A review of the state of sweeteners science: the natural versus artificial non-caloric sweeteners debate. Stevia rebaudiana and Siraitia grosvenorii into the spotlight.

The rapid increase in the worldwide prevalence of obesity and certain non-communicable diseases (NCDs), such as: cardiovascular diseases, cancers, chronic respiratory diseases, and diabetes, has been mainly attributed to an excess of sugar consumption. Although the potential benefits of the synergetic use of sweeteners have been known for many years, recent development based on synthesis strategies to produce sucrose-like taste profiles is emerging where biocatalyst approaches may be preferred to produce and supply specific sweetener compounds. From a nutritional standpoint, high-intensity sweeteners have fewer calories than sugars while providing a major sweet potency, placing them in the spotlight as valuable alternatives to sugar. Due to the modern world awareness and incidence of metabolic diseases, both food research and growing markets have focused on two generally regarded as safe (GRAS) groups of compounds: the sweet diterpenoid glycosides present on the leaves of Stevia rebaudiana and, more recently, on the cucurbitane triterpene glycosides present on the fruits of Siraitia grosvenorii. In spite of their flavor advantages, biological benefits, including: antidiabetic, anticancer, and cardiovascular properties, have been elucidated. The present bibliographical review dips into the state-of-the-art of sweeteners and their role in human health as sugar replacements, as well as the biotransformation methods for steviol gylcosides and mogrosides apropos of enzymatic technology to update and locate the discoveries to date in the scientific literature to help boost the continuity of research efforts of the ongoing sweeteners.

Comparison of a Daily Steviol Glycoside Beverage compared with a Sucrose Beverage for Four Weeks on Gut Microbiome in Healthy Adults.

BACKGROUND: Recent studies suggest that some nonnutritive sweeteners (NNS) have deleterious effects on the human gut microbiome (HGM). The effect of steviol glycosides on the HGM has not been well studied. OBJECTIVE: We aimed to evaluate the effects of stevia- compared with sucrose-sweetened beverages on the HGM and fecal short-chain fatty acid (SCFA) profiles. METHODS: Using a randomized, double-blinded, parallel-design study, n = 59 healthy adults [female/male, n = 36/23, aged 31±9 y, body mass index (BMI): 22.6±1.7 kg/m2] consumed 16 oz of a beverage containing either 25% of the acceptable daily intake (ADI) of stevia or 30 g of sucrose daily for 4 weeks followed by a 4-week washout. At weeks 0 (baseline), 4, and 8, the HGM was characterized via shotgun sequencing, fecal SCFA concentrations were measured using ultra-high performance liquid chromatography-tandem mass spectrometry and anthropometric measurements, fasting serum glucose, insulin and lipids, blood pressure, pulse, and 3-d diet records were obtained. RESULTS: There were no significant differences in the HGM or fecal SCFA between the stevia and sucrose groups at baseline (P > 0.05). At week 4 (after intervention), there were no significant differences in the HGM at the phylum, family, genus, or species level between the stevia and sucrose groups and no significant differences in fecal SCFA. At week 4, BMI had increased by 0.3 kg/m2 (P = 0.013) in sucrose compared with stevia, but all other anthropometric and cardiometabolic measures and food intake did not differ significantly (P > 0.05). At week 8 (after washout), there were no significant differences in the HGM, fecal SFCA, or any anthropometric or cardiometabolic measure between the stevia and sucrose groups (P > 0.05). CONCLUSIONS: Daily consumption of a beverage sweetened with 25% of the ADI of stevia for 4 weeks had no significant effects on the HGM, fecal SCFA, or fasting cardiometabolic measures, compared with daily consumption of a beverage sweetened with 30 g of sucrose. TRIAL REGISTRATION: clinicaltrials.gov as NCT05264636.

Chemical Analysis and Antidiabetic Potential of a Decoction from Stevia serrata Roots.

