Effects of Smallanthus sonchifolius Flour on Metabolic Parameters: A Systematic Review

Smallanthus sonchifolius, popularly known as yacon, is a member of the Asteraceae family. Due to its medicinal and edible value, yacon is consumed by different populations. Yacon is unique due to its high fructo-oligosaccharide and inulin content, as well as flavonoids, sesquiterpene lactones, and phenolic acids. Roots can be used to produce flour, which is less perishable and can be applied in various industrial products. This systematic review focuses on the effects of yacon flour on metabolic parameters. PubMed, Cochrane, Embase, Science Direct, Scopus, Web of Science, and Google Scholar databases were consulted, and PRISMA guidelines were followed in the selection of the studies. In total, 526 articles were found in the databases, and of these, only 28 full texts were eligible for inclusion. After applying the inclusion and exclusion criteria, seven studies were finally included. The results showed that the use of yacon flour can reduce glycemia, HbA1c, advanced glycation ends, plasma lipids, body fat mass, body weight, and waist circumference and improve intestinal microbiota and the antioxidant status. Further exploration of the effects of yacon flour is warranted, and additional clinical trials are necessary to determine the optimal daily consumption levels required to assist in improving metabolic parameters.

Improved Bacterial Survival and Antioxidant Activity After In Vitro Digestion of Fermented Dairy Beverages by Lacticaseibacillus casei LC-01 and Lactiplantibacillus plantarum BG-112 Containing Yacon

The fermentation of milk containing 0%, 3%, 6%, and 9% (w/v) yacon root flour (YRF) by Lacticaseibacillus casei LC-1 and Lactiplantibacillus plantarum BG-112 was evaluated for bacterial survival and antioxidant activity (AA) before and after simulated gastrointestinal digestion. After 28 days of refrigerated storage, samples of the beverages were analyzed for cell viability, AA (using ferric ion reducing antioxidant power (FRAP) and (ABTS), and molecular mass profile of proteins (using electrophoresis). The presence of 9% YRF increased bacterial survival during 28 days of storage and passage through the gastrointestinal tract for both L. casei and L. plantarum, which showed a greater capacity to reduce ferric ions compared to 0% YRF, and the ability to capture free radicals increased from below 5 mM to over 15 mM TE after digestion. Milk proteins are hydrolyzed during digestion, and the generation of bioactive peptides with AA may explain the increase in AA levels. Since peptides are generated from milk proteins, YRF did not influence AA after digestion. These results showed that fermentation of milk by L. casei and L. plantarum with YRF increased the chances of these bacteria reaching the colon in adequate quantities. After simulated digestion, the beverages showed improved AA due to milk protein hydrolysis.

Consumption of yacon flour and energy-restricted diet increased the relative abundance of intestinal bacteria in obese adults

Prebiotics can alter the gastrointestinal environment, favoring the growth of health-promoting bacteria. Although yacon is a functional food, with prebiotic properties (fructooligosaccharides), its effects on the intestinal microbiota have not been investigated yet. The objective of this study was to evaluate the effects of yacon flour consumption and energy-restricted diet in the intestinal microbiota in adults with excess body weight. Twenty-one adults with excess body weight were included in this randomized, parallel, double-blind, placebo-controlled, 6-week clinical trial. Subjects daily consumed at breakfast a drink containing 25 g of yacon flour (n = 11) or not containing yacon (n = 10) and received the prescription of energy-restricted diets. Fecal samples were collected on the first and on last day of the study. 16S rRNA sequencing was assessed to evaluate the effect of yacon fermentation on intestinal microbiota bacterial composition. There was an increase in the genera Bifidobacterium, Blautia, Subdoligranulum, and Streptococcus after the consumption of yacon and energy-restricted diet. In the yacon group, we also observed a positive correlation between the concentrations of short-chain fatty acids versus the genera Coprococcus and Howardella, besides a negative correlation between the concentrations of advanced glycation end products and early glycation products versus the genera Ruminococcus and Prevotella, respectively. Consumption of yacon flour and energy-restricted diet selectively changed the intestinal microbiota composition in adults with excess body weight. TRIAL REGISTRATION: Register number: RBR-6YH6BQ. Registered 23 January, 2018.

Chemical profile and toxicogenetic safety assessment of Smallanthus sonchifolius (yacon) organic extracts

The interest in Smallanthus sonchifolius (yacon) has strongly resurfaced due to its multiple beneficial effects on human health. This study aimed at determining the toxicity and the chemical profile of an ethanol extract (EE) and a crude lactone mixture (CLM) of yacon leaves. Cytotoxicity and genotoxicity tests were performed by the MTT assay and the alkaline version of the comet assay respectively. The phytochemical analysis, performed by chromatographic and spectroscopy techniques, revealed the presence of nine sesquiterpene lactones (STLs) and two acyclic diterpene acids. In all cases, cell viability was inversely proportional to the extract concentration employed. The effects obtained with the highest dose of EE were significantly different from those obtained with the negative and solvent controls. Conversely, no significant differences were observed between the lowest doses of EE and controls. As for CLM, all tested doses showed statistically significant increases, as compared to negative and solvent controls.

