Identification and in vitro Characterization of Novel Antidiabetic Peptides Released Enzymatically from Peanut Protein.

Bioactive peptides derived from proteins found in various foods provide significant health benefits, including regulating blood sugar levels by inhibiting carbohydrate-hydrolyzing enzymes. Hydrolysates of peanut protein were prepared using alcalase (AH) or trypsin (TH) to generate antidiabetic peptides with high activity against α-amylase (IC50 of 6.46 and 5.71 mg/mL) and α-glucosidase (IC50 of 6.30 and 5.57 mg/mL), as well as antiradical activity to scavenge DPPH• (IC50 of 4.18 and 3.12 mg/mL) and ABTS•+ (IC50 of 2.87 and 2.56 mg/mL), respectively. The bioactivities of hydrolysates were greatest in the ultrafiltration-generated F3 fraction (< 3 kDa). The most active fraction was TH-F3, which was purified by gel filtration chromatography to generate sub-fractions (SF). With IC50 values of 1.05 and 0.69 mg/mL, the F3-SF8 fraction was the most effective at inhibiting the activity of α-amylase and α-glucosidase, respectively. This fraction was further purified using RP-HPLC to generate sub-subfractions (SSF), the most active of which were F3-SF8-SSF9 and SSF10. The peptide sequences F3-SF8-SSF9 and SSF10 were determined using LC-MS/MS. Two novel antidiabetic peptides with the potential to inhibit α-amylase and α-glucosidase were identified, with the sequences Asp-Trp-Arg (476.22 Da, IC50 of 0.78, and 0.35 mg/mL) and Phe-Tyr (329.15 Da, IC50 of 0.91, and 0.41 mg/mL). These results suggest that peptides derived from peanut protein are attractive natural ingredients for diabetes management applications.

Genome-wide identification of Aux/IAA and ARF gene families reveal their potential roles in flower opening of Dendrobium officinale.

BACKGROUND: The auxin indole-3-acetic acid (IAA) is a vital phytohormone that influences plant growth and development. Our previous work showed that IAA content decreased during flower development in the medicinally important orchid Dendrobium officinale, while Aux/IAA genes were downregulated. However, little information about auxin-responsive genes and their roles in D. officinale flower development exists. RESULTS: This study validated 14 DoIAA and 26 DoARF early auxin-responsive genes in the D. officinale genome. A phylogenetic analysis classified the DoIAA genes into two subgroups. An analysis of cis-regulatory elements indicated that they were related by phytohormones and abiotic stresses. Gene expression profiles were tissue-specific. Most DoIAA genes (except for DoIAA7) were sensitive to IAA (10 µmol/L) and were downregulated during flower development. Four DoIAA proteins (DoIAA1, DoIAA6, DoIAA10 and DoIAA13) were mainly localized in the nucleus. A yeast two-hybrid assay showed that these four DoIAA proteins interacted with three DoARF proteins (DoARF2, DoARF17, DoARF23). CONCLUSIONS: The structure and molecular functions of early auxin-responsive genes in D. officinale were investigated. The DoIAA-DoARF interaction may play an important role in flower development via the auxin signaling pathway.

Dietary γ-mangostin triggers immunogenic cell death and activates cGAS signaling in acute myeloid leukemia.

Immunogenic cell death (ICD), one of cell-death types through release of damage-associated molecular patterns from dying tumor cells, activates tumor-specific immune response and elicits anti-tumor immunity by traditional radiotherapy and chemotherapy. However, whether natural products could induce ICD in leukemia is not elucidated. Here, we report dietary γ-mangostin eradicates murine primary leukemic cells and prolongs the survival of leukemic mice. As well, it restrains primary leukemic cells and CD34+ leukemic progenitor cells from leukemia patients. Strikingly, γ-mangostin attenuates leukemic cells by inducing ICD as characterized by expression of HSP90B1, ANXA1 and IL1B. Additionally, γ-mangostin accelerates cytoplasmic chromatin fragments generation, promoting DNA damage response, and enhances cGAS activation, leading to up-regulation of chemokines. Meanwhile, it induces HDAC4 degradation and acetylated histone H3 accumulation, which promotes chemokines transcription. Ultimately, CD8+ T cell is activated and recruited by γ-mangostin-induced chemokines in the microenvironment. Our study identifies γ-mangostin triggers ICD and activates cGAS signaling through DNA damage response and epigenetic modification. Therefore, dietary γ-mangostin would act as a potential agent to provoke anti-tumor immunity in the prevention and treatment of leukemia.

The First Racemic Total Syntheses of the Antiplasmodials Watsonianones A and B and Corymbone B.

