Quinoa Saponins Research Articles

Crude Saponins from Chenopodium quinoa Willd. Reduce Fusarium Wilt Infection in Tomato Seedlings

Quinoa saponins are pentacyclic triterpene compounds composed of one triterpenoid glycoside and two different sugar chains. Previous studies have showed that natural quinoa saponins showed little or no antifungal activity, and there are few reports about their antifungal effects in recent decades. Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (FOL) is the most serious for tomatoes in the field and under greenhouse conditions. The main objective of this study was to investigate the effectiveness of different concentrations and application modes of crude saponins from quinoa bran against the causal pathogen of tomato wilt under a greenhouse experiment. The results showed that the anti-FOL activity of quinoa saponins was weak in vitro, but significantly enhanced in vivo. Tomato seeds and seedlings treated with solution of quinoa saponins at 0.5 and 1.0 g/L significantly reduced the disease incidence (%) of tomato Fusarium wilt. The treatment types of saponin solution have influence on the preventive effects (%) of tomato seedlings against Fusarium wilt, among them, root soaking > foliar spray > seed soaking. The treatment of seed soaking with quinoa saponins inhibited germination of tomato seeds to some extent. However, the germination rate of tomato seeds after saponin soaking was comparable to the chemical pesticide (thiram carboxin); therefore, it could be used to control tomato wilt disease. This is due to the fact that the antifungal activity of quinoa saponins in vivo was much higher than that in vitro when the saponin concentration was between 0.5–1.0 g/L, indicating that the antifungal activity of quinoa saponins may be achieved mainly by inducing resistance. This investigation supports the potential use of quinoa saponins as a supplier of antifungal compounds, and could be the foundation for a future study examining the use of quinoa bran as a new resource against FOL.

Saponins from Chenopodium quinoa Willd. husks alleviated high-fat-diet-induced hyperlipidemia via modulating the gut microbiota and multiple metabolic pathways.

Hyperlipidemia is characterized by abnormally elevated blood lipids. Quinoa saponins (QS) have multiple pharmacological activities, including antitumor, bactericidal and immune-enhancing effects. However, the lipid-lowering effect and mechanisms of QS in vivo have been scarcely reported. The effect of QS against hyperlipidemia induced by high-fat diet in rats was explored based on gut microbiota and serum non-targeted metabolomics. The study demonstrated that the supplementation of QS could reduce serum lipids, body weight, liver injury and inflammation. 16S rRNA sequencing demonstrated that QS mildly increased alpha-diversity, altered the overall structure of intestinal flora, decreased the relative richness of Firmicutes, the ratio of Firmicutes/Bacteroidetes (P < 0.05) and increased the relative richness of Actinobacteria, Bacteroidetes, Bifidobacterium, Roseburia and Coprococcus (P < 0.05). Simultaneously, metabolomics analysis showed that QS altered serum functional metabolites with respect to bile acid biosynthesis, arachidonic acid metabolism and taurine and hypotaurine metabolism, which were closely related to bile acid metabolism and fatty acid β-oxidation. Furthermore, QS increased protein levels of farnesoid X receptor, peroxisome proliferator-activated receptor α and carnitine palmitoyltransferase 1, which were related to the screened metabolic pathways. Spearman correlation analysis showed that there was a correlation between gut microbiota and differential metabolites. QS could prevent lipid metabolism disorders in hyperlipidemic rats, which may be closely associated with the regulation of the gut microbiota and multiple metabolic pathways. This study may provide new evidence for QS as natural active substances for the prevention of hyperlipidemia. © 2023 Society of Chemical Industry.

Does saponin in quinoa really embody the source of its bitterness?

