Degree of methyl esterification: A key factor for the encapsulation of icaritin with pectin.

Pectin is a promising nano-carrier. The degree of methyl esterification (DM) influences the physiochemical properties of pectin. However, the effect of DM on the encapsulation capacity of pectin remains unclear. In this work, low methyl-esterified pectin (LMP) and high methyl-esterified pectin (HMP) were prepared. The molecular weight, rheological properties of these pectins with various DM levels were determined. Then icaritin/pectin micelles (IPMs) were prepared using HMP and LMP. Notably, higher loading capacities (18.75-20.12 %) were observed in HMP-IPMs compared to LMP-IPMs (15.72-16.64 %). Furthermore, LMP-IPMs demonstrated a DM-dependent reduction in particle sizes, ranging from 449 to 527 nm. In contrast, the particle sizes of HMP-IPMs varied between 342 and 566 nm, with smaller particle sizes observed in HMP-IPMs at higher DM levels. A significant positive correlation was found between DM and the formation of IPMs, including encapsulation efficiency, loading capacity, Zeta potential, and polydispersity index. Alkali de-esterification showed a weak impact on the pectin structure. Hydroxyl groups like 7-OH and 5-OH of icaritin might be involved in the formation of IPMs. The hydrogen-bond interactions between pectin and icaritin could be enhanced as DM increased.

Interaction between ultrasound-modified pectin and icaritin.

Pectin can improve the bioaccessibility of icaritin as a nanocarrier, and ultrasound can modify the pectin structure. However, the interaction between ultrasound-modified pectin (UMP) and icaritin remains unclearly. In this work, the effects of UMP on the physiochemical properties of icaritin/pectin micelles (IPMs) were investigated. The IPMs prepared with UMP (UMP-IPMs) showed lower encapsulation efficiencies and loading capacities, comparing with native IPMs. UMP-IPMs had smaller particle sizes (325-399 nm) than native IPMs (551 nm). The Mw, viscosity, G' and G" of pectin were determined. NMR spectra indicated that the repeating unit in pectins remained consistently before and after ultrasound treatment, and 7-OH of icaritin was involved in hydrogen bond formation with pectin. The larger chemical shift movement of 6-H and 7-OH for U3-IPMs than P0-IPMs suggested that stronger hydrogen bond interaction between icaritin and pectin. UMP-IPMs exhibited stronger anti-proliferation activities against HepG2 cells than native IPMs.

Identification of prenylated phenolics in mulberry leaf and their neuroprotective activity.

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 < 0.50 µM. The neuroprotective mechanisms of moracin N included inhibition of glutathione depletion, glutathione peroxidase 4 (GPx4) inactivation, reactive oxygen species (ROS) overproduction and iron accumulation, as well as improvement of intracellular antioxidant enzyme activities. Moracin N augmented the transcriptional levels of genes involved in antioxidant defense and glutathione biosynthesis in the early state of ferroptosis induction, and downregulated expression of genes related to iron accumulation and lipid peroxidation. CONCLUSION: The results confirmed that moracin N was a good ferroptosis inhibitor, which exerted neuroprotective activity through preventing from oxidative stress.

Structural characterization of Lanzhou lily (Lilium davidii var. unicolor) polysaccharides and determination of their associated antioxidant activity.

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.

The antioxidant activity and neuroprotective mechanism of isoliquiritigenin.

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.

Identification of two novel prenylated flavonoids in mulberry leaf and their bioactivities.

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.

Modification of structural, physicochemical and digestive properties of normal maize starch by thermal treatment.

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.

Natural Estrogen Receptor Modulators and Their Heterologous Biosynthesis.

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.

Identification of a flavonoid C-glycoside as potent antioxidant.

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-ß-D-xylosylvitexin by nuclear magnetic resonance spectroscopy. The cellular antioxidant activity and anticancer activity of 2″-O-ß-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-ß-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-ß-D-xylosylvitexin.

Major triterpenoids in Chinese hawthorn "Crataegus pinnatifida" and their effects on cell proliferation and apoptosis induction in MDA-MB-231 cancer cells.

The cytotoxicity and antiproliferative effect of phytochemicals presenting in the fruits of Chinese hawthorn (Crataegus pinnatifida) were evaluated. Shanlihong (Crataegus pinnatifida Bge. var. major N.E.Br.) variety possessed significant levels of flavonoids and triterpenoids, and showed potent antiproliferative effect against HepG2, MCF-7 and MDA-MB- 231 human cancer cells lines. Triterpenoids-enriched fraction (S9) prepared by Semi-preparative HPLC, and its predominant ingredient ursolic acid (UA) demonstrated remarkably antiproliferative activities for all the tested cancer cell lines. DNA flow cytometric analysis showed that S9 fraction and UA significantly induced G1 arrest in MDA-MB-231 cells in a dose-dependent manner. Western blotting analysis revealed that S9 fraction and UA significantly induced PCNA, CDK4, and Cyclin D1 downregulation in MDA-MB-231 cells, followed by p21Waf1/Cip1 up-regulation. Additionally, flow cytometer and DNA ladder assays indicated that S9 fraction and UA significantly induced MDA-MB-231 cells apoptosis. Mitochondrial death pathway was involved in this apoptosis as significantly induced caspase-9 and caspase-3 activation. These results suggested that triterpenoids-enriched fraction and UA exhibited antiproliferative activity through the cell cycle arrest and apoptosis induction, and was majorly responsible for the potent anticancer activity of Chinese hawthorn.

Phenolic contents and cellular antioxidant activity of Chinese hawthorn "Crataegus pinnatifida".

