Sweet potato leaves: properties and synergistic interactions that promote health and prevent disease

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.

Genetic fingerprint construction and genetic diversity analysis of sweet potato (Ipomoea batatas) germplasm resources

BACKGROUND

China is the largest producer of sweet potato in the world, accounting for 57.0% of the global output. Germplasm resources are the basis for promoting innovations in the seed industry and ensuring food security. Individual and accurate identification of sweet potato germplasm is an important part of conservation and efficient utilization.

RESULTS

In this study, nine pairs of simple sequence repeat molecular markers and 16 morphological markers were used to construct genetic fingerprints for sweet potato individual identification. Combined with basic information, typical phenotypic photographs, genotype peak graphs, and a two-dimensional code for detection and identification were generated. Finally, a genetic fingerprint database containing 1021 sweet potato germplasm resources in the "National Germplasm Guangzhou Sweet Potato Nursery Genebank in China" was constructed. Genetic diversity analysis of the 1021 sweet potato genotypes using the nine pairs of simple sequence repeat markers revealed a narrow genetic variation range of Chinese native sweet potato germplasm resources, and Chinese germplasm was close to that from Japan and the United States, far from that from the Philippines and Thailand, and the furthest from that from Peru. Sweet potato germplasm resources from Peru had the richest genetic diversity, supporting the view that Peru is the center of origin and domestication of sweet potato varieties.

CONCLUSIONS

Overall, this study provides scientific guidance for the conservation, identification, and utilization of sweet potato germplasm resources and offers a reference to facilitate the discovery of important genes to boost sweet potato breeding.

Anti-Colorectal Cancer Effects of Fucoidan Complex-Based Functional Beverage Through Retarding Proliferation, Cell Cycle and Epithelial-Mesenchymal Transition Signaling Pathways

BACKGROUND

Fucus vesiculosus-derived fucoidan, a multifunctional bioactive polysaccharide sourced from marine organisms, exhibits a wide range of therapeutic properties, including its anti-tumor effects. While previous research has reported on its anti-cancer potential, limited studies have explored its synergistic capabilities when combined with other natural bioactive ingredients. In this current study, we present the development of an integrative functional beverage, denoted as VMW-FC, which is composed of a fucoidan complex (FC) along with a blend of various herbal components, including vegetables (V), mulberries and fruits (M), and spelt wheat (W).

OBJECTIVE

Colorectal cancer (CRC) remains a significant cause of mortality, particularly in metastatic cases. Therefore, the urgent need for novel alternative medicines that comprehensively inhibit CRC persists. In this investigation, we assess the impact of VMW-FC on CRC cell proliferation, cell cycle dynamics, metastasis, in vivo tumorigenesis, and potential side effects.

METHODS

Cell growth was assessed using MTT and colony formation assays, while metastatic potential was evaluated through wound healing and transwell migration assays. The underlying signaling mechanisms were elucidated through qPCR and western blot analysis. In vivo tumor formation and potential side effects were evaluated using a subcutaneous tumor-bearing NOD/SCID mouse model.

RESULTS

Our findings demonstrate that VMW-FC significantly impedes CRC proliferation and migration in a dose- and time-dependent manner. Furthermore, it induces sub-G1 cell cycle arrest and an increase in apoptotic cell populations, as confirmed through flow-cytometric analysis. Notably, VMW-FC also suppresses xenograft tumor growth in NOD/SCID mice without causing renal or hepatic toxicity.

CONCLUSION

The integrative herbal concoction VMW-FC presents a promising approach for inhibiting CRC by slowing proliferation and migration, inducing cell cycle arrest and apoptosis, and suppressing markers associated with proliferation (Ki-67, PCNA, and CDKs) and epithelial-mesenchymal transition (EMT) (Vimentin, N-cadherin, and β-catenin).

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.

