Identifying the temporal contributors and their interactions during dynamic formation of black tea cream.

Tea cream formed in hot and strong tea infusion while cooling deteriorates quality and health benefits of tea. However, the interactions among temporal contributors during dynamic formation of tea cream are still elusive. Here, by deletional recombination experiments and molecular dynamics simulation, it was found that proteins, caffeine (CAF), and phenolics played a dominant role throughout the cream formation, and the contribution of amino acids was highlighted in the early stage. Furthermore, CAF was prominent due to its extensive binding capacity and the filling complex voids property, and caffeine-theaflavins (TFs) complexation may be the core skeleton of the growing particles in black tea infusion. In addition to TFs, the unidentified phenolic oxidation-derived products (PODP) were confirmed to contribute greatly to the cream formation.

Anti-inflammatory effects of the Thai herbal remedy Yataprasen and biflavonoids isolated from Putranjiva roxburghii in RAW264.7 macrophages.

ETHNOPHARMACOLOGICAL RELEVANCE: Yataprasen is a topical Thai herbal remedy for the treatment of musculoskeletal pain and is included in Kumpe Thart Phra Narai, the first Thai textbook of traditional medicine. The herbal preparation is made from a hydroethanolic extract of a mixture of 13 medicinal plants, of which Putranjiva roxburghii Wall. leaves are the major ingredient. AIM OF THE STUDY: In this study, we investigated the underlying mechanism of action for the anti-inflammatory effects of the Yataprasen remedy, its main ingredients, and the phytochemicals isolated from P. roxburghii leaves. MATERIALS AND METHODS: The anti-inflammatory effects of the Yataprasen remedy, along with its main ingredients, including the leaves of Baliospermum solanifolium (Burm.) Suresh, Melia azedarach L., P. roxburghii, Senna siamea (Lam.) Irwin & Barneby, and Tamarindus indica L. were determined by measuring prostaglandin E2 (PGE2) secretion, nitric oxide (NO) production, and the synthesis of inflammatory biomarkers in lipopolysaccharide (LPS)-treated RAW264.7 macrophage cells. The active ingredients of the P. roxburghii leaves were separated by chromatography and spectroscopic measurements were used to identify their chemical structures. RESULTS: Ethanol extracts of the Yataprasen remedy and some of its ingredients significantly suppressed LPS-induced PGE2 secretion and NO production in a dose-dependent manner. Treatment of RAW264.7 cells with ethanolic extracts of the Yataprasen remedy (50 µg/mL) significantly inhibited LPS-induced mRNA expression of TNF-α, COX-2, iNOS, and NF-κB. Among the plant ingredient extracts, P. roxburghii leaf extract exhibited the highest inhibitory effects on LPS-induced TNF-α and iNOS expression. Moreover, T. indica leaf extract showed the highest activity on the inhibition of LPS-induced COX-2 and NF-κB expression. Putraflavone, podocarpusflavone A, and amentoflavone were isolated biflavonoids from P. roxburghii leaf extract and showed the inhibitory effects on LPS-induced PGE2 secretion and NO synthesis in RAW264.7 cells. Of the isolated biflavonoids, amentoflavone exhibited the strongest anti-inflammatory activity by inhibiting the expression of TNF-α, COX-2, and iNOS. CONCLUSION: The results support reported the anti-inflammatory effects of the Yataprasen remedy, which are associated with the downregulation of proinflammatory mediators. P. roxburghii, along with its biflavonoids, are the impact components that contribute to the anti-inflammatory effects of the herbal remedy.

Ginkgetin exhibits antifibrotic effects by inducing hepatic stellate cell apoptosis via STAT1 activation.