Complete chloroplast genome and phylogenetic analysis of Smallanthus sonchifolius (Asteraceae)

Smallanthus sonchifolius (Asteraceae), is an important food plant in the world. There is no systematic report on the chloroplast genome of S. sonchifolius. Here we reported its complete chloroplast genome and analyzed the basic characteristics. The chloroplast genome was 152,301 bp in length, had a GC content of 37.55%, and encoded 113 unique genes, including 79 protein-coding genes, 4 ribosomal RNA genes, and 30 transfer RNA genes. Phylogenetic analysis showed that the tribe Millerieae and the tribe Madieae are closely related in the Asteraceae family. In the tribe Millerieae, Smallanthus was more closely related to Guizotia and Sigesbeckia. This chloroplast genome not only enriches the genome information of Smallanthus, but also lays the foundation for understanding the phylogeny within the genus Smallanthus.

Quantification of Enhydrin and Uvedalin in the Ethanolic Extract of Smallanthus sonchifolius Leaves Validated by the HPLC Method

Yacon leaf (Smallanthus sonchifolius, Asteraceae) ethanolic extracts are widely used in herbal medicine preparation for diabetes. They contain two sesquiterpene lactones (enhydrin (1) and uvedalin (2)) as major bioactive compounds. To provide a suitable method of analysis for the extract's quality control, we developed and validated a simultaneous HPLC-UV method using the compounds as markers. Compounds 1 and 2 were isolated using a freeze crystallization technique followed by a preparative HPLC. Spectrometry data for 1 and 2 were determined and compared to the literature. Chromatographic separation was carried out for 30 min with a mobile phase that used 60% water and 40% acetonitrile and a C18 column (250 × 4.6 mm, 5 µm) as the stationary phase. The flow was set to 1 mL min^-1 and detection was conducted at 210 nm. The validation method was conducted according to the ICH guidelines, which included linearity, precision, accuracy, LOD, and LOQ. The calibration curve of both compounds was linear (R ² > 0.9999), with the limit of detection and quantification as follows, respectively, 0.52 and 1.57 µg/mL for 1, and 0.144 and 0.436 µg/mL for 2. The percentages of recovery and repeatability (%RSD) were, 101.46 and 0.30% for 1, and 97.68 and 0.08% for 2, respectively. The 1 and 2 were 1.67 and 0.88% in the Ykal extract, and 1.26 and 0.56% in the Ycin extract, respectively. The method was found to be linear, precise, accurate, and suitable to be applied for control quality analyses of yacon leaf extract.

Yacon-based product improves intestinal hypertrophy and modulates the production of glucagon-like peptide-1 in postmenopausal experimental model

AIMS

The progressive decline in estrogen level puts postmenopausal women at a higher risk of developing cardiometabolic diseases. Thus, we evaluated the potential beneficial effects of yacon-based product (YBP) on glycemic profile and intestinal health of postmenopausal rats.

METHODS

Eighty Wistar rats were randomized into 4 ovariectomized (OVX) groups or 4 celiotomized groups treated with a standard diet (SD) or diet supplemented with YBP at 6% of fructooligosaccharide (FOS)/inulin.

KEY FINDINGS

The continued consumption of YBP at 6% of FOS/inulin did not generate liver damage and gastrointestinal disorders. Rats fed with YBP displayed higher food consumption, but this did not increase the body weight gain, abdominal circumference and body fat percentual of OVX rats. Furthermore, we also found that the FOS/inulin fermentation present in the YBP resulted in cecum, ileum and colon crypts hypertrophy and increased the lactic acid levels in the cecal content. We observed an increase of glucagon-like peptide-1 (GLP-1) immunoreactive cells and there was no change in the glucose and insulin plasma levels of YBP-fed OVX rats.

SIGNIFICANCE

Our findings indicated that YBP when consumed previously and after the menopausal period has important effects on the morphology and function of intestinal mucous of rats and has potential to modulate indirectly the glycemic and insulinemic profiles, weight gain and body fat percentual in the hypoestrogenic period through metabolites produced in the fermentation process.

Yacon as an alternative host plant for Encarsia formosa mass-rearing: validating a multinomial theorem for bootstrap technique in life table research

BACKGROUND

Yacon (Smallanthus sonchifolius) is a broadleaf host plant suitable for rearing the greenhouse whitefly, Trialeurodes vaporariorum (Westwood). Here, the possibility of using yacon as an alternative host plant for production of the parasitoid, Encarsia formosa Gahan, one of the most important natural enemies of whiteflies, was explored. Data on the demographic characteristics, parasitism rate, and host-feeding rate were collected and analyzed using the TWOSEX-MSChart, CONSUME-MSChart, and TIMING-MSChart computer programs, and then contrasted with comparable data from the more commonly utilized host plant, tobacco.