Exploring and exploiting genetics and genomics for sweetpotato improvement: Status and perspectives

Sweetpotato (Ipomoea batatas (L.) Lam.) is one of the most important root crops cultivated worldwide. Because of its adaptability, high yield potential, and nutritional value, sweetpotato has become an important food crop, particularly in developing countries. To ensure adequate crop yields to meet increasing demand, it is essential to enhance the tolerance of sweetpotato to environmental stresses and other yield-limiting factors. The highly heterozygous hexaploid genome of I. batatas complicates genetic studies and limits improvement of sweetpotato through traditional breeding. However, application of next-generation sequencing and high-throughput genotyping and phenotyping technologies to sweetpotato genetics and genomics research has provided new tools and resources for crop improvement. In this review, we discuss the genomics resources that are available for sweetpotato, including the current reference genome, databases, and available bioinformatics tools. We systematically review the current state of knowledge on the polyploid genetics of sweetpotato, including studies of its origin and germplasm diversity and the associated mapping of important agricultural traits. We then outline the conventional and molecular breeding approaches that have been applied to sweetpotato. Finally, we discuss future goals for genetic studies of sweetpotato and crop improvement via breeding in combination with state-of-the-art multi-omics approaches such as genomic selection and gene editing. These approaches will advance and accelerate genetic improvement of this important root crop and facilitate its sustainable global production.

Natural Products in Mitigation of Bisphenol A Toxicity: Future Therapeutic Use

Bisphenol A (BPA) is a ubiquitous environmental toxin with deleterious endocrine-disrupting effects. It is widely used in producing epoxy resins, polycarbonate plastics, and polyvinyl chloride plastics. Human beings are regularly exposed to BPA through inhalation, ingestion, and topical absorption routes. The prevalence of BPA exposure has considerably increased over the past decades. Previous research studies have found a plethora of evidence of BPA’s harmful effects. Interestingly, even at a lower concentration, this industrial product was found to be harmful at cellular and tissue levels, affecting various body functions. A noble and possible treatment could be made plausible by using natural products (NPs). In this review, we highlight existing experimental evidence of NPs against BPA exposure-induced adverse effects, which involve the body’s reproductive, neurological, hepatic, renal, cardiovascular, and endocrine systems. The review also focuses on the targeted signaling pathways of NPs involved in BPA-induced toxicity. Although potential molecular mechanisms underlying BPA-induced toxicity have been investigated, there is currently no specific targeted treatment for BPA-induced toxicity. Hence, natural products could be considered for future therapeutic use against adverse and harmful effects of BPA exposure.

Sweet Potato (Ipomoea batatas L.) Phenotypes: From Agroindustry to Health Effects

Sweet potato (SP; Ipomoea batatas (L.) Lam) is an edible tuber native to America and the sixth most important food crop worldwide. China leads its production in a global market of USD 45 trillion. SP domesticated varieties differ in specific phenotypic/genotypic traits, yet all of them are rich in sugars, slow digestible/resistant starch, vitamins, minerals, bioactive proteins and lipids, carotenoids, polyphenols, ascorbic acid, alkaloids, coumarins, and saponins, in a genotype-dependent manner. Individually or synergistically, SP’s phytochemicals help to prevent many illnesses, including certain types of cancers and cardiovascular disorders. These and other topics, including the production and market diversification of raw SP and its products, and SP’s starch as a functional ingredient, are briefly discussed in this review.

An Evaluation of Phenolic Compounds, Carotenoids, and Antioxidant Properties in Leaves of South African Cultivars, Peruvian 199062.1 and USA's Beauregard

In this study, leaves of sweet potato cultivars from South Africa (“Ndou,” “Bophelo,” “Monate,” and “Blesbok”), “Beauregard,” a sweet potato cultivar from the USA, and a Peruvian cultivar “199062. 1” were analyzed using UPLC/QTOF/MS and chemometrics, with the aim of characterizing the locally developed sweet potato cultivars and comparing them with already well-known established varieties on the market. A set of 13 phenolic compounds was identified. A partial least squares discriminant analysis, a hierarchical cluster analysis, and variables importance in projection were used to successfully distinguish sweet potato varieties based on their distinct metabolites. Caffeic acid enabled to distinguish Cluster 1 leaves of varieties (“Beauregard” and “Ndou”) from Cluster 2 (“199062.1,” “Bophelo,” “Monate,” and “Blesbok”). The leaves of “Bophelo” contained the highest concentrations of rutin, quercetin 3-O-galactoside, 3-caffeoylquinic acid (3-CQA), (5-CQA), 1,3 dicaffeoylquinic acid (1,3-diCQA), 1,4-diCQA, and 3,5-diCQA. Furthermore, Bophelo leaves showed the highest antioxidant activities (FRAP 19.69 mM TEACg⁻¹ and IC₅₀ values of (3.51 and 3.43 mg ml⁻¹) for DPPH and ABTS, respectively, compared to the other varieties. Leaves of “Blesbok” contained the highest levels of β-carotene (10.27 mg kg⁻¹) and zeaxanthin (5.02 mg kg⁻¹) on a dry weight basis compared to all other varieties. This study demonstrated that the leaves of local cultivars “Bophelo” and “Blesbok” have the potential to become functional ingredients for food processing.