Liver fibrosis affects approximately 800 million patients worldwide, with over 2 million deaths each year. Nevertheless, there are no approved medications for treating liver fibrosis. In this study, we investigated the impacts of ginkgetin on liver fibrosis and the underlying mechanisms. The impacts of ginkgetin on liver fibrosis were assessed in mouse models induced by thioacetamide or bile duct ligation. Experiments on human LX-2 cells and primary mouse hepatic stellate cells (HSCs) were performed to explore the underlying mechanisms, which were also validated in the mouse models. Ginkgetin significantly decreased hepatic extracellular matrix deposition and HSC activation in the fibrotic models induced by thioacetamide (TAA) and bile duct ligation (BDL). Beneficial effects also existed in inhibiting hepatic inflammation and improving liver function. In vitro experiments showed that ginkgetin markedly inhibited HSC viability and induced HSC apoptosis dose-dependently. Mechanistic studies revealed that the antifibrotic effects of ginkgetin depend on STAT1 activation, as the effects were abolished in vitro after STAT1 silencing and in vivo after inhibiting STAT1 activation by fludarabine. Moreover, we observed a meaningful cross-talk between HSCs and hepatocytes, in which IL-6, released by ginkgetin-induced apoptotic HSCs, enhanced hepatocyte proliferation by activating STAT3 signaling. Ginkgetin exhibits antifibrotic effects by inducing HSC apoptosis via STAT1 activation and enhances hepatocyte proliferation secondary to HSC apoptosis via the IL-6/STAT3 pathway.

The substitution sites of hydroxyl and galloyl groups determine the inhibitory activity of human pancreatic α-amylase in twelve tea polyphenol monomers.

Tea polyphenols have been reported as potential α-amylase inhibitors. However, the quantitative structure-activity relationship (QSAR) between tea polyphenols and human pancreas α-amylase (HPA) is not well understood. Herein, the inhibitory effect of twelve tea polyphenol monomers on HPA was investigated in terms of inhibitory activity, as well as QSAR analysis and interaction mechanism. The results revealed that the HPA inhibitory activity of theaflavins (TFs), especially theaflavin-3'-gallate (TF-3'-G, IC50: 0.313 mg/mL), was much stronger than that of catechins (IC50: 18.387-458.932 mg/mL). The QSAR analysis demonstrated that the determinant for the inhibitory activity of HPA was not the number of hydroxyl and galloyl groups in tea polyphenol monomers, while the substitution sites of these groups potentially might play a more important role in modulating the inhibitory activity. The inhibition kinetics and molecular docking revealed that TF-3'-G as a mixed-type inhibitor had the lowest inhibition constant and bound to the active sites of HPA with the lowest binding energy (-7.74 kcal/mol). These findings could provide valuable insights into the structures-activity relationships between tea polyphenols and the HPA inhibitors.

Five new biflavonoids with acetylcholinesterase inhibitory activity from Diphylleia sinensis.

Five new biflavonoids, diphybiflavonoids A - E (1-5), were isolated from the roots and rhizomes of Diphylleia sinensis. Their structures were elucidated by extensive spectroscopic data, including UV, IR, HR-ESI-MS and 2D NMR. Their absolute configurations were determined by ECD spectra. All isolated compounds were evaluated for acetylcholinesterase (AChE) inhibitory activity. Compounds 1-4 exhibited the potent AChE inhibitory activities with IC50 values of 1.62, 2.10, 2.08, and 5.15 µM, respectively. The preliminary structure-activity relationship study indicated that the connection mode (C2-O-C4'''/C3-O-C3''' or C2-O-C3'''/C3-O-C4''') of biflavonoid subunits, and 3-hydroxy group of flavonol subunit were important structural factors for AChE inhibitory activity. Biflavonoids, containing a C2-O-C4'''/C3-O-C3''' or C2-O-C3'''/C3-O-C4''' linkage, can be a potentially useful platform for development of cholinesterase inhibitors.

The Antiobesity Effects and Potential Mechanisms of Theaflavins.

