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 ).     

Phenolic Compounds from Clinopodium chinense (Benth.) O. Kuntze and Their Inhibitory Effects on α‐Glucosidase and Vascular Endothelial Cells Injury

Following an in vitro bioactivity‐guided fractionation procedure, 14 compounds including eight flavonoids and six phenylpropanoids were isolated and identified from the AcOEt fraction of Clinopodium chinense (Benth .) O. Kuntze . All constituents were tested for α‐glucosidase and high glucose‐induced injury in human umbilical vein endothelial cells (HUVECs) inhibitory activities. All constituents exhibited varying degrees α‐glucosidase inhibitory activity and protective activity on HUVECs. Among them, luteolin ( 2 ), eriodictyol ( 5 ), ethyl rosmarinate ( 13 ), and clinopodic acids B ( 14 ) were proved to be potent α‐glucosidase inhibitors with IC₅₀ value ranging from 0.6 to 2.0 μm . Additionally, luteolin ( 2 ), naringenin ( 4 ), eriodictyol ( 5 ), ethyl (2R)‐3‐(3, 4‐dihydroxyphenyl)‐2‐hydroxypropanate ( 9 ), caffeic acid ( 11 ), ethyl rosmarinate ( 13 ), and clinopodic acids B ( 14 ) significantly ameliorate HUVECs injury induced by high glucose with an approximate EC₅₀ value of 3 – 36 μm . These results suggest that the 14 bioactive constituents were responsible for hypoglycemic and protective vascular endothelium effect of C. chinense (Benth .) O. Kuntze and their structure–activity relationship was also analyzed briefly. Eriodictyol, luteolin, ethyl rosmarinate, and clinopodic acids B were the potential lead compounds of antidiabetic drugs.     

Effects of solvent fractions of Allomyrina dichotoma larvae through the inhibition of in vitro BACE1 and β‐amyloid(25–35)‐induced toxicity in rat pheochromocytoma PC12 cells

Amyloid‐β peptide (Aβ) generation initiated by β‐site amyloid precursor protein cleaving enzyme 1 BACE1 is a critical cause of Alzheimer's disease. In the course of our ongoing investigation of natural anti‐dementia resources, the ethyl acetate (EtOAc) fraction exerted strong BACE1‐specific inhibition with the half maximal inhibitory concentration (IC₅₀) value of 9.2 × 10^?5 μg/mL. Furthermore, Aβ(25–35)‐induced cell death was predominantly prevented by the EtOAc fraction of Allomyrina dichotoma larvae through diminishing of cellular oxidative stress and attenuating apoptosis by inhibiting caspase‐3 activity. Taken together, the present study demonstrated that A. dichotoma larvae possess novel neuroprotective properties not only via the selective and specific inhibition of BACE1 activity but also through the alleviation of Aβ(25–35)‐induced toxicity, which may raise the possibility of therapeutic application of A. dichotoma larvae for preventing and/or treating dementia.     

Superbanone,A New 2‐Aryl‐3‐benzofuranone and Other Bioactive Constituents from the Tube Roots of Butea superba

Phytochemical investigation from the tube roots of Butea superba, led to the isolation and identification of a new 2‐aryl‐3‐benzofuranone named superbanone ( 1 ), one benzoin, 2‐hydroxy‐1‐(2‐hydroxy‐4‐methoxyphenyl)‐2‐(4‐methoxyphenyl)ethanone ( 2 ), eight pterocarpans ( 3  –  10 ), and eleven isoflavonoids ( 11  –  21 ). Compound 2 was identified for the first time as a natural product. The structure of the isolated compounds was elucidated using spectroscopic methods, mainly 1D‐ and 2D‐NMR. The isolated compounds and their derivatives were evaluated for α‐glucosidase inhibitory and antimalarial activities. Compounds 3 , 7 , 8 , and 11 showed promising α‐glucosidase inhibitory activity (IC₅₀ = 13.71 ± 0.54, 23.54 ± 0.75, 28.83 ± 1.02, and 12.35 ± 0.36 μm , respectively). Compounds 3 and 11 were twofold less active than the standard drug acarbose (IC₅₀ = 6.54 ± 0.04 μm ). None of the tested compounds was found to be active against Plasmodium falciparum strain 94. On the basis of biological activity results, structure–activity relationships are discussed.     