Se-O Bond Is Unique to High Se Enriched Sweet Potato Stem Protein with Better Antioxidant Ability

Sweet potato plants were treated with selenium (Se). Spraying Se on the sweet potato leaves was an effective Se enrichment method and proteins were extracted from the sweet potato stem. The structural characteristics of the protein were investigated. Fourier transform infrared spectroscopy (FT-IR) detected more signals from the Se-enriched sweet potato stem protein (SSP), and the number of forms of Se chemical bonds gradually increased with increasing Se content, such as the Se-O bond in high Se-enriched SSP, indicating altered secondary structures.Scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) indicated more Se atoms in the Se-enriched SSPs (SSSPs). The DSC results revealed that Se enrichment enhanced the thermal stability of the samples. Moreover, selenomethionine (SeMet), selenocystine (SeCys₂), and methylselenocysteine (MeSeCys) were determined to be the main Se forms in the SSSPs. Furthermore, the SSSPs showed relatively higher superoxide anion radical and DPPH radical scavenging activities than the blank, which indicates that SSSPs can be used as antioxidants. By recovering the proteins, the agricultural by-product-sweet potato stem can be further utilized, and the obtained Se-enriched proteins may contribute to human health.

Sweetpotato Leaves Inhibit Lipopolysaccharide-Induced Inflammation in RAW 264.7 Macrophages via Suppression of NF-κB Signaling Pathway

Limited information is available regarding the health-promoting activities of sweetpotato leaves (SPL). The present study investigated antioxidant and anti-inflammatory effects, and phenolic contents in 29 SPL cultivars harvested in 2018 and 2019. Extracts showed total phenolic contents 9.4–23.1 mg gallic acid equivalent/g, and DPPH radical scavenging activity indicated 36.6–247.3 mM of Trolox equivalent/g. SPL extracts were identified to contain bioactive components such as, chlorogenic acid (11.7–22.1 μg/mg), 3,4-dicaffeoylquinic acid (16.3–59.9 μg/mg), 3,5-dicaffeoylquinic acid (50.9–72.7 μg/mg), chlorophyll B (6.1–12.3 μg/mg), lutein (1.9–4.9 μg/mg), chlorophyll A (2.7–4.3 μg/mg) and β-carotene (0.1 ≤ μg/mg). RAW 264.7 murine macrophage cells were pretreated with 100–200 μg/mL of SPL extracts and 20 μM of dexamethasone, and inflammation was stimulated by lipopolysaccharide (LPS, 100 ng/mL) treatment for 24 h. In LPS-treated cells, prostaglandin E2 production and COX-2 expression were not downregulated by pretreatment of SPL extracts. However, SPL pretreated cells showed significant suppression of nitric oxide (NO), TNF-α, and IL-1β levels under the LPS-induced inflammatory condition. In addition, SPL extracts induced an anti-inflammatory effect in LPS-stimulated RAW 264.7 cells through suppression of NF-κB nuclear translocation, IKK-α and IκB-α phosphorylation, and iNOS expression. These results indicate that SPL extract can be utilized as a functional food ingredient.

Sweet Potato Leaf Feeding Decreases Cholesterol, Oxidative Stress and Thrombosis Formation in Syrian Hamsters with a High-Cholesterol Diet