It is evident from various epidemiological studies that consumption of fruits and vegetables is essential to maintain health and in the disease prevention. Present study was designed to examine phenolic contents and antioxidant properties of three varieties of Crataegus pinnatifida (Chinese hawthorn). Shanlihong variety exhibited elevated levels of total phenolics and flavonoid contents, including free and bond phenolics. Procyanidin B2 was most abundant phenolic compound in all samples, followed by epicatechin, chlorogenic acid, hyperoside, and isoquercitrin. The free ORAC values, and free hydro-PSC values were 398.3-555.8 µmol TE/g DW, and 299.1-370.9 µmol VCE/g DW, respectively. Moreover, the free cellular antioxidant activity (CAA) values were 678-1200 µmol of QE/100 g DW in the no PBS wash protocol, and 345.9-532.9 µmol of QE/100 g DW in the PBS wash protocol. C. pinnatifida fruit could be valuable to promote consumer health.

Identification of phenolics in litchi and evaluation of anticancer cell proliferation activity and intracellular antioxidant activity.

Litchi leaf is a good resource for phenolics, which are good candidates for medicines. In this work, three phenolics were isolated from litchi leaf by column chromatography. Their structures were identified by electrospray ionization-mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy as secoisolariciresinol 9'-O-ß-D-xyloside (1), 4,7,7',8',9,9'-hexahydroxy-3,3'-dimethoxy-8,4'-oxyneolignan (2), and cinnamtannin B1 (3). Cinnamtannin B1 showed better extra- and intracellular antioxidant activities than Compounds 1 and 2. The intracellular antioxidant activity of cinnamtannin B1 was related to the upregulation of endogenous antioxidant enzyme activities (superoxide dismutase, catalase, and glutathione peroxidase), and inhibition of ROS generation. Furthermore, cinnamtannin B1 exhibited strong antiproliferative effects against HepG2 and Siha cell lines with no significant cytotoxicities. In the case of the HepG2 cell line, cell cycle arrest and apoptosis induction were the underlying anticancer mechanisms of cinnamtannin B1. The results indicated that cinnamtannin B1 was a potent cancer cell proliferation inhibitor and a good intracellular antioxidant.

Production of quercetin, kaempferol and their glycosidic derivatives from the aqueous-organic extracted residue of litchi pericarp with Aspergillus awamori.

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.

Structural identification of (1→6)-α-d-glucan, a key responsible for the health benefits of longan, and evaluation of anticancer activity.

Longan is a delicious subtropical fruit with great health-beneficial effects. It has been utilized for disease prevention and health care since ancient age. To explore the chemicals responsible for the health benefits, water-soluble polysaccharides were extracted from longan flesh in this work. A pure polysaccharide (LPS1) was obtained through column purification. Analysis by gas chromatography showed LPS1 was a homopolysaccharide of glucose with glycosidic linkage of →6)-d-Glc-(1→. Nuclear magnetic resonance (NMR) spectra indicated that the configuration of anomeric carbon in glucose residual was α-form. The polysaccharide structure was further confirmed to be (1→6)-α-d-glucan by chemcial shift of C6. The molecular weight of LPS1 was calculated to be 108 kDa, which had 661 glucose residuals. Anticancer assay showed that LPS1 had anticancer activity against the growth of HepG2 cells to a certain extent. However, it did not show any cytotoxicity against MCF-7 breast cancer cells.

Identification of a novel phenolic compound in litchi (Litchi chinensis Sonn.) pericarp and bioactivity evaluation.

Litchi (Litchi chinensis Sonn.) is a delicious fruit widely accepted by consumers all over the world. In this work, phytochemical investigation of litchi pericarp methanol extracts led to the isolation of a novel phenolic, 2-(2-hydroxyl-5-(methoxycarbonyl) phenoxy) benzoic acid, together with kaempferol, isolariciresinol, stigmasterol, butylated hydroxytoluene, 3,4-dihydroxyl benzoate, methyl shikimate and ethyl shikimate. Most were found in litchi pericarp for the first time. Their structures were mainly elucidated by NMR and MS evidences. Antioxidant activities of the eight compounds were determined by a DPPH radical scavenging assay and the results showed that 2-(2-hydroxy-5-(methoxycarbonyl) phenoxy)benzoic acid, kaempferol, isolariciresinol, butylated hydroxytoluene and 3,4-dihydroxy benzoate exhibited good antioxidant activities. An interesting finding was that butylated hydroxytoluene was detected as a natural antioxidant in this work, which was usually taken as a synthesized antioxidant. Furthermore, the novel compound exhibited no inhibitory effects against tyrosinase and α-glucosidase activities.

Comparative evaluation of rosmarinic acid, methyl rosmarinate and pedalitin isolated from Rabdosia serra (MAXIM.) HARA as inhibitors of tyrosinase and α-glucosidase.

Rabdosia serra has been used in traditional Chinese medicine for centuries. In order to illustrate the pharmaceutical activity of R. serra as hypoglycaemic and skin-whitening agents, rosmarinic acid (confirmed as the major compound in R. serra), methyl rosmarinate and pedalitin isolated from R. serra were evaluated for their inhibitory effects and mechanisms on tyrosinase and α-glucosidase. The inhibitory effects on both tyrosinase and α-glucosidase were in decreasing order, pedalitin>methyl rosmarinate>rosmarinic acid. The IC50 values for the tyrosinase and α-glucosidase activity inhibited by pedalitin were 0.28 and 0.29mM, respectively. Both rosmarinic acid and methyl rosmarinate were considered as noncompetitive inhibitors of tyrosinase, while pedalitin was suggested to be a mixed-type inhibitor of tyrosinase. In the assay of α-glucosidase inhibition, rosmarinic acid was found to be a competitive inhibitor, whereas both methyl rosmarinate and pedalitin were considered as mixed-type inhibitors.