RESULTS

Higher fecundity (F) (190.13 eggs/female) and more oviposition days (O_d ) (16.60 days) were observed in E. formosa when yacon was used as the host plant for rearing T. vaporariorum, compared with when tobacco was used (F = 150.13 eggs/female, O_d = 15.27 days). The intrinsic rate of increase (r), finite rate of increase (λ), and net reproduction rate (R₀ ) were significantly higher in E. formosa parasitizing T. vaporariorum reared on yacon compared with those parasitizing tobacco-reared T. vaporariorum. Furthermore, the net host-feeding rate (C₀ = 40.87 prey/parasitoid), net killing rate (Z₀ = 239.73 prey/parasitoid), and finite killing rate ( υ  = 0.2560/day) for E. formosa on yacon-reared whiteflies were significantly higher than those from tobacco-reared whiteflies.

CONCLUSION

Our results showed that yacon is more suitable than tobacco as a host plant for mass-rearing E. formosa for biological control programs to manage whiteflies. An innovative application of the multinomial theorem for calculating the exact probability of bootstrap samples in life table research was also introduced. © 2021 Society of Chemical Industry.

Acute postprandial effect of yacon syrup ingestion on appetite: A double blind randomized crossover clinical trial

Yacon syrup is a rich source of fructooligosaccharides (FOS); however, its diet supplementation effect on subjective sensation and appetite biomarkers in human is still unknown. This study aimed to evaluate the acute postprandial effect of yacon syrup ingestion on appetite. The double-blind crossover clinical trial was carried out with 40 adult women: 20 eutrophic and 20 obese grade I. On each day, the first blood collection was performed after a 12-h fast. Then, the volunteers ingested either intervention A (breakfast + 40 g of placebo) or intervention B (breakfast + 40 g of yacon syrup, containing 14 g of FOS). New aliquots of blood were collected at 45, 60, 90, 120, and 180 min. Appetite was assessed by estimating ghrelin and glucagon-like peptide-1 (GLP-1) levels and by assessing subjective appetite sensation. Analysis was performed using two-way ANOVA, followed by Bonferroni's multiple comparison test. No effect of yacon syrup was observed on postprandial ghrelin and GLP-1 levels at all times evaluated. Similar observations were made after stratifying the analysis by BMI (body mass index) (eutrophic and obese). The effect of yacon syrup on postprandial subjective sensations of hunger, satiety, fullness, and desire to eat was not evident in the total group of women evaluated and even after BMI stratification. We concluded that yacon syrup had no effect on postprandial ghrelin and GLP-1 levels and on the subjective appetite sensation in young adult women.

Extraction of Inulin from Andean Plants: An Approach to Non-Traditional Crops of Ecuador

Inulin is a polysaccharide of fructose widely used in the food and pharmaceutical industry due to its physicochemical properties and technological applications. Inulin from jicama (Smallanthus sonchifolius) and cabuya (Agave americana) was obtained. The steps for inulin obtention were: raw material preparation, extraction and purification. The extraction conditions were determined using a random design with three levels of stirring speed (0, 130 and 300 rpm), and a 3² factorial experimental design with three levels of temperature (40, 60 and 80 °C) and solid:liquid ratio (1:2, 1:3 and 1:5 S:L). The results showed that the best extractions conditions for jicama were 130 rpm, 75 °C, 1:5 S:L and 25 min; while for cabuya were 80 °C, 300 rpm, 1:5 S-L and 100 min. The weight average molecular weight of inulin from jicama and cabuya were 5799.9 and 4659.75 g/mol, respectively. The identity of the obtained inulin from jicama and cabuya were confirmed by infrared (IR) and Raman spectroscopy. In addition, scanning electron microscopy, differential scanning calorimetry and thermogravimetry analyses were performed to characterize both inulins.

Toxicogenetic evaluation of Smallanthus sonchifolius (yacon) as a herbal medicine

ETHNOPHARMACOLOGICAL RELEVANCE

Smallanthus sonchifolius (Poepp. & Endl.) H. Robinson, commonly known as yacon, is a medicinal plant belonging to the Asteraceae family used in traditional folk medicine. Its roots and leaves have been used by people suffering from diabetes or from various digestive or renal disorders.

AIM OF THE STUDY

This study aimed at evaluating the in vitro potential genotoxic effects of the aqueous extract of yacon in order to determine its safety and at characterizing its phytochemical composition.

MATERIALS AND METHODS

The aqueous extract of S. sonchifolius was prepared in a similar way to that commonly used in popular medicine as tea bags. Thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC-MS/MS) were used to identify the main compounds. The MTT test was performed to determine the range of doses and the Cytochalasine B-blocked micronucleus (Cytome assay) was used to assess geneotoxicity.

