Mineral determination and anti-LDL oxidation activity of sweet potato (Ipomoea batatas L.) leaves

Reclaiming Agriceuticals from Sweetpotato (Ipomoea batatas [L.] Lam.) By-Products

Sweetpotato (SP, Ipomoea batatas [L.] Lam.) is a globally significant food crop known for its high nutritional and functional values. Although the contents and compositions of bioactive constituents vary among SP varieties, sweetpotato by-products (SPBs), including aerial parts, storage root peels, and wastes generated from starch processing, are considered as excellent sources of polyphenols (e.g., chlorogenic acid, caffeoylquinic acid, and dicaffeoylquinic acid), lutein, functional carbohydrates (e.g., pectin, polysaccharides, and resin glycosides) or proteins (e.g., polyphenol oxidase, β-amylase, and sporamins). This review summarises the health benefits of these ingredients specifically derived from SPBs in vitro and/or in vivo, such as anti-obesity, anti-cancer, antioxidant, cardioprotective, and anti-diabetic, evidencing their potential to regenerate value-added bio-products in the fields of food and nutraceutical. Accordingly, conventional and novel technologies have been developed and sometimes combined for the pretreatment and extraction processes aimed at optimising the recovery efficiency of bioactive ingredients from SPBs while ensuring sustainability. However, so far, advanced extraction technologies have not been extensively applied for recovering bioactive compounds from SPBs except for SP leaves. Furthermore, the incorporation of reclaimed bioactive ingredients from SPBs into foods or other healthcare products remains limited. This review also briefly discusses current challenges faced by the SPB recycling industry while suggesting that more efforts should be made to facilitate the transition from scientific advances to commercialisation for reutilising and valorising SPBs.

Toxic effects of lead on plants: integrating multi-omics with bioinformatics to develop Pb-tolerant crops

MAIN CONCLUSION

Lead disrupts plant metabolic homeostasis and key structural elements. Utilizing modern biotechnology tools, it's feasible to develop Pb-tolerant varieties by discovering biological players regulating plant metabolic pathways under stress. Lead (Pb) has been used for a variety of purposes since antiquity despite its toxic nature. After arsenic, lead is the most hazardous heavy metal without any known beneficial role in the biological system. It is a crucial inorganic pollutant that affects plant biochemical and morpho-physiological attributes. Lead toxicity harms plants throughout their life cycle and the extent of damage depends on the concentration and duration of exposure. Higher levels of lead exposure disrupt numerous key metabolic activities of plants including oxygen-evolving complex, organelles integrity, photosystem II connectivity, and electron transport chain. This review summarizes the detrimental effects of lead toxicity on seed germination, crop growth, and yield, oxidative and ultra-structural alterations, as well as nutrient absorption, transport, and assimilation. Further, it discusses the Pb-induced toxic modulation of stomatal conductance, photosynthesis, respiration, metabolic-enzymatic activity, osmolytes accumulation, and antioxidant activity. It is a comprehensive review that reports on omics-based studies along with morpho-physiological and biochemical modifications caused by lead stress. With advances in DNA sequencing technologies, genomics and transcriptomics are gradually becoming popular for studying Pb stress effects in plants. Proteomics and metabolomics are still underrated and there is a scarcity of published data, and this review highlights both their technical and research gaps. Besides, there is also a discussion on how the integration of omics with bioinformatics and the use of the latest biotechnological tools can aid in developing Pb-tolerant crops. The review concludes with core challenges and research directions that need to be addressed soon.

Natural Deep Eutectic Solvent-Based Microwave-Assisted Extraction of Total Flavonoid Compounds from Spent Sweet Potato (Ipomoea batatas L.) Leaves: Optimization and Antioxidant and Bacteriostatic Activity