A decoction of the roots (31.6-316 mg/kg) from Stevia serrata Cav. (Asteraceae) as well as the main component (5-150 mg/kg) showed hypoglycemic and antihyperglycemic effects in mice. The fractionation of the active extract led to the isolation of dammaradiene acetate (1), stevisalioside A (2), and three new chemical entities characterized by spectroscopic methods and named stevisaliosides B-D (3-5). Glycoside 2 (5 and 50 mg/kg) decreased blood glucose levels and the postprandial peak during oral glucose and insulin tolerance tests in STZ-hyperglycemic mice. Compounds 1-5 were tested also against PTP1B1-400 and showed IC50 values of 1180.9 ± 0.33, 526.8 ± 0.02, 532.1 ± 0.03, 928.2 ± 0.39, and 31.8 ± 1.09 µM, respectively. Compound 5 showed an IC50 value comparable to that of ursolic acid (IC50 = 30.7 ± 0.00 µM). Docking studies revealed that 2-5 and their aglycones bind to PTP1B1-400 in a pocket formed by the C-terminal region. The volatilome of S. serrata was characterized by a high content of (E)-longipinene, spathulenol, guaiadiene, seychellene, and aromandendrene. Finally, a UHPLC-UV method was developed and validated to quantify the content of 2 in the decoction of the plant.

Transcriptomic Analyses Reveal Insights into the Shared Regulatory Network of Phenolic Compounds and Steviol Glycosides in Stevia rebaudiana.

Stevia rebaudiana (Bertoni) is a highly valuable crop for the steviol glycoside content in its leaves, which are no-calorie sweeteners hundreds of times more potent than sucrose. The presence of health-promoting phenolic compounds, particularly flavonoids, in the leaf of S. rebaudiana adds further nutritional value to this crop. Although all these secondary metabolites are highly desirable in S. rebaudiana leaves, the genes regulating the biosynthesis of phenolic compounds and the shared gene network between the regulation of biosynthesis of steviol glycosides and phenolic compounds still need to be investigated in this species. To identify putative candidate genes involved in the synergistic regulation of steviol glycosides and phenolic compounds, four genotypes with different contents of these compounds were selected for a pairwise comparison RNA-seq analysis, yielding 1136 differentially expressed genes. Genes that highly correlate with both steviol glycosides and phenolic compound accumulation in the four genotypes of S. rebaudiana were identified using the weighted gene co-expression network analysis. The presence of UDP-glycosyltransferases 76G1, 76H1, 85C1, and 91A1, and several genes associated with the phenylpropanoid pathway, including peroxidase, caffeoyl-CoA O-methyltransferase, and malonyl-coenzyme A:anthocyanin 3-O-glucoside-6″-O-malonyltransferase, along with 21 transcription factors like SCL3, WRK11, and MYB111, implied an extensive and synergistic regulatory network involved in enhancing the production of such compounds in S. rebaudiana leaves. In conclusion, this work identified a variety of putative candidate genes involved in the biosynthesis and regulation of particular steviol glycosides and phenolic compounds that will be useful in gene editing strategies for increasing and steering the production of such compounds in S. rebaudiana as well as in other species.

Nitrogen starvation modulates the sensitivity of rhizobacterial community to drought stress in Stevia rebaudiana.