RESULTS

The chemical analysis of the aqueous extract revealed the presence of the sesquiterpene lactones (STLs) enhydrin and the dimer enhydrofolin, as the main compounds together with phenolic compounds. Increasing concentrations of the extract induced a cytotoxic effect on CHO-K1 and HepG2 cells. A statistically significant increase in the frequency of MNi, NBUDs and NPBs was observed in CHO-K1 cells, while in HepG2 cells a statistically significant frequency increase was observed with three of the four tested doses for MNi and only with the highest dose for NPBs and NBUs (genotoxic effect).

CONCLUSION

Results demonstrated the inability of the metabolic system to counteract the genetic instability, allowing the safe consumption of the leaves as a 2% tea infusion in quantities of up to 250 mL/day.

Metabolomic and Gene Expression Studies Reveal the Diversity, Distribution and Spatial Regulation of the Specialized Metabolism of Yacón (Smallanthus sonchifolius, Asteraceae)

Smallanthus sonchifolius, also known as yacón, is an Andean crop species commercialized for its nutraceutical and medicinal properties. The tuberous roots of yacón accumulate a diverse array of probiotic and bioactive metabolites including fructooligosaccharides and caffeic acid esters. However, the metabolic diversity of yacón remains unexplored, including the site of biosynthesis and accumulation of key metabolite classes. We report herein a multidisciplinary approach involving metabolomics, gene expression and scanning electron microscopy, to provide a comprehensive analysis of the diversity, distribution and spatial regulation of the specialized metabolism in yacón. Our results demonstrate that different metabolic fingerprints and gene expression patterns characterize specific tissues, organs and cultivars of yacón. Manual inspection of mass spectrometry data and molecular networking allowed the tentative identification of 71 metabolites, including undescribed structural analogues of known bioactive compounds. Imaging by scanning electron microscopy revealed the presence of a new type of glandular trichome in yacón bracts, with a distinctive metabolite profile. Furthermore, the high concentration of sesquiterpene lactones in capitate glandular trichomes and the restricted presence of certain flavonoids and caffeic acid esters in underground organs and internal tissues suggests that these metabolites could be involved in protective and ecological functions. This study demonstrates that individual organs and tissues make specific contributions to the highly diverse and specialized metabolome of yacón, which is proving to be a reservoir of previously undescribed molecules of potential significance in human health.

Yacon syrup reduces postprandial glycemic response to breakfast: A randomized, crossover, double-blind clinical trial

Yacon is a root rich in fructooligosaccharides (FOS), which act as prebiotics. Numerous studies have shown promising results in the technological aspects of producing yacon syrup. However, uncertainties exist concerning whether yacon syrup can modulate postprandial glucose and lipid profiles. In order to assess the effect of yacon syrup on postprandial glucose, insulin and triglyceride (TG) responses, a randomized, crossover, double-blind clinical intervention with 40 women (20 normal weight and 20 grade I obese) was performed. Participants underwent two-arms of intervention with at least a one-week wash-out period between visits. On each intervention day, after 12 h of fasting, an aliquot of blood was collected. For intervention A, volunteers consumed breakfast +40 g of placebo, whereas for intervention B, participants consumed breakfast +40 g of yacon syrup (14 g of FOS). Blood samples were drawn at 15, 30, 45, 60, 90, and 120 min. Glucose and insulin concentrations were lowered after yacon syrup intake as compared to placebo at following times: 30 min for glucose and 15, 30 and 45 min for insulin. In conclusion, yacon syrup has a postprandial decreasing effect glucose and insulin concentrations in adult women. This effect was not evident for triglyceride concentration. Clinical trial registry: RBR-33wf46. Available in: http://www.ensaiosclinicos.gov.br/rg/RBR-33wf46/.

Robinson] accessions based on iPBS markers and metabolomic fingerprinting

The present study is focused on the characterization of yacon [Smallanthus sonchifolius (Poepp. et Endl.) H. Robinson] accessions from different geographic origins (Bolivia, Ecuador, and Peru) by iPBS markers and metabolomic fingerprinting. The results showed that the number of amplified polymorphic fragment levels ranged from 20 up to 27 with a level of polymorphism ranging from 80 to 100%. Five of the iPBS primers used in this study provided no specific banding pattern able to discriminate between the different yacon accessions. However, two iPBS primer pairs were able to separate Peru accessions from those of Ecuador and Bolivia. The UPLC-HRMS/MS-based metabolomic fingerprinting showed highly similar metabolomic fingerprints characterized by the accumulation of high quantities of sesquiterpene lactones and diterpenes, but no apparent geographic clustering. The present study demonstrates that yacon accessions from different geographical origins maintained ex situ (in the Czech Republic) present a rather low chemical and genetic diversity.

