Macroelements and Microelements in the Soil and Their Relationship with the Content of Steviol Glucosides in Stevia rebaudiana Bert from Five Regions of Colombia

This study was conducted to determine the effect of edaphic environmental conditions in the concentration of principal steviol glycosides and Stevia rebaudiana Bert yield, utilizing leaves from five Colombian regions. The structure of the experiment was a randomized complete block design with two treatments in a 5 × 2 factorial arrangement (5 locations × 2 radiation levels). In each experimental unit (UE), five healthy plants of similar physiological growth age were selected for the extraction of total glycosides (GT), stevioside (Stv), rebaudioside A (Rb-A),and leaf yield. Results were analyzed with the SAS statistical package (version 9.1). Concentrations of total glycosides and rebaudioside A showed a positive effect with the increase of nitrogen (N), phosphorus (P), magnesium (Mg), and copper (Cu). Therefore, they are important in the available phase of the soil to obtain an increase in these glycosides. Meanwhile, boron (B) presented a negative correlation under these conditions. For the production of stevioside, N, Mg, manganese (Mn) had a positive correlation, and calcium (Ca) and sodium (Na) had a negative correlation. Similarly, for leaf yields by locality, it was found that N, Ca, Mg, and B have a positive correlation with leaf production, while Mg, Mn, and iron (Fe) negatively correlate with biomass gain.The cultivation of stevia can be established in different soil conditions, precipitation and solar radiation in Colombia. Therefore, it is necessary to advance fertilization plans with these nutrients, considering the response of these metabolites to their application.

Stevia rebaudiana Bertoni: The Interaction of Night Interruption on Gas Exchange, Flowering Delay, and Steviol Glycosides Synthesis

The Stevia market is estimated to be USD 1.14 billion in 2028 due to its acceptance in the food and beverage industry. Stevia rebaudiana and its two more relevant edulcorants: stevioside (St) and rebaudioside A (Reb-A) can reach 450-fold sweeter than sucrose. The species is considered a long night plant, promoting flowering and shortening vegetative growth. Thus, to increase the leaf area and St and Reb-A increase, we broke the long night with a short light pulse, here called night interruption (NI). In this study, three NI times and two S. rebaudiana genotypes were tested to promote larger vegetative growth, flowering delay, and higher synthesis of steviol glycosides (SvGly). The main goal of this study was to demonstrate that NI increased net photosynthesis (9% to 20%), the internode length (59%), the leaf area (25%), while delays in 4 to 10 days of the flowering phase, impacting in 17% to 25% more St and Reb-A, respectively. Here we describe an inexpensive flowering delay, elongation of vegetative growth, allowing extended harvesting, which could yield four to five annual harvesting of leaves, increasing the production in 21% to 24% more St and Reb-A yield (kg ha−1).

The effect of methods and drying temperature on glycoside content (Stevioside and Rebaudioside A) in Stevia (Stevia rebaudiana): A systematic review

The utilization of Stevia rebaudiana as an alternative sweetener in Indonesia is still low, this is caused by a lack of information about its processing from raw material until the extraction process to obtain the glycosides content. Glycosides are the sweetener compound in Stevia rebaudiana with a sweet taste up to 300 times of sucrose, which are stevioside and rebaudioside A. To obtain the glycosides content in stevia, stevia needs to be dried after harvest. Then, dried Stevia will be extracted to obtain the glycosides content. The research method used in this study was a systematic review of selected journals on a specific topic, then were analysed in both the theory and content. The purpose of this research is to analysing the effect of drying temperature on different drying methods on the glycoside compound of Stevia rebaudiana, observing drying temperature that is useful to obtain the optimal glycoside compound in Stevia rebaudiana, and to recommend the utilization of Stevia rebaudiana as an alternative sweetener in Indonesia. The result is the high temperature and low temperature can decrease the glycoside compound in Stevia rebaudiana. The dried temperature that is effective for drying stevia leaves to obtain the maximal glycosides is in the range of 40-60°C. The drying method that is effectively used is by an oven at 60°C as the suggested temperature. Stevia’s sweetener is potentially applied and developed in Indonesia and can be served in powder form because it is more efficient and decrease defect in dried condition and a much longer lifetime.

