The importance of starch and sucrose digestion in nutritive biology of synanthropic acaridid mites: α‐Amylases and α‐glucosidases are suitable targets for inhibitor‐based strategies of mite control

The adaptation of nine species of mites that infest stored products for starch utilization was tested by (1) enzymatic analysis using feces and whole mite extracts, (2) biotests, and (3) inhibition experiments. Acarus siro, Aleuroglyphus ovatus, and Tyroborus lini were associated with the starch‐type substrates and maltose, with higher enzymatic activities observed in whole mite extracts. Lepidoglyphus destructor was associated with the same substrates but had higher activities in feces. Dermatophagoides farinae, Chortoglyphus arcuatus, and Caloglyphus redickorzevi were associated with sucrose. Tyrophagus putrescentiae and Carpoglyphus lactis had low or intermediate enzymatic activity on the tested substrates. Biotests on starch additive diets showed accelerated growth of species associated with the starch‐type substrates. The inhibitor acarbose suppressed starch hydrolysis and growth of the mites. We suggest that the species with higher starch hydrolytic activity in feces were more tolerant to acarbose, and α‐amylase and α‐glucosidase of synanthropic mites are suitable targets for inhibitor‐based strategies of mite control. © 2009 Wiley Periodicals, Inc.     

A TLC bioautographic method for the detection of α‐ and β‐glucosidase inhibitors in plant extracts

Introduction – Bioautographic assays using TLC play an important role in the search for active compounds from plants. A TLC assay has previously been established for the detection of β‐glucosidase inhibitors but not for α‐glucosidase. Nonetheless, α‐glucosidase inhibition is an important target for therapeutic agents against of type 2 diabetes and anti‐viral infections. Objective – To develop a TLC bioautographic method to detect α‐ and β‐glucosidase inhibitors in plant extracts. Methodology – The enzymes α‐ and β‐d ‐glucosidase were dissolved in sodium acetate buffer. After migration of the samples, the TLC plate was sprayed with enzyme solution and incubated at room temperature for 60 min in the case of α‐d ‐glucosidase, and 37°C for 20 min in the case of β‐d ‐glucosidase. For detection of the active enzyme, solutions of 2‐naphthyl‐α‐D‐glucopyranoside or 2‐naphthyl‐β‐D‐glucopyranoside and Fast Blue Salt were mixed at a ratio of 1 : 1 (for α‐d ‐glucosidase) or 1 : 4 (for β‐d ‐glucosidase) and sprayed onto the plate to give a purple background colouration after 2–5 min. Results – Enzyme inhibitors were visualised as white spots on the TLC plates. Conduritol B epoxide inhibited α‐d ‐glucosidase and β‐d ‐glucosidase down to 0.1 µg. Methanol extracts of Tussilago farfara and Urtica dioica after migration on TLC gave enzymatic inhibition when applied in amounts of 100 µg for α‐glucosidase and 50 µg for β‐glucosidase. Conclusion – The screening test was able to detect inhibition of α‐ and β‐glucosidases by pure reference substances and by compounds present in complex matrices, such as plant extracts. Copyright © 2009 John Wiley & Sons, Ltd.     

Protein‐based nanoformulations for α‐tocopherol encapsulation

Nanoparticles of BSA and silk fibroin (SF) with entrapped α‐tocopherol were produced via ultrasonic emulsification. Populations with particle size of 200–300 nm and highly negatively charged were obtained for all the tested formulations. Entrapment efficiencies of around 99% revealed the effective encapsulation of α‐tocopherol into the produced nanoformulations. Generally, these nanodevices did not induce significant cytotoxicity to human skin keratinocytes for all the concentrations tested. The developed formulations showed free radical scavenging of ABTS.⁺ ability resulting from the synergistic effect between the proteins in formulation and the entrapped tocopherol. Overall, the results contribute for the establishment of BSA:VO and BSA:SF:VO as biodegradable and non‐toxic nanoformulations for the functionalization of textile devices and controlled delivery of tocopherol into the skin.     

Synthesis of β‐Ketoamide Curcumin Analogs for Anti‐Diabetic and AGEs Inhibitory Activities

Two different series of novel β‐ketoamide curcumin analogs enriched in biological activities have been synthesized. The synthesized compounds were screened for their in vitro anti‐diabetic and AGEs inhibitory activities and exhibited potent to good anti‐diabetic and AGEs inhibitory activities. The molecular docking study was also performed with the α‐amylase enzyme.     