Two new sesquiterpene lactones from leaves of yacon, Smallanthus sonchifolius

The chemical constituents of 95% EtOH extract of yacon leaves were separated to yield two new sesquiterpene lactones, together with three known compounds. The two new compounds were characterized to be 8β-angeloyloxy-13-methoxyl-11, 13-dihydromelampolid-14-oic acid methyl ester (1) and 8β-(3-methylbut-2-enoyl) oxy-13-methoxyl-11, 13-dihydromelampolid-14-oic acid methyl ester (2) on the basis of NMR spectra, HR-MS and other spectroscopic methods. The cytotoxicity of compounds 1-5 were evaluated on human hepatoma cell Bel-7402 and all the compounds showed moderate cytotoxicity.

Phytochemical Properties and Nutrigenomic Implications of Yacon as a Potential Source of Prebiotic: Current Evidence and Future Directions

The human gut is densely populated with diverse microbial communities that are essential to health. Prebiotics and fiber have been shown to possess the ability to modulate the gut microbiota. One of the plants being considered as a potential source of prebiotic is yacon. Yacon is an underutilized plant consumed as a traditional root-based fruit in South America. Yacon mainly contains fructooligosaccharides (FOS) and inulin. Therefore, it has bifidogenic benefits for gut health, because FOS are not easily broken down by digestive enzymes. Bioactive chemical compounds and extracts isolated from yacon have been studied for their various nutrigenomic properties, including as a prebiotic for intestinal health and their antimicrobial and antioxidant effects. This article reviewed scientific studies regarding the bioactive chemical compounds and nutrigenomic properties of extracts and isolated compounds from yacon. These findings may help in further research to investigate yacon-based nutritional products. Yacon can be considered a potential prebiotic source and a novel functional food. However, more detailed epidemiological, animal, and human clinical studies, particularly mechanism-based and phytopharmacological studies, are lacking for the development of evidence-based functional food products.

Bioactive Potential of Andean Fruits, Seeds, and Tubers

The Andes is considered the longest continental mountain range in the world. It covers 7000km long and about 200-700km wide and an average height of about 4000m. Very unique plant species are endemic of this area including fruits (e.g., lucuma, cherimoya, sweet pepino, sauco), roots and tubers (potatoes, sweet potatoes, yacón, chicuru, mashua, olluco, etc.), and seeds (quinoa, amaranth, tarwi, etc.). These crops have been used for centuries by the native population and relatively recently have gained the world attention due to the wide range of nutrients and/or phytochemicals they possess. In this chapter, main Andean fruits, seeds, and roots and tubers have been selected and detailed nutritional and functional information is provided. In addition, traditional and current uses are provided and their bioactive potential is reported based on published scientific literature.

Evaluation of nutritional and chemical composition of yacon syrup using 1H NMR and UPLC-ESI-Q-TOF-MSE

A complete characterization of yacon syrup was performed by analytical techniques, including NMR and UPLC-QTOF-MS^E. The effect of the different stages of yacon syrup production on fructooligosaccharides (FOS) and chlorogenic acid (CGA) contents were also evaluated. As a result, in addition to higher levels of FOS and CGA, some mineral elements, such as K, Ca and P, and essential amino acids, such as tryptophan, valine, and threonine, were determined in yacon syrup. Twenty-five compounds were putatively identified, and the main compounds were phenolics derived from quinic and trans-cinnamic acids. Considering the different stages of yacon syrup production, the results indicate that the contents of FOS and CGA were maintained in the pulping, enzymatic maceration and microfiltration, leading to a concentration of these components in the last stage of processing (vacuum concentration). These results will be used to fortify this innovative and promising product in the area of functional foods.

Germacranolide-type sesquiterpene lactones from Smallanthus sonchifolius with promising activity against Leishmania mexicana and Trypanosoma cruzi

Background

Leishmaniasis and Chagas disease are life-threatening illnesses caused by the protozoan parasites Leishmania spp. and Trypanosoma cruzi, respectively. They are known as “neglected diseases” due to the lack of effective drug treatments and the scarcity of research work devoted to them. Therefore, the development of novel and effective drugs is an important and urgent need. Natural products are an important source of bioactive molecules for the development of new drugs. In this study, we evaluated the activity of enhydrin, uvedalin and polymatin B, three sesquiterpene lactones (STLs) isolated from Smallanthus sonchifolius, on Leishmania mexicana (MNYC/BZ/62/M) and Trypanosoma cruzi (Dm28c). In addition, the in vivo trypanocidal activity of enhydrin and uvedalin and the effects of these STLs on parasites’ ultrastructure were evaluated.