Alterations in water regimes or nitrogen (N) availability lead to shifts in the assemblage of rhizosphere microbial community; however, how the rhizosphere microbiome response to concurrent changes in water and N availability remains largely unclear. Herein, we investigated the taxonomic and functional characteristics of rhizobacteria associated with stevia (Stevia rebaudiana Bertoni) under varying combinations of water and N levels. Community diversity and predicted functions of rhizobacteria were predominantly altered by drought stress, with N-starvation modulating these effects. Moreover, N fertilization simplified the ecological interactions within rhizobacterial communities and heightened the relative role of stochastic processes on community assembly. In terms of rhizobacterial composition, we observed both common and distinctive changes in drought-responsive bacterial taxa under different N conditions. Generally, the relative abundance of Proteobacteria and Bacteroidetes phyla were depleted by drought stress but the Actinobacteria phylum showed increases. The rhizobacterial responses to drought stress were influenced by N availability, where the positive response of δ-proteobacteria and the negative response of α- and γ-proteobacteria, along with Bacteroidetes, were further heightened under N starvation. By contrast, under N fertilization conditions, an amplified negative or positive response to drought were demonstrated in Firmicutes and Actinobacteria phyla, respectively. Further, the drought-responsive rhizobacteria were mostly phylogenetically similar, but this pattern was modulated under N-rich conditions. Overall, our findings indicate an N-dependent specific restructuring of rhizosphere bacteria under drought stress. These changes in the rhizosphere microbiome could contribute to enhancing plant stress tolerance.

Identifying Potential Sources of Phthalate Contamination in the Leaves of Stevia Rebaudiana (Bertoni) and the Development of Removal Technology.

Steviosides extracted from the leaves of the plant Stevia rebaudiana are increasingly used in the food industry as natural low-calorie sweeteners. Phthalates in food are often assumed to arise from food containers or packaging materials. Here, experiments were carried out to identify the potential sources of DMP, DBP, DIBP, and DEHP in the leaves of stevioside through investigation of their content in native stevioside tissues, soils, and associated agronomic materials. The results show that phthalate contamination was present in all the samples tested, and the influence of regional factors at the provincial level on the content of plasticizers in stevia leaves was not significant. Phthalates in stevia leaves can be absorbed into the plant body through leaves and roots. Using resin removal, the phthalate content in stevioside glycosides was reduced to less than 0.05 ppm, and some indicators were far lower than the limit standard in EU food.

Influence of the Nitrogen Fertilization on the Yield, Biometric Characteristics and Chemical Composition of Stevia rebaudiana Bertoni Grown in Poland.

Stevia rebaudiana Bertoni is a plant native to South America that has gathered much interest in recent decades thanks to diterpene glycosides, called steviosides, which it produces. These compounds are characterised by their sweetness, which is 250-300 times higher than saccharose, and they contain almost no caloric value. Stevia is currently also grown outside the South American continent, in various countries characterised by warm weather. This research aimed to determine whether it is viable to grow Stevia rebaudiana plants in Poland, a country characterised by a cooler climate than the native regions for stevia plants. Additionally, the impact of adding various dosages and forms of nitrogen fertiliser was analysed. It was determined that Stevia rebaudiana grown in Poland is characterised by a rather low concentration of steviosides, although proper nitrogen fertilisation can improve various characteristics of the grown plants. The addition of 100 kg or 150 kg of nitrogen per hectare of the field in the form of urea or ammonium nitrate increased the yield of the stevia plants. The stevioside content can be increased by applying fertilisation using 100 kg or 150 kg of nitrogen per hectare in the form of ammonium sulfate. The total yield of the stevia plants grown in Poland was lower than the yield typically recorded in warmer countries, and the low concentration of steviosides in the plant suggests that more research about growing Stevia rebaudiana in Poland would be needed to develop profitable methods of stevia cultivation.

Application of multiple-intake temporal check all that apply: a case study of strawberry yoghurt formulated with alternative sweeteners.