Theaflavins are the characteristic polyphenols in black tea which can be enzymatically synthesized. In this review, the effects and molecular mechanisms of theaflavins on obesity and its comorbidities, including dyslipidemia, insulin resistance, hepatic steatosis, and atherosclerosis, were summarized. Theaflavins ameliorate obesity potentially via reducing food intake, inhibiting pancreatic lipase to reduce lipid absorption, activating the adenosine monophosphate-activated protein kinase (AMPK), and regulating the gut microbiota. As to the comorbidities, theaflavins ameliorate hypercholesterolemia by inhibiting micelle formation to reduce cholesterol absorption. Theaflavins improve insulin sensitivity by increasing the signaling of protein kinase B, eliminating glucose toxicity, and inhibiting inflammation. Theaflavins ameliorate hepatic steatosis via activating AMPK. Theaflavins reduce atherosclerosis by upregulating nuclear factor erythropoietin-2-related factor 2 signaling and inhibiting plasminogen activator inhibitor 1. In randomized controlled trails, black tea extracts containing theaflavins reduced body weight in overweight people and improved glucose tolerance in healthy adults. The amelioration on the hyperlipidemia and the prevention of coronary artery disease by black tea extracts were supported by meta-analysis.

Inhibitory effects against SARSCoV-2 main protease (Mpro) of biflavonoids and benzophenones from the fruit of Platonia insignis.

The SARS-CoV-2 mutation and the limitation of the approved drug against COVID-19 are still a challenge in many country healthcare systems and need to be affronted despite the set of vaccines to prevent this viral infection. To contribute to the identification of new antiviral agents, the present study focused on natural products from an edible fruit with potential inhibitory effects against the SARS-CoV-2 main protease (Mpro). First, LC-ESIMS analysis of Platonia insignis fruits was performed and showed the presence of biflavonoids and benzophenones in the seed and pulp, respectively. Then, maceration and chromatographic purification led to the identification of two triglycerides (1 and 2) alongside chamaejasmine (3) and volkensiflavone (4) from the seed and isogarcinol (5) and cycloxanthochymol (6), from the pulp. Compounds 1-6 after evaluating their inhibitory against Mpro, displayed from no to significant activity. Compound 5 was the most potent with an IC50 value of 0.72 µM and was more active than the positive control, Ebselen (IC50 of 3.4 µM). It displayed weak and no cytotoxicity against THP-1 (CC50 of 116.2 µM) and Vero cell lines, respectively. Other active compounds showed no cytotoxicity against THP-1. and Vero cell lines. Molecular docking studies revealed interactions in the catalytic pocket between compound 5 and amino acid residues that composed the catalytic dyads (His 41 and Cyst 145).

Spiro-Flavonoids in Nature: A Critical Review of Structural Diversity and Bioactivity.

Based on the literature data from 1973 to 2022, this work summarizes reports on spiro-flavonoids with a spiro-carbon at the center of their structure and how this affects their isolation methods, stereochemistry, and biological activity. The review collects 65 unique structures, including spiro-biflavonoids, spiro-triflavonoids, spiro-tetraflavonoids, spiro-flavostilbenoids, and scillascillin-type homoisoflavonoids. Scillascillin-type homoisoflavonoids comprise spiro[bicyclo[4.2.0]octane-7,3'-chromane]-1(6),2,4-trien-4'-one, while the other spiro-flavonoids contain either 2H,2'H-3,3'-spirobi[benzofuran]-2-one or 2'H,3H-2,3'-spirobi[benzofuran]-3-one in the core of their structures. Spiro-flavonoids have been described in more than 40 species of eight families, including Asparagaceae, Cistaceae, Cupressaceae, Fabaceae, Pentaphylacaceae, Pinaceae, Thymelaeaceae, and Vitaceae. The possible biosynthetic pathways for each group of spiro-flavonoids are summarized in detail. Anti-inflammatory and anticancer activities are the most important biological activities of spiro-flavonoids, both in vitro and in vivo. Our work identifies the most promising natural sources, the existing challenges in assigning the stereochemistry of these compounds, and future research perspectives.

The inhibitory effect and mechanism of theaflavins on fluoride transport and uptake in HIEC-6 cell model.

