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Backgroud The Lanzhou lily (Lilium davidii var. unicolor) is the only Lilium species that is used for both culinary and medicinal purposes in China. Its bulbs contain various bioactive substances, such as polysaccharides, saponins and colchicine. Lanzhou lily polysaccharides are known to have anti-immunity, anti-tumor and anti-oxidation functions. Results The present study used a Box-Behnken design to optimize the ultrasound-assisted extraction of Lanzhou lily polysaccharides. Compared to other enzymes, trypsin significantly increased the polysaccharide yields, whereas the protein content of polysaccharides extracted with trypsin was the lowest. Monosaccharide mainly includes glucose (> 50%) and mannose (> 10%). 1,1-Diphenyl-2-picrylhydrazyl radical scavenging activity, chelating activity, total antioxidant capacity and hydroxyl radical scavenging activity of Lanzhou lily polysaccharides extracted with trypsin were stronger than those extracted without enzymes (control). Structural characteristics of Lanzhou lily polysaccharides extracted with trypsin and extracted without enzymes were characterized by scanning electron microscopy and nuclear magnetic resonance spectroscopy. When water extracted polysaccharide and trypsin extracted polysaccharide concentrations were 200 μg mL-1 , Raw264.7 proliferation rates were 101.69% and 159.41%, respectively. Conclusion The Lanzhou lily polysaccharide was identified as α-(1 → 6)-d-glucan. Consequently, the effects of both potential antioxidant and proliferative activity of trypsin are significant. © 2020 Society of Chemical Industry.

Glycyrrhizae radix has been widely accepted as a functional food in Asia. Isoliquiritigenin is a characteristic bioactive chemical in this medicinal plant. In this work, the neuroprotective effect of isoliquiritigenin and the possible mechanisms were investigated. The results revealed that isoliquiritigenin exhibited better neuroprotective and antioxidant activities than quercetin, a commercial natural antioxidant. Isoliquiritigenin significantly inhibited the release of lactate dehydrogenase, and the generation of reactive oxygen species in H2O2-treated cells. The activities of superoxide dismutase, glutathione peroxidase and catalase were improved. The mRNA expression levels related to oxidative defense and cell apoptosis were reversed by isoliquiritigenin. Moreover, isoliquiritigenin might inhibit the cell apoptosis via ameliorating the loss of mitochondrial membrane potential and the change of nucleus morphology.

Soybean peptides serve as functional foods with impressive health benefits. The structure characteristics of peptides are highly related to the health benefits. The structure-activity relationship and mechanism underlined are important scientific questions in this field. To answer these questions, soybean peptides were produced by combinatory enzymatic hydrolysis in this work. Fifty-two peptide sequences were identified by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The anti-inflammatory activities of these peptides were investigated by using a lipopolysaccharide (LPS)-induced inflammation cell model. Soybean peptides could significantly promote cell proliferation. Additionally, soybean peptides could alleviate LPS-induced inflammation by reducing the production and expression of nitric oxide (NO), tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). Moreover, soybean peptides could promote the mRNA expression of proteins related to inflammation inhibition (IL-10) and tight junction modulation. The structure-activity relationship was addressed. The results documented the potential of soybean peptides as functional foods.

Walnut peptides are widely accepted as nutraceuticals with multiple health benefits. However, information about the structure and biological activity of walnut peptides is limited. In this work, walnut protein hydrolysate (WPH) was prepared by enzymatic hydrolysis. The total and free amino acids compositions in WPH were determined. The peptides sequence of WPH was analyzed by UPLC-MS/MS, and forty eight bioactive peptides were identified. Antioxidant activities were detected for WPH in both extracellular and intercellular assays. QGRPWG, PSRADIY and AYNIPVNIAR were the peptides that accounted for the antioxidant activity of WPH. Among them, QGRPWG showed the highest ORAC value (2801 µmol TE/g), and AYNIPVNIAR possessed the strongest protective effect against H