A New Long‐Chain Alkene and Antituberculosis Constituents from the Leaves of Pourthiaea lucida

A new long‐chain alkene, dotriacont‐1‐ene ( 1 ), was isolated from the leaves of Pourthiaea lucida, together with twelve known compounds. The structure of this new compound was determined by NMR and mass‐spectrometric analyses. Among the isolated compounds, α‐tocospiro A ( 2 ), α‐tocopheryl quinone ( 4 ), and (E)‐phytol ( 5 ) exhibited antituberculosis activities (MICs ≤30 μg/ml) against Mycobacterium tuberculosis H₃₇Rv in vitro.     

Cytotoxic (9βH)‐Pimarane and (9βH)‐17‐Norpimarane Diterpenes from the Tuber of Icacina trichantha

Three (9βH)‐pimaranes, 1, 2 , and 3 , and two (9βH)‐17‐norpimaranes, 4 and 5 , belonging to a rare compound class in nature, were obtained from the tubers of Icacina trichantha for the first time. Compound 1 is a new natural product, and 2 – 5 have been previously reported. The structures were elucidated based on NMR and MS data, and optical rotation values. The absolute configurations of (9βH)‐pimaranes were unambiguously established based on X‐ray crystallographic analysis. Full NMR signal assignments for the known compounds 2, 4 , and 5 , which were not available in previous publications, are also reported. All five isolates displayed cytotoxic activities on MDA‐MB‐435 cells (IC₅₀ 0.66–6.44 μM ), while 2, 3 , and 4 also exhibited cytotoxicities on HT‐29 cells (IC₅₀ 3.00–4.94 μM ).     

DIGESTION IN ADULT FEMALES OF THE LEAF‐FOOTED BUG Leptoglossus zonatus (HEMIPTERA: COREIDAE) WITH EMPHASIS ON THE GLYCOSIDE HYDROLASES α‐AMYLASE, α‐GALACTOSIDASE,AND α‐GLUCOSIDASE

The leaffooted bug, Leptoglossus zonatus (Hemiptera: Coreidae) is an emerging pest of several crops around the World and up to now very little is known of its digestive system. In this article, glycoside hydrolase (carbohydrase) activities in the adult midgut cells and in the luminal contents of L. zonatus adult females were studied. The results showed the distribution of digestive carbohydrases in adults of this heteropteran species in the different intestinal compartments. Determination of the spatial distribution of α‐glucosidase activity in L. zonatus midgut showed only one major molecular form, which was not equally distributed between soluble and membrane‐bound isoforms, being more abundant as a membrane‐bound enzyme. The majority of digestive carbohydrases were found in the soluble fractions. Activities against starch, maltose and the synthetic substrate NPαGlu were found to show the highest levels of activity, followed by enzymes active against galactosyl oligosaccharides. Based on ion‐exchange chromatography elution profiles and banding patterns in mildly denaturing electrophoresis, both midgut α‐amylases and α‐galactosidases showed at least two isoforms. The data suggested that the majority of carbohydrases involved in initial digestion were present in the midgut lumen, whereas final digestion of starch and of galactosyl oligosaccharides takes place partially within the lumen and partially at the cell surface. The complex of carbohydrases here described was qualitatively appropriate for the digestion of free oligosaccharides and oligomaltodextrins released by α‐amylases acting on maize seed starch granules.     

Naphtho‐γ‐pyrones from Endophyte Aspergillus niger Occurring in the Liverwort Heteroscyphus tener (Steph.) Schiffn.

Bioactivity‐guided fractionation of the cytotoxic extract of Aspergillus niger, an endophytic fungus from the Chinese liverwort Heteroscyphus tener (Steph .) Schiffn ., afforded five new naphtho‐γ‐pyrones, rubrofusarin‐6‐O‐α‐D ‐ribofuranoside ( 1 ), (R)‐10‐(3‐succinimidyl)‐TMC‐256A1 ( 2 ), asperpyrone E ( 3 ), isoaurasperone A ( 4 ), and isoaurasperone F ( 5 ), as well as four known ones, dianhydroaurasperone C ( 6 ), aurasperone D ( 7 ), asperpyrone D ( 8 ), and asperpyrone A ( 9 ), together with a cytotoxic cyclic pentapeptide, malformin A₁ ( 10 ). Their structures were determined by extensive spectroscopic analysis. The absolute configurations of dimeric naphtho‐γ‐pyrones 3 – 9 were also determined by analysis of their respective CD spectra.     