The first biomimetic total syntheses of three biologically meaningful acylphloroglucinols, watsonianones A and B and corymbone B, with potent antiplasmodial activity, were performed. Their total syntheses were carried out through a diversity-oriented synthetic strategy from congener 2,2,4,4-tetramethyl-6-(3-methylbutylidene)cyclohexane-1,3,5-trione with high step efficiency. The spontaneous enolization/air oxidation of the precursor 2,2,4,4-tetramethyl-6-(3-methylbutylidene)cyclohexane-1,3,5-trione through a singlet O2-induced Diels-Alder reaction pathway to assemble the key biosynthetic peroxide intermediate is also discussed.

Antibacterial sesquiterpenes from the stems and roots of Thuja sutchuenensis.

Eight new sesquiterpenes with diverse skeletons involving four cuparenes, denominated thujasutchins F-I (1-4), one eudesmane and one cedrol, named thujasutchin J (5) and thujasutchin K (6), as well as two thujopsenes thujasutchins L-M (7-8) together with three known congener compounds (9-11) were isolated from EtOAc soluble fraction of ethanolic extract of the stems and roots of Thuja sutchuenensis. Their structures including absolute configurations were unambiguously established by extensive interpretation of the NMR and mass spectroscopic data, X-ray diffractions, and ECD measurements powered by molecular calculations. The biological assays disclosed that 5 and 9 displayed potent inhibitory effect against Staphylococcus. aureus (CMCC 26003), methicillin-resistant Staphylococcus aureus (JCSC 4744), Bacillus cereus (ATCC 10876), and Staphylococcus epidermidis (ATCC 12228) with MICs ranging from 6.25 to 25 µg/mL.

Callistemonols A and B, Potent Antimicrobial Acylphloroglucinol Derivatives with Unusual Carbon Skeletons from Callistemon viminalis.

A phytochemical investigation on the leaves of Callistemon viminalis resulted in the isolation of two unusual compounds, callistemonols A (1) and B (2). Callistemonol A (1) possesses a novel skeleton of a furan ring fusing both an α,ß-triketone and a phloroglucinol unit, while callistemonol B (2) is an acylphloroglucinol derivative featuring two methyl substituents on a five-membered ring and an isovaleryl side chain. Their structures were fully characterized on the basis of extensive spectroscopic analysis, including 1D and 2D NMR parameters, as well as the IR and HRESIMS data. Callistemonol A (1) represents an example of a natural dibenzofuran with two phenyl moieties, and a plausible biogenetic pathway to generate this novel dibenzofuran through a C-C bond-forming radical SAM enzyme is proposed. Moreover, antimicrobial assays, in conjunction with time-killing and biophysical studies, revealed that 1 and 2 exert potent bactericidal activities against a panel of methicillin-resistant pathogenic microbes.

Two new 12-membered macrolides from the endophytic fungal strain Cladosprium colocasiae A801 of Callistemon viminalis.

Two new polyketide metabolites, the 12-membered macrolides 4-hydroxy-12-methyloxacyclododecane-2,5,6-trione (1) and 12-methyloxacyclododecane-2,5,6-trione (2), were isolated from the endophytic fungal strain Cladosprium colocasiae A801 of the plant Callistemon viminalis, together with five known derivatives. Their structures were fully characterized by means of detailed spectroscopic analysis for new structures, and in comparison with published data for known compounds. The antibacterial, cytotoxic, and α-glucosidase inhibitory activities of the new compounds 1 and 2 were evaluated.

Three new kavalactone dimers from Piper methysticum (kava).

Three new dimeric kavalactones, designated as diyangonins A-C (1-3), along with two known analogs were isolated from the roots of Piper methysticum. Their structures were elucidated by means of extensive analysis of their 1D, 2D NMR, and mass spectroscopic data. All these dimers possess a skeleton featuring a cyclobutane ring connecting two kavalactone units in head-to-tail or head-to-head mode. Compounds 1-5 were evaluated for their cytotoxic activities against human tumor cell lines.

Two new ent-kaurane diterpenes from the stems of Eurya chinensis.

Two new ent-kaurane diterpenes (1-2), together with five known analogs, were isolated from the stems of Eurya chinensis. The structures of new compounds were established by extensive analysis of mass spectrometric and 1D and 2D NMR spectroscopic data. Compound 3 exhibited noticeable anti-inflammatory activity as denoted by inhibiting LPS-induced nitric oxide (NO) production in RAW264.7 cells with an IC50 value of 7.82 µM. Compound 4 showed potent cytotoxic activity against human cancer cell lines NCI-H46, HepG2 and SW480 with IC50 values ranging from 7.45 to 8.54 µM.