Chemical Composition,Antioxidant Properties, α‐Glucosidase Inhibitory,and Antimicrobial Activity of Essential Oils from Acacia mollissima and Acacia cyclops Cultivated in Tunisia

The genus Acacia is quite large and can be found in the warm subarid and arid parts, but little is known about its chemistry, especially the volatile parts. The volatile oils from fresh flowers of A. mollissima and A. cyclops (growing in Tunisia) obtained by hydrodistillation were analyzed by GC then GC/MS. Eighteen (94.7% of the total oil composition) and 23 (97.4%) compounds were identified in these oils, respectively. (E,E)‐α‐Farnesene (51.5%) and (E)‐cinnamyl alcohol (10.7%) constituted the major compounds of the flower oil of A. mollissima, while nonadecane (29.6%) and caryophyllene oxide (15.9%) were the main constituents of the essential oil of A. cyclops. Antioxidant activity of the isolated oils was studied by varied assays, i.e., 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and 2,2‐azinobis 3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS); the isolated oils showed lowest IC₅₀ (4 – 39 μg/ml) indicating their high antioxidant activity. The α‐glucosidase inhibitor activity was also evaluated and Acacia oils were found to be able to strongly inhibit this enzyme with IC₅₀ values (81 – 89 μg/ml) very close to that of acarbose which was used as positive control. Furthermore, they were tested against five Gram‐positive and Gram‐negative bacteria and one Candida species. Essential oil of A. mollissima was found to be more active than that of A. cyclops, especially against Pseudomonas aeruginosa (MIC = 0.31 mg/ml and MBC = 0.62 mg/ml).     

Angupyrones A – E, α‐Pyrone Analogues with ARE‐Activation from a Sponge‐Associated Fungus Truncatella angustata

TLC‐DPPH guided fractionation of a sponge‐associated fungus Truncatella angustata with a solid culture resulted in the isolation of five new α‐pyrone‐based analogues namely angupyrones A – E ( 1  –  5 ), and 3‐ethyl‐4‐hydroxy‐6‐methyl‐2‐pyrone. Their structures were determined on the basis of extensive spectroscopic analyses, including the modified Mosher's method, bulkiness rule, and specific rotation for the configurational assignments. Angupyrones A – E exhibited moderate antioxidant response element activation in HepG2C8 cells, while the preliminary structure‐activity relationship was discussed.     

Bergamotane Sesquiterpenes with Alpha‐Glucosidase Inhibitory Activity from the Plant Pathogenic Fungus Penicillium expansum

Two new bergamotane sesquiterpene lactones, named expansolides C and D ( 1 and 2 ), together with two known compounds expansolides A and B ( 3 and 4 ), were isolated from the plant pathogenic fungus Penicillium expansum ACCC37275. The structures of the new compounds were established by detailed analyses of the spectroscopic data, especially 1D‐, 2D‐NMR, and HR‐ESI‐MS. In an in vitro bioassay, the epimeric mixture of expansolides C and D ( 1 and 2 ) (in a ratio of 2:1 at the temprature of the bioassay) exhibited more potent α‐glucosidase inhibitory activity (IC₅₀ =0.50 ± 0.02 mm ) as compared with the positive control acarbose (IC₅₀ = 1.90 ± 0.05 mm ). To the best of our knowledge, it was the first report on the α‐glucosidase inhibitory activity of bergamotane sesquiterpenes.     

A dominant‐negative form of Arabidopsis AP‐3 β‐adaptin improves intracellular pH homeostasis

Intracellular pH (pH_i) is a crucial parameter in cellular physiology but its mechanisms of homeostasis are only partially understood. To uncover novel roles and participants of the pH_i regulatory system, we have screened an Arabidopsis mutant collection for resistance of seed germination to intracellular acidification induced by weak organic acids (acetic, propionic, sorbic). The phenotypes of one identified mutant, weak acid‐tolerant 1‐1D (wat1‐1D) are due to the expression of a truncated form of AP‐3 β‐adaptin (encoded by the PAT2 gene) that behaves as a as dominant‐negative. During acetic acid treatment the root epidermal cells of the mutant maintain a higher pH_i and a more depolarized plasma membrane electrical potential than wild‐type cells. Additional phenotypes of wat1‐1D roots include increased rates of acetate efflux, K⁺ uptake and H⁺ efflux, the latter reflecting the in vivo activity of the plasma membrane H⁺‐ATPase. The in vitro activity of the enzyme was not increased but, as the H⁺‐ATPase is electrogenic, the increased ion permeability would allow a higher rate of H⁺ efflux. The AP‐3 adaptor complex is involved in traffic from Golgi to vacuoles but its function in plants is not much known. The phenotypes of the wat1‐1D mutant can be explained if loss of function of the AP‐3 β‐adaptin causes activation of channels or transporters for organic anions (acetate) and for K⁺ at the plasma membrane, perhaps through miss‐localization of tonoplast proteins. This suggests a role of this adaptin in trafficking of ion channels or transporters to the tonoplast.     

