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mihair, en
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The essential oil extracted by hydrodistillation from the flowering twigs of Stevia rebaudiana Bertoni (Asteraceae) was fractioned by chromatography. Forty-three constituents were characterized with the help of GC, GC-MS and other spectroscopic techniques. The essential oil was found to be a complex mixture of mono- and sesqui-terpenes. The cytotoxicity of the essential oil and its fractions was evaluated by sulforhodamine B (SRB) based assay against two cancer cell types viz. C-6 (rat glioma cells) and CHOK1 (Chinese hamster ovary cells). The essential oil and its fractions showed promising cytotoxicity against both cell lines. The highest activity (95.6+/-0.6%) was show by the essential oil on the C-6 cell line at a concentration of 400 microg/mL, which was comparable with that of the standard drug vinblastin.

https://pubmed.ncbi.nlm.nih.gov/25026731/

mihair, en
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Stevia, a zero-calorie sugar substitute, is recognized as safe by the Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA). In vitro and in vivo studies showed that stevia has antiglycemic action and antioxidant effects in adipose tissue and the vascular wall, reduces blood pressure levels and hepatic steatosis, stabilizes the atherosclerotic plaque, and ameliorates liver and kidney damage. The metabolism of steviol glycosides is dependent upon gut microbiota, which breaks down glycosides into steviol that can be absorbed by the host. In this review, we elucidated the effects of stevia's consumption on the host's gut microbiota. Due to the lack of randomized clinical trials in humans, we included in vitro using certain microbial strains and in vivo in laboratory animal studies. Results indicated that stevia consumption has a potential benefit on the microbiome's alpha diversity. Alterations in the colonic microenvironment may depend on the amount and frequency of stevia intake, as well as on the simultaneous consumption of other dietary components. The anti-inflammatory properties of stevioside were confirmed in vitro by decreasing TNF-α, IL-1β, IL-6 synthesis and inhibiting of NF-κB transcription factor, and in vivo by inhibiting NF-κB and MAPK in laboratory animals.

https://pubmed.ncbi.nlm.nih.gov/35456796/

mihair, en
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Steviol glycosides (SGs) in Stevia (Stevia rebaudiana Bertoni) leaves are important due to their high sweetness and low calorific value. The yield of SGs is dependent on fertilization regimes, but the relationship between nitrogen (N) administration and SGs synthesis is still unclear. In this study, we investigate the effects of N rates on SGs production through hydroponic and plot experiments. The SGs yield was not significantly changed by N fertilization, but leaf SGs concentrations were significantly reduced due to the "dilution effect". Additionally, N addition decreased leaf carbon (C)/N ratio and soluble sugar concentration, accompanied with the inhibited phosphoenolpyruvate carboxylase and L-phenylalanine ammonia_lyase activities. A significant positive correlation between leaf SGs concentrations, C/N ratio and soluble sugar concentration was observed. Overall, we suggest that N-driven Stevia growth negatively affects SGs concentrations. The leaf C/N ratio and soluble sugar changes indicated the occurrence of metabolic reprogramming.

https://pubmed.ncbi.nlm.nih.gov/31195254/

mihair, en
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Plant growth and secondary metabolism are commonly regulated by external cues such as light, temperature and water availability. In this study, the influences of low and high temperatures, dehydration, photoperiods, and different growing stages on the changes of steviol glycosides (SGs) contents and transcription levels of fifteen genes involved in SGs biosynthesis of Stevia rebaudiana Bertoni were examined using HPLC and RT-PCR. The observations showed that the transcript levels of all the fifteen genes were maximum under 25 °C treatment, and the transcription of SrDXS, SrDXR, SrMCT, SrCMK, SrMDS, SrHDS, SrHDR, SrIDI, SrGGDPS, SrCPPS1, SrUGT85C2 and SrUGT76G1 were restrained both in low temperature (15 °C) and high temperature (35 °C). Most genes in SGs biosynthesis pathway exhibited down-regulation in dehydration. To elucidate the effect of photoperiods, the plants were treated by different simulated photoperiods (8 L/16 D, 1 0L/14 D, 14 L/10 D and 16 L/8 D), but no significant transcription changes were observed. In the study of growing stages, there were evident changes of SGs contents, and the transcript levels of all the fifteen genes were minimal in fast growing period, and exhibited evident increase both in flower-bud appearing stage and flowering stage. The obtained results strongly suggest that the effect of environmental cues on steviol glycosides contents and transcription of corresponding biosynthetic genes in S. rebaudiana is significant. It is worth to study deeply.