Banana is a fruit widely accepted by people over the world. Besides having delicious taste, it shows multiple health benefits. In this work, the major polysaccharide was isolated from banana and purified. It was identified to be α-(1 → 6)- d -glucan. The in vivo immunomodulatory activity assay indicated that α-(1 → 6)- d -glucan could improve the immune status by elevating T cell proliferation, phagocytic function of macrophage, CD3+ T cell level, CD4+/CD8+ ratio, IL-6, IgG, IgM, TNF-α and hemolysin antibody levels. The immunostimulatory activities of α-(1 → 6)- d -glucan were similar to β-(1 → 3)- d -glucan, a clinical immunostimulatory drug. This work revealed that α-(1 → 6)- d -glucan was an important bioactive chemical for the immunostimulatory activity of banana. It could be used as a nutraceuticals candidate.

Estrogen receptors (ERs) are transcription factors highly involved in physiological development and metabolism in the human body. They also play important roles in the treatment of cancer and metabolic diseases. Chemicals that interact with ERs can be used to treat diseases and maintain health. Phytoestrogens are natural chemicals that have been documented to possess significant ER modulatory activities. However, since phytoestrogens usually exist at low quantities in nature, heterologous biosynthesis techniques have quickly developed in recent years in order meet the demands for needed therapeutic amounts. In this review, the performance of phytoestrogens as ER modulators is described along with recent advances in biosynthesis techniques.

The peel of Citrus reticulate ‘Chachiennsis’ (Chachi) is widely accepted as a functional food. It is generally recognized that its health benefits are dependent on storage time. However, the chemicals responsible for this phenomonon remain unclear. As bioactive polysaccharides are dominant in Chachi, Chachi polysaccharides with various storage times (5–20 years) were prepared. The monosaccharide composition was analyzed by GC-MS. NMR data revealed that Chachi polysaccharides were mainly consisted of arabinogalacturonan and another pectin with side chain of →4)-β-D-Galp-(1 → . α-L-Araf-(1→, →5)-α-L-Araf-(1→, →4)-α-D-GalpA-(1→, →4)-α-D-GalpAMe-(1→, →4)-β-D-Galp-(1→ and →4)-β-D-Glcp-(1→ were detected. The molecular weight of Chachi polysaccharides decreased along with the extension of storage time. However, the basic structure characteristics remained stable. The immumomodulatory activities of Chachi polysaccharides were improved as the storage time extended. The change of molecular weight was responsible for the improved immunomodulatory activity. The results explained how polysaccharides contributed to the enhanced health benefits of Chachi during storage.

Background Neurodegenerative diseases are becoming increasingly prevalent over the world. Therefore, drug development in this field is urgently required. Neuron impairment leads to the pathogenesis of neurodegenerative diseases, while amelioration of oxidative stress can inhibit the impairment. As a traditional Chinese medicine, mulberry leaf exhibits various pharmacological properties, including neuroprotective activity. But the major components responsible for the neuroprotective activity of mulberry leaf remained unknown. Phytochemicals were potent candidates of neuroprotective drug. Prenylated phenolics are the leading phytochemicals present in mulberry leaf. Purpose The aim of this study was to investigate the neuroprotective activities and mechanisms of prenylated phenolics. Methods The chemical structure of isolated compounds were elucidated by MS and NMR. UPLC-MS/MS was used to determine the contents of prenylated phenolics in fresh mulberry leaf. Neurotoxicity was induced by erastin in HT22 cells. CCK-8 assay was performed to assess cell viability. ROS production, GSH level and iron release were monitored by using DCFH-DA, monobromobimane, and FeRhoNox™-1, respectively. qRT-PCR and Western blotting assays were performed to assess gene and protein expression, respectively. Results Four prenylated phenolics, including isobavachalcone, morachalcone B, moracin N and morachalcone A were isolated and identified from mulberry leaf. Their levels in fresh mulberry leaf were in a decreasing order, moracin N > morachalcone A > morachalcone B > isobavachalcone. Moreover, moracin N showed a good neuroprotective activity with an EC50 Conclusion The results confirmed that moracin N was a good ferroptosis inhibitor, which exerted neuroprotective activity through preventing from oxidative stress.