While it is widely reported that saponins are the main source of the bitter taste in quinoa, this work found that some saponin compounds in quinoa husks elicit an umami response. The saponins were analyzed qualitatively and quantified by mass spectrometry (UPLC-MS). Two quinoa saponin compounds RT 46 (3-O-β-d-glucopyranosyl-(1 → 3)-α-l-arabino-pyranosyl-phytolaccagenic acid 28-O-β-d-gluco-pyranosyl), and RT 53 (3-O-β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl-28-O-hederagenin) were isolated from quinoa husks through separation and purification. According to eletronic tongue, the main taste response for those compounds was umami. It was found that the two quinoa saponins could bind to sweet and umami receptors. Besides saponins, various flavonoids and polyphenols also appeared in the UPLC-MS spectrum of crude saponins. The electronic tongue and sensory evaluation revealed that flavonoids and polyphenols showed obvious bitterness and astringency at very low concentrations. The study inferred that flavonoids and polyphenols are the main compounds that generate quinoa's bitter taste.

Complexation of phycocyanin with hydroxypropyl-β-cyclodextrin and its application in blue beer containing quinoa saponins as foaming agents.

With the increasing importance attached to human health, the inclusion complex (IC) of phycocyanin (PC) into hydroxypropyl-β-cyclodextrin (HP-β-CD) have been devoted to developing the use of food preservation in this study. In this experiment, the IC of PC into HP-β-CD was prepared by the freeze-drying method and characterized by OM, TEM, UV, FTIR and TG/DSC methods. The spectroscopic features were evaluated by Ultraviolet-visible (UV-vis) spectroscopy and Fourier transform infrared spectroscopy (FT-IR) confirming that PC was located in the hydrophobic cavity of HP-β-CD. Consistent with the structural properties, optical microscopy (OM) and Transmission electron microscope (TEM) observed that the addition of PC subjected the IC to an aggregation state with irregular lamellar structures. Stability assessment showed that pH, heat and light tolerance of PC significantly regulated and improved due to the PC/HP-β-CD complexation. The formation of ICs was helpful to enhancing the antioxidant activity of PC. Molecular modeling suggested that the D-pyrrole ring and its associated C=C group of phycocyanin entered the HP-β-CD cavity from the wider edge. On this basis, the development of blue beer with quinoa saponins as foaming agent and ICs as colorant was explored. The addition of quinoa saponins made the foam richer and more delicate without destroying the overall taste coordination of beer. Moreover, the protective effect of HP-β-CD presents a positive impact on the stability of blue beer pigment. Hence, PC encapsulated into HP-β-CD will be an impressive approach in food-related application of PC.

Optimization of green deep eutectic solvent (DES) extraction of Chenopodium quinoa Willd. husks saponins by response surface methodology and their antioxidant activities.

Quinoa saponins have outstanding activity, and there are an increasing number of extraction methods, but there are few research programs on green preparation technology. The extraction conditions of quinoa saponins with deep eutectic solvents (DESs) were optimized by single-factor experiments combined with response surface methodology. The antioxidant capacity of saponins extracted by DESs and traditional methods was evaluated by the DPPH clearance rate, iron ion chelation rate and potassium ferricyanide reducing power. The results show that the optimal DES is choline chloride: 1,2-propylene glycol (1 : 1), and its water content is 40%. The optimal extraction conditions were as follows: the solid-to-solvent ratio was 0.05 g mL-1, the extraction time was 89 min, and the extraction temperature was 75 °C. Under these conditions, the extraction of quinoa saponins by DES was more effective than the traditional extraction methods. The saponins extracted by DES and traditional methods were analyzed by UPLC-MS, and five main saponins were identified. Quantitative analysis by HPLC-UV showed that Q1 (m/z = 971) and Q2 (m/z = 809) had higher contents of saponins. In vitro antioxidant experiments showed that all DES saponin extracts showed good antioxidant capacity. This study provides new insight into the development and utilization of quinoa saponins.