Nutritional strategies to reduce hyperlipidemia and the risk of cardiovascular disease are gaining more public favor and medical professionals’ attention. The authors of this study explored the effect of sweet potato leaf powder (SPLP) feeding on the parameters of plasma lipids, reactive oxygen species, and time to thrombosis formation in Syrian hamsters fed with high-cholesterol diets. The animals were separated into six groups: a feeding control diet, a control diet containing 0.1% cholesterol, a control diet containing 0.2% cholesterol, a control diet containing 0.1% cholesterol plus 2.5% SPLP, a control diet containing 0.1% cholesterol plus 5% SPLP, and a control diet containing 0.2% cholesterol plus 5% SPLP for six weeks. The levels of serum total cholesterol (51% increase), low-density lipoprotein cholesterol (70.6% increase), very-low-density lipoprotein cholesterol (51.3% increase), and the triglyceride and atherogenic index (LDL-C/HDL-C) significantly increased in the high-cholesterol diet groups. Concomitant 5% sweet potato leaf powder ingestion significantly decreased the lipid profiles, with a 20.6% total cholesterol reduction in the 0.1% cholesterol diet groups, a 17.2% reduction in the 0.2% group, a 48.7% LDL reduction in the 0.1% cholesterol group, and a 30.3% reduction in the 0.2% group, with a consequent decrease in the atherogenic index. SPLP feeding was found to be associated with increased fecal sterol contents, with a 188.6% increase in the 0.1% cholesterol-fed group and a 177.3% increase in the 0.2% group. The SPLP-fed groups had depressed ROS levels, elongated FeCl₃-induced times to thrombosis formation, and increased liver superoxide dismutase contents and SREBP-1 protein expression. Sweet potato leaf intake could reduce plasma total cholesterol, LDL, and oxidative stress. We suggest sweet potato leaf intake as a choice of nutritional strategy for hyperlipidemia and cardiovascular disease prevention.

Characterization of polyphenol oxidase from purple sweet potato (Ipomoea batatas L. Lam) and its affinity towards acylated anthocyanins and caffeoylquinic acid derivatives

Biochemical characterization of polyphenol oxidase (PPO) present in purple sweet potato (PSP) is a key step in developing efficient methodologies to control oxidative damage caused by this enzyme to the valuable components of PSP, such as caffeoylquinic acid derivatives and acylated anthocyanins. Thus, this work focused on the assessment of the effects of pH, temperature, and chemical agents on the PPO activity as well as characterization of the PPO substrate specificity towards major phenolic compounds found in PSP. The optimum conditions of enzyme activity were pH 7 and a temperature range of 20-30 °C at which phenolic substrates were oxidized with 72.5-99.8% yield. Zn²⁺ ions remarkably reduced PPO activity while Cu²⁺ ions improved enzyme performance. The highest substrate preference was shown for 3,4,5-tri-caffeoylquinic and 3,5-di-caffeoylquinic acid, followed by 5-caffeoylquinic and caffeic acid, 3,4- and 4,5-di-caffeoylquinic acids, peonidin-3-caffeoyl-p-hydroxybenzoyl-sophoroside-5-glucoside. The highest Km values were found for 4,5-feruloyl-caffeoylquinic acid and catechol.

Integrated transcriptome, small RNA and degradome sequencing approaches proffer insights into chlorogenic acid biosynthesis in leafy sweet potato

Leafy sweet potato is rich in total phenolics (TP) which play key roles in health protection, the chlorogenic acid (CGA) constitutes the major components of phenolic compounds in leafy sweet potato. Unfortunately, the mechanism of CGA biosynthesis in leafy sweet potato is unclear. To dissect the mechanisms of CGA biosynthesis, we performed transcriptome, small RNA (sRNA) and degradome sequencing of one low-CGA content and one high-CGA content genotype at two stages. A total of 2,333 common differentially expressed genes (DEGs) were identified, and the enriched DEGs were related to photosynthesis, starch and sucrose metabolism and phenylpropanoid biosynthesis. The functional genes, such as CCR, CCoAOMT and HCT in the CGA biosynthetic pathway were down-regulated, indicating that the way to lignin was altered, and two possible CGA biosynthetic routes were hypothesized. A total of 38 DE miRNAs were identified, and 1,799 targets were predicated for 38 DE miRNAs by using in silico approaches. The target genes were enriched in lignin and phenylpropanoid catabolic processes. Transcription factors (TFs) such as apetala2/ethylene response factor (AP2/ERF) and Squamosa promoter binding protein-like (SPL) predicated in silico were validated by degradome sequencing. Association analysis of the DE miRNAs and transcriptome datasets identified that miR156 family negatively targeted AP2/ERF and SPL. Six mRNAs and six miRNAs were validated by qRT-PCR, and the results showed that the expression levels of the mRNAs and miRNAs were consistent with the sequencing data. This study established comprehensive functional genomic resources for the CGA biosynthesis, and provided insights into the molecular mechanisms involving in this process. The results also enabled the first perceptions of the regulatory roles of mRNAs and miRNAs, and offered candidate genes for leafy sweet potato improvements.

