Search Results (162)

α-L-Rhamnosidase can specifically hydrolyze plant natural glycosides and holds significant potential for biocatalytic applications in functional foods, healthy products, and pharmaceutical industries. Herein, a novel thermophilic and acidophilic α-L-rhamnosidase TsRha from Thermotoga sp. 2812B belonging to glycoside hydrolase family 78 was identified by genome mining and comprehensively characterized by bioinformatics, computer-aided structural analysis, and biochemical characterization. TsRha possesses a domain architecture comprising one catalytic (α/α)₆-barrel domain and four β-sheet domains. TsRha displayed optimal activity at 90 °C and pH 5.0, remarkable thermostability at 80 °C, and considerable tolerance to organic solvents. TsRha exhibited broad substrate selectivity and might efficiently hydrolyze a series of natural flavonoid glycosides with various glycosidic bonds (α-1, α-1, 2, α-1, 6) from different aglycone subgroups (flavanone, flavone, flavonol, and dihydrochalcone). Moreover, it demonstrated high conversion efficiencies toward a variety of natural flavonoid diglycosides rutin, naringin, naringin dihydrochalcone, hesperidin, and troxerutin, achieving ≥99.1% conversion within 20~100 min. The excellent properties including high activity, thermophilicity, acidophilicity, good thermostability, broad substrate spectrum will make the α-L-rhamnosidase TsRha a promising biocatalyst for the efficient production of rare and high-value flavonoid glucosides with improved bioavailability and bioactivity. Full article

Propolis is a resinous natural product produced by honeybees from plant exudates and beeswax. Its complex chemical composition varies significantly with geographical origin and seasonal factors. This study aimed to characterize the chemical composition of propolis samples collected from different regions of Latvia using gas chromatography–mass spectrometry (GC-MS). In total, 47 metabolites were identified, with chemical profiles dominated by phenolic acids and their esters—compounds typical of European propolis. Regional variations reflected differences in local vegetation, and two samples exhibited flavonoid constituents indicative of poplar-type botanical sources. The Daugavpils sample, which showed a particularly rich chemical profile, was further fractionated chromatographically, leading to the isolation of twelve metabolites: 2’,4’,6’-trihydroxy-4-methoxy dihydrochalcone, 2’,6’,4-trihydroxy-4’-methoxy dihydrochalcone, 2’,6’-dihydroxy-4,4’-dimethoxy dihydrochalcone, 2’,6’-dihydroxy-4’-methoxy dihydrochalcone, 2’,4’,6’-trihydroxy dihydrochalcone, palmitic acid, benzyl benzoate, cinnamyl cinnamate, pinostrobin, pinostrobin chalcone, pinocembrin, and pinobanksin. Given the limited prior research on Latvian propolis, this study provides valuable insights into its chemical diversity and the influence of regional flora on its composition. Full article

This study presents a comprehensive analysis of the polyphenolic profiles of six red prickly pear varieties across eight ripening stages, employing liquid chromatography and machine learning. We identified 29 phenolic compounds, including flavonols, phenolic acids, flavan-3-ols, and dihydrochalcones. The ‘Grifa’ variety showed a robust biosynthesis pathway, indicating higher antioxidant potential. Notably, significant variety-specific variations were observed, particularly in hydroxycinnamic and hydroxybenzoic acids, suggesting genetic influences on phenolic biosynthesis. The Random Forest algorithm was effectively used for classifying fruit varieties and ripening stages, with key metabolites like chlorogenic acid playing a crucial role in differentiation. The study highlights the dynamic nature of phenolic metabolism in red prickly pear fruit and underscores the potential of machine learning in agricultural research. Our findings contribute significantly to understanding the phenolic composition of these fruits, offering valuable insights for agricultural practices and nutritional evaluations, as well as highlighting their potential as sources of antioxidants. Full article