BACKGROUND: It is crucial to reduce the high sugar content of fruit yoghurts in response to the excessive weight gain epidemic. The use of alternative sweeteners in yoghurts is often associated with the negative sensory attributes that can have an impact on yoghurt liking. The main objective of this research was to investigate the effect of alternative sweeteners and strawberry puree addition on the temporal sensory profile of yoghurt using multiple-intake temporal check all that apply (TCATA). A novel approach to the statical analysis of the temporal sensory data was employed by using aligned rank transformation-analysis of variance to investigate the differences between sensory attributes within different products and within different intakes. RESULTS: Results showed that the attributes sweet and fruity decreased when the concentration of fruit puree was increased at low concentration of sucrose. Interestingly, when the concentration of fruit puree was increased, fruitiness increased and mouthcoating decreased at low concentration of stevia. With successive intakes, the attributes sweet, sour, creamy and fruity significantly decreased in yoghurts sweetened with sucrose, xylitol and stevia. Yoghurts containing low concentrations of sucrose or xylitol and fruit puree were liked the most. However, stevia-sweetened yoghurts varying in sweetener and puree concentration were not significantly different in liking. In order to investigate the consumer acceptance of yoghurts, a novel approach was used - that is, utilizing TCATA temporal data to investigate temporal drivers of liking for each yoghurt type. CONCLUSION: The use of multiple statistical analysis to analyse temporal data suggested that both sweetener and puree concentration need to be considered when developing products using alternative sweeteners. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Genome-wide identification of SrbHLH transcription factors highlights its potential role in rebaudioside A (RA) biosynthesis in Stevia rebaudiana.

Stevia rebaudiana Bertoni is a valuable medicinal plant and an essential source of natural sweetener, steviol glycosides (SGs), with rebaudioside A (RA) being one of the main components of SGs. bHLH transcription factors play a crucial role in plant development and secondary metabolism. In this study, 159 SrbHLH genes were identified from the S. rebaudiana genome, and each gene was named based on its chromosome location. The SrbHLH proteins were then clustered into 18 subfamilies through phylogenetic analysis. The analysis of conserved motifs and gene structure further supported the classification of the SrbHLH family. Chromosomal location and gene duplication events of SrbHLH genes were also studied. Moreover, based on the RNA-Seq data of different tissues of S. rebaudiana, 28 SrbHLHs were co-expressed with structural genes involved in RA biosynthesis. The expression pattern of candidate SrbHLH genes were confirmed by qPCR. Finally, dual luciferase reporter assays (DLAs) and subcellular localization analysis verified SrbHLH22, SrbHLH111, SrbHLH126, SrbHLH142, and SrbHLH152 are critical regulators of RA biosynthesis. This study provides new insights into the function of SrbHLHs in regulating SGs biosynthesis and lays the foundation for future applications of SrbHLH genes in molecular breeding of S. rebaudiana.

The effects of artificial- and stevia-based sweeteners on lipid profile in adults: a GRADE-assessed systematic review, meta-analysis, and meta-regression of randomized clinical trials.

It has been posited that Non-nutritive sweeteners (NNS) intake may affect lipid profile. However, its proven effects on lipid profile are unclear, as clinical studies on this topic have produced inconsistent results. To fill this gap in knowledge, this systematic review and meta-analysis of randomized controlled trials (RCTs) sought to evaluate the effects of artificial- and stevia-based sweeteners consumption on lipid profile markers. To identify eligible RCTs, a systematic search up to April 2021 was completed in PubMed/Medline, Scopus, and EMBASE, using relevant keywords. A random-effect model was utilized to estimate the weighted mean difference (WMD) and 95% confidence (95% CI) for TG, TC, and LDL. On the other hand, a fixed-effect model was used to estimate the WMD and 95% CI for HDL. Fourteen RCTs were included in the present meta-analysis. The pooled analysis revealed that NNS did not affect TG (WMD:-1.31, 95% CI:-5.89, 3.27 mg/dl), TC (WMD:-2.27,95% CI:-7.61,3.07 mg/dl), LDL (WMD:1,95% CI: -2.72, 4.71 mg/dl), and HDL (WMD:0.06, 95% CI:-0.62,0.73 mg/dl). Subgroup analysis showed that NNS may be related to a small, but statistically significant, increase in LDL (WMD:4.23, 95% CI:0.50,7.96 mg/dl) in subjects with normal levels of LDL (<100 mg/dl). We found that consumption of artificial- and stevia-based sweeteners is not associated with lipid profile changes in adults. This study has been registered at PROSPERO (registration number: CRD42021250025).