Growth and photosynthetic characteristics of sweet potato (Ipomoea batatas) leaves grown under natural sunlight with supplemental LED lighting in a tropical greenhouse

Leaf growth and photosynthetic characteristics of sweet potato (Ipomoea batatas var. Biru Putih) grown under different light quantities were studied in a tropical greenhouse. The stem cuttings of I. batataswith adventitious roots were grown hydroponically under (1) only natural sunlight (SL); (2) SL with supplemental LED at a PPFD of 150 μmol m^-2 s^-1 (SL + L-LED); and (3) SL with supplemental LED at a PPFD of 300 μmol m^-2 s^-1 (SL + H-LED). One week after emergence, all leaves had similar area and water content. However, leaf fresh weight and dry weight were significantly higher in plants grown under SL+L-LED and SL + H-LED than under SL due to their thicker leaves reflected by the lower specific leaf area. Plants grown under SL had significantly lower concentrations of total chlorophyll (Chl) and total carotenoids (Car) but higher Chl a/b ratio than under SL + L-LED and SL + H-LED. However, all plants had similar Chl/Car ratios. Although midday F_v/F_m ratio was the lowest in leaves grown under SL+ H-LED followed by SL + L-LED and SL, predawn F_v/F_m ratios of all leaves were higher than 0.8. Increasing growth irradiance with supplemental LED resulted in higher electron transport rate and photochemical quenching but lower non-photochemical quenching compared to those of plants grown under SL. Measured under their respective growth irradiance in the greenhouse, attached leaves grown under SL + L-LED and SL+H-LED had significantly higher photosynthetic CO₂ assimilation rate and stomatal conductance than under SL. However, measuring the detached leaves at 25 °C in the laboratory, there were no significant differences in PS II and Cyt b₆f concentrations although light- and CO₂-statured photosynthetic O₂ evolution rates were slightly higher in leaves grown under SL+ H-LED than under SL. Impacts of supplemental LED on leaf growth and photosynthetic characteristics were discussed.

The Content of Phenolic Acids and Flavonols in the Leaves of Nine Varieties of Sweet Potatoes (Ipomoea batatas L.) Depending on Their Development, Grown in Central Europe

The aim of the study was the qualitative and quantitative analysis of the bioactive components present in the leaves of 9 sweet potato cultivars grown in the moderate climate in Poland, which were harvested at different growth stages according to the BBCH (Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie) scale (14, 51, 89). It was found that sweet potato leaves contained 7 polyphenolic compounds, including 5 chlorogenic acids-neochlorogenic acid (5-CQA), chlorogenic acid (3-CQA), 4-cryptochlorogenic acid (4-CQA), 34-di-O-caffeoylqunic acid (3,4-CQA), 3,5-di-O-caffeoylqunic acid (3,5-CQA)-and 2 flavonoids, quercetin-3-O-galactoside (Q-3-GA) and quercetin-3-O-glucoside (Q-3-GL). Their content depended on the genotype of the examined cultivars and on the stage of leaf development. The mean content of the identified polyphenolic compounds in the examined cultivars ranged from 148.2 to 14.038.6 mg/100 g^-1 DM for the leaves harvested at growth stage 14 according to the BBCH scale. In the case of leaves harvested at BBCH stage 51, the concentration of polyphenolic compounds ranged from 144.76 to 5026.8 mg/100 g^-1 DM and at BBCH stage 89 from 4078.1 to 11.183.5 mg/100 g^-1 DM. The leaves of the Carmen Rubin cultivar collected at stage 14 contained the highest amount of polyphenolic compounds, while Okinava leaves had the highest amount of these compounds at stage 51. The highest content of polyphenolic compounds in leaves at BBCH growth stage 89 was found in the Radiosa variety. The highest concentration levels were found for 3-CQA at all stages of leaf development. Significant correlations between polyphenol content and antioxidant activity measured by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing/antioxidant power (FRAP) were found. The results of this experiment revealed that the growth stages and genetic properties of cultivars have a very significant influence on the content of phenolic acids and flavonols in sweet potato leaves. The results are innovative and can have a practical application, as the knowledge of the content of the substances under study makes it possible to determine the optimal management practice of sweet potato leaf harvest in order to obtain more top-quality raw material.