Yield, phenology and triterpene saponins in Colombian quinoa

Exploring yield, phenology and their relationship with secondary metabolites in seeds provides a fundamental analysis that expands knowledge on the nutritional quality of seeds and the effect on productive potential. This knowledge is fundamental when improving or selecting nutritionally important crops, including Chenopodium quinoa Willd, which has excellent nutritional properties and contributes to global food security. This species contains saponins, a metabolite that imparts a bitter taste and can be highly toxic to consumers in large quantities. Therefore, the identification and selection of genotypes according to their saponin contents and outstanding agronomic characteristics are fundamental objectives for the genetic improvement programs of these species. Therefore, the objective of this research was to evaluate the characteristics of the grain, the phenology and the saponin content of 30 C. quinoa accessions with an aim to select or relate genotypes according to their yield and grain quality. The accessions were sown using randomized complete blocks (RCB) with nine repetitions for each material. Seven FAO-defined descriptors were evaluated to characterize the grain and physiological maturity. Saponin was extracted using microwave, and the quantification was done with high-performance liquid chromatography (HPLC) which a UV-VIS detector at 277 nm wavelength. The accessions were classified according to their phenology: semi-late (56.7%), late (36.7%), and semi-early (3.3%). The total triterpene saponin content varied from 0.018 to 0.537%. The multivariate and cluster analyses formed groups of accessions with good yields (&amp;gt;62.02 g of seeds per plant) and desirable grain morphological characteristics. The more suitable accessions for the production of saponins are Quinoa semiamarga (0.537%), Quinoa peruana (0.412%) and Amarilla de maranganí (0.305%). Quinoa real and Quinoa primavera are more suitable for food products, which can be used as parents in future quinoa genetic improvement programs in Colombia.

Transcriptomics-metabolomics joint analysis: New highlight into the triterpenoid saponin biosynthesis in quinoa (Chenopodium quinoa Willd.).

Quinoa (Chenopodium quinoa Willd.) contains various physiologically active substances, including vitamins, polyphenols, flavonoids, phytosterols, and saponins. Research showed that saponins were the protective substances in the outer layer of quinoa seeds to defend against microbes, herbivores, and insects. Because the aglycones of quinoa saponins are triterpenoids, they are called triterpenoid saponins (TSs). In addition, the presence of TS imparted bitterness in quinoa and resulted in anticancer and anti-inflammatory effects. In this study, the seeds of low-saponin quinoa, NT376-2 (N), and high-saponin quinoa, B-12071(B), at 30 and 60 days after flowering (DAF) were used to measure the TS content and evaluated for their transcriptomic and metabolomic profiles. The amounts of TS were found to significantly differ between all possible comparisons: N and B at 30 DAF (N1_vs_B1), N and B at 60 DAF (N2_vs_B2), N at 30 DAF and 60 DAF (N1_vs_N2), and B at 30 DAF and 60 DAF (B1_vs_B2). RNA sequencing (RNA-seq) was used to screen differentially expressed genes (DEGs) and revealed 14,703 upregulated DEGs and 26,267 downregulated DEGs in the four comparison groups. The 311 overlapping DEGs found in the four comparisons were used for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses to screen for DEGs related to TS biosynthesis in quinoa. Metabolomics analysis identified acetyl-CoA, 1-hydroxy-2-methyl-2-butenyl-4-diphosphate, farnesal, and (S)-2,3-epoxysqualene as the key differentially accumulated metabolites (DAMs). Transcriptomics-metabolomics joint analysis showed that triterpenoid biosynthesis and terpenoid backbone biosynthesis were the enriched pathways of TS biosynthesis; farnesal were the key DAMs shared in the four comparison groups and associated with 10 key candidate DEGs related to TS biosynthesis in quinoa. These results provided important references for in-depth research on the metabolic mechanism of TS in quinoa.

Study on extraction, isolation, and biological activity of saponins from quinoa bran

Quinoa (Chenopodium quinoa Willd) contains 2 to 5% of saponins, which are mainly exist in the bran of seeds in the form of oleanane-type triterpenoid glycosides or sapogenins. In this study, the extraction process of total saponins from quinoa bran has been optimized. The results showed that the optimal extraction conditions for quinoa saponins were extraction time of 2 h, ethanol concentration of 70%, solid–liquid ratio of 1:25 (g/ml), and extraction temperature of 70°C. Macroporous resin separation test demonstrated that HPD600 resin had an excellent adsorption and desorption capacities for the separation of quinoa saponins. The antioxidant experiment demonstrated that the EC50 of quinoa saponins against DPPH-free radical, ABTS-free radical, ·OH-free radical, and O2−-free radical were 0.10, 0.51, 0.57, and 0.17 mg/ml, respectively. The scavenging effect of the saponins on O2−-free radical was stronger than that of Vc. The reducing power was equivalent to 1.28% of that of Vc. The anticancer test showed that when the concentration of quinoa saponins was 0.5 mg/ml, the inhibitory rate on HepG-2 cell was 58%. This study contributes to further exploration on the biological activities of quinoa saponin. Novelty impact statement A macroporous resin suitable for separating quinoa saponins was screened. The adsorption isotherms and kinetics of quinoa saponins on HPD600 were studied. The in vitro biological activities of quinoa saponins were studied.