Fluoride (F-) is widely present in nature, while long-term excessive F- intake can lead to fluorosis. Theaflavins are an important bioactive ingredient of black and dark tea, and black and dark tea water extracts showed a significantly lower F- bioavailability than NaF solutions in previous studies. In this study, the effect and mechanism of four theaflavins (theaflavin, theaflavin-3-gallate, theaflavin-3'-gallate, theaflavin-3,3'-digallate) on F- bioavailability were investigated using normal human small intestinal epithelial cells (HIEC-6) as a model. The results showed that theaflavins could inhibit the absorptive (apical - basolateral) transport of F- while promote its secretory (basolateral - apical) transport in HIEC-6 cell monolayers in a time- and concentration-dependent (5-100 µg/mL) manner, and significantly reduce the cellular F- uptake. Moreover, the HIEC-6 cells treated with theaflavins showed a reduction in cell membrane fluidity and cell surface microvilli. Transcriptome, qRT-PCR and Western blot analysis revealed that theaflavin-3-gallate (TF3G) addition could significantly enhance the mRNA and protein expression levels of tight junction-related genes in HIEC-6 cells, such as claudin-1, occludin and zonula occludens-1 (ZO-1). Overall, theaflavins may reduce F- absorptive transport by regulating tight junction-related proteins, and decreasing intracellular F- accumulation by affecting the cell membrane structure and properties in HIEC-6 cells.

Structure elucidation of olasubscorpioside C, a new rotameric biflavonoid glycoside from the stem barks of Olax subscorpioidea (Oliv).

From the n-butanol soluble fraction of the ethanol extract of the medicinal plant Olax subscorpioidea, a previously unreported rotameric biflavonoid glycoside constituted of 4'-O-methylgallocatechin-(4α → 8)-4'-O-methylgallocatechin as aglycone named olasubscorpioside C (1) along with the known 4'-O-methylgallocatechin (2) were isolated. Their structures were determined on the basis of spectrometric and spectroscopic techniques including HRFABMS, 1 H and 13 C NMR, DEPT 135o , HSQC, HMBC, ROESY, and CD followed by comparison with the reported data.

Ginkgetin suppresses ovarian cancer growth through inhibition of JAK2/STAT3 and MAPKs signaling pathways.

BACKGROUND: Ginkgo biloba L., a kind of traditional Chinese medicine, is always used to treat various diseases. Ginkgetin is an active biflavonoid isolated from leaves of Ginkgo biloba L., which exhibits diverse biological activities, including anti-tumor, anti-microbial, anti-cardiovascular and cerebrovascular diseases, and anti-inflammatory effects. However, there are few reports on the effects of ginkgetin on ovarian cancer (OC). HYPOTHESIS/PURPOSE: OC is one of the most common cancers with high mortality in women. The purpose of this study was to find out how ginkgetin inhibited OC and which signal transduction pathways was involved to suppress OC. METHODS: The OC cell lines, A2780, SK-OV-3 and CP70, were used for in vitro experiments. MTT assay, colony formation, apoptosis assay, scratch wound assay and cell invasion assay were used to determine the inhibitory effect of ginkgetin. BALB/c nude female mice were injected with A2780 cells subcutaneously, then treated with ginkgetin by intragastric administration. Western blot experiment was used to verify the inhibitory mechanism of OC in vitro and in vivo. RESULTS: We found that ginkgetin inhibited the proliferation and induced apoptosis in OC cells. In addition, ginkgetin reduced migration and invasion of OC cells. In vivo study showed that ginkgetin significantly reduced tumor volume in the xenograft mouse model. Furthermore, the anti-tumor effects of ginkgetin were associated with a down regulation of p-STAT3, p-ERK and SIRT1 both in vitro and in vivo. CONCLUSION: Our results suggest that ginkgetin exhibits anti-tumor activity in OC cells via inhibiting the JAK2/STAT3 and MAPK pathways and SIRT1 protein. Ginkgetin could be a potential candidate for the treatment of OC.

Advances in the Anti-Tumor Activity of Biflavonoids in Selaginella.