Methods

The inhibitory effect of the three STLs on the growth of L. mexicana amastigotes and promastigotes as well as T. cruzi epimastigotes was evaluated in vitro. The changes produced by the STLs on the ultrastructure of parasites were examined by transmission electron microscopy (TEM). Enhydrin and uvedalin were also studied in a murine model of acute T. cruzi infection (RA strain). Serum activities of the hepatic enzymes alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase were used as biochemical markers of hepatotoxicity.

Results

The three compounds exhibited leishmanicidal activity on both parasite forms with IC₅₀ values of 0.42–0.54 μg/ml for promastigotes and 0.85–1.64 μg/ml for intracellular amastigotes. Similar results were observed on T. cruzi epimastigotes (IC₅₀ 0.35–0.60 μg/ml). The TEM evaluation showed marked ultrastructural alterations, such as an intense vacuolization and mitochondrial swelling in both L. mexicana promastigotes and T. cruzi epimastigotes exposed to the STLs. In the in vivo study, enhydrin and uvedalin displayed a significant decrease in circulating parasites (50–71%) and no signs of hepatotoxicity were detected.

Conclusions

Enhydrin, uvedalin and polymatin B possess significant leishmanicidal and trypanocidal activity on different parasite stages. These results show that these compounds may provide valuable leads for the development of new drugs against these neglected parasitic diseases.

Yacon syrup: Food applications and impact on satiety in healthy volunteers

Syrup obtained from yacon roots could be well positioned as a nutritional product due to its high fructooligosaccharides (FOS) content. Considering this, we examined the potential food applications of yacon syrup, using the focal group methodology, and its sensorial acceptability when incorporated in yogurt. The beneficial effects of the consumption of yacon syrup were studied over a 2-week period in a double-blind placebo-controlled experiment (namely Test A) and other consistent of only one day of yacon syrup consumption (namely Test B) were also evaluated. The doses of yacon syrup for both experiments were 8.74g of FOS/day. Energy intake, hunger, satiety, fullness and prospective food consumption were assessed with analogue scales at the end of each test. The results indicate that the yogurt was the food most suggested by the focus group, and the average of the scores given to the attributes when the yacon syrup was incorporated into a yogurt were: 7.78 for appearance; 7.72 for aroma; 7.02 for flavor and 6.96 for overall acceptability, corresponding to "like very much" and "like moderately". Furthermore, the results indicate that yacon syrup has a positive effect on appetite and its effect was dependent on gender and period of intervention, being statistically significant (P<0.05) in women, after 2-week period. These findings suggested that increasing FOS intake could help to increase satiety, and consequently, be helpful in the management of type 2-diabetes or control of the current high prevalence of overweight or obesity.

Enhydrin Regulates Postprandial Hyperglycemia in Diabetic Rats by Inhibition of α-Glucosidase Activity

During the last few years, numerous attempts were made to identify effective α-glucosidase inhibitors from natural sources in order to develop new alternatives for diabetes management. Smallanthus sonchifolius (yacon) leaves were found to be effective in controlling postprandial hyperglycemia. Enhydrin, a constituent of yacon leaves, was noted for its significant hypoglycemic properties in diabetic rats. These properties were also demonstrated for yacon leaves decoction, which is rich in phenolic compounds such as chlorogenic acid and its derivatives. The purpose of the present study was to evaluate the potential of yacon leaves decoction and the isolated compound enhydrin to inhibit α-glucosidase enzyme, a possible mechanism of the above antihyperglycemic effect. In vitro assays showed that both 10% decoction and enhydrin significantly inhibited the activity of the yeast α-glucosidase enzyme in a dose-dependent manner, IC₅₀ values being 50.40 and 134.17 μg/ml, respectively. In vivo experiments showed a rapid decrease in the hyperglycemic peak after sucrose load (2 g/kg body weight) in normal rats treated with the 10% decoction (140 mg/kg) and enhydrin (0.8 mg/kg). Both treatments caused a significant decrease in blood glucose levels in diabetic rats after sucrose load compared to diabetic control. These results suggest that both products assayed could be effective in the management of postprandial hyperglycemia through inhibition of α-glucosidase in the small intestine.

Flower structure and developmental stages of the capitulum of Smallanthus sonchifolius (Asteraceae): reproductive implications

Yacon (Smallanthus sonchifolius, Asteraceae) is an ancient andean crop that has numerous dietary and medicinal properties. Morphological and anatomical features and developmental changes of the capitulum were studied. A ray floret is a pistillate, female flower, while a disc floret is a staminate male flower, and the former opens before the latter, being pseudanthium protogynous. The capitulum presents interesting attributes for pollinators such as flower structure, nectaries and pollenkitt. Gynoecial nectaries were found on undeveloped ovary in the disc floret, but not in the ray floret. Glandular trichomes were observed on the abaxial epidermis of corolla in the ray floret, but not in the disc floret. Capitulum development was divided into eight stages. Stigma receptivity varied with these stages. Pollen viability was low (15%). In accordance with low viability, pollen grains exhibit diverse sizes and shapes, reduction in length of spines, and abnormal protoplasm. Examination of ovary development in the ray floret showed that a mature ovule was formed, but fertilization did not occur. In advanced developmental stages, the capitulum showed proliferation of the endothelium, degeneration of the embryo sac, and all harvested cypselae had aborted seeds. Problems found in pollen viability and aborted cypselae could be the result of a history of vegetative propagation in the domestication process.