Functional foods play an important role in health care and chronic diseases prevention, particularly cancer. Prenylated flavonoids are presented in many food resources. They are recognized as neutraceuticals due to their diverse health benefits. Up to now, more than 1000 prenylated flavonoids have been identified in plants. Their food resources are reviewed in this paper. Due to the good safety and cancer prevention effect of prenylated flavonoids, this paper reviews the cancer prevention activities and mechanisms reported in last decade. The structure-activity relationship is discussed. Due to the limited availability in nature, the heterologously biosynthetic technique of prenylated flavonoids is discussed in this review. Inclusion of dietary prenylated flavonoids into human diet is highly desirable. This paper combines the up-to-date information and give a clear image regarding prenylated flavonoids as neutraceuticals.

The physicochemical properties of starch in Chinese yam (Dioscorea opposita Thunb.) are highly dependent on the growth stage. However, relevant information available is limited. In this work, native starch and resistant starch (RS) were prepared from Chinese yam tuber at expansion stage and dormant stage, respectively. Their structural and physicochemical properties were determined. They presented A-type polymorphic structure. The starches from dormant stage had smaller granule sizes, lower amylose contents, less branching degrees of amylopectin, and higher proportions of double helix than those from expansion stage. Dormant stage induced starch to form a more compact structure with a higher crystallinity and larger amount of short-range ordering than expansion stage. Moreover, the starch paste from dormant stage had a high thermal stability. These results were helpful for further application of Chinese yam starch in food products.

The study explored the changes of a sulfated polysaccharide (SP) from Gracilaria Lemaneiformis during simulated human digestive system. The results showed SP was scarcely degraded without significant difference. Moreover, the results of fermentation in vitro indicated 53.7% of SP were utilized by gut microbiota with the molecular weight decreasing by 59.41% at 48 h. Meanwhile, 50.07 ± 2.82 mM of short chain fatty acids were produced in culture medium. Besides, in contrast with the regulation of galacto-oligosaccharide sacrificing diversity and richness of community, SP could regulate the composition of microbiota in a mild way. What’s more, Proteobacteria and Firmicutes were the most sensitive phyla responding to changes of pH values in this study. And Sutterella, Phascolarctobacterium, Parabacteroides, Lachnospiraceae_UCG-004, Desulfovibrio and Bacteroides were dominant genera for degrading and utilizing SP. Furthermore, the metagenomic function characteristics of microbes might be changed by SP. Thus, SP could be a potential prebiotic.

Ganoderma lucidum spore serves as a well-known immunomodulatory functional food in Asia. The polysaccharides in G. lucidum spore are responsible for the claimed immunomodulatory activity. However, the structural information of polysaccharides remains unclear. In this work, the leading water-soluble polysaccharide in G. lucidum spore (GLSP-I) with a molecular weight of 128.0 kDa was isolated and purified. The monosaccharide composition analysed by gas chromatography indicated that GLSP-I was a glucan. Three side chains, including Glc-(1 → 3)-Glc-(1 → 3)-Glc-(1 → 6)-Glc, Glc-(1 → 6)-Glc-(1 → 6)-Glc-(1 → 6)-Glc and Glc-(1 → 3)-Glc-(1 → 3)-Glc-(1 → 3)-Glc-(1 → 3)-Glc, were identified by UPLC-MS/MS. The structural characteristics were further identified by NMR spectra. The results indicated that the backbone of GLSP-I was (1 → 3)-β-D-glucan, with side chains linking at O-6. The proposed structure was drawn as below. The immunomodulatory activity assay indicated that GLSP-I could activate macrophages in a dose-dependent manner. Download : Download high-res image (29KB) Download : Download full-size image