Phlorizin (PHZ) is a glucoside of phloretin, belonging to the dihydrochalcone class within flavonoids; It is one of the active ingredients of the plant Cynomorium, and it has been shown that PHZ can regulate lipid metabolism disorders as well as having anti-aging properties. However, no studies have investigated whether PHZ ameliorates Aβ-induced toxicity in Alzheimer’s disease (AD) by regulating fatty acid β-oxidation. This study aims to investigate the effects of PHZ on the regulation of fatty acid β-oxidation and resistance to Aβ-associated toxicity on the AD Caenorhabditis elegans and the mechanisms of action. Wild-type N2 and AD model CL4176 C. elegans were used; lifespan, heat stress resistance, chronic paraquat stress, reactive oxygen species (ROS), behavioral performance, and lipofuscin accumulation assays were examined to evaluate the anti-aging effects; and non-esterified fatty acid (NEFA), triglyceride (TG) and lipidomic contents were quantified after PHZ treatment. The detection of genes related to fatty acid β-oxidation pathways was performed using qRT-PCR. nhr-49 knockout mutant RB1716; and GFP-binding mutants PMD150 WBM170 were used to observe the effect of PHZ on NHR-49 pathways, and molecular docking studies were performed by combining PHZ with NHR-49 proteins. Results showed that PHZ improved worms’ survival and delayed senescence, as demonstrated by enhanced performance in lifespan, heat stress, ROS, and paraquat assays and chronic paraquat assays; PHZ also reduced lipid accumulation in worms, affected the unsaturated fatty acid pathway, and significantly increased the expression of fatty acid metabolism-related genes nhr-49, acs-2, and cpt-5, and can be tightly coupled to NHR-49 targets. PHZ may play an anti-Aβ toxicity role by regulating lipid metabolism disorders through the NHR-49—related pathway and anti-aging in AD worms. Full article

This study investigates the impact of light exposure on the biotransformation of chalcones in yeast cultures. 4′-Hydroxychalcones, with a hydroxyl group in the A-ring, are characteristic substrates efficiently converted into 4′-hydroxydihydrochalcones—compounds naturally occurring in medicinal plants such as Glycyrrhiza glabra (licorice), Stevia rebaudiana, and Angelica keiskei (ashitaba). These compounds are valued for their bioactivity and are relevant to natural product research. In this research, we present the outcomes of the selective microbial reduction of chalcones to dihydrochalcones using the yeast Yarrowia lipolytica KCh 71, cultivated under both light and dark conditions. The aim was to determine whether light exposure affects the efficiency or selectivity of the transformation. Furthermore, the effect of substrate photoisomerisation induced by light was investigated, as the trans–cis isomerisation of chalcones may affect their availability and affinity toward enzymatic systems. The resulting metabolites were analysed using chromatographic and spectroscopic methods. No significant differences in transformation efficiency were observed between light and dark conditions. In all tested conditions, the 4′-hydroxydihydrochalcones were obtained with high yield, typically exceeding 90% conversion. Additionally, the selective bioreduction of the α,β-unsaturated bond in selected 4′-hydroxychalcones by the studied yeast culture is an exceptionally efficient process. The primary factor influencing the reaction rate is the structure of the substrate, particularly the number and distribution of methoxyl groups on the B-ring. In addition, we establish biocatalytic access to three target dimethoxy dihydrochalcones—4′-hydroxy-2,4-dimethoxydihydrochalcone (5a), 4′-hydroxy-2,5-dimethoxydihydrochalcone (6a), and 4′-hydroxy-3,5-dimethoxydihydrochalcone (7a)—under mild conditions using Yarrowia lipolytica KCh 71. Under preparative-scale conditions (7-day incubation), a minor additional product (≤10%) was detected only for the 4′-hydroxy-2,5-dimethoxydihydrochalcone transformation and identified as 4′,5-dihydroxy-2-methoxydihydrochalcone (6b); no such side reaction was observed in short-term experiments. Full article

Lithocarpus litseifolius, a traditional sweet tea rich in dihydrochalcones, relies on plant nutrients for secondary metabolite accumulation. However, nutrient distribution patterns during leaf development and its relationship with secondary metabolites remain inadequately characterized. This study examined mineral elements, carbon and nitrogen metabolites, and primary dihydrochalcones in L. litseifolius leaves at various developmental stages, and analyzed their interrelationships. Mineral nutrients such as phosphate (P), potassium (K), magnesium (Mg), zinc (Zn), boron (B), and copper (Cu), along with trilobatin, were most abundant in the youngest leaves. Conversely, calcium (Ca), iron (Fe), sulfur (S), manganese (Mn), selenium (Se), sugars, soluble protein, amino acids, chlorophyll, and carotenoids predominantly accumulated in old leaves, paralleling the distribution of phlorizin. Nitrogen (N) and molybdenum (Mo) concentrations were higher in mature leaves. In young leaves, P, K, Mg, S, Mn, Zn, and B positively correlated with phlorizin and trilobatin, while N, chlorophyll, carotenoids, and fructose correlated negatively. Trilobatin was the primary contributor to hydroxyl radical (·OH) scavenging capacity. Redundancy analysis highlighted N, P, Mg, B, Zn, Cu, Fe, Mo, and Se as key mineral nutrients influencing phlorizin and trilobatin accumulation. These findings offer insights for mineral nutrient management and effective utilization of L. litseifolius. Full article