New Sesquiterpene Lactone Dimer, Uvedafolin, Extracted from Eight Yacon Leaf Varieties (Smallanthus sonchifolius): Cytotoxicity in HeLa, HL-60, and Murine B16-F10 Melanoma Cell Lines

Uvedafolin, 1, a new sesquiterpene lactone dimer, was isolated from the leaves of Smallanthus sonchifolius with five related compounds, 2-6, and their cytotoxicity was assessed against three tumor cell lines (HeLa, HL-60, B16-F10 melanoma). The stereostructure of 1 was newly elucidated by ESI-TOF-MS, 1D/2D NMR, and single-crystal X-ray diffraction. Dimers 1 and 2 had the most effective IC50 values, 0.2-1.9 μM, against the three tumor cell lines when compared with monomers 3-6 (IC50 values 0.7-9.9 μM) and etoposide (IC50 values 0.8-114 μM). The ester linkages of two sets of monomers, uvedalin, 5, and sonchifolin, 6, for 1, and enhydrin, 4, and sonchifolin, 6, for 2, as well as the acetyl group at the C-9 position, were essential for the high cytotoxicity. Dimers 1 and 2 would have potential as anticancer agents.

Antioxidant Effects of Herbal Tea Leaves from Yacon (Smallanthus sonchifolius) on Multiple Free Radical and Reducing Power Assays, Especially on Different Superoxide Anion Radical Generation Systems

Yacon (Smallanthus sonchifolius), a native Andean plant, has been cultivated as a crop and locally used as a traditional folk medicine for the people suffering from diabetes and digestive/renal disorders. However, the medicinal properties of this plant and its processed foods have not been completely established. This study investigates the potent antioxidative effects of herbal tea leaves from yacon in different free radical models and a ferric reducing model. A hot-water extract exhibited the highest yield of total polyphenol and scavenging effect on 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical among four extracts prepared with hot water, methanol, ethanol, and ethylacetate. In addition, a higher reducing power of the hot-water extract was similarly demonstrated among these extracts. Varying concentrations of the hot-water extract resulted in different scavenging activities in four synthetic free radical models: DPPH radical (EC50 28.1 μg/mL), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) cation radical (EC50 23.7 μg/mL), galvinoxyl radical (EC50 3.06 μg/mL), and chlorpromazine cation radical (EC50 475 μg/mL). The yacon tea-leaf extract further demonstrated superoxide anion (O2(-)) radical scavenging effects in the phenazine methosulfate-NADH-nitroblue tetrazolium (EC50 64.5 μg/mL) and xanthine oxidase assay systems (EC50 20.7 μg/mL). Subsequently, incubating human neutrophilic cells in the presence of the tea-leaf extract could suppress the cellular O2(-) radical generation (IC50 65.7 μg/mL) in a phorbol 12-myristate 13-acetate-activated cell model. These results support yacon tea leaves may be a good source of natural antioxidants for preventing O2(-) radical-mediated disorders.

PRACTICAL APPLICATION

Yacon has been considered to be a potent alternative food source for patients who require a dietary cure in regional area, while the leaf part has been provided and consumed as an herbal tea in local markets. We demonstrated here potent antioxidative effects of the tea leaves from yacon in different free radical assays, reducing power assay, and cellular superoxide anion radical generation assay. Results support yacon tea leaves may be a good source of natural antioxidants for preventing O2(-) radical-mediated disorders.

The sesquiterpene lactone polymatin B from Smallanthus sonchifolius induces different cell death mechanisms in three cancer cell lines

A 8β-angeloyloxy-9α-hydroxy-14-oxo-acanthospermolide and five known melampolide sesquiterpene lactones (uvedalin, enhydrin, polymatin B, sonchifolin, and fluctuanin) were isolated from the leaves of Smallanthus sonchifolius. The compounds were identified by 1D-, 2D-NMR, HRMS, IR and UV analyses. In vitro cytotoxicity assays (MTT) showed that these sesquiterpene lactones display poor cytotoxic effects on peripheral blood mononuclear cells (PBMC) of healthy human subjects, whereas a strong cytotoxicity was observed in leukemia and pancreas cancer cells. For the mechanism of action of polymatin B, oxidative stress seems to be involved. Interestingly, reactive oxygen species (ROS) formation mainly induced different effects: apoptosis in CCRF-CEM cells, necroptosis in CEM-ADR5000 cells through induction of RIP1K, neither apoptosis nor necroptosis in MIA-PaCa-2 cells. Additionally, cells also died partly by necrosis.