Unlike common orange fruit, Citrus reticulata Blanco ‘Chachiensis’ (CRB) is usually served as traditional herbal medicine and function food. It is an abundant source of bioactive polysaccharides which contribute to the health benefits of CRB. However, the structure information of polysaccharides still remains unknown. In this work, the leading polysaccharide (CRBP) was purified from CRB peel. The structure was identified by nuclear magnetic resonnance spectroscopy. The backbone was (1 → 4)-α-D-galacturonan, while the branch was α-L-Araf-(1 → 5)-α-L-Araf-(1 → . The molecular weight was calculated to be 55.4 kDa. The proposed structure was drawed as below. The cell assays indicated that CRBP was not toxic to macrophage cells, and could promote the NO production significantly in a dose-dependent manner. These results demonstrated that CRBP was a good candidate for functional food development.

In order to evaluate the release of phenolics and the changes in antioxidant activities, fruits of Crataegus pinnatifida were subjected to in vitro digestion including simulated oral, gastric, small/large intestine digestion. Results showed that totally 37.41 ± 3.09 and 31.51 ± 2.35 mg GAE/g fruit, DW of phenolics were released for Shanlihong and Dajinxing, respectively, and the phenolics released were mainly flavonoids. Catechin, chlorogenic acid, procyanidine B2, epicatechin, paracoumaric acid, hyperoside and isoquercitrin were identified in the soluble fractions by high-performance liquid chromatography (HPLC). Results indicated that procyanidine B2, epicatechin, chlorogenic acid and catechin are four major released antioxidants. Oxygen radical absorption capacity and rapid peroxyl radical scavenging capacity were significantly positive-correlated with the release amount of total phenolics or flavonoids, demonstrating the major roles of phenolics and flavonoids in antioxidant activities. Our results implied that Shanlihong and Dajinxing could be considered as good sources of natural antioxidants.

Sour orange (Citrus aurantium) is a popular fruit with health benefits. Phenolics are the dominant bioactive compounds in this fruit. However, the full phenolics composition remains unclear. In this work, UHPLC-MS/MS was used to qualify and quantify the phenolics in sour orange fruits of cv. Morocco (MSO) and United (USO). Fifty-eight phenolics, including 26 flavonoid glycosides, 22 polymethoxylated flavonoids, 8 coumarins and 2 phenolic acids, were identified. Four limonoids were characterized. Flavonoid glycosides were the leading phenolics in MSO, while polymethoxylated flavonoids (including nobiletin, tangeritin and sinensetin) were dominant in USO. The phenolic extracts showed good antioxidant activities. USO extract had a significantly (p

In this study, Sargassum fusiforme polysaccharide was purified using a DEAE-Sepharose fast-flow column to obtain Sargassum fusiforme polysaccharides fraction (SFP-P1). As expected, the SFP-P1 contains mainly carbohydrates (87%) with less than 1% protein. Within the carbohydrate, it contains about 10% sulfate and 18% uronic acids. SFP-P1 consisted of l -fucose (13.17%), galactose (4.28%), glucose (1.95%), xylose (5.50%), and mannose (75.10%) with an average molecular weight of 113 kDa. Mannose and l -fucose were two predominant monosaccharides. In addition, (1 → )-linked or (1 → 6)-linked, (1 → 2)-linked or (1 → 4)-linked and (1 → 3)-linked glycosyl linkages accounted for 1.62%, 60.69% and 37.69% of all linkages in the molecule, respectively. The glycosidic linkage types of SFP-P1 were proven to be → 3,6)-α- d -Man p (1 →, → 4)-α- d -GalA p (1 →, → 4)-β- d -Xyl p (1 → and → 3,4)-α- d -GlcA p (1 →. The results indicated the SFP-P1 had cytoprotective activity against UVB-induced oxidative stress in HaCaT cells through stimulation of SOD, GSH-P X enzymes activities and ROS. Also SFP-P1 suppressed the UVB-induced expression of MMP-1 & MMP-9.

