterization of dry pineapple core (DPC) samples revealed their nutritional composition, including protein, lipid, and carbohydrate weight percentages of 1.20 ± 0.05%, 5.3 ± 0.4%, and 88.6 ± 0.5%, respectively. The high extractives content (40.0 ± 4.5%) suggests a substantial presence of phenolic compounds, making the pineapple core a valuable source of natural antioxidants. The optimal UAE conditions for phenolic compound extraction were 70% amplitude, 5 min extraction time, and 2 cycles, yielding an antioxidant extract rich in phenolic compounds with a desirability value of 81.2%. Therefore, DPC was considered a valuable source of natural antioxidants. The extraction of β-carotene also showed promising results with optimal UAE conditions of 20% amplitude, 3 min extraction time, and 2 cycles. This research promotes the sustainable use of pineapple waste and demonstrates the potential to obtain valuable additives for the food, pharmaceutical, and cosmetic industries, encouraging a more circular and efficient use of resources in the pineapple processing industry.

Characterization of two bacterial tyrosinases from the halophilic bacterium Hahella sp. CCB MM4 relevant for phenolic compounds oxidation in wetlands.

Tyrosinases (TYRs) are type-3 copper proteins that are widely distributed in nature. They can hydroxylate and oxidize phenolic molecules and are mostly known for producing melanins that confer protection against photo induced damage. TYRs are also thought to play an important role in the 'latch mechanism', where high concentrations of phenolic compounds inhibit oxidative decomposition of organic biomass and subsequent CO2 release, especially relevant in wetland environments. In the present study, we describe two TYRs, HcTyr1 and HcTyr2, from halophilic bacterium Hahella sp. CCB MM4 previously isolated at Matang mangrove forest in Perak, Malaysia. The structure of HcTyr1 was determined by X-ray crystallography at a resolution of 1.9 Å and represents an uncharacterized group of prokaryotic TYRs as demonstrated by a sequence similarity network analysis. The genes encoding the enzymes were cloned, expressed, purified and thoroughly characterized by biochemical methods. HcTyr1 was able to self-cleave its lid-domain (LID) in a protease independent manner, whereas the LID of HcTyr2 was essential for activity and stability. Both enzymes showed variable activity in the presence of different metals, surfactants and NaCl, and were able to oxidize lignin constituents. The high salinity tolerance of HcTyr1 indicates that the enzyme can be an efficient catalyst in the habitat of the host.

Stevia By-product Fraction has Antioxidant Capacity and has been Evaluated for its Antihyperglycemic and Antilipid Potential

Introduction/Objective: The ethanolic pretreatment of stevia leaves is considered ecologically favorable and increases its yield, purity level, and sensory profile of sweeteners. We investigated the by-product generated so that we can provide a viable and applicable destination to effectively contribute to the production and industrial chain of stevia sweeteners. Recently, an antioxidant and antidiabetic fraction was obtained through stevia methanolic extraction. However, this process is costly, has a low yield, and is non-green. In this study, we got an antioxidant fraction of stevia from its pretreatment by-product, the ethanolic extract, characterized its bioactive compounds – mainly phenolic acids and flavonoids – and evaluated its antidiabetic and antilipid capacity. Methods: The ethanolic extract was fractionated, then the ethyl acetate fraction was microencapsulated. Physicochemical, Mass Spectrometry (UHPLC/MS-MS), scanning electron microscopy, microencapsulation efficiency, and antioxidant capacity analyses were carried out. The antioxidant capacity was evaluated. Antihyperglycemic capacity was assessed by inhibition of α-glucosidase and α-amylase. For antilipid potential, inhibition of pancreatic lipase was measured. Results: Antioxidant potential was observed mainly in the fraction. Microencapsulation improved the stability of the fraction. Mass spectrometry allowed comparison with phenolic and flavonoid compounds from the methanolic and ethanolic fractions of the by-product. Many compounds were coincident, which may explain the similar antioxidant capacity found. The samples showed more than 90% inhibition of alpha-glucosidase, which may indicate potential antidiabetic activity. All samples showed inhibition of the pancreatic lipase enzyme higher than 80%, reaching 91.05% for the free fraction. Conclusion: This study represented the recovery of a by-product and showed that this antioxidant fraction deserves further investigation for its bioactive potential, especially antioxidant, antidiabetic, and anti-lipid.