Deep eutectic solvents for the extraction and stabilization of Ecuadorian quinoa (Chenopodium quinoa Willd.) saponins

In this work, a simple, fast (10 min) and environmentally friendly extraction method using deep eutectic solvents (DES), based on choline chloride and glycerol, was established to extract saponins from five quinoa samples: a) husks of bitter seeds, b) bitter seeds, c) water-washed bitter seeds, d) sweet seeds of the INIAP-Tunkahuan variety, and e) sweet seeds of the INIAP-Pata de Venado variety. The selected green solvent was a eutectic mixture of choline chloride - glycerol - water at a 1:2:1 M ratio. The extractions were performed in a ball mixer mill at room temperature (RT). A classical methanol - water (70:30, v/v) extraction was performed for comparison. In all quinoa samples, the characterization and relative quantification of saponins were achieved based on mass spectrometry analyses. Regardless of the type of solvent used (conventional or green solvents), hederagenin and phytolaccagenic acid were the major detected sapogenins in all tested quinoa samples. The husks of bitter seeds were the matrix with the highest saponin content. Although methanol - water (70:30, v/v) was shown to extract three times more saponins compared to DES, the green solvent offered a higher stabilization of quinoa saponin liquid extracts - up to 2 months - compared to conventional solvents (ethanol - methanol - water; 67:23:10, v/v/v). The present research shows that DES represent an efficient green media for the stabilization of bioactive saponins from quinoa and have a potential as possible alternatives to organic solvents . Our work opens new perspectives for the valorization of saponin-rich quinoa by-products (the husks of bitter seeds) as components for pharmaceutical, nutraceutical and agro-food applications. • A green and rapid extraction method, using DES-based ball mixer mill, was developed for extraction of quinoa saponins. • DES based on choline chloride/glycerol/water as an alternative to toxic organic solvents in quinoa saponin extraction. • Eleven quinoa saponins were identified by mass spectrometry-based methods from Ecuadorian bitter genotype. • DES improve the shelf-life of quinoa saponin liquid extracts in comparison to conventional solvents.

Impact of the Hydrolysis and Methanolysis of Bidesmosidic Chenopodium quinoa Saponins on Their Hemolytic Activity.

Saponins are specific metabolites abundantly present in plants and several marine animals. Their high cytotoxicity is associated with their membranolytic properties, i.e., their propensity to disrupt cell membranes upon incorporation. As such, saponins are highly attractive for numerous applications, provided the relation between their molecular structures and their biological activities is understood at the molecular level. In the present investigation, we focused on the bidesmosidic saponins extracted from the quinoa husk, whose saccharidic chains are appended on the aglycone via two different linkages, a glycosidic bond, and an ester function. The later position is sensitive to chemical modifications, such as hydrolysis and methanolysis. We prepared and characterized three sets of saponins using mass spectrometry: (i) bidesmosidic saponins directly extracted from the ground husk, (ii) monodesmosidic saponins with a carboxylic acid group, and (iii) monodesmosidic saponins with a methyl ester function. The impact of the structural modifications on the membranolytic activity of the saponins was assayed based on the determination of their hemolytic activity. The natural bidesmosidic saponins do not present any hemolytic activity even at the highest tested concentration (500 µg·mL−1). Hydrolyzed saponins already degrade erythrocytes at 20 µg·mL−1, whereas 100 µg·mL−1 of transesterified saponins is needed to induce detectable activity. The observation that monodesmosidic saponins, hydrolyzed or transesterified, are much more active against erythrocytes than the bidesmosidic ones confirms that bidesmosidic saponins are likely to be the dormant form of saponins in plants. Additionally, the observation that negatively charged saponins, i.e., the hydrolyzed ones, are more hemolytic than the neutral ones could be related to the red blood cell membrane structure.