Flavonoids have been documented to have good antioxidant activities in vitro. However, reports on the cellular antioxidant activities of flavonoid C-glycosides are very limited. In this work, an apigenin C-glycoside was purified from Artocarpus heterophyllus by column chromatography and was identified to be 2″-O-β-D-xylosylvitexin by nuclear magnetic resonance spectroscopy. The cellular antioxidant activity and anticancer activity of 2″-O-β-D-xylosylvitexin were evaluated for the first time. The quantitative structure-activity relationship was analysed by molecular modeling. Apigenin presented an unexpected cellular antioxidation behaviour. It had an antioxidant activity at low concentration and a prooxidant activity at high concentration, whereas 2″-O-β-D-xylosylvitexin showed a dose-dependent cellular antioxidant activity. It indicated that C-glycosidation improved the cellular antioxidation performance of apigenin and eliminated the prooxidant effect. The ortho-dihydroxyl at C-3'/C-4' and C-3 hydroxyl in the flavonoid skeleton play important roles in the antioxidation behaviour. The cell proliferation assay revealed a low cytotoxicity of 2″-O-β-D-xylosylvitexin.

Polysaccharides from Gracilaria lemaneiformis possess various beneficial bioactive functions, but the immunomodulatory activity remains incompletely known. In the present study, a new low molecular-weight sulfated polysaccharide named as GLP-2 was isolated from G. lemaneiformis. The chemical composition and structural characteristics of GLP-2 were determined by high-performance gel permeation chromatography (HPGPC), gas chromatography (GC), infrared (IR) spectrum, methylation and nuclear magnetic resonance (NMR) analyses. In addition, the immunomodulatory activity and underlying mechanism of GLP-2 were examined using murine macrophage RAW264.7 cells. The results indicated GLP-2 could significantly improve the proliferation and pinocytic capability of RAW264.7 cells, and promote the production of reactive oxygen species (ROS), nitric oxide (NO), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) by activating iNOS, IL-6 and TNF-α gene expressions. These results suggested that GLP-2 could be developed as a potent immunomodulatory agent for use in functional foods and dietary supplements.

Methylated flavonoids are an important type of natural flavonoid derivative with potentially multiple health benefits; among other things, they have improved bioavailability compared with flavonoid precursors. Flavonoids have been documented to have broad bioactivities, such as anticancer, immunomodulation, and antioxidant activities, that can be elevated, to a certain extent, by methylation. Understanding the structure, bioactivity, and bioavailability of methylated flavonoids, therefore, is an interesting topic with broad potential applications. Though methylated flavonoids are widely present in plants, their levels are usually low. Because developing efficient techniques to produce these chemicals would likely be beneficial, we provide an overview of their chemical and biological synthesis.

In the present study, polysaccharides from Gracilaria lemaneiformis (GLP) were obtained by citric acid extraction, and had a low molecular weight (21.2 kDa) with a high amount of galactose. GLP showed effective inhibitory effects on α-amylase activity. After a six-week animal trial, GLP was found to combat streptozotocin (STZ)-induced diabetes and associated with oxidative stress, via its regulation of glucose and lipid metabolism, repair of pancreatic β-cells, protection of liver and kidney function, promotion of the activities of endogenous antioxidant enzymes, and suppression of lipid peroxidation. A dose-dependent manner was found in these examinations except for the glucokinase level, superoxide dismutase activity, and malondialdehyde content. GLP treatments were also more effective at regulating the insulin level, lipidemic parameters and blood urea nitrogen level than metformin treatment. Thus, GLP is more advantageous than metformin not only in the naturalness of GLP but also in the action of combating STZ-induced diabetes. Accordingly, GLP may be utilized as a potential functional food supplement for diabetes prevention in the future.