Quick Identification of Piperidine Alkaloid from Roots of Grewia nervosa and Their Glucosidase Inhibitory Activity

Grewia nervosa is a herbal plant used in traditional medicine for different purposes. Bioassay‐guided chemical fractionation of G. nervosa roots resulted in an identification of two known and one new compound, namely microgrewiapine A, homomicrogrewiapine, and N‐methylmicrocosamine, respectively. Their structures were determined using combination of LC/HR‐MS, ¹H‐NMR, and IR spectral analyses and followed by comparison with those reported in the literature. The problematic separation of these alkaloids on traditional column chromatography (Silica gel, Octadecyl silane, Sephadex) was resolved by using HPLC. Structurally similar compounds from the piperidine family have been characterized by using HR‐MS analysis in combination with NMR data of crude samples. The major constituent i.e. N‐methylmicrocosamine isolated from the butanol fraction of methanol root extract (MRE) was found to possess the dose dependent α‐glucosidase inhibition activity with an IC₅₀ value of 53.40 μm . Furthermore, N‐methylmicrocosamine showed maximum α‐glucosidase inhibition of 97.48 ± 0.7% at 107.5 μm , which is approximately 1.3 × 10³ fold higher than the activity shown by acarbose (97.72% inhibition at 61.95 mm ), a standard anti‐diabetic drug available commercially. This work also reports the in vitro α‐glucosidase inhibitory activity of the major alkaloids isolated from G. nervosa for the first time.     

Phenolic Composition,Anti‐Inflammatory,Antioxidant, and Antimicrobial Activities of Alchemilla mollis (Buser) Rothm.

The current study was designed to evaluate the antioxidant, anti‐inflammatory and antimicrobial activities of Alchemilla mollis (Buser ) Rothm . (Rosaceae) aerial parts extracts. Chemical composition was analyzed by spectrophotometric and chromatographic (HPLC) techniques. The antioxidant properties assessed included DPPH^· and ABTS^·+ radical scavenging, β‐carotene‐linoleic acid co‐oxidation assay. Antimicrobial activity was evaluated with disc diffusion and micro dilution method. In order to evaluate toxicity of the extracts, with the sulforhodamine B colorimetric assay L929 cell line (mouse fibroblast) was used. The anti‐inflammatory activities of the potent antioxidant extracts (methanol, 70% methanol, and water extracts) were determined by measuring the inhibitory effects on NO production and pro‐inflammatory cytokine TNF‐α levels in lipopolysaccharide stimulated RAW 264.7 cells. 70% methanol and water extracts which were found to be rich in phenolic compounds (184.79 and 172.60 mg GAE/g extract) showed higher antioxidant activity. Luteolin‐7‐O‐glucoside was the main compound in the extracts. Ethyl acetate and 70% methanol extracts showed higher antibacterial activity against Staphylococcus aureus and Salmonella enteritidis with MIC value of 125 μg/ml. 70% methanol extract potentially inhibited the NO and TNF‐α production (18.43 μm and 1556.22 pg/ml, respectively, 6 h).     

Effect of the Polyphenol Rich Ethyl Acetate Fraction from the Leaves of Lycium chinenseMill. on Oxidative Stress,Dyslipidemia, and Diabetes Mellitus in Streptozotocin‐Nicotinamide Induced Diabetic Rats