Natural deep eutectic solvents (NADESs) coupled with microwave-assisted extraction (MAE) were applied to extract total flavonoid compounds from spent sweet potato (Ipomoea batatas L.) leaves. In this study, ten different NADESs were successfully synthesized for the MAE. Based on single-factor experiments, the response surface methodology (RSM) was applied, and the microwave power, extraction temperature, extraction time, and solid−liquid ratio were further evaluated in order to optimize the yields of total flavonoid compounds. Besides, the extracts were recovered by macroporous resin for the biological activity detection of flavonoid compounds. As a result, NADES-2, synthesized by choline chloride and malic acid (molar ratio 1:2), exhibited the highest extraction yield. After that, the NADES-2-based MAE process was optimized and the optimal conditions were as follows: microwave power of 470 W, extraction temperature of 54 °C, extraction time of 21 min, and solid−liquid ratio of 70 mg/mL. The extraction yield (40.21 ± 0.23 mg rutin equivalents/g sweet potato leaves) of the model validation experiment was demonstrated to be in accordance with the predicted value (40.49 mg rutin equivalents/g sweet potato leaves). In addition, flavonoid compounds were efficiently recovered from NADES-extracts with a high recovery yield (>85%) using AB-8 macroporous resin. The bioactivity experiments in vitro confirmed that total flavonoid compounds had good DPPH and O2−· radical-scavenging activity, as well as inhibitory effects on E. coli, S. aureus, E. carotovora, and B. subtilis. In conclusion, this study provides a green and efficient method to extract flavonoid compounds from spent sweet potato leaves, providing technical support for the development and utilization of sweet potato leaves’ waste.

Total Phenolics and Anthocyanins Contents and Antioxidant Activity in Four Different Aerial Parts of Leafy Sweet Potato (Ipomoea batatas L.)

Leafy sweet potato (Ipomoea batatas L.) is an excellent source of nutritious greens and natural antioxidants, but reports on antioxidants content and activity at buds, leaves, petioles, and stems are scarce. Therefore, the total phenolics content (TPC), total anthocyanins content (TAC), and antioxidant activity (assessed by DPPH and ABTS radical scavenging activities and ferric reducing antioxidant power (FRAP)) were investigated in four aerial parts of 11 leafy sweet potato varieties. The results showed that varieties with pure green aerial parts, independently of the part analyzed, had higher TPC, FRAP, and ABTS radical scavenging activities. The green-purple varieties had a significantly higher TAC, while variety GS-17-22 had the highest TAC in apical buds and leaves, and variety Ziyang in petioles and stems. Among all parts, apical buds presented the highest TPC and antioxidant capacity, followed by leaves, petioles, and stems, while the highest TAC level was detected in leaves. The TPC was positively correlated with ABTS radical scavenging activity and FRAP in all parts studied, whereas the TAC was negatively correlated with DPPH radical scavenging activity. Collectively, the apical buds and leaves of sweet potato had the higher levels of nutritional values. These results would provide reference values for further breeding of leafy sweet potatoes.

In vitro and in vivo ameliorative effects of polyphenols from purple potato leaves on renal injury and associated inflammation induced by hyperuricemia

In the present study, the ameliorative effects of polyphenols from purple potato leaves (PSPLP) on hyperuricemia were investigated. HPLC-MS analysis showed that PSPLP was mainly composed of caffeoylquinic acid derivatives (84%). PSPLP inhibited the levels of cytokines (IL-1β, IL-6, and TNF-α) in monosodium urate-induced RAW264.7 cells. In vivo, PSPLP significantly inhibited the level of uric acid in hyperuricemia mice from 209.6 to 166.6 μM, and significantly interfered with the activities of xanthine oxidase (XOD) and adenosine deaminase in liver, the activity of XOD decreased from 13.5 to 11.6 U/gprot. PSPLP can decrease serum creatinine level from 105 to 59 μM, and urea nitrogen level from 21.9 to 14.1 mM, which can effectively protect kidney. These results provide a reference for future research and application of PSPLP as a functional food to intervene hyperuricemia and associated inflammation. PRACTICAL APPLICATIONS: This study evaluated the effect of polyphenols from purple potato leaves (PSPLP) on hyperuricemia. The results suggested that PSPLP has an important role in the intervention of hyperuricemia and hyperuricemic-related inflammation or renal injury, and can be used in the application of functional foods. These results provided a basis for further study on the biological activities of polyphenols from purple sweet potato leaves.

Hydrothermal Processing and In Vitro Simulated Human Digestion Affects the Bioaccessibility and Bioactivity of Phenolic Compounds in African Pumpkin (Momordica balsamina) Leaves