Anti-inflammatory and antimicrobial coumarins from the stems of Eurya chinensis.

Two new coumarins, named (±)-euryacoumarin A (1) and 6-demethylobtusinin (2), and one new natural coumarin, named euryacoumarin B (3), along with two known compounds, scopoletin (4) and obtusinol (5), were isolated from the stems of Eurya chinensis. Their structures were elucidated by means of extensive spectroscopic methods and comparison with data reported in the literatures. Compound 1 exhibited significant inhibition of LPS-induced nitric oxide (NO) production in RAW264.7 cells with IC50 value of 35.64 ± 1.73 µM, and showed marginal antibacterial activities against Bacillus subtilis and B. cereus with MIC values of 50.59 ± 2.12 and 35.42 ± 0.96 µM, respectively.

Rhodomentones A and B, novel meroterpenoids with unique NMR characteristics from Rhodomyrtus tomentosa.

Two novel meroterpenoids, rhodomentones A and B bearing an unprecedented caryophyllene-conjugated oxa-spiro[5.8] tetradecadiene skeleton, were isolated from the leaves of Rhodomyrtus tomentosa. Their structures with unique NMR characteristics were determined by extensive spectroscopic analysis, single-crystal X-ray diffraction, quantum molecular calculation, chemical transformation as well as total synthesis.

Antimicrobial acylphloroglucinols from the leaves of Rhodomyrtus tomentosa.

Phytochemical study on the leaves of Rhodomyrtus tomentosa resulted in the isolation of fourteen compounds including a new acylphloroglucinol, named tomentosone C (1), and a new flavonol glycoside, namely myricetin-3,7,3'-trimethyl ether-5'-O-ß-glucopyranoside (2). Their structures were characterized by spectral data interpretation for new structures and in comparison with published data for known compounds. The antimicrobial activity evaluation revealed that 1 and the known acylphloroglucinol rhodomyrtone (3) exhibited significant antimicrobial activity with MIC 3.66 and 1.83 µg ml(-1), respectively, toward Staphylococcus aureus, responsible for the antimicrobial activity observed with the n-hexane and EtOAc-soluble fraction of the ethanol extract of R. tomentosa leaves.

[Chemical Constituents from Mitrasacme pygmaea].

Objective: To study the chemical constituents from Mitrasacme pygmaea. Methods: The compounds were isolated and purified by column chromatography and their structure were identified by NMR and MS,and comparison spectral data with literature. Results: Eleven compounds were isolated and identified as tricin-7-O-ß-D-glucopyranoside( 1),massonianoid A( 2),kaempferol( 3),cinnamic acid( 4),quercetin( 5),tiliroside( 6),tricin( 7),ß-sitosterol( 8),adenosine( 9),α-tocopherolquinone( 10)and ß-daucosterol( 11). Conclusion: All the compounds are isolated from this genus for the first time.

[Chemical Constituents from Periploca forrestii].

Objective: To study the chemical constituents from Periploca forrestii. Methods: The constituents were separated by column chromatography and their structures were elucidated by spectroscopic methods. Results: Seven compounds were isolated from Periploca forrestii and identified as wogonin( 1),negletein( 2),vanilline( 3),isovanilline( 4),periplocoside L( 5),ß-sitosterol( 6) and ß-daucosterol( 7). Conclusion: Compounds 1 and 2 are obtained from this genus for the first time,and compounds 3 ~ 5 are isolated from this plant for the first time.

Racemic total synthesis of dactyloidin and demethyldactyloidin through the DL-proline-catalyzed Knoevenagel condensation/[4 + 2] cycloaddition cascade.

An efficient approach towards the first racemic total synthesis of dactyloidin (2) and demethyldactyloidin (3) is described. Their oxygen-bridged tricyclic ketal systems were rapidly constructed by using a remarkable biomimetic Knoevenagel condensation/[4 + 2] cycloaddition cascade as the critical strategy and the 1,5-dicarbonyl segment was assembled by Grignard addition.

A Halogen-Containing Stilbene Derivative from the Leaves of Cajanus cajan that Induces Osteogenic Differentiation of Human Mesenchymal Stem Cells.

A new natural halogen-containing stilbene derivative was isolated from the leaves of Cajanus cajan (L.) Millsp. and identified as 3-O-(3-chloro-2-hydroxyl-propanyl)-longistylin A by comprehensive spectroscopic and chemical analysis, and named cajanstilbene H (1). It is the first halogen-containing stilbene derivative found from plants. In human mesenchymal stem cells (hMSC) from bone marrow, 1 did not promote cell proliferation, but distinctly enhanced osteogenic differentiation of hMSC in time- and dose-dependent manners. In six human cancer cell lines, 1 showed a moderate inhibitory effect on cell proliferation, with IC50 values of 21.42-25.85 µmol·L(-1).

