Search Results (150)

A novel steviol glycoside, Rebaudioside D17, was identified from the leaf extract of Stevia rebaudiana Bertoni. This compound features a rare β-1→4 glycosidic linkage between two glucose units at the C19 position, distinguishing it from its structural isomer, Rebaudioside D. The aim of this study was to isolate and characterize Rebaudioside D17 and investigate its biosynthetic origin. The compound was isolated and structurally characterized using comprehensive NMR spectroscopy including ¹H, ¹³C, COSY, NOESY, Heteronuclear Single Quantum Coherence–Distortionless Enhancement by Polarization Transfer (HSQC-DEPT), Heteronuclear Multiple Bond Correlation (HMBC), Heteronuclear Single Quantum Coherence–Total Correlated Spectroscopy (HSQC-TOCSY), along with mass spectrometry analysis. A tentative biosynthetic pathway is proposed, involving Rebaudioside E19, a putative intermediate bearing the same β-1→4 glycosidic linkage at C19. Rebaudioside E19 may serve as a common precursor to both Rebaudioside D17 and Rebaudioside U3, a minor steviol glycoside previously reported in Stevia rebaudiana leaf extract, which also contains the same β-1→4 glycosidic linkage. The discovery of Rebaudioside D17 expands the known diversity of steviol glycosides and provides new insights into glycosylation patterns in Stevia rebaudiana, which may support the development and production of novel sweeteners with improved sensory and physicochemical properties. Full article

Salt stress is one of the most harmful abiotic stresses that strongly affects plant growth and crop yield, limiting agricultural production across the Mediterranean area. Consequently, there is a growing need to identify resilient crops capable of adapting to saline conditions and enhancing desirable qualitative traits through a wide spectrum of physiological, biochemical, and molecular mechanisms. Therefore, this study aimed to investigate the effects of four different NaCl concentrations (0, 12.5, 25, and 50 mM) on the growth rates, biometric and productive characteristics, leaf gas exchange, and biochemical traits of Stevia rebaudiana Bertoni plants grown hydroponically (in a floating raft system) in a glasshouse. The results showed that NaCl-treated plants exhibited reduced growth parameters and productivity and a lower content of photosynthetic pigment content compared to the control. On the other hand, an increase in antioxidant capacity was observed due to the significant accumulation of total phenols and flavonoids, especially when stevia plants were treated with 50 mM NaCl. Similarly, the leaf concentration of ascorbic acid and glutathione remarkably increased. This provides new insight into the antioxidant defense strategy of S. rebaudiana under salt stress, demonstrating that stevia plants rely mainly on non-enzymatic mechanisms to counter oxidative stress. Although the highest salinity level (50 mM NaCl) resulted in the lowest content of steviol glycosides (stevioside + rebaudioside A), plants treated with 25 mM NaCl showed both the highest rebaudioside A content and Reb A/Stev ratio, which are desirable properties for the production of high-quality natural sweeteners. Overall, these findings underline that stevia can be considered a moderately salt-tolerant species, and mild stress conditions are able to promote the biosynthesis of interesting secondary metabolites, such as polyphenols and rebaudioside A. Full article

The Cutting Development Chamber (CDC) design is presented as an innovative solution to crucial human challenges, such as food and plant medicinal production. Unlike conventional propagation chambers, the CDC is a much more comprehensive research tool, specifically designed to optimize plant reproduction from cuttings. It maintains precise control over humidity, temperature, and lighting, which are essential parameters for plant development, thus maximizing the success rate, even in difficult-to-propagate species. Its modular design is one of its main strengths, allowing users to adapt the chamber to their specific needs, whether for research studies or for larger-scale propagation. The most distinctive feature of this chamber is its ability to collect detailed, labeled data, such as images of plant growth and environmental parameters that can be used in artificial intelligence tasks, which differentiate it from chambers that are solely used for propagation. A study that validated and calibrated the chamber design using cuttings of various species demonstrated its effectiveness through descriptive statistics, confirming that CDC is a powerful tool for research and optimization of plant growth. In validation experiments (Aloysia citrodora and Stevia rebaudiana), the system generated 6579 labeled images and 67,919 environmental records, providing a robust dataset that confirmed stable control of temperature and humidity while documenting cutting development. Full article