The African pumpkin (Momordica balsamina) contains bioactive phenolic compounds that may assist in reducing oxidative stress in the human body. The leaves are mainly consumed after boiling in water for a specific time; this hydrothermal process and conditions of the gastrointestinal tract may affect the presence and bioactivity of phenolics either positively or negatively. In this study, the effects of hydrothermal processing (boiling) and in vitro simulated human digestion on the phenolic composition, bioaccessibility and bioactivity in African pumpkin were investigated in comparison with those of spinach (Spinacia oleracea). A high-resolution ultra-performance liquid chromatography, coupled with diode array detection, quadrupole time-of-flight and mass spectrometer (UPLC-DAD-QTOF-MS) was used to profile phenolic metabolites. Metabolites such as 3-caffeoylquinic acid, 5-caffeoylquinic acid, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid and 4,5-dicaffeoylquinic acid were highly concentrated in the boiled vegetable extracts compared to the raw undigested and all digested samples. The majority of African pumpkin and spinach extracts (non-digested and digested) protected Deoxyribonucleic acid (DNA), (mouse fibroblast) L929 and human epithelial colorectal adenocarcinoma (Caco-2) cells from 2,2'-Azobis(2-methylpropionamidine) dihydrochloride (AAPH)-induced oxidative damage. From these results, the consumption of boiled African pumpkin leaves, as well as spinach, could be encouraged, as bioactive metabolites present may reduce oxidative stress in the body.

Bioactive Compounds, Antioxidants, and Health Benefits of Sweet Potato Leaves

Sweet potato (Ipomoea batatas) is one of the most important food crops worldwide and its leaves provide a dietary source of nutrients and various bioactive compounds. These constituents of sweet potato leaves (SPL) vary among varieties and play important roles in treating and preventing various diseases. Recently, more attentions in health-promoting benefits have led to several in vitro and in vivo investigations, as well as the identification and quantification of bioactive compounds in SPL. Among them, many new compounds have been reported as the first identified compounds from SPL with their dominant bioactivities. This review summarizes the current knowledge of the bioactive compositions of SPL and their health benefits. Since SPL serve as a potential source of micronutrients and functional compounds, they can be further developed as a sustainable crop for food and medicinal industries.

Optimization of the formula and processing of a sweet potato leaf powder-based beverage

For the development of a sweet potato leaf powder (SPLP)-based beverage, we investigated the effects of blanching methods on SPLP quality (including color, nutritional and functional compositions and antioxidant activity), and the effects of particle size and stabilizers on suspension stability of final product. The total polyphenol and antioxidant activity of SPLP of uncut group were 1.69 and 1.91 times those of cut group, respectively, and the indices of nutritional quality of copper, manganese and vitamin E of uncut group were significantly greater than cut group. The ultrafine SPLP-produced lowest gravitational sedimentation ratio (49%), indicating it had greatest suspension stability. The optimized formula of SPLP-based beverage was as follows: ultrafine SPLP of uncut group was mixed with 2.5% (w/w, powder basis) xanthan gum, 1% calcium lactate, 2% ascorbic acid, 12% maltodextrin, 20% xylitol, and 0.9% apple essence. The final product had high nutritional value along with consumer-acceptable flavor and texture.

Chemical Characterization and Antioxidant Properties of Ethanolic Extract and Its Fractions from Sweet Potato (Ipomoea batatas L.) Leaves

Sweet potato (Ipomoea batatas L.) leaf is a natural source of phenolic compounds with strong antioxidant activity and potential utility as an antioxidant. The aim of this study was to evaluate the polyphenol composition and antioxidant activities of ethanol extracts and their various solvent-partitioned fractions (petroleum ether, ethyl acetate, and aqueous fraction) from sweet potato leaves and petioles. Seven caffeoylquinic acid (CQA) derivatives and four flavonoids were detected in sweet potato leaves by HPLC-ESI-MS. The total phenolic content (TPC) and total flavonoid content (TFC) in leaf (112.98 ± 4.14 mg gallic acid equivalent (GAE)/g of dried extract, 56.87 ± 5.69 mg rutin equivalent (RE)/g of dried extract) was more than ten times higher than in petiole (9.22 ± 2.67 mg GAE/g of dried extract, 3.81 ± 0.52 mg RE/g of dried extract). The antioxidant contents of ethyl acetate fractions increased dramatically relative to those of crude extracts for both leaves and petioles. Purification using solvent partition with ethyl acetate increased TPC and TFC of crude extracts, especially the CQA derivatives including 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid, 4,5-dicaffeoylquinic acid, and 3,4,5-tricaffeoylquinic acid. Meanwhile, the ethyl acetate fractions with the highest CQA content were associated with the highest scavenging activities towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) and higher ferric ion reducing antioxidant power (FRAP)-reducing power.

Upregulation of endogenous erythropoietin expression by DLBS6747, a bioactive fraction of Ipomoea batatas L. leaves, via increasing HIF1α transcription factor in HEK293 kidney cells

ETHNOPHARMACOLOGICAL RELEVANCE

Ipomoea batatas L., locally known as ubi jalar, is widely used in Indonesia and other countries as a folk remedy for various chronic diseases, including anemia-associated chronic kidney disease by increasing hematological parameters such as packed cell volume, white blood cells and platelet counts.