Extraction and Quantification of Saponins in Quinoa (Chenopodium quinoa Willd.) Genotypes from Colombia.

Quinoa has a high nutraceutical potential because of the presence of secondary metabolites called saponins, which have industrial and medicinal uses and protect against attacks by pathogens. These compounds are found especially in the seed coat and give the grain a bitter taste; therefore, they must be eliminated before consumption. Despite the potential use in Colombia, there are few studies aimed at quantifying this metabolite. Therefore, the objective of this research was to evaluate two extraction methodologies (physical and chemical) and two methods for quantifying saponins in five quinoa genotypes grown in Colombia. The most efficient extraction method was the physical method. The saponin contents of the five genotypes were variable. The cluster analysis differentiated the genotypes into two groups: low saponin content (<4.49 mg/g seed) and high saponin content (>14.76 mg/g seeds). Blanca de Jericó had the lowest saponin content (<0.40%), and Amarilla de Maranganí had the highest content (>0.18%). Identifying more efficient methodologies for extracting and quantifying saponins will allow a better characterization of the germplasm and selection of genotypes with desirable characteristics for both consumption and industrial use.

Facile and High-yield Synthesis of N-doped Carbon Quantum Dots from Biomass Quinoa Saponin for the Detection of Co2.

Hydrothermal synthesis of carbon quantum dots (CQDs) from natural biomass is a green and sustainable route for CQDs applications in various fields. In this work, the preparation and characterization of CQDs based on quinoa saponin were investigated. The optimum synthetic conditions determined by orthogonal experiments were as follows: 2 g quinoa saponin powder and 0.04 mol ethylenediamine reacted at 200°C for 10 h. The relative fluorescence quantum yield (QY = 22.2%) can be obtained, which is higher than some results reported in the literatures. The prepared CQDs had a small and uniform size (∼2.25 nm) and exhibited excitation wavelength-dependent blue light emission behavior. The CQDs displayed excellent sensitivity for Co2+ detection along with good linear correlation ranging from 20 to 150 µM and the detection limit of 0.49 µM. The CQDs prepared in this experiment were successfully implanted into soybean sprouts for fluorescence imaging. The sprouts could grow healthily even soaked in the CQDs solution for two weeks, demonstrating the low toxicity of the CQDs. The advantages of the CQDs, such as low cost, ease of manufacture, nontoxicity, and stability, have potential applications in many areas such as metal ion detection and biosensing.

Safety assessment of crude saponins from Chenopodium quinoa willd. husks: 90-day oral toxicity and gut microbiota & metabonomics study in rats

The subchronic toxicity of saponins of Chenopodium quinoa Willd. husks in healthy adult Sprague-Dawley (SD) rats was explored. Female and male rats were randomly divided into 0, 5, 50, and 500 mg/kg body weight (BW)/day groups. Subchronic general toxicity, metabonomics and gut microbiota were assessed. The rats treated with saponins weighed less and had lower blood sugar levels (P < 0.05). Thirty-two differential metabolites were found in female rats and 23 in male rats. Saponins also led to changes in metabonomics. Slight necrosis was observed in the intestinal mucosa, which was associated with an increase in the gut microbiota diversity of female rats in the high-dose saponin treatment group and metabolic changes in the liver and kidney. In conclusion, the toxic effect of quinoa saponins is sex-dependent; however, the no-observed-adverse-effect level for quinoa saponins was evaluated to be under 50 mg/kg BW/day for both sexes in the current study.

Optimization of the ultrasoud-assisted extraction of saponins from quinoa (Chenopodium quinoa Wild) using response surface methodology.