Diterpenoids and a Diarylheptanoid from Hedychium coronarium with Significant Anti‐Angiogenic and Cytotoxic Activities

Two new labdane diterpenoids, namely hedycoronals A and B ( 1 and 2 , resp.), were isolated from the rhizomes of Hedychium coronarium, together with eight known diterpenoids, 4 – 11 , and a known diarylheptanoid, 3 . The structures of 1 and 2 were established by detailed interpretation of their 1D‐ and 2D‐NMR spectra and HR‐ESI‐MS data. Inhibitory activities against human umbilical vein endothelial cells (HUMECs) proliferation and cytotoxic activities against four cancer cell lines were assessed for all the isolates. Most of these metabolites showed moderate or potent cytotoxic activities against four cancer cell lines. Moreover, compounds 3 and 8 exhibited promising inhibitory activities against HUMECs with the IC₅₀ values of 6.4 to 3.3 μM .     

Cytotoxic ent‐Kaurane Diterpenoids from Isodon nervosus

Four new ent‐kaurane diterpenoids, rabdonervosins G–J ( 1 – 4 , resp.), were isolated from the leaves and stems of Isodon nervosus. Their structures were elucidated by extensive spectroscopic analyses, including 1D‐, 2D‐NMR and HR mass spectra. Compound 2 showed potent cytotoxicity against the HepG2 and PC‐9/ZD cell lines with IC₅₀ values of 2.36 and 6.07 μM , respectively, and compound 3 exhibited cytotoxicity against the HepG2 and CNE2 cell lines with IC₅₀ values of 8.64 and 9.77 μM , respectively.     

Cytotoxic Activities and Anti‐Tumor‐Promoting Effects of Microbial Transformation Products of Prenylated Chalcones from Angelica keiskei

Three prenylated chalcones, 4‐hydroxyderricin ( 1 ), xanthoangelol ( 2 ), and xanthoangelol F ( 3 ), isolated from Angelica keiskei, were transformed by the fungus Aspergillus saitoi. These chalcones were converted to flavanones (i.e., 4, 8 , and 12 ), and prenyl‐chain‐hydrated (i.e., 5, 7, 9 – 11 , and 13 ) and ring‐B‐hydroxylated (i.e., 6 ) chalcones. The structures of three new metabolites, 7, 9 , and 13 , were established as 2″,3″‐dihydro‐4,3″‐dihydroxyderricin, 6″,7″‐dihydro‐7″‐hydroxyxanthoangelol, and 6″,7″‐dihydro‐7″‐hydroxyxanthoangelol F, respectively. Upon evaluation of cytotoxic activities of compounds 1 – 13 , the metabolite 7 exhibited potent cytotoxicity against HL60 cells, and this cell death was revealed to be mostly due to apoptosis. In addition, compounds 1 – 4, 7 – 10, 12 , and 13 were examined for their inhibitory effects on the induction of Epstein? Barr virus early antigen (EBV‐EA) by 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) in Raji cells. All compounds tested showed inhibitory effects against EBV‐EA activation with potencies higher than that of β‐carotene. Furthermore, the metabolite 13 exhibited inhibitory effect on skin tumor promotion in an in vivo two‐stage mouse skin carcinogenesis test based on 7,12‐dimethylbenz[a]anthracene (DMBA) as initiator, and with TPA as promoter.     

Interaction of antidiabetic α‐glucosidase inhibitors and gut bacteria α‐glucosidase

Carbohydrate hydrolyzing α‐glucosidases are commonly found in microorganisms present in the human intestine microbiome. We have previously reported crystal structures of an α‐glucosidase from the human gut bacterium Blaubia (Ruminococcus) obeum (Ro‐αG1) and its substrate preference/specificity switch. This novel member of the GH31 family is a structural homolog of human intestinal maltase‐glucoamylase (MGAM) and sucrase–isomaltase (SI) with a highly conserved active site that is predicted to be common in Ro‐αG1 homologs among other species that colonize the human gut. In this report, we present structures of Ro‐αG1 in complex with the antidiabetic α‐glucosidase inhibitors voglibose, miglitol, and acarbose and supporting binding data. The in vitro binding of these antidiabetic drugs to Ro‐αG1 suggests the potential for unintended in vivo crossreaction of the α‐glucosidase inhibitors to bacterial α‐glucosidases that are present in gut microorganism communities. Moreover, analysis of these drug‐bound enzyme structures could benefit further antidiabetic drug development.     