The effect of alginate as an elicitor on transcription of steviol glycosides biosynthesis pathway related key genes and sweeteners content in in vitro cultured Stevia rebaudiana.

BACKGROUND: Stevia rebaudiana is a medicinal herb that accumulates non-caloric sweeteners called steviol glycosides (SGs) which are approximately 300 times sweeter than sucrose. This study used alginate (ALG) as an elicitor to increase steviol glycosides accumulation and elucidate gene transcription in the steviol glycosides biosynthesis pathway. METHODS AND RESULTS: To minimize the grassy taste associated with stevia sweeteners, plantlets were grown in complete darkness. ALG was applied to stevia plants grown in suspension culture with a Murashige and Skoog (MS) medium to determine its effect on SGs' content and the transcription profile of SG-related genes using the HPLC and RT-qPCR methods, respectively. Treatment with alginate did not significantly affect plantlet growth parameters such as shoot number, dry and fresh weight. Rebaudioside A (Reb A) content increased approximately sixfold in the presence of 1g L-1 alginate and KS, KAH, and UGT74G1 genes showed significant up-regulation. When the concentration was increased to 2g L-1, the transcription of KO and UGT76G1, responsible for the conversion of stevioside to Reb A, was increased about twofold. CONCLUSIONS: The current study proposes that adding alginate to the MS suspension medium can increase Reb A levels by altering the SG biosynthesize pathway's transcription profile. The present experiment provides new insights into the biochemical and transcriptional response mechanisms of suspension-cultured stevia plants to alginate.

The protective effect of aqueous extract of Stevia rebaudiana against tartrazine toxicity in male Wistar rat.

Tartrazine is a yellow colouring agent that is commonly used in foods; however, high dosages of Tartrazine affect fertility and create oxidative stress by generating free radicals. A plant species known as Stevia rebaudiana has natural antioxidants that show promise for protecting testicular tissue. Consequently, this study was intended to examine the ameliorative effect of the aqueous extract of S. rebaudiana (Stevia) on the fertility of male Wistar rats induced by the daily oral intake of Tartrazine. Utilizing gas chromatography-mass spectrometry, phytochemical identification was accomplished for Stevia extract. Study groups were separated into several groups: the first group (the control) got distilled water for up to 56 days; the Stevia group (1000 mg/kg), the Tartrazine group (300 mg/kg) and the Stevia and Tartrazine group (the group was given Tartrazine after 1 h of Stevia extract intake). Also, the oxidative damage in testicular tissues was assessed by measuring the levels of malondialdehyde (MDA) and antioxidants (catalase [CAT], superoxide dismutase [SOD] and glutathione reductase [GSH]). Further, histological alterations were examined. In addition, cyclic AMP-responsive element modulator (Crem) gene expression levels and their relative proteins were measured in the testicular tissues using quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assays, respectively. Sperm analysis and testosterone concentration were also performed. SPSS version 25 was used for the analysis of results while (p < .05) was regarded as significant. Compared with the control group, the results demonstrated that Tartrazine caused a significant reduction (p < .05) in the testosterone hormone level (0.70 ± 0.21) and the Crem protein quantity (1.21 ± 0.23) in the treated Tartrazine group. Also, it had a significant decrease (p < .05) in sperm motility, viability, count and antioxidant levels. Moreover, there was a significant increase (p < .05) in sperm abnormalities, MDA level (7.40 ± 1.10), kidney and liver function parameters, and DNA degradation in the treated Tartrazine group compared with the control group. On the contrary, the Stevia extract intake enhanced the testosterone (2.50 ± 0.60), antioxidants and Crem protein levels (2.33 ± 0.10) with an improvement in sperm quality in the Stevia and Tartrazine-treated group compared with the Tartrazine group. Stevia also caused a significant decrease (p < .05) in the MDA level (3.20 ± 0.20), and sperm abnormalities with an enhancement of the liver and kidney function parameters in the Stevia and Tartrazine-treated group compared to the Tartrazine group. Stevia administration has a protective effect on the testicular tissues and sperm quality against toxicity induced by Tartrazine exposure, so it will be a good antioxidant drug to be administered daily before daily administration of Tartrazine.