AIM OF THE STUDY

The aim of this study is to evaluate the effect of DLBS6747, a bioactive fraction of I. batatas L. leaves, on increasing EPO expression through the upregulation of HIF1α.

MATERIALS AND METHODS

Effect of DLBS6747 on EPO expression and its transcription factor, HIFs, was evaluated in normoxia and hypoxia conditions. Effect of DLBS6747 on several genes involved in EPO expression were evaluated in a time-course manner using conventional and real-time PCR, while the protein level were revealed using western blot and ELISA. The involvement of HIF1α was also confirmed by HIF1α siRNA.

RESULTS

Administration of DLBS6747 increased transcriptional activity of EPO through the regulation of its transcriptional factors, which include HIF1α, HIF2α and NFᴋB. The effect was found to be dependent on oxygen availability, wherein DLBS6747-increased EPO expression was found to be more significant in hypoxic condition. In normoxia and hypoxia, 40 μg/mL DLBS6747 increased HIF1α and HIF2α expressions at mRNA level, wherein the peak appeared in 12 h treatment (up to 7.9- and 8.6-folds, respectively). On the other hand, increased protein level was only found in hypoxia, where the highest HIF1α expression was observed at 6 h (7.5-folds increase) and started to decrease after the hours, while HIF2α was found to be increased time-dependently (up to 13.8-folds in 24 h). The mechanism of action of DLBS6747 as erythropoietin stimulating agent is more likely to affect the regulation of HIF1α, as confirmed by HIF1α siRNA which showed that DLBS6747 failed to increase EPO expression during co-incubation with HIF1α siRNA. DLBS6747 treatment also decreased NFᴋB time-dependently in normoxia, while no NFᴋB was detected in hypoxia, which revealed mimicking hypoxia activity of DLBS6747 to increase EPO expression.

CONCLUSION

These findings showed convincing evidences that DLBS6747 increases endogenous EPO production primarily via upregulation of its transcription factors, especially HIF1α, in human embryonic kidney HEK293 cells. This is the first molecular report that reveals the mechanism of action of natural-based erythropenia drug in different oxygen availability.

Immunomodulatory potential of recombinant filarial protein, rWbL2, and its therapeutic implication in experimental ulcerative colitis in mouse

OBJECTIVE

Immunomodulation by helminth proteins has potential therapeutic implications in inflammatory bowel disease. In the present study, we have explored the therapeutic effect of a RAL family protein of filarial parasite Wuchereria bancrofti i.e., rWbL2 protein against DSS induced colitis in a mouse model.

MATERIALS AND METHODS

Anti-inflammatory activity of rWbL2 on mice peritoneal exudate cells was analyzed under in vitro condition. The colitis mice were treated intraperitoneally (i.p.) with rWbL2 in increasing doses (10 µg, 25 µg, and 50 µg) on days 4, 5, and 6. Disease severity was assessed by disease activity index (DAI), macroscopic and histopathological scores, and enzyme myeloperoxidase activity (MPO) in the colon. The response of the cultured splenocytes from treated mice to Con-A stimulation, in terms of ELISA-based assessment of the protein followed by the assessment of mRNA expression of cytokines, was measured by real-time PCR analysis.

RESULT

rWbL2 protein showed anti-inflammatory activity in vitro. Treatment with rWbL2 (at 25 µg/dose) effectively attenuated disease severity by reducing weight loss, DAI, mucosal edema, colon damage, and MPO activity. This therapeutic effect was found to be associated with increased release of anti-inflammatory cytokine IL-10 and decreased release of pro-inflammatory cytokine IFN-γ and TNF-α by the splenocytes of treated mice followed by stimulation with Con-A.

CONCLUSIONS

These results provide evidence of the strong immunomodulatory potential of rWbL2 protein implicating its therapeutic application against ulcerative colitis.

Effect of different home-cooking methods on textural and nutritional properties of sweet potato genotypes grown in temperate climate conditions

BACKGROUND

The European Union (EU) market for sweet potato is small but is growing considerably and and has increased by 100% over the last 5 years. The cultivation of sweet potato in temperate climate conditions has not considered extensively and could be a new opportunity for the EU market. Healthy and qualitative traits of different sweet potato cultivars grown in temperate climate conditions were evaluated in accordance with four cooking methods.