α‐Glucosidase Inhibitory Xanthones from the Roots of Garcinia fusca

Two new compounds, fuscaxanthones J ( 1 ) and K ( 2 ), together with eight known xanthones ( 3 – 10 ) were isolated from an ethyl acetate extract of the roots of Garcinia fusca. Their structures were determined using spectroscopic methods, mainly 1D‐ and 2D‐NMR. α‐Glucosidase inhibitory activity of the isolated compounds was evaluated and fuscaxanthone J ( 1 ) showed the most significant effect with an IC₅₀ value of 8.3 ± 1.8 μm (compared with acarbose, IC₅₀ = 214.5 ± 2.3 μm ).     

Structure of full‐length class I chitinase from rice revealed by X‐ray crystallography and small‐angle X‐ray scattering

The rice class I chitinase OsChia1b, also referred to as RCC2 or Cht‐2, is composed of an N‐terminal chitin‐binding domain (ChBD) and a C‐terminal catalytic domain (CatD), which are connected by a proline‐ and threonine‐rich linker peptide. Because of the ability to inhibit fungal growth, the OsChia1b gene has been used to produce transgenic plants with enhanced disease resistance. As an initial step toward elucidating the mechanism of hydrolytic action and antifungal activity, the full‐length structure of OsChia1b was analyzed by X‐ray crystallography and small‐angle X‐ray scattering (SAXS). We determined the crystal structure of full‐length OsChia1b at 2.00‐Å resolution, but there are two possibilities for a biological molecule with and without interdomain contacts. The SAXS data showed an extended structure of OsChia1b in solution compared to that in the crystal form. This extension could be caused by the conformational flexibility of the linker. A docking simulation of ChBD with tri‐N‐acetylchitotriose exhibited a similar binding mode to the one observed in the crystal structure of a two‐domain plant lectin complexed with a chitooligosaccharide. A hypothetical model based on the binding mode suggested that ChBD is unsuitable for binding to crystalline α‐chitin, which is a major component of fungal cell walls because of its collisions with the chitin chains on the flat surface of α‐chitin. This model also indicates the difference in the binding specificity of plant and bacterial ChBDs of GH19 chitinases, which contribute to antifungal activity. Proteins 2010. © 2010 Wiley‐Liss,Inc.     

IFN‐γ inhibits basal and α‐MSH‐induced melanogenesis

Inflammatory cytokines are closely related to pigmentary changes. In this study, the effects of IFN‐γ on melanogenesis were investigated. IFN‐γ inhibits basal and α‐MSH‐induced melanogenesis in B16 melanoma cells and normal human melanocytes. MITF mRNA and protein expressions were significantly inhibited in response to IFN‐γ. IFN‐γ inhibited CREB binding to the MITF promoter but did not affect CREB phosphorylation. Instead, IFN‐γ inhibited the association of CBP and CREB through the increased association between CREB binding protein (CBP) and STAT1. These findings suggest that IFN‐γ inhibits both basal and α‐MSH‐induced melanogenesis by inhibiting MITF expression. The inhibitory action of IFN‐γ in α‐MSH‐induced melanogenesis is likely to be associated with the sequestration of CBP via the association between CBP and STAT1. These data suggest that IFN‐γ plays a role in controlling inflammation‐ or UV‐induced pigmentary changes.     

Synthesis and DNA‐binding study of imidazole linked thiazolidinone derivatives

A novel series of imidazole‐linked thiazolidinone hybrid molecules were designed and synthesized through a feasible synthetic protocol. The molecules were characterized with Fourier transform infrared (FT‐IR), ¹H nuclear magnetic resonance (NMR), ¹³C NMR and high‐resolution mass spectrometry (HRMS) techniques. In vitro susceptibility tests against Gram‐positive (S. aureus and B. subtilis ) and Gram‐negative bacteria (E. coli and P. aeruginosa ) gave highly promising results. The most active molecule (3e) gave a minimal inhibitory concentration (MIC) value of 3.125 μg/mL which is on par with the reference drug streptomycin. Structure–activity relationships revealed activity enhancement by nitro and chloro groups when they occupied meta position of the arylidene ring in 2‐((3‐(imidazol‐1‐yl)propyl)amino)‐5‐benzylidenethiazolidin‐4‐ones. DNA‐binding study of the most potent molecule 3e with salmon milt DNA (sm‐DNA) under simulated physiological pH was probed with UV–visible absorption, fluorescence quenching, gel electrophoresis and molecular docking techniques. These studies established that compound 3e has a strong affinity towards DNA and binds at DNA minor groove with a binding constant (K_b) 0.18 × 10² L mol^?1. Molecular docking simulations predicted strong affinity of 3e towards DNA with a binding affinity (ΔG) ‐8.5 kcal/mol. Van der Waals forces, hydrogen bonding and hydrophobic interactions were predicted as the main forces of interaction. The molecule 3e exhibited specific affinity towards adenine–thiamine base pairs. Copyright © 2016 John Wiley & Sons, Ltd.     