Introduction: Stevia rebaudiana Bertoni has recently gained significant attention due to the presence of intensely sweet yet low-calorie steviol glycosides (SGs) in its leaves, making it a promising natural sugar alternative with applications in the food, pharmaceutical, and cosmetics industries. The primary goal of this study was to determine whether generating somaclonal variation from plant material obtained by indirect regeneration results in further genetic changes identifiable using the SCoT marker (Start Codon Targeted). Methods: In the first stage, callus tissue was initiated from first-generation somaclones on MS medium supplemented with 4.0 mg/L 6-benzylaminopurine (BAP), 2.0 mg/L 1-naphthaleneacetic acid (NAA), and 2.0 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D). Their morphogenetic potential was analyzed on four media with different BAP and Kinetin concentrations. Donor plants, first and second generation somaclones, were also analyzed for genetic diversity using SCoT markers. Results: All first-generation somaclones demonstrated a very high callus initiation capacity, ranging from 95 to 100%. It was found that for most of the studied somaclones, the greatest number of shoots were developed by explants grown in a medium supplemented with 0.5 mg/L BAP and 0.25 mg/L Kin. The studied group of somaclones exhibits a high degree of polymorphism (55.2%). The analysis of genetic similarity of somaclones presented in the form of individual dendrograms indicates that in most cases, greater genetic diversity was revealed as a result of indirect regeneration in the first generation of somaclones compared to the second. Indirect organogenesis allows for the production of subsequent generations of genetically unstable somaclones, creating the potential for obtaining new phenotypic variants useful in plant breeding. 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

Background: Potential advantages for improving plant growth, stress tolerance, and valuable metabolites generation are provided by the implementation of nanotechnology into plant biotechnology. A recently discovered technique with significant promise for agricultural practices is the use of biopolymer-based nanomaterials, like peptidomimetics, as insecticides, growth regulators, and nutrient carriers. This study explores the impact of biopolymer-based organic nanofibers—specifically peptidomimetics formed through the self-assembly of L-valine and nicotinic acid (NA) (denoted as M6) on Stevia rebaudiana in vitro propagation and specialized metabolite production. The central hypothesis was that such nanofibers, particularly when used as hormone carriers, can beneficially influence plant morphology, physiology, and biochemistry, thereby promoting the synthesis of antioxidant compounds with therapeutic potential. Methods: The nanofibers were tested either alone (M6) or as carriers of the plant hormone indole-3-acetic acid (IAA) (M6+IAA), supplemented to the cultivation MS medium at variable concentrations (0, 1, 10, and 50 mg L⁻¹). Results: The results revealed that treatment with 10 mg L⁻¹ M6 significantly enhanced shoot growth parameters, including the highest fresh weight (0.249 g), mean shoot height (9.538 cm), shoot number (1.95), and micropropagation rate. Plants treated with M6 alone outperformed those treated with M6+IAA in terms of shoot growth, total soluble sugars, and steviol glycoside content. Conversely, M6+IAA treatment more effectively promoted root initiation, the increased accumulation of mono- and dicaffeoylquinic acids, and boosted antioxidant enzyme activity. Conclusions: These findings highlight the potential of organic nanofibers, both with and without hormone loading, as novel tools for optimizing micropropagation and metabolite enhancement in Stevia rebaudiana. Full article

In this study, Stevia rebaudiana biomass was hydrothermally carbonized (HTC) at 215 °C for 60 min with acrylic acid (AA) as a catalyst at concentrations of 0.25, 0.50, and 1.00 mol L⁻¹. The maximum hydrochar yield (48.5%) was obtained at 0.25 mol L⁻¹ AA, while fixed carbon contents ranged from 20.79% to 34.27%. Higher heating values (HHV) varied between 26.95 and 36.61 MJ kg⁻¹, with the highest catalytic HHV (32.20 MJ kg⁻¹) achieved at 1.00 mol L⁻¹ AA (HC15). Acrylic acid addition significantly promoted deoxygenation, reducing the O/C ratio from 0.67 in raw biomass to 0.21, thereby improving fuel quality. FT-IR and XRD analyses indicated enhanced aromatization and partial graphitization with increasing acid concentration, while SEM images revealed carbon microspheres and porous morphologies. Thermogravimetric analysis showed that HC15 exhibited the lowest mass loss and highest residual carbon, indicating superior thermal stability. GC-MS analysis demonstrated that acrylic acid markedly increased phenolic derivatives, with phenol content rising from 19.47% (without catalyst) to 40.92% (1.00 mol L⁻¹ AA). The aqueous phase contained TOC values of 14,280–28,728 mg/L and COD values of 43,227–113,920 mg/L. Overall, acrylic acid-assisted HTC enhances both the energy-related properties of hydrochars and the chemical diversity of liquid products, providing a sustainable route for valorizing Stevia rebaudiana waste into value-added fuels and chemicals. Full article