Porphyromonas gingivalis is a key periodontal pathogen whose cysteine proteases, gingipains (Rgp and KGP), are essential for nutrient acquisition and virulence. Targeting gingipains may attenuate bacterial pathogenicity and prevent related systemic diseases. This paper aimed to review advances in food-derived natural products that inhibit P. gingivalis or gingipains, with emphasis on mechanisms, potency, and translational potential. A literature search of several databases identified 64 studies on food-derived compounds demonstrating in vitro, in vivo, or clinical effects against P. gingivalis or gingipains. The results showed that tea polyphenols and dihydrochalcones (e.g., phloretin and phlorizin) inhibited gingipain activity, and a variety of food-derived natural products (especially polyphenols and polysaccharides) suppressed the growth, survival, biofilm formation, and virulence of P. gingivalis. Structure–activity relationships suggest galloyl moieties and dihydrochalcone scaffolds enhance gingipain inhibition. Polysaccharides and alkaloids exhibited anti-adhesion or protease inhibition, though with limited potency data. In summary, food-derived natural products represent promising gingipain inhibitors. These inhibitors have potential structure–activity relationships, indicating that food-derived natural products have considerable research prospects. Future research should prioritize structure-based discovery and structure optimization to realize their therapeutic potential. Full article

Aizoon africanum (L.) Klak (Synonym Galenia africana L.) is traditionally used for a variety of medicinal purposes; however, it has been reported to cause liver damage and severe ascites, particularly in sheep and Angora goats in the arid regions of the Western Cape. This study explores its cytotoxic properties to identify potential cytotoxic compound(s) in the plant. The methanolic extract of A. africanum was re-investigated and subjected to various chromatographic techniques, including preparative HPLC, resulting in the isolation of eight compounds (1–8). Structural elucidation was primarily based on NMR data. Among the isolated compounds, four were flavanones, one was a flavonone, and three were chalcones. Notably, compound 8 was identified as a new chalcone, while compounds 2 and 3 were reported for the first time from this plant. The toxicity of these isolated compounds was evaluated against the HepG2 and SH-SY5Y cancer cell lines using the MTT assay. We further investigated markers of cell death using spectrophotometric and luminometric methods. Among the isolated compounds, 7 and 8 exhibited cytotoxic activities within the range of 3.0–20.0 µg/mL. Notably, the compounds demonstrated greater cytotoxicity towards liver-derived HepG2 cells compared to the neuronal SH-SY5Y cell line. Compound 7 (2′,4′-dihydroxychalcone) was identified as inducing apoptosis through the intrinsic pathway without causing overt necrosis. The findings indicate that the phytochemicals derived from A. africanum exhibit differential cytotoxic effects based on cell type, suggesting potential for developing novel anticancer agents, particularly compound 7. Additionally, the identification of compound 8 provides insight into the liver toxicity of this plant observed in sheep in South Africa. Full article

The excessive use of synthetic pesticides has not only resulted in increased resistance among weeds and pests, leading to significant economic loss, but has also raised serious health and environmental concerns. Chalcones and their derivatives, known for their herbicidal, fungicidal, bactericidal, and antiviral properties, are emerging as promising bio-based candidates. These naturally occurring compounds have long been recognized for their beneficial health effects and wide-range applications. However, their limited concentration in plants, along with poor solubility and bioavailability, brings challenges for their development. The aim of this study was to examine the properties of a synthetic substance, pinocembrin dihydrochalcone (3-phenyl-1-(2,4,6-trihydroxyphenyl)-1-propanone), including its soil dissipation and adsorption. Additionally, we evaluated its antioxidant activity through the DPPH assay and FRAP experiments. This analysis aims to provide insights into its potential classification as a low risk pesticide. Full article