Evaluation of Antioxidant, Antidiabetic and Anticholinesterase Activities of Smallanthus sonchifolius Landraces and Correlation with Their Phytochemical Profiles

The present study aimed to investigate the phytochemical profile of leaf methanol extracts of fourteen Smallanthus sonchifolius (yacon) landraces and their antioxidant, anticholinesterase and antidiabetic activities that could lead to the finding of more effective agents for the treatment and management of Alzheimer's disease and diabetes. For this purpose, antioxidant activity was assessed using different tests: ferric reducing ability power (FRAP), 2,2-diphenyl-1-picryl hydrazyl (DPPH), nitric oxide (˙NO) and superoxide (O2˙-) scavenging and lipid peroxidation inhibition assays. Anticholinesterase activity was investigated by quantifying the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities, whereas antidiabetic activity was investigated by α-amylase and α-glucosidase inhibition tests. To understand the contribution of metabolites, phytochemical screening was also performed by high performance liquid chromatography-diode array detector (HPLC-DAD) system. Among all, methanol extract of PER09, PER04 and ECU44 landraces exhibited the highest relative antioxidant capacity index (RACI). ECU44 was found to be rich in 4,5-di-O-caffeoylquinic acid (CQA) and 3,5-di-O-CQA and displayed a good α-amylase and α-glucosidase inhibition, showing the lowest IC50 values. Flavonoids, instead, seem to be involved in the AChE and BChE inhibition. The results of this study revealed that the bioactive compound content differences could be determinant for the medicinal properties of this plant especially for antioxidant and antidiabetic activities.

The spermatogenic effect of yacon extract and its constituents and their inhibition effect of testosterone metabolism

We screened the pharmacological effects of a 50% ethanol extract of Yacon tubers and leaves on spermatogenesis in rats. As a result, we found that Yacon tuber extracts increased sperm number and serum testosterone level in rats. It has been reported that the crude extract of Yacon tubers and leaves contain phenolic acids, such as, chlorogenic acid, ferulic acid and caffeic acid by HPLC/MS analysis. We were interested in the contributions made by phenolic acid, particularly chlorogenic acid of Yacon tuber extract to the spermatogenic activity. After administering Yacon tuber extract or chlorogenic acid to rats for 5 weeks, numbers of sperm in epididymis were increased by 34% and 20%, respectively. We also administered ferulic acid, which has been reported to be a metabolite of chlorogenic acid and a constituent of Yacon tuber extract to investigate its spermatogenic activity in rats. Yacon tuber extract and ferulic acid increased sperm numbers by 43% and 37%, respectively. And, Yacon tuber extract, and chlorogenic acid showed significantly inhibition effect of testoeterone degradation in rat liver homogenate. We considered that the spermatogenic effect of Yacon tuber extract might be related to phenolic compounds and their inhibitory effect of testosterone degradation. Yacon showed the possibility as ameliorable agents of infertility by sperm deficiency and late onset hypogonadism syndrome with low level of testosterone.

Comparison of Yacon (Smallanthus sonchifolius) Tuber with Commercialized Fructo-oligosaccharides (FOS) in Terms of Physiology, Fermentation Products and Intestinal Microbial Communities in Rats

The yacon (Smallanthus sonchifolius) tuber was examined with regard to its prebiotic effects compared with commercialized fructo-oligosaccharides (FOS). A feed containing 10% yacon tuber, which is equivalent to 5% commercialized FOS in terms of the amount of fructo-oligosaccharides (GF2, GF3 and GF4), was administrated to rats for 28 days. The yacon diet changed the intestinal microbial communities beginning in the first week, resulting in a twofold greater concentration of cecal short-chain fatty acids (SCFAs). The SCFA composition differed, but the cecal pH in rats fed yacon tuber was equal to that in rats fed FOS. Serum triglycerides were lower in rats fed yacon compared with rats fed FOS and the control diet. Cecal size was greater with the yacon tuber diet compared with the control diet. The abundant fermentation in the intestines created a selective environment for the intestinal microbiota, which included Lactobacillus acidophilus, Bifidobacterium pseudolongum, Bifidobacterium animalis and Barnesiella spp. according to identification with culture-independent analysis, 16S rRNA gene PCR-DGGE combined with cloning and sequencing. Barnesiella spp. and B. pseudolongum were only found in the rats fed the yacon diet, while L. acidophilus and B. animalis were found in abundance in rats fed both the yacon and FOS diets. The genus Barnesiella has not previously been reported to be associated with yacon or FOS fermentation. We concluded that the physiological and microbiological effects of the yacon tuber were different from those of FOS. Differences in cecal size, blood triglycerides and microbial community profiles including their metabolites (SCFAs) between the yacon tuber and FOS were shown to be more greatly affected by the yacon tuber rather than FOS.