Lycium chinenseMill ., popularly known as boxthorn, is a plant that is traditionally used for treating night sweat, cough, inflammation and diabetes mellitus. However, the leaves have received little or no attention despite their potentials as a potent therapeutic agent. This study was aimed at investigating the hypoglycemic and hypolipidemic effects of the polyphenols‐rich ethyl acetate fraction from the leaves of Lycium chinenseMill . on streptozotocin‐nicotinamide induced diabetic rats. The ethyl acetate fraction (LFE) was selected and orally gavaged at 100, 200, and 400 mg/kg dose to streptozotocin (STZ)‐nicotinamide induced diabetic rats. The rats’ body weight, fasting blood glucose (FBG), lipid profile and oxidative stress markers were evaluated after the treatment period. Treatment with LFE resulted in a significant decrease in the FBG level, altered lipid profiles, and reduced the activities of the enzymes alkaline phosphatase (ALP), aspartate transaminase (AST), alanine transaminase (ALT) in the treated diabetic rats. Furthermore, LFE significantly elevated the antioxidant status (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH‐Px) activities) and reducing malondialdehyde (MDA) levels in the treated rats. The present study has revealed that L. chinenseMill . possess anti‐hyperglycemic and anti‐hyperlipidemic properties which is mediated through modulation of oxidative stress and polyphenolics might be responsible for the action.     

Characterization of an ethanol‐tolerant 1,4‐β‐xylosidase produced by Pichia membranifaciens

Aims: The purification and biochemical properties of the 1,4‐β‐xylosidase of an oenological yeast were investigated. Methods and Results: An ethanol‐tolerant 1,4‐β‐xylosidase was purified from cultures of a strain of Pichia membranifaciens grown on xylan at 28°C. The enzyme was purified by sequential chromatography on DEAE cellulose and Sephadex G‐100. The relative molecular mass of the enzyme was determined to be 50 kDa by SDS‐PAGE. The activity of 1,4‐β‐xylosidase was optimum at pH 6·0 and at 35°C. The activity had a K_m of 0·48 ± 0·06 mmol l^?1 and a V_max of 7·4 ± 0·1 μmol min^?1 mg^?1 protein for p‐nitrophenyl‐β‐d ‐xylopyranoside. Conclusions: The enzyme characteristics (pH and thermal stability, low inhibition rate by glucose and ethanol tolerance) make this enzyme a good candidate to be used in enzymatic production of xylose and improvement of hemicellulose saccharification for production of bioethanol. Significance and Impact of the Study: This study may be useful for assessing the ability of the 1,4‐β‐xylosidase from P. membranifaciens to be used in the bioethanol production process.     

Breaking Down the Barriers to a Natural Antiviral Agent: Antiviral Activity and Molecular Docking of Erythrina speciosa Extract,Fractions, and the Major Compound

The in vitro cytotoxic activity in Vero cells and the antiviral activity of Erythrina speciosa methanol extract, fractions, and isolated vitexin were studied. The results revealed that E. speciosa leaves ethyl acetate soluble fraction of the methanol extract (ESLE) was the most active against herpes simplex virus type 1 (HSV‐1). Bioactivity‐guided fractionation was performed on ESLE to isolate the bioactive compounds responsible for this activity. One sub‐fraction from ESLE (ESLE IV) showed the highest activity against HSV‐1 and Hepatitis A HAV‐H10 viruses. Vitexin isolated from ESLE VI exhibited a significant antiviral activity (EC₅₀=35±2.7 and 18±3.3 μg/mL against HAV‐H10 and HSV‐1 virus, respectively), which was notably greater than the activity of the extract and the fractions. Molecular docking studies were carried out to explore the molecular interactions of vitexin with different macromolecular targets. Analysis of the in silico data together with the in vitro studies validated the antiviral activity associated with vitexin. These outcomes indicated that vitexin is a potential candidate to be utilized commendably in lead optimization for the development of antiviral agents.     

The crystal structure of Z‐Gly‐Aib‐Gly‐Aib‐OtBu

The synthetic peptide Z‐Gly‐Aib‐Gly‐Aib‐OtBu was dissolved in methanol and crystallized in a mixture of ethyl acetate and petroleum ether. The crystals belong to the centrosymmetric space group P4/n that is observed less than 0.3% in the Cambridge Structural Database. The first Gly residue assumes a semi‐extended conformation (φ ±62°, ψ ?131°). The right‐handed peptide folds in two consecutive β‐turns of type II' and type I or an incipient 3₁₀‐helix, and the left‐handed counterpart folds accordingly in the opposite configuration. In the crystal lattice, one molecule is linked to four neighbors in the ab‐plane via hydrogen bonds. These bonds form a continuous network of left‐ and right‐handed molecules. The successive ab‐planes stack via apolar contacts in the c‐direction. An ethyl acetate molecule is situated on and close to the fourfold axis. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.     