Banana is a delicious fruit with potent immunomodulatory function. In this study, α-D-(1→6)-glucan was purified from banana pulp. It could significantly promote pinocytic activity and production of nitric oxide (NO), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). The mRNA expression of nitric oxide synthase (iNOS), IL-6 and TNF-α was increased in RAW264.7 macrophages. α-D-(1→6)-glucan could not only increase the expression levels of p-p65 and p-IκBα, but also induce the translocation of nuclear factor-kappa B (NF-κB) p65 into the nucleus. Moreover, mitogen-activated protein kinases (MAPKs), including p-ERK, p-JNK and p-p38, were upregulated. These results suggested that NF-κB and MAPK signaling pathways were involved in the immunomodulatory mechanisms of α-D-(1→6)-glucan. The results revealed that α-D-(1→6)-glucan might be the critical component responsible for the health benefits of banana.

Banana as a typical climacteric fruit soften rapidly, resulting in a very short shelf life after harvest. Sodium dichloroisocyanurate (NaDCC) is reported to be an effectively antibacterial compound. Here, we investigated the effects of NaDCC on ripening and senescence of harvested banana fruit at physiological and molecular levels. Application of 200 mg L−1 NaDCC solution effectively inhibited the ripening and senescence of banana fruit after harvest. NaDCC treatment reduced greatly ethylene production rate and expressions of genes encoding 1-aminocyclopropane-1-carboxylate synthetase, 1-aminocyclopropane-1-carboxylate oxidase, ethylene-responsive transcription factor and EIN3-binding F-box protein. Meanwhile, NaDCC treatment down-regulated markedly the expressions of xyloglucan endotransglucosylase/hydrolase and pectinesterase genes. Furthermore, NaDCC treatment affected significantly the accumulation of ripening-related primary metabolites such as sugars and organic acids. Additionally, NaDCC treatment decreased the production of hydroxyl radical and increased 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, reducing power and hydroxyl radical scavenging activity. In conclusion, NaDCC delayed effectively the ripening and senescence of harvested banana fruit via the reduced ethylene effect and enhanced antioxidant activity. Electronic supplementary material The online version of this article (10.1186/s13065-018-0503-5) contains supplementary material, which is available to authorized users.

The phenolic contents, antioxidant, and antiproliferative activities of Malus doumeri were evaluated. Heyuanxiaoguo variety contained higher level of total phenolics (101.9 mg GAE/g fruit, DW), whereas Xinyishanzha variety exhibited the highest total flavonoids (85.35 mg CE/g fruit, DW), and highest cellular antioxidant and antiproliferative activities. Higher ORAC and PSC values were found in Limushan variety. Chlorogenic acid, phloretin-2′-xyloglucoside and ursolic acid were the predominant phenolics in M. doumeri , their contents were highest in Limushan (1850 mg/100g fruit, DW), Xinyishanzha (2212 mg/100g fruit, DW), and Heyuanxiaoguo variety (506.3 mg/100g fruit, DW), respectively. Among the 14 compounds identified, chlorogenic acid and phloretin glycosides accounted for 55.95% of the extracellular antioxidant capacity, while quercetin, luteolin, ursolic acid, and chlorogenic acid contributed significantly to the intracellular antioxidant activity. Furthermore, the intracellular antioxidant property of the Xinyishanzha extracts was related to the protection of endogenous antioxidant enzymes activities and inhibition of reactive oxygen species production.