The browning of fruit juices and nectars is a common issue in the beverage industry and is a particular problem in strawberry nectars, where it significantly reduces the shelf-life. Polyphenol oxidases (PPOs), which are multicopper enzymes responsible for the oxidation of a wide plethora of polyphenols in plants, have been widely assumed to be involved in the enzymatic browning of strawberry nectar. To investigate the possible involvement of PPOs, the substrate specificity of four recombinant PPOs and their gene expression pattern in 10 cultivars of Fragaria × ananassa at five ripening stages were determined. This allowed us to obtain adequate amounts of enzymes to study them independently and without interfering matrix effects. All four PPOs possess monophenolase activity, which was particularly high for PPO4. PPO3 did not show sufficient stability for the kinetic studies. The other three showed a high preference for the flavan 3-ol catechin with a 2-fold higher catalytic efficiency compared to dopamine for PPO1 and PPO2. At a neutral pH, they also showed activity with cyanidin but not with pelargonidin, which is the prevalent anthocyanidin type in strawberry. The enzymes showed a high affinity but only low turnover rates for the dihydrochalcone phloretin, resulting in an inhibitory effect that was strong enough to extend the shelf-life of the strawberry nectar by one week if phloretin was added in high concentrations (600 µM). PPO1 and PPO2 were prevalently expressed in all fruit stages. The gene expression of the four PPOs did not correlate with the color stability of the nectars of the 10 varieties and also showed a random expression pattern during fruit development. The limited activity in acidic conditions and the low substrate specificity for pelargonidin does not point to a crucial role for PPOs in the browning of strawberry nectar, but the high catalytic efficiency with catechin as a substrate could contribute to anthocyanin degradation via mechanisms such as copolymerization. Full article

Background:Sweet Tea (Lithocarpus polystachyus Rehd.), a traditional ethnobotanical medicine, contains phlorizin, a dihydrochalcone compound with antioxidative and anti-inflammatory properties. Given the critical role of oxidative stress and inflammation in age-related macular degeneration (AMD), this study tested the hypothesis that phlorizin mitigates oxidative damage and inflammation in AMD models, thereby offering therapeutic potential. Materials and Methods: Adult retinal pigmented epithelial cells (ARPE-19) were pre-treated with phlorizin (0.01–0.1 μM) and subjected to oxidative stress induced by ultraviolet A (UVA) radiation or sodium iodate (NaIO₃). Cell viability, reactive oxygen species (ROS) production, MAPK/NF-κB signaling, and the level of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) and pro-angiogenic factors (VEGF, MMP2, MMP9) expression were assessed using MTT assays, fluorescence imaging, Western blotting, and RT-qPCR. In vivo, a laser-induced choroidal neovascularization (CNV) mouse model was used to evaluate phlorizin’s effects on CNV formation and vascular leakage via fundus photography and fluorescence angiography. Result: Phlorizin significantly enhanced cell viability, reduced ROS production, inhibited MAPK/NF-κB activation, and downregulated inflammatory and angiogenic mediators. In vivo studies confirmed the reduced CNV formation and vascular leakage following the phlorizin treatment. Conclusions: Phlorizin demonstrated significant protective effects against oxidative stress and inflammation, highlighting its therapeutic potential for treating AMD. Full article

The genotypes of red-fleshed apples can vary in the intensity of red color and other fruit quality parameters. Crossing red-fleshed apple genotypes may lead to the development of new genotypes with increased health properties desired by apple processors. For fruit samples belonging to 5 genotypes, such as the cultivar ‘Trinity’ and four clones (90, 120, 156, and 158), image textures and the contents of sucrose, fructose, glucose, sorbitol, total sugars, L-ascorbic acid, malic acid, citric acid, and phenolic compounds were measured. Five groups of polyphenols, namely, flavanols, dihydrochalcones, anthocyanins, flavonols, and phenolic acids, were determined. The correlations between the chemical and image properties of apple samples were determined. The regression equations to estimate the chemical compounds content in red-fleshed apple samples based on image features were set. Generally, the results revealed that red-fleshed apple clones and a cultivar can statistically significantly differ in the content of phenolic compounds, sugars, and acids. Strong relationships between all examined chemical parameters with selected image texture features were observed. The highest correlation coefficients were found between citric acid with texture ZS5SH3Correlat (R = −0.999), total flavanols with RS5SH5Correlat (R = 0.999), quercetin-xyloside (group of flavonols) with XS5SH5Entropy (R = 0.999), and total sugars with GS5SH1SumVarnc (R = −0.998). The developed regression equations allowed for correct estimations of acid, sugar, and phenolic compound contents based on image textures with the coefficients of determination (R²) reaching 0.998 for citric acid, total flavanols, and quercetin-xyloside, and 0.996 for total sugars. Full article