https://pubmed.ncbi.nlm.nih.gov/25500454/

madalinai, en
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More than 60 naturally occurring steviol glycosides in the Stevia rebaudiana Bertoni plant share a similar molecular structure with an aglycone steviol backbone conjugated with β- and α-glycosidic bonds to different sugar moieties. These glycosides are naturally produced in different quantities within the stevia leaf. Certain minor glycosides with superior sensory attributes, such as Reb D and Reb M, are found less than 0.1% in traditional stevia leaves. New technologies can now produce better tasting steviol glycosides by using enzymatic conversion of stevioside and Reb A, which are abundant in stevia leaf. Several regulatory authorities recently evaluated steviol glycosides produced by enzymatic conversion of stevia leaf extract and approved them safe for human consumption. Steviol glycosides undergo microbial hydrolysis in the colon to generate steviol, which is absorbed and metabolized into steviol glucuronide, and excreted primarily via human's urine. Previous studies have shown the hydrolysis of highly purified individual steviol glycosides extracted from stevia leaf are converted to steviol in the presence of colonic microbiota of adults. Since colonic microbiota of children may be different from adults, this study investigates the metabolic fate in the colonic microbiota of adults and children of the minor steviol glycosides produced by extraction and enzymatic conversion of major steviol glycosides from stevia leaf. Several in vitro incubation tests were conducted in human fecal homogenates collected from adult and pediatric populations with steviol glycoside test samples comprised of a complex stevia leaf extract, a blend of minor glycosides isolated from stevia extract and two mixtures of steviol glycosides produced by enzymatic conversion of Reb A to larger molecules by attaching glucose units via β- or α-glycosidic bonds. Results from these studies clearly demonstrate steviol glycosides produced by extraction from stevia leaf, or enzymatic conversion of stevia leaf extract, share the same metabolic fate in the human gut microbiota from adults and children. Considering a common metabolite structure and a shared metabolic fate in all ages, safety data for individual steviol glycosides can be used to support safety of all steviol glycosides produced by extraction and enzymatic conversion of stevia leaf extract.

https://pubmed.ncbi.nlm.nih.gov/32745585/

madalinai, en
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Stevia rebaudiana Bertoni is a valuable plant whose products are increasingly used in medicine, pharmacy and the food industry. This necessitates the use of biotechnological approaches for its mass propagation. Establishing optimal conditions for in vitro cultivation is essential for obtaining high biomass and secondary metabolites production. A large number of articles considering the role of plant growth regulators and other additives in the culture medium in the growth and development of Stevia are available in the literature. However, there are no summarized data about the use of nanoparticles in Stevia tissue cultures. Therefore, this review also includes the research conducted so far on the effect of nanoparticles on Stevia micropropagation. Furthermore, the influence of different elicitors on secondary metabolite production and antioxidant activity of in vitro-cultivated Stevia plants have been discussed. By referring to the collected literature, we concluded that biotechnological approaches applied to S. rebaudiana cultivation might improve the agronomic traits of plants and steviol glycosides production.

https://pubmed.ncbi.nlm.nih.gov/36616282/

readbeanicecream, en
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Scientists Discover Source of Mysterious Earth Tremors | Scitech Daily

Kobac, sr
jooleee, en

Recent research dives deep into the impact of autism on marital bonds. Over a 30-year span, parents of children with autism showcased a 36% divorce rate, with specific peak periods. Surprisingly, families of verbally adept autistic teenagers faced unique stressors, leading to higher divorce rates. The strength and resilience of these families remind us of the unique challenges they face.

readbeanicecream, en
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New Research Reveals That Butterflies and Moths Share Ancient “Blocks” of DNA | SciTech Daily

readbeanicecream, en
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Lithium’s Supersized Volcano May Be More Smoke Than Fire - Bloomberg
The discovery of deposits rarely upends the mining industry, and few see long-term supply shortages for the battery-making ingredient.

readbeanicecream, en
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technologicalcaveman,

@readbeanicecream it's me. It's too big already.

readbeanicecream, en
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A remote Air Force base in Alaska is getting its own nuclear reactor -PopSci
If all goes according to plan, the micro reactor will be online at Eielson Air Force Base by 2027.

readbeanicecream, en
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‘Living material’ water filter uses bacteria to neutralize water pollutants. The algae-derived mixture can also safely break down after coming into contact with a molecular relative of caffeine. https://www.popsci.com/technology/water-filter-cyanobacteria-3d-print/

Denial-Same338, en
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