Phytochemicals in Leaves and Roots of Selected Kenyan Orange Fleshed Sweet Potato (OFSP) Varieties

This study reports the inherent phytochemical contents in leaves and roots of nine sweet potato varieties from Kenya. Results indicated that vitamin C content varied significantly (P < 0.05) among the sweet potato varieties regardless of the plant part, leaves having significantly (P < 0.05) higher levels than in the roots. Total flavonoids and phenolic compounds differed significantly (P < 0.05) among varieties, higher values were found in leaves than in roots. Flavonoid contents in roots ranged from below detectable limits (Whitesp) to 25.8 mg CE/100 g (SPK031), while in leaves it ranged from 4097 to 7316 mg CE/100 g in SPK4 and Kenspot 5, respectively. Phenolic content was below detectable limits in the roots of whitesp but it was in substantial amounts in orange fleshed varieties. The β-carotene content was significantly (P < 0.05) higher in leaves (16.43-34.47 mg/100 g dry weight) than in roots (not detected-11.1 mg/100 g dry weight). Total and phytic phosphorus were directly correlated with phytate contents in leaves and the roots. Tannins and soluble oxalates varied significantly (P < 0.05) with variety and plant part being higher in leaves. The current information is important for ration formulations and dietary recommendations utilizing sweet potato leaves and roots. Future studies on effects of processing methods on these phytochemicals are recommended.

Uncovering anthocyanin biosynthesis related microRNAs and their target genes by small RNA and degradome sequencing in tuberous roots of sweetpotato

BACKGROUND

Compared with white-fleshed sweetpotato (WFSP), purple-fleshed sweetpotato (PFSP) is a desirable resource for functional food development because of the abundant anthocyanin accumulation in its tuberous roots. Some studies have shown that the expression regulation mediated by miRNA plays an important role in anthocyanin biosynthesis in plants. However, few miRNAs and their corresponding functions related to anthocyanin biosynthesis in tuberous roots of sweetpotato have been known.

RESULTS

In this study, small RNA (sRNA) and degradome libraries from the tuberous roots of WFSP (Xushu-18) and PFSP (Xuzishu-3) were constructed, respectively. Totally, 191 known and 33 novel miRNAs were identified by sRNA sequencing, and 180 target genes cleaved by 115 known ib-miRNAs and 5 novel ib-miRNAs were identified by degradome sequencing. Of these, 121 miRNAs were differently expressed between Xushu-18 and Xuzishu-3. Integrated analysis of sRNA, degradome sequencing, GO, KEGG and qRT-PCR revealed that 26 differentially expressed miRNAs and 36 corresponding targets were potentially involved in the anthocyanin biosynthesis. Of which, an inverse correlation between the expression of ib-miR156 and its target ibSPL in WFSP and PFSP was revealed by both qRT-PCR and sRNA sequencing. Subsequently, ib-miR156 was over-expressed in Arabidopsis. Interestingly, the ib-miR156 over-expressing plants showed suppressed abundance of SPL and a purplish phenotype. Concomitantly, upregulated expression of four anthocyanin pathway genes was detected in transgenic Arabidopsis plants. Finally, a putative ib-miRNA-target model involved in anthocyanin biosynthesis in sweetpotato was proposed.

CONCLUSIONS

The results represented a comprehensive expression profiling of miRNAs related to anthocyanin accumulation in sweetpotato and provided important clues for understanding the regulatory network of anthocyanin biosynthesis mediated by miRNA in tuberous crops.

Influence of Green Leafy Vegetables in Diets with an Elevated ω-6:ω-3 Fatty Acid Ratio on Rat Blood Pressure, Plasma Lipids, Antioxidant Status and Markers of Inflammation

The typical Western dietary pattern has an elevated ω-6:ω-3 fatty acid ratio (FAR), which may exacerbate the risk of chronic disease. Conversely, the consumption of diets containing green leafy vegetables (GLVs) have been demonstrated to attenuate disease risk. This study investigated the effects of collard greens (CG), purslane (PL) and orange flesh sweetpotato greens (SPG) on measures of disease risk in rats fed diets with a 25:1 ω-6:ω-3 FAR. Male spontaneously hypertensive rats (SHRs) were randomly assigned to four dietary groups (n = 10/group) with a 25:1 ω-6:ω-3 FAR. Experimental diets contained 4% (dried weight) CG, PL or SPG. Dietary intake, body weight, blood pressure, plasma adiponectin, high sensitivity C-reactive protein (hsCRP), oxygen radical absorbance capacity and lipid profile were determined using standardized procedures. Following a 6-week consumption period, systolic blood pressure, plasma adiponectin, total and low-density lipoprotein (LDL) cholesterol decreased following the consumption of diets containing GLVs. While hsCRP increased in SHRs fed diets containing CG and PL, plasma antioxidant capacity was significantly reduced (p < 0.05) with the consumption of diets containing the GLVs. These findings suggest that CG, PL and SPG have the potential to decrease risks for cardiovascular disease (CVD) associated with the consumption of diets with an elevated ω-6:ω-3 FAR.