Efficient conversion of rebaudioside C to steviol by Paenarthrobacter ilicis CR5301.

To improve the conversion efficiency of rebaudioside C, this study screened the Paenarthrobacter ilicis CR5301 from soil samples and identified it by 16S rRNA. The conversion experiment proved that P. ilicis CR5301 was capable of converting rebaudioside C. The effects of initial pH, temperature, inoculation amount, and substrate concentration on rebaudioside C conversion rate were investigated. The results showed that the conversion rate of rebaudioside C reached up to 100% when CR5301 was incubated in a conversion medium with an initial pH of 7.0 for 8 h at 28°C and 270 rpm. The conversion time was reduced by at least 16 h compared with previous studies. The conversion product was analyzed and identified as steviol by high performance liquid chromatography, ultra performance liquid chromatography-triple-time of flight mass spectrometer, and Fourier transform infrared spectroscopy methods. In addition, stevioside, rebaudioside A, dulcoside A, and some unknown components in steviol glycosides byproduct were all efficiently converted to steviol. These findings provide an efficient approach to the conversion of rebaudioside C and byproduct to steviol to simplify the subsequent industrial process and improve the reuse value of steviol glycosides.

Impact of acute consumption of beverages containing plant-based or alternative sweetener blends on postprandial appetite, food intake, metabolism, and gastro-intestinal symptoms: Results of the SWEET beverages trial.

Project SWEET examined the barriers and facilitators to the use of non-nutritive sweeteners and sweetness enhancers (hereafter "S&SE") alongside potential risks/benefits for health and sustainability. The Beverages trial was a double-blind multi-centre, randomised crossover trial within SWEET evaluating the acute impact of three S&SE blends (plant-based and alternatives) vs. a sucrose control on glycaemic response, food intake, appetite sensations and safety after a carbohydrate-rich breakfast meal. The blends were: mogroside V and stevia RebM; stevia RebA and thaumatin; and sucralose and acesulfame-potassium (ace-K). At each 4 h visit, 60 healthy volunteers (53% male; all with overweight/obesity) consumed a 330 mL beverage with either an S&SE blend (0 kJ) or 8% sucrose (26 g, 442 kJ), shortly followed by a standardised breakfast (∼2600 or 1800 kJ with 77 or 51 g carbohydrates, depending on sex). All blends reduced the 2-h incremental area-under-the-curve (iAUC) for blood insulin (p < 0.001 in mixed-effects models), while the stevia RebA and sucralose blends reduced the glucose iAUC (p < 0.05) compared with sucrose. Post-prandial levels of triglycerides plus hepatic transaminases did not differ across conditions (p > 0.05 for all). Compared with sucrose, there was a 3% increase in LDL-cholesterol after stevia RebA-thaumatin (p < 0.001 in adjusted models); and a 2% decrease in HDL-cholesterol after sucralose-ace-K (p < 0.01). There was an impact of blend on fullness and desire to eat ratings (both p < 0.05) and sucralose-acesulfame K induced higher prospective intake vs sucrose (p < 0.001 in adjusted models), but changes were of a small magnitude and did not translate into energy intake differences over the next 24 h. Gastro-intestinal symptoms for all beverages were mostly mild. In general, responses to a carbohydrate-rich meal following consumption of S&SE blends with stevia or sucralose were similar to sucrose.

Ameliorative effect of Stevia rebaudiana Bertoni on sperm parameters, in vitro fertilization, and early embryo development in a streptozotocin-induced mouse model of diabetes.