Quinoa grain has a bitter tasting layer in the pericarp called saponin, a triterpenoid glycoside with industrial potential. Traditionally, quinoa saponins are extracted with a large amount of water, which is why ultrasound technology constitutes an emerging technological alternative which is considered efficient and profitable compared to traditional extraction methods. The objective of this research was to determine the amplitude, time, and concentration of ethanol that guarantee a higher content of saponin through extraction assisted by ultrasound. To find the optimal extraction conditions, the response surface methodology was used using the Box Behnken design with 5 central points, taking as a response the content of saponins (expressed in oleanolic acid as it is the most abundant sapogenin). According to the results obtained, the R2 values were in agreement with the adjusted R2, showing that the data fit the model well. The results showed that ethanol concentration has a significant effect (p < 0.05) on the saponin content in the extract. Optimization showed that the optimal extraction conditions were 70% ethanol, 59% amplitude and an exposure time of 12 min. These values were obtained experimentally to compare theoretical values and found residual error percentages less than 3%. The emulsifying activity was evaluated, reporting a value of 52,495 units of emulsion activity per milliliter (UAE/mL), and the foaming stability indicated that 87.54% of the initial foam was maintained after 5 min, indicating high stability. The parameters of ethanol concentration, amplitude and time were optimized in the extraction of saponins, assisted by ultrasound. Furthermore, the extract obtained had good foaming and emulsifying characteristics, suggesting its suitability for use in industry.

Quinoa saponins, biological controller against Cercospora coffeicola and Moniliophthora roreri

An extract rich in saponins obtained from quinoa residues showed in vitro anti-fungal activity against the coffee phytopathogen Cercospora coffeicola, with an antifungal index of inhibition (AI) of 22.39 ± 4.5% at 120 mg/mL, and against the cocoa phytopathogen Moniliophthora roreri, with an AI of 55.8 ± 1.6% at 60 mg/mL. The results showed a potential of this saponin-extract for the biological control of these phytopathogens.

In vivo acute toxicity and mutagenic analysis of crude saponins from Chenopodium quinoa Willd husks.

Background: As a functional food factor, quinoa saponins are valuable as additives and in medical care, pharmaceutical development, cosmetics and other fields. However, few studies have investigated the toxicity of saponins. The main purpose of this study was to evaluate the toxicity of crude saponins extracted from quinoa husks. Thus, acute toxicity and excretion experiments were carried out in rats. The Ames test, micronucleus test and mouse sperm aberration test were carried out in mice. Results: In the acute toxicity study, the obtained LD50 was more than 10 g per kg per bw for both sexes, the food intake of all rats decreased over a period of time, and some rats developed diarrhea. In the case of large-dose gavage, the saponin excretion time in rats was approximately four days. When the dosage was 10 mg kg−1, quinoa saponins were hydrolyzed into aglycone within 24 hours and excreted out of the body. The results of the mutagenicity experiment showed that saponins had no mutagenicity in mice. Conclusion: This work has demonstrated that quinoa saponins have limited acute toxicity effects, which provides a theoretical basis for their rational utilization.

Effects of Biosurfactants on Enzymatic Saccharification and Fermentation of Pretreated Softwood.

The enzymatic hydrolysis of cellulose is inhibited by non-productive adsorption of cellulases to lignin, and that is particularly problematic with lignin-rich materials such as softwood. Although conventional surfactants alleviate non-productive adsorption, using biosurfactants in softwood hydrolysis has not been reported. In this study, the effects of four biosurfactants, namely horse-chestnut escin, Pseudomonas aeruginosa rhamnolipid, and saponins from red and white quinoa varieties, on the enzymatic saccharification of steam-pretreated spruce were investigated. The used biosurfactants improved hydrolysis, and the best-performing one was escin, which led to cellulose conversions above 90%, decreased by around two-thirds lignin inhibition of Avicel hydrolysis, and improved hydrolysis of pretreated spruce by 24%. Red quinoa saponins (RQS) addition resulted in cellulose conversions above 80%, which was around 16% higher than without biosurfactants, and it was more effective than adding rhamnolipid or white quinoa saponins. Cellulose conversion improved with the increase in RQS addition up to 6 g/100 g biomass, but no significant changes were observed above that dosage. Although saponins are known to inhibit yeast growth, no inhibition of Saccharomyces cerevisiae fermentation of hydrolysates produced with RQS addition was detected. This study shows the potential of biosurfactants for enhancing the enzymatic hydrolysis of steam-pretreated softwood.