Tremella fuciformis Berk, a popular nutritious mushroom in China, has attracted increasing attention due to its various bioactivities. In the present work, T. fuciformis polysaccharides (TP) were extracted with hot water. It mainly consisted of mannose, as well as 10.77% (w/w) uronic acid. In additional, the anti-photoaging effects of TP were evaluated using a 30-day UV-irradiated animal assay. TP could efficiently reduce the water and collagen losses of the skin, and inhibit the increase of glycosaminoglycans. Moreover, a histopathological study showed that, UV-induced skin structural alterations were alleviated as well as repairing endogenous collagen breakdown and maintaining the ratio of type I/III collagen, after oral treatment of TP. The activities of SOD, GSH-Px and CAT were increased compared to the irradiated control group without treatment. Accordingly, TP can be used as a potential functional food supplement for skin function protection.

Mulberry leaf is a vegetable used in daily diet. It can bring delicious taste and multiple health benefits. However, the chemicals responsible for these health benefits remain unveiled. In this work, two novel prenylated flavonoids were isolated from mulberry leaf. Their structures were identified and named as morachalcone D and morachalcone E. The protective effects of these two compounds were investigated, against endogenous oxidative damage (oxytosis/ferroptosis) induced by glutamate and erastin in HT22 cells. The results revealed that morachalcone D was much more potent in preventing from glutamate- and erastin-induced cell death than morachalcone E. The neuroprotective effect of morachalcone D was related to the prevention of ROS production, glutathione depletion, and iron accumulation. Morachalcone D upregulated the expression of genes involved in antioxidant defense, including GPx4, CAT, SOD2, Nrf2, HMOX1 and SLC7A11. These findings indicated that morachalcone D was responsible for the health benefits of mulberry leaf, and could be a potent neuroprotective agent for use in dietary supplements and functional foods.

Thermal treatment is an effective technique to modify the physiochemical properties of starch. However, investigation on the effect of repeated dry-heat treatment (RDHT) on the starch properties is limited. In this work, RDHT and continuous dry-heat treatment (CDHT) were conducted on normal maize starch. Both treatments increased pore no on the granule surface and facilitated the granule aggregation. The solubility and swelling power of normal maize starch were improved. The levels of slowly digestible starch (SDS) and resistant starch (RS) + SDS were increased. The structural characteristics, including crystallinity and short-range order, were impaired. The peak viscosity and thermal properties (To, Tp, Tc and ΔH) of starch paste were decreased. When comparing of CDHT samples with the same treating time, RDHT samples showed a lower crystallinity, a weaker thermal stability, a higher paste viscosity and a lower resistance to amylase. These results were useful for industrial application of thermal treatment on starch.

The degradation of cell wall polysaccharides is highly associated with the softening process of banana. In this work, banana was treated by morin to delay softening during storage. Water-soluble polysaccharides were extracted from banana pulp at four storage stages. Their levels increased when the banana was green, but decreased when turned to yellow. Three types of polysaccharides were identified by nuclear magnetic resonance spectroscopy, including starches, homogalacturonans and arabinogalactan proteins. (1 → 4)-α-D-galacturonan constructed the backbone of homogalacturonans, which was the leading water-soluble polysaccharide in the last stage. Starch was the dominant polysaccharide at all stages in morin-treated banana. Deassembly of insoluble starch granules and degradation of soluble starches were responsible for its high level in banana. Arabinogalactan proteins were only detected in late stages, and could be a marker for banana deterioration. The inhibited degradation of cell wall polysaccharides contributed to the preservative effect of morin.

Additional file 3: Table S1. Detailed information of the identified primary metabolites.

Litchi (Litchi chinensis Sonn.) is a well-known traditional medicine since ancient times. The crude extract of litchi leaf exhibited good bioactivity against cancer cells. In this work, three sesquilignans, ehletianol C (1), sesquipinsapol B (2) and sesquimarocanol B (3), and one lignan glycoside schizandriside (4) were isolated from the ethyl acetate-soluble extract of litchi leaf by column chromatography. Their structures were further elucidated by ESI-MS and NMR spectral studies. Ehletianol C, sesquipinsapol B and sesquimarocanol B were detected from this species for the first time. Sesquipinsapol B (EC50 values less than 2.0 μg/mL) and sesquimarocanol B (EC50 values less than 2.4 μg/mL) showed very high cytotoxicities against nasopharynx carcinoma cells CNE1 and CNE2 cells, respectively. Thus, they could be utilized as good drug candidates against nasopharynx cancer. Moreover, three sesquilignans showed effective in vitro cytotoxicities against human cancer cells HepG2 and Hela. Four lignans showed better antioxidant activities than butylated hydroxytoluene (BHT).