Despite the many strategies employed to slow the spread of cancer, the development of new anti-tumor drugs and the minimization of side effects have been major research hotspots in the anti-tumor field. Natural drugs are a huge treasure trove of drug development, and they have been widely used in the clinic as anti-tumor drugs. Selaginella species in the family Selaginellaceae are widely distributed worldwide, and they have been well-documented in clinical practice for the prevention and treatment of cancer. Biflavonoids are the main active ingredients in Selaginella, and they have good biological and anti-tumor activities, which warrant extensive research. The promise of biflavonoids from Selaginella (SFB) in the field of cancer therapy is being realized thanks to new research that offers insights into the multi-targeting therapeutic mechanisms and key signaling pathways. The pharmacological effects of SFB against various cancers in vitro and in vivo are reviewed in this review. In addition, the types and characteristics of biflavonoid structures are described in detail; we also provide a brief summary of the efforts to develop drug delivery systems or combinations to enhance the bioavailability of SFB monomers. In conclusion, SFB species have great potential to be developed as adjuvant or even primary therapeutic agents for cancer, with promising applications.

JFD, a Novel Natural Inhibitor of Keap1 Alkylation, Suppresses Intracellular Mycobacterium Tuberculosis Growth through Keap1/Nrf2/SOD2-Mediated ROS Accumulation.

It is an effective strategy to treat tuberculosis by enhancing reactive oxygen species- (ROS-) mediated killing of Mycobacterium tuberculosis in macrophages, but there are no current therapeutic agents targeting this pathway. Honeysuckle has been used as the traditional medicine for tuberculosis treatment for 1500 years. Japoflavone D (JFD) is a novel biflavonoid isolated from Honeysuckle promoting ROS accumulation by Nrf2 pathway in hepatocarcinoma cells. However, its activity to kill M. tuberculosis in macrophages and molecular mechanism has not been reported. Our results showed that JFD enhances the M. tuberculosis elimination by boosting ROS levels in THP-1 cells. Moreover, the massive ROS accumulation activates p38 to induce apoptosis. Notably, the mechanism revealed that JFD suppresses the nuclear transport of Nrf2, thereby inhibiting SOD2 transcription, leading to a large ROS accumulation. Further studies showed that JFD disrupts the Keap1 alkylation at specific residues Cys14, Cys257, and Cys319, which is crucial for Nrf2 activation, thereby interrupts the nuclear transport of Nrf2. In pharmacokinetic study, JFD can stay as the prototype for 24 h in mice and can be excreted in feces without any toxicity. Our data reveal for the first time that a novel biflavonoid JFD as a potent inhibitor of Keap1 alkylation can suppress the nuclear transport of Nrf2. And it is the first research of the inhibitor of Keap1 alkylation. Furthermore, JFD robustly promotes M. tuberculosis elimination from macrophages by inhibiting Keap1/Nrf2/SOD2 pathway, resulting in the ROS accumulation. This work identified Keap1 alkylation as a new drug target for tuberculosis and provides a preliminary basis for the development of antituberculosis lead compounds based on JFD.

An In Vitro Catalysis of Tea Polyphenols by Polyphenol Oxidase.

Tea polyphenol (TPs) oxidation caused by polyphenol oxidase (PPO) in manufacturing is responsible for the sensory characteristics and health function of fermented tea, therefore, this subject is rich in scientific and commercial interests. In this work, an in vitro catalysis of TPs in liquid nitrogen grinding of sun-dried green tea leaves by PPO was developed, and the changes in metabolites were analyzed by metabolomics. A total of 441 metabolites were identified in the catalyzed tea powder and control check samples, which were classified into 11 classes, including flavonoids (125 metabolites), phenolic acids (67 metabolites), and lipids (55 metabolites). The relative levels of 28 metabolites after catalysis were decreased significantly (variable importance in projection (VIP) > 1.0, p < 0.05, and fold change (FC) < 0.5)), while the relative levels of 45 metabolites, including theaflavin, theaflavin-3'-gallate, theaflavin-3-gallate, and theaflavin 3,3'-digallate were increased significantly (VIP > 1.0, p < 0.05, and FC > 2). The increase in theaflavins was associated with the polymerization of catechins catalyzed by PPO. This work provided an in vitro method for the study of the catalysis of enzymes in tea leaves.

Screening for α-glucosidase inhibitors from Selaginella uncinata based on the ligand fishing combined with ultra-high-performance liquid chromatography-quadrupole time-of-flight-tandem mass spectrometry.