Stevioside, a natural high-intensity sweetener, is widely employed across the food, pharmaceutical, and daily chemical industries due to its intense sweetness and health benefits. However, traditional extraction and purification processes for steviol glycosides from Stevia rebaudiana are plagued by low efficiency, high energy consumption, substantial environmental impact, and inconsistent product quality. This study systematically optimized the extraction, decolorization, decontamination, and desalting processes to overcome these challenges. The extraction method was refined using 20% ethanol as the solvent, an optimal temperature of 50 °C, and a 1:10 material-to-liquid ratio, increasing the steviol glycoside yield from 32.0% to 49.1%. Decolorization employing a combination of resins D940 and T5 achieved decolorization rates of 89–92% with minimized steviol glycoside loss, surpassing the non-selective adsorption limitations of activated carbon. For decontamination, calcium hydroxide (Ca(OH)₂) outperformed diatomaceous earth, attaining a 98% protein removal rate while maintaining steviol glycoside loss below 20%. The desalting resin LXP-016 demonstrated superior performance at 40 °C, enhancing the ability of ionic impurity removal. These optimizations collectively improve the efficiency, sustainability, and quality of steviol glycoside production, offering a promising framework for industrial-scale applications. Full article

Stevia rebaudiana leaves and extracts need to be promptly dried after harvest to prevent microbial activity and preserve their bioactive compounds, including glycosides, flavonoids, and essential oils. Effective drying also reduces moisture and volume, which lowers packaging, storage, and transportation costs. Therefore, innovative drying methods are necessary to maintain stevia’s physicochemical, sensory, and nutritional properties for functional food formulations. This review evaluates various drying technologies for stevia leaves and extracts, including convective hot air, infrared, vacuum, microwave, freeze, and shade drying, and their impacts on product quality and energy efficiency. It also explores the growing applications of dried and extracted stevia in food products. By comparing different drying methods and highlighting the benefits of stevia in these food formulations, this investigation aims to identify future research directions and optimization strategies for utilizing stevia as a natural sweetener and functional ingredient. Convective hot air drying at higher temperatures was found to be the most energy-efficient, though several studies have reported moderate degradation of key bioactive compounds such as stevioside and rebaudioside A, particularly at elevated temperatures and extended drying times. Infrared drying enhanced antimicrobial activity but resulted in lower levels of polyphenols and antioxidants. Vacuum drying effectively preserved anti-inflammatory compounds like flavonoids. Microwave drying presented strong protection of antioxidant activity and superior particle morphology. Freeze drying, while less energy-efficient, was the most effective at retaining antioxidants, polyphenols, and volatile compounds. Shade drying, though time-consuming, maintained high levels of polyphenols, flavonoids, and essential oils. Advanced techniques like spray drying and electrospraying have been reported to enhance the sensory qualities and stability of stevia extracts, making them ideal for food applications such as dairy and baked products, confectionery, syrups, snacks, jams, preserves, and meat products. Overall, stevia not only serves as a natural, zero-calorie sweetener but also contributes to improved health benefits and product quality in these diverse food formulations. Full article

Stevia rebaudiana Bertoni, a semi-perennial herb from the Asteraceae family, is native to the Paraguay–Brazil border region. The growing industrial interest in this species is due to its natural sweetening properties, such as steviol and its derivatives, which offer sweetness without adding calories. Morphological traits are crucial for assessing genetic variability and ensuring distinctness, homogeneity, and stability (DHS) for cultivar protection. This study characterized 19 elite Stevia genotypes from Embrapa Cerrados’ Active Germplasm Bank (BAG) using 21 morphological descriptors from Brazil’s Ministry of Agriculture, Livestock, and Supply (MAPA). Genetic distances were calculated using the simple coincidence index complement method, and clustering was performed via the Unweighted Pair-Group Method with Arithmetic Mean (UPGMA). The results showed that 17 of the 21 descriptors (>80%) effectively differentiated the genotypes, revealing significant genetic variability. Dendrogram analysis identified at least four major similarity groups, highlighting the potential of these genotypes for Stevia breeding programs. These findings underscore the suitability of these elite genotypes for developing superior varieties adapted to Cerrado conditions, supporting future cultivation and genetic improvement efforts. Full article