Phytostimulant properties of highly stable silver nanoparticles obtained with saponin extract from Chenopodium quinoa.

Quinoa (Chenopodium quinoa Willd) is an Andean original pseudocereal with high nutritional value. During quinoa processing, large amounts of saponin-rich husks byproducts are obtained. Quinoa saponins, which are biologically active, could be used for various agriculture purposes. Silver nanoparticles have increasingly attracted attention for the management of crop diseases in agriculture. In this work, silver nanoparticles are synthesized by a sustainable and green method, using quinoa husk saponin extract (QE) to evaluate their potential for application in agriculture as biostimulants. Quinoa extract was obtained and characterized by liquid chromatography with tandem mass spectrometry (LC-MS/MS). Sixteen saponin congeners were successfully identified and quantified. The QE obtained was used as a reducing agent for silver ions to synthesize silver nanoparticles (QEAgNPs) under mild conditions. The morphology, particle size, and stability of Ag nanoparticles were investigated by transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-visible), energy-dispersive X-ray (EDS), zeta potential, and Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR). Ultraviolet-visible spectroscopy measurements confirmed the formation of silver nanoparticles in the presence of QE, with estimated particle sizes in a range between 5 and 50 nm. According to the zeta potential values, highly stable nanoparticles were formed. The QE and QEAgNPs (200-1000 μg/mL) were also tested in radish seed bioassay to evaluate their phytotoxicity. The seed germination assays revealed that QEAgNPs possessed a phytostimulant effect on radish seeds in a dose-dependent manner, and no phytotoxicity was observed for both QE and QEAgNPs. Silver nanoparticles obtained by a so-called 'green' method could be considered as good candidates for application in the agricultural sector for seed treatment, or as foliar sprays and plant-growth-promoters. © 2020 Society of Chemical Industry.

Study of bitterness perception of quinoa (Chenopodium quinoa wild.) saponin extracts

The thresholds and behavior of bitterness perception over time were studied for quinoa saponins. The detection threshold was calculated in two ways using R-index values: linear equation (as previously used) and regression analysis (proposed hereby). Panelists were grouped depending on their bitterness sensitivity, and differences were found among dynamic panelist perceptions. At the threshold level, the sensation dynamic was lower than the caffeine threshold. By HPLC analysis, we identified three main types of saponins (A, B, and C), which positively correlated with the stimulus concentration. The saponin fractions were more related to the time-intensity parameters than the total saponins. Pearson's correlations showed that maximum intensity, total duration, area under the curve, and rising slope were best correlated with A, B, and C saponins. Interestingly, bitterness was perceived before chemical differentiation. It is important to study the saponin bitterness thresholds and perception, as they directly influence consumer choices and must be addressed before being used in quinoa products in the food industry.

Enhancing the Membranolytic Activity of Chenopodium quinoa Saponins by Fast Microwave Hydrolysis.

Saponins are plant secondary metabolites. There are associated with defensive roles due to their cytotoxicity and are active against microorganisms. Saponins are frequently targeted to develop efficient drugs. Plant biomass containing saponins deserves sustained interest to develop high-added value applications. A key issue when considering the use of saponins for human healthcare is their toxicity that must be modulated before envisaging any biomedical application. This can only go through understanding the saponin-membrane interactions. Quinoa is abundantly consumed worldwide, but the quinoa husk is discarded due to its astringent taste associated with its saponin content. Here, we focus on the saponins of the quinoa husk extract (QE). We qualitatively and quantitively characterized the QE saponins using mass spectrometry. They are bidesmosidic molecules, with two oligosaccharidic chains appended on the aglycone with two different linkages; a glycosidic bond and an ester function. The latter can be hydrolyzed to prepare monodesmosidic molecules. The microwave-assisted hydrolysis reaction was optimized to produce monodesmosidic saponins. The membranolytic activity of the saponins was assayed based on their hemolytic activity that was shown to be drastically increased upon hydrolysis. In silico investigations confirmed that the monodesmosidic saponins interact preferentially with a model phospholipid bilayer, explaining the measured increased hemolytic activity.