Many specialized metabolites found in plants have significant potential for developing environmentally friendly weed management solutions. This review focuses on the phytotoxic effects of volatile terpenes and phenolic compounds, particularly nepetalactone, an iridoid monoterpenoid from Nepeta species, and phloretin, a dihydrochalcone predominantly found in the genus Malus. We highlight current findings on their herbicidal effects, including morphological, physiological, and biochemical responses in target plants. These results underscore their potential for developing sustainable herbicides that could control weeds with minimal environmental impact. We also discuss their soil persistence and methods to enhance their solubility, chemical stability, and bioavailability. Additionally, the possible effects on non-target organisms, such as pollinators, non-pollinating insects, and soil microbiota, are considered. However, further research and a deeper understanding of their long-term ecological impact, along with a resistance development risk assessment, is essential for the potential development of bioherbicides that could be applied in sustainable weed management practices. Full article

α-L-rhamnosidases play a key role in the metabolism and biodegradation of dietary flavonoid glycosides. We have developed a novel microplate spectrophotometric method to rapidly evaluate the conversion rates and substrate selectivities of mesophilic α-L-rhamnosidases towards citrus flavanone diglycosides by combining with a high-active and thermophilic β-D-glucosidase based on UV-visible spectral differences between citrus flavanone diglycosides and the corresponding aglycones under alkaline conditions. Furthermore, catalytic activities and enzyme kinetics of four α-L-rhamnosidases from human gut bacteria on various dietary flavonoid glycosides with different glycosidic bonds from various subclasses have been explored by HPLC. The α-L-rhamnosidase BtRha78A specifically removed the rhamnose group from the flavones, flavanones and flavonols diglycosides with the α-1,6 glycosidic bonds. Moreover, BtRha78A displayed higher catalytic activities on the rutinose group at 7-OH of the aglycones than at 3-OH. HFM-RhaA preferred to catalyze the flavones, flavanones and dihydrochalcones diglycosides with the α-1,2 glycosidic linkages at the 7-OH. However, this enzyme also showed high catalytic activity on the flavonol diglycoside rutin with the α-1,6 glycosidic bonds at the 3-OH. HFM-RhaC exhibited certain hydrolytic abilities towards all flavonoid diglycosides, and displayed higher activities on the flavonoid diglycosides with the α-1,6 glycosidic bonds. HFM-Rha78 weakly hydrolyzed the flavones, flavanones and dihydrochalcones diglycosides with the α-1,2 glycosidic bonds, and the flavonols diglycosides with α-1,6 glycosidic bonds. All four α-L-rhamnosidases from human gut bacteria did not exhibit catalytic activity towards the flavonoid glycosides with the α-1 glycosidic bonds. It was revealed that the α-L-rhamnosidases from human gut bacteria possessed diverse substrate selectivity on dietary flavonoid diglycosides. The structural basis for the specificity of BtRha78A on the flavonoid diglycosides with α-1,6 glycosidic bonds and the preference of HFM-RhaA on the flavonoid diglycosides with α-1,2 glycosidic bonds have been analyzed by molecular docking. Full article

Annatto (Bixa orellana L.) is cultivated primarily for the extraction of bixin, a natural dye with substantial industrial importance, resulting in the generation of large quantities of residues that remain underutilized. This study provides the first in-depth characterization of annatto byproducts derived through molecular distillation, highlighting their untapped potential for sustainable innovation. Employing state-of-the-art techniques—HS-SPME-GC-MS for volatile compounds and UPLC-MS/QTOF for non-volatile ones—the research identified a remarkable array of bioactive constituents. Over thirty pharmacologically significant compounds were unveiled, many appearing for the first time in annatto byproducts. Notable discoveries include diterpenoid alcohols, oleamide, δ-tocotrienol, n-alkanes, fatty acid methyl esters, and springene among the volatiles. Among the non-volatiles, groundbreaking identifications such as dihydroactinidiolide, dihydrochalcone, 3-phenyl propiofenone, novel tetracosan amides, halisphingosine A, kauranetriols, and phytoene derivatives redefine the chemical profile of this residue. Further amplifying the value of these findings, the study successfully transformed these byproducts into innovative antioxidant packaging materials, demonstrating their high potential for food preservation and sustainable applications. The packaging films, developed from samples devoid of vegetable oil, exhibited robust antioxidant properties, offering a compelling solution to extend shelf life and reduce spoilage. This work underscores the importance of revalorizing agricultural residues like annatto byproducts, turning waste into high-value resources that align with the principles of the circular economy. Full article