This Technical Note presents the design and implementation of a low-cost modular growth chamber developed to keep mother plants under controlled environmental conditions for vegetative propagation. The system was conceived as an accessible alternative to expensive commercial equipment, offering reproducibility and adaptability for small-scale and research-based cultivation. The proposed chamber integrates thermal insulation, LED lighting, forced ventilation through the implementation of extractors, a recirculating irrigation system with double filtration, and a sensor-based environmental monitoring platform operated via an Arduino UNO microcontroller. The design features a removable tray that serves as a support for the mother plant, an observation window covered by a movable dark acrylic that prevents the passage of external light, and a vertical structure that facilitates optimal space utilization and ergonomic access. Functionality was conducted using a Stevia rebaudiana Bertoni mother plant maintained for 30 days under monitored conditions. Environmental parameters—temperature, relative humidity, and illuminance—were recorded continuously. The plant showed vegetative development through new shoot emergence and the growth in height of the plant, and despite a loss in foliage expansion, it confirmed the chamber’s capacity to support sustained growth. Although no statistical replication or control group was included in this preliminary evaluation, the system demonstrates technical feasibility and practical utility. This chamber provides a replicable platform for future experimentation and propagation studies. Complete technical specifications, schematics, and component lists are provided to enable replication and further development by other researchers. The growth chamber design aligns with the goals of open-source agricultural innovation and supports knowledge transfer in controlled-environment plant propagation technologies. Full article

A high-fat, high-sugar diet (HFHS) is known to exacerbate oxidative stress and behavioral dysfunctions, increasing susceptibility to cognitive decline. This study aimed to evaluate the effects of Stevia rebaudiana and Stachys sieboldii on lipid peroxidation and behavioral alterations in rats fed an HFHS diet. Forty Wistar rats were divided into four groups: a control group on a standard diet, an HFHS group, and two experimental groups receiving HFHS supplemented with either Stevia or Stachys for 30 days. Behavioral responses were assessed using the Open Field Test, and oxidative stress markers (malondialdehyde, conjugated dienes, ketodienes, and Schiff bases) were measured in brain homogenates. Stevia significantly reduced oxidative stress markers by 30–51%, whereas Stachys decreased hyperactive locomotor behavior by 63–68%. Correlation analysis revealed strong associations between lipid peroxidation and behavioral parameters. These findings suggest that Stevia is more effective in reducing oxidative stress, while Stachys better regulates excessive locomotion. Both plant-based supplements exhibit neuroprotective potential, with distinct mechanisms of action, supporting their use as dietary interventions to mitigate the effects of an HFHS diet on brain function. Full article

Extracts of Stevia rebaudiana are rich in sweet-tasting steviol glycosides (SG), which are widely valued as natural sweeteners. This study investigated the effects of different light conditions on stevia growth and SG production across growth stages using a controlled hydroponic system. Four light conditions were introduced at a low photosynthetic photon flux density of 50 μmol·m⁻²·s⁻¹. Stevia growth was divided into four stages, and leaf weight and SG yield were analyzed. Red light resulted in the highest leaf fresh weights at 23.53 g·plant⁻¹, whereas green light resulted in the lowest at 17.15 g·plant⁻¹, marking a difference of 37.2%. However, green light performed the highest total SG content (LSG) at 190.68 mg·g⁻¹ and total SG yield (YSG) at 39.24 g·m⁻², compared to the lowest LSG under red light at 108.68 mg·g⁻¹ and YSG at 24.76 g·m⁻², derived differences of 75.45% and 58.48%, respectively. These results suggest a trade-off between vegetative growth and SG synthesis. Red light is optimal for early-stage biomass accumulation, while green light and blue light treatments during the last two stages, respectively, may enhance overall SG production. Consequently, the results offered insights into commercial stevia cultivation and the production of SG. Full article