RESULTS

Traditional cultivars showed high hardness and adhesiveness values. The highest concentrations of sugars (especially maltose) and phenolic acids (caffeic and chlorogenic) were found in samples treated by boiling and steaming. High antioxidant activity was found in fried potatoes. Qualitative traits of sweet potatoes treated by microwaves did not report any significant variation compared to the control.

CONCLUSION

Traditional and new sweet potato cultivars can be cultivated in temperate climate conditions and show interesting qualitative properties, especially as a result of the presence of antioxidant compounds. Concerning global quality, colored varieties expressed a better profile than traditional Italian ones and they are suitable for the European market, giving new opportunities for consumers and producers. © 2017 Society of Chemical Industry.

Feed and fuel: the dual-purpose advantage of an industrial sweetpotato

BACKGROUND

Sustainable agricultural systems must support nutritional requirements, meet the energy demands of a growing population, preserve environmental resources and mitigate climate change. The sweetpotato (Ipomoea batatas L.) is a high-yielding crop that requires minimal fertilization and irrigation, and the CX-1 industrial cultivar offers superior potential for feed and fuel.

RESULTS

CX-1 had the highest agronomic fresh vine yield (51.5 t ha^-1 ), averaged over two cropping seasons, compared with Hernandez (33.7) and Beauregard (21.8) varieties. CX-1 vines were more nutritional than the table varieties, specifically in regard to relative feed value (205), water-soluble carbohydrates (171 g kg^-1 dry matter (DM)), total digestible nutrients (643 g kg^-1 DM), metabolizable energy (10.2 MJ kg^-1 DM) and organic matter digestibility. Their lower fiber and lignin concentrations contributed to their freshness and digestibility throughout maturity. Significantly higher iron concentrations make the CX-1 vines a valuable, low-fat iron supplement for animal feed. The CX-1 roots also showed the highest bioethanol potential (82.3 g ethanol kg^-1 fresh root) compared to Hernandez (64.5) and Beauregard (48.1).

CONCLUSION

The CX-1 industrial sweetpotato is an ideal dual-purpose crop for tropical/subtropical climates that can be utilized as a non-grain-based feedstock for bioethanol production while contributing a valuable, high-yielding nutritional supplement for animal feed. © 2016 Society of Chemical Industry.

Chemical constituents and health effects of sweet potato

Sweet potatoes are becoming a research focus in recent years due to their unique nutritional and functional properties. Bioactive carbohydrates, proteins, lipids, carotenoids, anthocyanins, conjugated phenolic acids, and minerals represent versatile nutrients in different parts (tubers, leaves, stems, and stalks) of sweet potato. The unique composition of sweet potato contributes to their various health benefits, such as antioxidative, hepatoprotective, antiinflammatory, antitumor, antidiabetic, antimicrobial, antiobesity, antiaging effects. Factors affecting the nutritional composition and bio-functions of sweet potato include the varieties, plant parts, extraction time and solvents, postharvest storage, and processing. The assays for bio-function evaluation also contribute to the variations among different studies. This review summarizes the current knowledge of the chemical composition of sweet potato, and their bio-functions studied in vitro and in vivo. Leaves, stems, and stalks of sweet potato remain much underutilized on commercial levels. Sweet potato can be further developed as a sustainable crop for diverse nutritionally enhanced and value-added food products to promote human health.

Effects of domestic cooking methods on polyphenols and antioxidant activity of sweet potato leaves

In this study, effects of boiling, steaming, microwaving, baking, and frying on proximate composition, total and individual polyphenol contents, and antioxidant activity of sweet potato leaves were investigated. An increase of 9.44% in total polyphenol content was observed after steaming, whereas decreases of 30.51, 25.70, and 15.73% were noted after boiling, microwaving, and frying, respectively. Decreases of 63.82 and 32.35% in antioxidant activity were observed after boiling and microwaving, respectively, whereas increases of 81.40, 30.09, and 85.82% in antioxidant activity were observed after steaming, baking, and frying, respectively. Eight phenolic compounds were identified in sweet potato leaves. The correlation analysis between content of individual phenolic compounds and antioxidant activity suggested that antioxidant activity could be mainly attributed to 4,5-di-O-caffeoylquinic acid, 3,4-di-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, and 3,4,5-tri-O-caffeoylquinic acid. It was suggested that steaming is a preferred method to maintain polyphenols and antioxidant activity of sweet potato leaves.