Cholesterol-lowering effect of diet with added sweet potato (Ipomea batatas) vines in rabbits

The objective of this study was to evaluate the effect of sweet potato vines as a source of fiber on the plasma parameters in healthy rabbits. For this, 15 rabbits were allocated into five groups, and each group was fed a different diet for a period of 46 days. The diets were as follows: diet without sweet potato vines (0SPV), and experimental diets with 25%, 50%, 75% and 100% of sweet potato vines in replacement of alfalfa hay respectively (25SPV, 50SPV, 75SPV and 100SPV). Triglycerides and VLDL-cholesterol concentrations were approximately 53% lower in rabbits fed the 100SPV than in rabbits fed 0SPV. In addition, aspartate aminotransferase (AST) and total-cholesterol concentrations were lower approximately 40% and 14%, respectively, in rabbits fed the 100SPV than in rabbits fed 0SPV. No significant differences were found among HDL-cholesterol, glucose, proteins, albumin and alanine aminotransferase (ALT) concentrations of the five groups. These results demonstrate that the consumption of sweet potato vines reduces the triglycerides, VLDLcholesterol and total cholesterol while maintains HDL-cholesterol levels. Therefore, sweet potato vines consumption may be another option to prevent coronary heart diseases in rabbits.

Green leafy vegetables in diets with a 25:1 omega-6/omega-3 fatty acid ratio modify the erythrocyte fatty acid profile of spontaneously hypertensive rats

Background

In addition to the actual composition of the diet (i.e. nutrient composition, food groups), the omega-6/omega-3 fatty acid ratio has been demonstrated to influence the tissue fatty acid profile and subsequently the risk for cardiovascular and other diseases. Likewise, the consumption of green leafy vegetables (GLVs) may favorably reduce the risks associated with disease. Although an ~ 3:1 omega-6/omega-3 fatty acid ratio (ω-6/ω-3 FAR) is recommended, the typical American diet has an ~ 25:1 ω-6/ω-3 FAR. Previous research affirms the ability of collard greens (CG), purslane (PL), and sweet potato greens (SPG) to improve the hepatic profile of spontaneously hypertensive rats (SHRs). The aim of the present study was to determine the influence of GLVs, incorporated (4%) into diets with a 25:1 ω-6/ω-3 FAR, on the erythrocyte fatty acid profile of male SHRs.

Methods

SHRs (N = 50) were randomly assigned to one of five dietary groups – standardized control (AIN-76A), Control (25:1 ω-6/ω-3 FAR), CG (25:1 ω-6/ω-3 FAR + 4% CG), PL (25:1 ω-6/ω-3 FAR + 4% PL) or SPG (25:1 ω-6/ω-3 FAR + 4% SPG). Following 6 weeks consumption of diets, SHRs erythrocyte fatty acid profiles were determined by gas-liquid chromatography.

Results

Significantly lower percentages of total saturated fatty acids (p < 0.05) and greater percentages of polyunsaturated fatty acids were present among SHR erythrocytes following the consumption of diets containing CG, PL and SPG. Total polyunsaturated fatty acids were greatest among SHRs consuming diets containing purslane.

Conclusions

The present study demonstrates the ability of GLVs to mitigate the potential effects of an elevated ω-6/ω-3 FAR, which may contribute to an atherogenic fatty acid profile, inflammation and disease pathogenesis. Dietary recommendations for disease prevention should consider the inclusion of these GLVs, particularly among those consuming diets with an ω-6/ω-3 FAR that may promote disease.

A Review of Production, Post-harvest Handling and Marketing of Sweetpotatoes in Kenya and Uganda

Sweetpotato (Ipomea batatas) is a versatile crop that serves the roles of food and nutrition security, cash crop in both raw and processed forms. It is a source of livestock feed and has great potential as a raw material for industrial processing. The potential of sweetpotato has been greatly under exploited by the fact that it has been regarded as a poor man’s food and is mainly grown under marginal conditions for subsistence by most producers, who are rural small-scale farmers in developing countries, such as Kenya and Uganda. Losses in the highly perishable root crop and its leaves are exacerbated by lack of appropriate postharvest knowledge, technologies and facilities. Inadequate information on available cultivars also limits the maximum utilization of the crop and leaves. The current review examines production potential, post harvest handling practices, marketing, and physicochemical and nutritional properties of sweet potatoes.