Our previous work exhibited Aspergillus awamori fermentation of the litchi pericarp increased significantly antioxidant activity and DNA protection effect. In this present study, the litchi pericarp and its aqueous-organic extracted residues were fermented by A. awamori in order to elucidate the enhanced beneficial effects. The study identified that rutin which present in litchi pericarp could be deglycosylated to form quercetin and quercetin-3-glucoside after the fermentation. Application the standard compounds (rutin, quercetin 3-glucoside, quercetin, kaempferol-3-glucoside and kaempferol) further revealed the effective biotransformation by A. awamori fermentation. It was hypothesised that rutin was initially dehydroxylated to form kaempferol-3-rutinoside and then deglycosylated to form kaempferol-3-glucoside and kaempferol. To our best knowledge, it is the first report on dehydroxylated effect of polyphenols caused by A. awamori fermentation. Thus, A. awamori fermentation can provide an effective way to produce health benefiting value-added products from litchi pericarp in food industry.

Six flavonoids, namely luteolin (1), epicatechin (2), kaempferol 3-O-β-glucoside (3), kaempferol 3-O-α-rhamnoside (4), procyanidin A2 (5) and rutin (6) were purified from the EtOAc-soluble extract of litchi leaf by column chromatography. Their structures were elucidated by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) evidences. Luteolin and kaempferol 3-O-α-rhamnoside were found from this plant for the first time. Procyanidin A2 exhibited high anticancer activities against human hepatoma HepG2 and human cervical carcinoma Hela cells. However, it had poor anticancer activities against human lung cancer A549 and human breast cancer MCF-7 cells. Luteolin, epicatechin, procyanidin A2 and rutin showed good antioxidant activities than butylated hydroxytoluene (BHT). The antimicrobial activity assay indicated that luteolin possessed the strongest antimicrobial activity against Staphylococcus aureus, Escherichia coli, Shigella dysenteriae, Salmonella and Bacillus thuringiensis. Epicatechin, procyanidin A2 and rutin showed relatively weak antimicrobial activities.

Methylated flavonoids are an important type of natural flavonoid derivative with potentially multiple health benefits; among other things, they have improved bioavailability compared with flavonoid precursors. Flavonoids have been documented to have broad bioactivities, such as anticancer, immunomodulation, and antioxidant activities, that can be elevated, to a certain extent, by methylation. Understanding the structure, bioactivity, and bioavailability of methylated flavonoids, therefore, is an interesting topic with broad potential applications. Though methylated flavonoids are widely present in plants, their levels are usually low. Because developing efficient techniques to produce these chemicals would likely be beneficial, we provide an overview of their chemical and biological synthesis.

Mulberry leaf is a newly accepted vegetable for daily diet. It tastes good and has multiple health benefits, including antioxidant and anti-inflammatory activities. However, the chemicals responsible for these health benefits remain unveiled. Prenylated phenolics are characteristic bioactive compounds in mulberry leaf, which are recognized as good antioxidants. In this work, moracin N was purified from mulberry leaf. It showed better antioxidant activities than resveratrol. The EC50 value of cellular antioxidant activity was 24.92 μM, and the IC50 value against DPPH radical was 40.00 μM. The prenyl group rendered the molecule more membrane affinity which improved the bioavailability. The furan ring was critical for the antioxidant behaviour. The cell viability test revealed that moracin N had a good safety. These results pointed out that moracin N contributed to the antioxidant activity of mulberry leaf.