Biflavonoids are naturally occurring compounds consisting of two flavonoid moieties that have received substantial attention from researchers. Although many kinds of biflavonoids are typically distributed in Selaginella uncinata with hypoglycemic effect, their anti-α-glucosidase activities are not yet clear. In this study, a ligand fishing strategy for fast screening of α-glucosidase inhibitors from S. uncinata was proposed. α-Glucosidase was first immobilized on Fe3 O4 magnetic nanoparticles (MNPs) and then the α-glucosidase-functionalized MNPs were incubated with crude extracts of S. uncinata to fish out the ligands. Furthermore, considering the similarity and easy confusion of the structures of biflavonoids, the fragmentation patterns of different types of biflavonoids were studied. Based on this, 11 biflavonoids ligands with α-glucosidase inhibitory activities were accurately and quickly identified from S. uncinata with ultra-high-performance liquid chromatography-quadrupole time-of-flight-tandem mass spectrometry. Furthermore, these ligands were confirmed to be potential inhibitors through the in vitro inhibitory assay and molecular docking.

An integrated strategy for characterization of chemical constituents in Stephania tetrandra using LC-QTOF-MS/MS and the target isolation of two new biflavonoids.

LC-MS has been a widely used analytical technique for identification of natural compounds. However, sophisticated and laborious data analysis is required to identify chemical components, especially new compounds, from a large LC-MS dataset. The aim of this study is to develop an integrated data-mining strategy that combines molecular networking (MN), in-house polygonal mass defect filtering (MDF), and diagnostic fragment ion filtering (DFIF) to identify phytochemicals in Stephania tetrandra based on LC-MS data. S. tetrandra samples were prepared by matrix solid-phase dispersion extraction methods and then raw MS spectra were acquired using LC-QTOF-MS/MS. MN and in-house polygonal MDF classified the compounds roughly. Modified DFIF were then used in succession to place each spectrum into a specific class. Finally, the exact structures were deduced by fragmentation pathways and related botanical biogenesis, with the help of the narrowed classification from MN and MDF. The total workflow was a combination of data filtering and identification methods for rapid characterization of known compounds (dereplication) and discovery of new compounds. Consequently, 144 compounds were identified or tentatively identified in the aerial parts and roots of S. tetrandra, including 11 potentially new compounds and 63 compounds first identified in this species. Among 144 compounds, 61 were from the aerial parts exclusively, 8 were from the roots exclusively, and 75 were found in both parts. Furthermore, two new biflavonoids were isolated with the guide of LC-MS analysis and structurally elucidated by spectroscopic methods. In conclusion, the proposed data-mining strategy based on LC-MS can be used to profile chemical constituents with high efficiency and guide the isolation of new compounds from medicinal plants. The comparison of the components of the aerial parts and roots of S. tetrandra would be helpful for the rational utilization of the medicinal plant.

Characterization and bioactivity of A-type procyanidins from litchi fruitlets at different degrees of development.

Characterization and bioactivity of A-type procyanidins was investigated in litchi fruitlet (LF) at different stages and mature pericarp (MP) of 5 litchi cultivars. The content of total phenols in LFs was higher than that of MP and showed good antioxidant activity. Eleven procyanidins were identified in samples, including procyanidin A2, procyanidin A4, and 1 dimer, 2 trimers, and 1 tetramer of A-type procyanidin. Also, A-type procyanidin could stably exist in LFs stage, but declined substantially after maturity, which was about 1.45 - 3.56 times than mature pericarp. In addition, the second stage of LFs showed strong anti-inflammatory and anti-proliferative activities, in which monomer and A-type procyanidin trimers in LFs were significantly correlated with antioxidant (r > 0.72; p < 0.01) and anti-inflammatory (r = 0.53; p < 0.05) activities, respectively. Therefore, litchi in LF stage could be a good source of A-type oligomer procyanidins which had good application value.

Benzophenone Rhamnosides and Chromones from Hypericum seniawinii Maxim.