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.

De novo sequencing and comprehensive analysis of the mutant transcriptome from purple sweet potato (Ipomoea batatas L.)

Purple sweet potatoes, rich in anthocyanin, have been widely favored in light of increasing awareness of health and food safety. In this study, a mutant of purple sweet potato (white peel and flesh) was used to study anthocyanin metabolism by high-throughput RNA sequencing and comparative analysis of the mutant and wild type transcriptomes. A total of 88,509 unigenes ranging from 200nt to 14,986nt with an average length of 849nt were obtained. Unigenes were assigned to Gene Ontology (GO), Clusters of Orthologous Group (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Functional enrichment using GO and KEGG annotations showed that 3828 of the differently expressed genes probably influenced many important biological and metabolic pathways, including anthocyanin biosynthesis. Most importantly, the structural and transcription factor genes that contribute to anthocyanin biosynthesis were downregulated in the mutant. The unigene dataset that was used to discover the anthocyanin candidate genes can serve as a comprehensive resource for molecular research in sweet potato.

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.

Healthy aging diets other than the Mediterranean: a focus on the Okinawan diet

The traditional diet in Okinawa is anchored by root vegetables (principally sweet potatoes), green and yellow vegetables, soybean-based foods, and medicinal plants. Marine foods, lean meats, fruit, medicinal garnishes and spices, tea, alcohol are also moderately consumed. Many characteristics of the traditional Okinawan diet are shared with other healthy dietary patterns, including the traditional Mediterranean diet, DASH diet, and Portfolio diet. All these dietary patterns are associated with reduced risk for cardiovascular disease, among other age-associated diseases. Overall, the important shared features of these healthy dietary patterns include: high intake of unrefined carbohydrates, moderate protein intake with emphasis on vegetables/legumes, fish, and lean meats as sources, and a healthy fat profile (higher in mono/polyunsaturated fats, lower in saturated fat; rich in omega-3). The healthy fat intake is likely one mechanism for reducing inflammation, optimizing cholesterol, and other risk factors. Additionally, the lower caloric density of plant-rich diets results in lower caloric intake with concomitant high intake of phytonutrients and antioxidants. Other shared features include low glycemic load, less inflammation and oxidative stress, and potential modulation of aging-related biological pathways. This may reduce risk for chronic age-associated diseases and promote healthy aging and longevity.

De novo sequencing and a comprehensive analysis of purple sweet potato (Impomoea batatas L.) transcriptome

High-throughput RNA sequencing was performed for comprehensively analyzing the transcriptome of the purple sweet potato. A total of 58,800 unigenes were obtained and ranged from 200 nt to 10,380 nt with an average length of 476 nt. The average expression of one unigene was 34 reads per kb per million reads (RPKM) with a maximum expression of 1,935 RPKM. At least 40,280 (68.5%) unigenes were identified to be protein-coding genes, in which 11,978 and 5,184 genes were homologous to Arabidopsis and rice proteins, respectively. Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) analysis showed that 19,707 (33.5%) unigenes were classified to 1,807 terms of GO including molecular functions, biological processes, and cellular components and 9,970 (17.0%) unigenes were enriched to 11,119 KEGG pathways. We found that at least 3,553 genes may be involved in the biosynthesis pathways of starch, alkaloids, anthocyanin pigments, and vitamins. Additionally, 851 potential simple sequence repeats (SSRs) were identified in all unigenes. Transcriptome sequencing on tuberous roots of the sweet potato yielded substantial transcriptional sequences and potentially useful SSR markers which provide an important data source for sweet potato research. Comparison of two RNA-sequence datasets from the purple and the yellow sweet potato showed that UDP-glucose-flavonoid 3-O-glucosyltransferase was one of the key enzymes in the pathway of anthocyanin biosynthesis and that anthocyanin-3-glucoside might be one of the major components for anthocyanin pigments in the purple sweet potato. This study contributes to the molecular mechanisms of sweet potato development and metabolism and therefore that increases the potential utilization of the sweet potato in food nutrition and pharmacy.