Diabetes mellitus (DM) is a common metabolic disease characterized by high blood sugar levels. It is well known that men with diabetes frequently experience reproductive disorders and sexual dysfunction. In fact, sperm quality has a significant effect on fertilization success and embryo development. The current study aimed to investigate the effect of Stevia rebaudiana hydroalcoholic extract on serum testosterone levels, sperm parameters, in vitro fertilization (IVF) success, and in vitro embryonic developmental potential to reach the blastocyst stage in a streptozotocin (STZ)-induced mouse model of diabetes. In this research, 30 male mice were distributed randomly into control, diabetic (streptozotocin 150 mg/kg) and diabetic + Stevia (400 mg/kg) groups. The results revealed a decrease in body and testis weight and elevated blood fasting blood sugar (FBS) levels in the diabetic group, compared with the control. However, Stevia treatment significantly increased body and testis weight, while serum FBS levels were decreased compared with the diabetic group. In addition, Stevia significantly increased blood testosterone levels compared with the diabetic group. Moreover, sperm parameters were improved considerably by Stevia treatment compared with the diabetic group. Furthermore, Stevia administration significantly promoted IVF success rate and in vitro development of fertilized oocytes compared with the diabetic group. In summary, our data indicated that Stevia enhanced sperm parameters, IVF success, and in vitro embryonic developmental competency in diabetic mice, probably because of its antioxidant effects. Therefore, Stevia could ameliorate sperm parameters that, in turn, increase fertilization outcomes in experimental-induced diabetes.

Highly Oxygenated Labdane Diterpenoids from Stevia rebaudiana and Their Anti-Atherosclerosis Activities.

Five unknown labdane diterpenoids Stevelins A-E (1-5), three known labdane diterpenoids (6-8) and three labdane norditerpenoids (9-11) were isolated from the Stevia rebaudiana. The structures were determined primarily via NMR spectroscopic data and HR-ESI-MS experiments. X-ray crystallography using CuKα radiation was used to determine the absolute configurations of 1, and the absolute configurations of 2-5 were deduced by electronic circular dichroism (ECD) calculations. The potential anti-atherosclerosis activities of all compounds were evaluated by measuring their inhibitory effects on the macrophage foam cell formation. As a result, most isolated compounds could significantly inhibit oxidized low-density lipoprotein (ox-LDL)-induced macrophage foam cell formation, which suggests that these compounds may be promising candidates in the treatment for atherosclerosis.

Validation of Standard Area Diagrams to Estimate the Severity of Septoria Leaf Spot on Stevia in Paraguay, Mexico, and the United States.

Septoria leaf spot (SLS) affects stevia leaves, reducing their quality. Estimates of SLS severity on different genotypes are made to identify resistance and as a basis to compare management approaches. The use of standard area diagrams (SADs) can improve the accuracy and reliability of severity estimates. In this study, we developed new SADs with six illustrations (0.5, 1, 10, 25, 40, and 75% severity). The SADs were validated by raters with and without experience in estimating SLS. Raters evaluated 40 leaf photos with SLS severities ranging from 0 to 100% without and with the SADs. Agreement (ρc), bias (Cb), precision (r), and intracluster correlation (ρ) coefficients were significantly closer to "true" severity values when the SADs was used by inexperienced (ρc = 0.89; Cb = 0.97; r = 0.90, ρ = 0.81) and experienced (ρc = 0.94; Cb = 0.99; r = 0.95, ρ = 0.91) raters. The SADs were tested under field conditions in Paraguay, Mexico, and the United States, with inexperienced raters assigned to two groups, one SADs trained and the other not trained, that estimated SLS severity three times: first, all raters without SADs and no time limit for the estimates; second, only the SADs-trained group used SADs and no time limit; and third, only the SADs-trained group used SADs, with a time limit of 10 s imposed per specimen assessment. Agreement and reliability of SLS severity estimates significantly improved when raters used the SADs without a time limit. The use of the new SADs improved the accuracy, precision, and reliability of SLS severity estimates, enhancing the uniformity in assessment across different stevia programs.