Two new benzophenone glycosides, hypersens A and B, along with four known compounds, (S)-(+)-5,7-dihydroxy-2-(1-methylpropyl) chromone (3), 5,7-dihydroxy-2-isopropylchromone (4), urachromone B (5), and 3-8'' bisapigenin (6), were isolated from Hypericum seniawinii. The structures of new compounds (1 and 2) were elucidated according to comprehensive spectroscopic data analyses. The absolute configurations of 1 and 2 were determined by electronic circular dichroism (ECD) calculations. All isolated compounds were evaluated for their neuroprotective effect using corticosterone-induced PC12 cell injury. In addition, compounds 1-6 were evaluated for their anti-inflammatory activity in lipopolysaccharide-induced RAW 264.7 cells. Compound 6 was a biflavonoid and significantly inhibited the production of nitric oxide with an IC50 value of 11.48 ± 1.23 µM.

Siamenflavones A-C, three undescribed biflavonoids from Selaginella siamensis Hieron. and biflavonoids from spike mosses as EGFR inhibitor.

Three undescribed biflavonoids (BFVs), siamenflavones A-C along with twelve BFVs were isolated from Selaginella siamensis Hieron. and Selaginella bryopteris (L.) Baker (Selaginellaceae). The chemical structures of undescribed compounds were established through comprehensive spectroscopic techniques, chemical correlations, and X-ray crystallography. The ten isolated BFVs, siamenflavones A-C, delicaflavone, chrysocauflavone, robustaflavone, robustaflavone-4-methylether, amentoflavone, tetrahydro-amentoflavone, and sciadopitysin were evaluated for the antiproliferative effects against four human cancer cell lines A549, H1975, HepG2 and T47D. Delicaflavone and robustaflavone 4'-methylether exerted strong effects on the four human cancer cell lines. Siamenflavone B, delicaflavone and robustaflavone 4'-methylether showed potent inhibitory activities against wild-type EGFR. The inhibition of the compounds was further supported by molecular docking and predictive intermolecular interactions. Molecular dynamics simulation studies of siamenflavone B and robustaflavone-4'-methylether complexed to EGFR-TK further supported inhibition of the compounds to the ATP binding site. Finally, analysis of pharmacokinetic and electronic properties using density-functional theory and known drug index calculations suggest that the compounds are pharmaceutically compatible for drug administration.

Inhibition of Three Diabetes-Related Enzymes by Procyanidins from Lotus (Nelumbo nucifera Gaertn.) Seedpods.

The inhibitory effects of procyanidins from lotus (Nelumbo nucifera Gaertn.) seedpods on the activities of α-amylase, α-glucosidase and protein tyrosine phosphatase 1B (PTP1B), were studied and compared with those of (+)-catechin, (-)-epicatechin, epigallocatechin gallate (EGCG), procyanidin dimer B2 and trimer C1. The results showed that Lotus procyanidin extract (LPE) significantly inhibited α-amylase, α-glucosidase and PTP1B with IC50 values of 5.5, 1.0, and 0.33 µg/mL, respectively. The inhibition increased with the degree of polymerization and the existence of galloyl or gallocatechin units. Kinetic analysis showed that LPE inhibited α-glucosidase activity in a mixed competitive and noncompetitive mode. Fluorescence quenching revealed that α-glucosidase interacted with LPE or EGCG in an apparent static mode, or the model of "sphere of action". The apparent static (K) and bimolecular (kq) constants were 4375 M-1 and 4.375 × 1011 M-1 s-1, respectively, for LPE and 1195 M-1 and 1.195 × 1011 M-1 s-1, respectively, for EGCG. Molecular docking analysis provided further information on the interactions of (+)-catechin, (-)-epicatechin, EGCG, B2 and C1 with α-glucosidase. It is hypothesized that LPE may bind to multiple sites of the enzyme through hydrogen bonding and hydrophobic interactions, leading to conformational changes in the enzyme and thus inhibiting its activity. These findings first elucidate the inhibitory effect of LPE on diabetes-related enzymes and highlight the usefulness of LPE as a dietary supplement for the prophylaxis of diabetes.