Sequencing Analysis and Enzyme Activity Assay of SrUGT76G1 Revealed the Mechanism Toward on/off Production of Rebaudioside-A in Stevia Plants

Stevia plants is known for its ability to synthesize steviol glycosides (SGs), a natural sweetener blend. Stevioside (STEV) and Rebaudioside-A (Reb-A) are the main SGs. However, Reb-A is more palatable than STEV and shows reduced bitter aftertaste. SrUGT76G1 catalyzes the conversion of STEV to Reb-A, improving their organoleptic properties. The better understanding of the structure/activity of SrUGT76G1 would allow shedding light up on on/off production of Reb-A in stevia plants. Thus, we analyzed the STEV and Reb-A content in stevia leaves of plants from Brazil and Spain and did not find detectable levels of Reb-A in Brazilian samples (off production). For this reason, we used a sequencing tool to study at the genetic and structural level the SrUGT76G1 gene. Changes in key amino acid residues in Brazilian samples were found, such as Leu204Phe, Thr284Leu and Leu126Ile. Leu204Phe mutants can narrow substrate-binding pocket to favor flavonoids recognition and decrease SGs synthesis, while Thr284 is considered key for 1,3-glucosylation of SGs, including Reb-A. These punctual mutations may partly explain the lack of functionality of UGT76G1 enzyme and off production of Reb-A in stevia plants from Brazil. Following this trend, Brazilian samples exhibited a T-to-A substitution, resulting in premature stop codon. As expected, the relative expression of SrUGT76G1 gene showed a higher level in Spanish samples than in Brazilian ones. Collectively, the results presented here show the structure-activity interplay of SrUGT76G1 enzyme and provide new insights on structural features and its role toward Reb-A synthesis.

DEVELOPMENT OF TECHNOLOGY FOR PRODUCING FOOD SWEETENERS FROM STEVIA AND THEIR IMMUNOMODULATING EFFECT

The aim of the study is to develop a technology for the production of food sweetener from stevia (Stevia rebaudiana Bertoni) - a plant of the Asteraceae (Compositae) family, cultivated in Uzbekistan using alcohol extracts. Diterpene glycosides were isolated from the extract - stevioside (1), rebaudioside A (2) and other biologically active substances. Pharmacological studies in mice have shown the presence of an immunostimulating effect in the alcoholic extract and in the individual diterpene glycoside, stevioside (1).

Optimization of Rebaudioside A Extraction from Stevia Rebaudiana (Bertoni) and Quantification by High Performance Liquid Chromatography Analysis

A solid-liquid extraction and an HPLC method for determination of rebaudioside A from the leave parts of Stevia rebaudiana were developed. Separation method consisted of solvent extraction of leaf powder using various solvents like petroleum ether, methanol, diethyl ether and butanol followed by its purification using high performance liquid chromatography in order to obtain bioactive compound rebaudioside A. This solvent selection is very important prior to alternative extraction methods since it can be used as a pre-extraction solvents, main solvents, or co-solvents. The problem of hydrolysable components and solvent removal difficulties in the conventional extraction led us to study further the effects of solvent properties on the conventional extraction using Soxhlet method in order to determine the best solvent or solvent mixture for high extraction yield of S. rebaudiana. The chromatographic separation was realized using a C18 column, mobile phase consisting of methanol: water with UV detection at 210 nm. Based on the yield of extraction and glycosides content, methanol was found to be best solvent.

Drinking Non-nutritive Sweetness Solution of Sodium Saccharin or Rebaudioside a for Guinea Pigs: Influence on Histologic Change and Expression of Sweet Taste Receptors in Testis and Epididymis

Saccharin sodium and rebaudioside A are extensively used as non-nutritive sweeteners (NNSs) in daily life. NNSs elicit a multitude of endocrine influences on animals, differing across species and chemically distinct sweeteners, whose exposure induce activation of sweet taste receptors in oral and extra-oral tissues with consequences of metabolic changes. To evaluate the influence of NNSs on histologic change and expression of sweet taste receptors in testis and epididymis of young male guinea pigs, thirty 4-week-old male guinea pigs with body weight 245.73 ± 6.02 g were randomly divided into five groups (n = 6) and received normal water (control group) and equivalent sweetness low dose or high dose of sodium saccharin (L-SS, 1.5 mM or H-SS, 7.5 mM) or rebaudioside A (L-RA, 0.5 mM or H-RA, 2.5 mM) solution for 28 consecutive days. The results showed that the relative testis weight in male guinea pig with age of 56 days represented no significant difference among all groups; in spite of heavier body weight in L-SS and H-RA, NNS contributes no significant influence on serum testosterone and estradiol level. Low-dose 0.5 mM rebaudioside A enhanced testicular and epididymal functions by elevating the expressions of taste receptor 1 subunit 2 (T1R2) and gustducin α-subunit (GNAT3), and high-dose 7.5 mM sodium saccharin exerted adverse morphologic influences on testis and epididymis with no effect on the expression of T1R2, taste receptor 1 subunit 2 (T1R3), and GNAT3. In conclusion, these findings suggest that a high dose of sodium saccharin has potential adverse biologic effects on the testes and epididymis, while rebaudioside A is a potential steroidogenic sweetener for enhancing reproductive functions.