Low-no-calorie sweeteners exert marked compound-specific impact on the human gut microbiota ex vivo.

Low-no-calorie sweeteners (LNCS) are used as sugar substitutes as part of strategies to reduce the risk of chronic diseases related to high sugar intake (e.g. type 2 diabetes (T2D)). This study investigated how a range of sweeteners [tagatose (TA)/maltitol (MA)/sorbitol (SO)/stevia (ST)/sucralose (SU)/acesulfame K (ACK)] impact the gut microbiota of T2D subjects and healthy human adults using the ex vivo SIFR® technology (n = 12). The cohort covered clinically relevant interpersonal and T2D-related differences. ACK/SU remained intact while not impacting microbial composition and metabolite production. In contrast, TA/SO and ST/MA were respectively readily and gradually fermented. ST and particularly TA/SO/MA increased bacterial density and SCFA production product-specifically: SO increased acetate (∼Bifidobacterium adolescentis), whilst MA/ST increased propionate (∼Parabacteroides distasonis). TA exerted low specificity as it increased butyrate for healthy subjects, yet propionate for T2D subjects. Overall, LNCS exerted highly compound-specific effects stressing that results obtained for one LNCS cannot be generalised to other LNCS.

Seeds of Stevia rebaudiana Bertoni as a Source of Plant Growth-Promoting Endophytic Bacteria with the Potential to Synthesize Rebaudioside A.

In this study, a new strain of Pantoea vagans, SRS89, was isolated from surface-sterilized stevia seeds. The isolate was evaluated using morphological, molecular, and biochemical methods. The bacterium was 1.5 µm long, yellowish in color, and classified as Gram-negative. Whole genome sequencing of our strain revealed the presence of a 4,610,019 bp chromosome, and genome annotation resulted in the detection of 4283 genes encoding 4204 putative coding sequences. Phylogenic analysis classified the genome of our strain close to the MP7 and LMG 24199 strains of P. vagans. Functional analysis showed that the highest number of genes within the analyzed bacterium genome were involved in transcription, amino acid transport and metabolism, and carbohydrate transport and metabolism. We also identified genes for enzymes involved in the biosynthesis of carotenoids and terpenoids. Furthermore, we showed the presence of growth regulators, with the highest amount noted for gibberellic acid A3, indole-3-acetic acid, and benzoic acid. However, the most promising property of this strain is its ability to synthesize rebaudioside A; the estimated amount quantified using reversed-phase (RP)-HPLC was 4.39 mg/g of the dry weight of the bacteria culture. The isolated endophytic bacterium may be an interesting new approach to the production of this valuable metabolite.

Bioactive Compounds in Plasma as a Function of Sex and Sweetener Resulting from a Maqui-Lemon Beverage Consumption Using Statistical and Machine Learning Techniques.

The present study analyses the effect of a beverage composed of citrus and maqui (Aristotelia chilensis) with different sweeteners on male and female consumers. Beverages were designed and tested (140 volunteers) as a source of polyphenols, in a previous work. Plasma samples were taken before and after two months of daily intake. Samples were measured for bioactive-compound levels with metabolomics techniques, and the resulting data were analysed with advanced versions of ANOVA and clustering analysis, to describe the effects of sex and sweetener factors on bioactive compounds. To improve the results, machine learning techniques were applied to perform feature selection and data imputation. The results reflect a series of compounds which are more regulated for men, such as caffeic acid or 3,4-dihydroxyphenylacetic acid, and for women, trans ferulic acid (TFA) or naringenin glucuronide. Regulations are also observed with sweeteners, such as TFA with stevia in women, or vanillic acid with sucrose in men. These results show that there is a differential regulation of these two families of polyphenols by sex, and that this is influenced by sweeteners.