Sweet potato (Ipomoea batatas [L.] Lam)--a valuable medicinal food: a review

Ipomoea batatas (L.) Lam, also known as sweet potato, is an extremely versatile and delicious vegetable that possesses high nutritional value. It is also a valuable medicinal plant having anti-cancer, antidiabetic, and anti-inflammatory activities. Sweet potato is now considered a valuable source of unique natural products, including some that can be used in the development of medicines against various diseases and in making industrial products. The overall objective of this review is to give a bird's-eye view of the nutritional value, health benefits, phytochemical composition, and medicinal properties of sweet potato. Specifically, this review outlines the biological activities of some of the sweet potato compounds that have been isolated, the pharmacological action of the sweet potato extract, clinical studies, and plausible medicinal applications of sweet potato (along with a safety evaluation), and demonstrates the potential of sweet potato as a medicinal food.

Antioxidant capacity of betacyanins as radical scavengers for peroxyl radical and nitric oxide

This study was designed to assess the antioxidant capacity of betacyanins as indole derived plant pigments, such as betanin, phyllocactin and betanidin. The antioxidant capacity of the betacyanins was evaluated as an index of radical scavenging ability using the peroxyl radical generating system in the presence of AAPH and NO generating system using NOR3 as an NO donor. The peroxyl radical scavenging capacity was dose-dependent in the low concentration range (25-100 nM). The mol-Trolox equivalent activity/mol compound (mol-TEA/mol-compound) as an index of the antioxidant capacity indicated the following order at 10.70 ± 0.01, 3.31 ± 0.14 and 2.83 ± 0.01 mol-TEA/mol-compound for betanidin, betanin and phyllocactin, respectively. In addition, betacyanins reduced the nitrite-level in the low concentration range of 2.5-20 μM. The IC₅₀ values (μM) of nitrogen radical scavenging activity were 24.48, 17.51 and 6.81 for betanin, phyllocactin and betanidin. ESR studies provided evidence that the compounds directly scavenged NO. These results indicated that betacyanins have a strong antioxidant capacity, particularly betanidin with a catechol group had higher activity than those of the glycoside of betacyanins. This study demonstrated that the betacyanins will be useful as natural pigments to provide defence against oxidative stress.

Sweet potato (Ipomoea batatas L.) leaves as nutritional and functional foods

In this study, the nutritional compositions of leaves from 40 sweet potato (Ipomoea batatas L.) cultivars were assessed. The correlations between antioxidant activity and crude protein, crude fat, crude fiber, carbohydrate, and polyphenol contents were determined. The crude protein, crude fiber, crude fat, carbohydrate and ash contents ranged between 16.69-31.08, 9.15-14.26, 2.08-5.28, 42.03-61.36, and 7.39-14.66g/100gdryweight(DW), respectively. According to the index of nutritional quality, sweet potato leaves are good sources of protein, fiber, and minerals, especially K, P, Ca, Mg, Fe, Mn, and Cu. The correlation coefficient between antioxidant activity and total polyphenol content was the highest (0.76032, p<0.0001), indicating that polyphenols are important antioxidants in sweet potato leaves. Sweet potato leaves, which contain several nutrients and bioactive compounds, should be consumed as leafy vegetables in an attempt to reduce malnutrition, especially in developing countries.

Inhibition of the β-catenin/Tcf signaling by caffeoylquinic acids in sweet potato leaf through down regulation of the Tcf-4 transcription

Sweet potato leaves contain the highest levels of functional polyphenols. In this study the effects of the sweet potato leaf extract and its contents, such as mono (3, 4, and 5)-caffeoylquinic acid (CQA), di-CQA (4,5-diCQA, 3,5-diCQA, and 3,4-diCQA) and caffeic acid (CA), were evaluated on the β-catenin/Tcf-4 signaling in human colorectal cancer HCT116 cells. The extract and the CQA derivatives inhibited the β-catenin/Tcf-4 signaling, and the inhibition of the di-CQA (with two caffeoyl groups) was higher than that of the mono-CQA (one-caffeoyl group) and CA, suggesting that the caffeoyl structure in the presence of a catechol group plays a significant role in interfering with the β-catenin/Tcf-4 signaling. In addition, the CQA derivatives had no effect on the β-catenin protein expression, but all test compounds inhibited the expression of the Tcf-4 transcription, and the inhibition of the di-CQA derivatives was stronger than those of the mono-CQA derivatives as well as the β-catenin/Tcf-4 transcriptional activity. These compounds can modulate the downstream Wnt signaling pathway, suggesting that sweet potato leaves can be a protective food for colorectal cancer.