Anti‐Androgenic Activity of Fatty Acids

In this study, we show that 5α‐reductase derived from rat fresh liver was inhibited by certain aliphatic free fatty acids. The influences of chain length, unsaturation, oxidation, and esterification on the potency to inhibit 5α‐reductase activity were studied. Among the fatty acids we tested, inhibitory saturated fatty acids had C₁₂–C₁₆ chains, and the presence of a C?C bond enhanced the inhibitory activity. Esterification and hydroxy compounds were totally inactive. Finally, we tested the prostate cancer cell proliferation effect of free fatty acids. In keeping with the results of the 5α‐reductase assay, saturated fatty acids with a C₁₂ chain (lauric acid) and unsaturated fatty acids (oleic acid and α‐linolenic acid) showed a proliferation inhibitory effect on lymph‐node carcinoma of the prostate (LNCaP) cells. At the same time, the testosterone‐induced prostate‐specific antigen (PSA) mRNA expression was down‐regulated. These results suggested that fatty acids with 5α‐reductase inhibitory activity block the conversion of testosterone to 5α‐dihydrotestosterone (DHT) and then inhibit the proliferation of prostate cancer cells.     

Drug‐binding energetics of human α‐1‐acid glycoprotein assessed by isothermal titration calorimetry and molecular docking simulations

This study utilizes sensitive, modern isothermal titration calorimetric methods to characterize the microscopic thermodynamic parameters that drive the binding of basic drugs to α‐1‐acid glycoprotein (AGP) and thereby rationalize the thermodynamic data in relation to docking models and crystallographic structures of the drug–AGP complexes. The binding of basic compounds from the tricyclic antidepressant series, together with miaserine, chlorpromazine, disopyramide and cimetidine, all displayed an exothermically driven binding interaction with AGP. The impact of protonation/deprotonation events, ionic strength, temperature and the individual selectivity of the A and F1*S AGP variants on drug‐binding thermodynamics was characterized. A correlation plot of the thermodynamic parameters for all of the test compounds revealed that an enthalpy–entropy compensation is in effect. The exothermic binding energetics of the test compounds were driven by a combination of favorable (negative) enthalpic (?Hº) and favorable (positive) entropic (?Sº) contributions to the Gibbs free energy (?Gº). Collectively, the data imply that the free energies that drive drug binding to AGP and its relationship to drug serum residency evolve from the complex interplay of enthalpic and entropic forces from interactions with explicit combinations of hydrophobic and polar side‐chain sub‐domains within the multi‐lobed AGP ligand binding cavity.Copyright © 2012 John Wiley & Sons, Ltd.     

Cytotoxic Constituents and Mechanism from Peganum harmala

Peganum harmala L. is a traditional Chinese and Uygur medicine used to treat cancer. Bioactivity‐guided fractionation was applied to determine the cytotoxic constituents from P. harmala. A novel triterpenoid and a phenolic glycoside were isolated and identified, as well as seven known compounds. The novel metabolites were elucidated to be 3α‐acetoxy‐27‐hydroxyolean‐12‐en‐28‐oic acid methyl ester ( 1 , OA) and N‐acetyl‐9‐syringinoside ( 9 ). Some compounds exhibited potent cytotoxicity against human tumor cells. Among them, OA showed the highest cytotoxicity against human lung cancer cells A549 with an IC₅₀ value of 8.03 ± 0.81 μm . OA had a potent anti‐NSCLC cell activity by interfering with the epidermal growth factor receptor (EGFR) activation and its downstream signaling, and could exert an antiproliferative effect by inactivation of EGFR‐driven antiapoptotic pathway followed by the release of mitochondrial cytochrome c, which might prove to be a promising leading compound for the development of an anti‐lung cancer drug.