Rapid bactericidal action of alpha-mangostin against MRSA as an outcome of membrane targeting.

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) has created the need for better therapeutic options. In this study, five natural xanthones were extracted and purified from the fruit hull of Garcinia mangostana and their antimicrobial properties were investigated. α-Mangostin was identified as the most potent among them against Gram-positive pathogens (MIC=0.78-1.56 µg/mL) which included two MRSA isolates. α-Mangostin also exhibited rapid in vitro bactericidal activity (3-log reduction within 5 min). In a multistep (20 passage) resistance selection study using a MRSA isolated from the eye, no resistance against α-mangostin in the strains tested was observed. Biophysical studies using fluorescence probes for membrane potential and permeability, calcein encapsulated large unilamellar vesicles and scanning electron microscopy showed that α-mangostin rapidly disrupted the integrity of the cytoplasmic membrane leading to loss of intracellular components in a concentration-dependent manner. Molecular dynamic simulations revealed that isoprenyl groups were important to reduce the free energy for the burial of the hydrophobic phenyl ring of α-mangostin into the lipid bilayer of the membrane resulting in membrane breakdown and increased permeability. Thus, we suggest that direct interactions of α-mangostin with the bacterial membrane are responsible for the rapid concentration-dependent membrane disruption and bactericidal action.

Griffipavixanthone from Garcinia oblongifolia champ induces cell apoptosis in human non-small-cell lung cancer H520 cells in vitro.

Griffipavixanthone (GPX) is a dimeric xanthone which was isolated in a systematic investigation of Garcinia oblongifolia Champ. In this study, we investigate the effect of GPX on cell proliferation and apoptosis on human Non-small-cell lung cancer (NSCLC) cells in vitro and determine the mechanisms of its action. GPX inhibited the growth of H520 cells in dose- and time-dependent manners, with IC50 values of 3.03 ± 0.21 µM at 48 h. The morphologic characteristics of apoptosis and apoptotic bodies were observed by fluorescence microscope and transmission electron microscope. In addition, Annexin V/PI double staining assay revealed that cells in early stage of apoptosis were significantly increased upon GPX treatment dose-dependently. Rh123 staining assay indicated that GPX reduced the mitochondrial membrane potential. DCFH-DA staining revealed that intracellular ROS increased with GPX treatment. Moreover, GPX cleaved and activated caspase-3. In summary, this study showed that GPX inhibited H520 cell proliferation in dose- and time-dependent manner. Further mechanistic study indicated that GPX induced cell apoptosis through mitochondrial apoptotic pathway accompanying with ROS production. Our results demonstrate the potential application of GPX as an anti-non-small cell lung cancer agent.

Three new anti-inflammatory stilbenoids and a diphenyl ether derivative from Cajanus cajan.

Three new stilbenoids, namely two rare plant-derived phenanthrenes denominated Cajananthrenes A and B (1, 2) and one bibenzyl named Cajanbenzyl (3), together with a diphenyl ether derivative designated Cajanether (4), as well as five other known compounds (5-9) were isolated from the ethanolic extract of the leaves of Cajanus cajan. Their structures were determined through extensive spectroscopic analysis including UV, IR, NMR (1D and 2D) and HRESIMS as well. A plausible biogenesis pathway was proposed for the biosynthesis of compounds 1-3. Compounds 1 and 2 displayed moderate anti-inflammatory activity as evident from the inhibitory effect on NO production in LPS-stimulated RAW 264.7 macrophages with IC50 values of 73.6 and 44.6 µM respectively.

Progress of Antimicrobial Mechanisms of Stilbenoids.

Antimicrobial drugs have made outstanding contributions to the treatment of pathogenic infections. However, the emergence of drug resistance continues to be a major threat to human health in recent years, and therefore, the search for novel antimicrobial drugs is particularly urgent. With a deeper understanding of microbial habits and drug resistance mechanisms, various creative strategies for the development of novel antibiotics have been proposed. Stilbenoids, characterized by a C6-C2-C6 carbon skeleton, have recently been widely recognized for their flexible antimicrobial roles. Here, we comprehensively summarize the mode of action of stilbenoids from the viewpoint of their direct antimicrobial properties, antibiofilm and antivirulence activities and their role in reversing drug resistance. This review will provide an important reference for the future development and research into the mechanisms of stilbenoids as antimicrobial agents.