Synthesis and Biological Evaluation of 3,5‐Dimethoxystilbene Analogs

In our continuing effort to discover natural product‐based pest management agents, derivatives of 3,5‐dimethoxystilbene were synthesized yielding 27 new and six known compounds. Compounds 11 and 12 showed strong Aedes aegypti larvicidal activity (LC₅₀ 45.31 and 49.93 μm , respectively). Furthermore, 11 and 12 exhibited high effectiveness against larvae of pesticide‐susceptible and pyrethroid‐resistant strains of Ae. aegypti; activity against the adult mosquitoes was low. Compounds 6f , 6g , and 6i at either 83.3 or 166.7 μg/ml reduced the mobility of second‐stage juveniles (J2) of the root‐knot nematode (Meloidogyne incognita) that hatched from eggs immersed in the test compounds for 7 days. However, there was little or no effect on J2 placed directly into these compounds, and none of the analogs suppressed M. incognita egg hatch. The compounds were tested for inhibition of some agriculturally important fungi; 6a , 7a , and 7e demonstrated strong inhibition of Colletotrichum species. Activity of the stilbenes against some human pathogens was also explored; 11 , 12 , and 16 showed moderate inhibitory activity against Cryptococcus neoformans, Staphylococcus aureus, methicillin‐resistant S. aureus, and Mycobacterium intracellulare. Except for 11 and 12 , which were active against mosquito larvae and some human pathogens, no single analog demonstrated activity in all the tests, indicating specific activities. Synthesis of the analogs and structure–activity relationships are discussed.     

Mutant Alleles at the Brown Locus Encoding Tyrosinase‐Related Protein‐1 (TRP‐1) Affect Proliferation of Mouse Melanocytes in Culture *

Tyrosinase related protein‐1 (TRP‐1) is a melanocyte‐specific gene product involved in eumelanin synthesis. Mutation in the Tyrp1 gene is associated with brown pelage in mouse and oculocutaneous albinism Type 3 in humans (OCA3). It has been demonstrated that TRP‐1 expresses DHICA oxidase activity in the murine system. However, its actual function in the human system is still unclear. The study was designed to determine the effects of mutation at two Typr1 alleles, namely the Tyrp1^b (brown) and Tyrp1^b‐cj (cordovan) compared with wild type Tyrp1^B (black) on melanocyte function and melanin biosynthesis. The most significant finding was that both of the Tyrp1 mutations (i.e. brown expressing a point mutation and cordovan expressing decreased amount of TRP‐1 protein) resulted in attenuation of cell proliferation rates. Neither necrosis nor apoptosis was responsible for the observed decrease in cell proliferation rates of the brown and cordovan melanocytes. Ultrastructural evaluation by electron microscopic analysis revealed that both mutations in Tyrp1 affected melanosome maturation without affecting its structure. These observations demonstrate that mutation in Tyrp1 compromised tyrosinase activity within the organelle. DOPA histochemistry revealed differences in melanosomal stages between black and brown melanocytes but not between black and cordovan melanocytes. There were no significant differences in tyrosine hydroxylase activities of tyrosinase and TRP‐1 in wild type black, brown and cordovan melanocyte cell lysates. We conclude that mutations in Tyrp1 compromise cell proliferation and melanosomal maturation in mouse melanocyte cultures.     

Sub‐lethal UV‐C radiation induces callose,hydrogen peroxide and defence‐related gene expression in Arabidopsis thaliana

Exposure of plants to UV‐C irradiation induces gene expression and cellular responses that are commonly associated with wounding and pathogen defence, and in some cases can lead to increased resistance against pathogen infection. We examined, at a physiological, molecular and biochemical level, the effects of and responses to, sub‐lethal UV‐C exposure on Arabidopsis plants when irradiated with increasing dosages of UV‐C radiation. Following UV‐C exposure plants had reduced leaf areas over time, with the severity of reduction increasing with dosage. Severe morphological changes that included leaf glazing, bronzing and curling were found to occur in plants treated with the 1000 J·m^?2 dosage. Extensive damage to the mesophyll was observed, and cell death occurred in both a dosage‐ and time‐dependent manner. Analysis of H₂O₂ activity and the pathogen defence marker genes PR1 and PDF1.2 demonstrated induction of these defence‐related responses at each UV‐C dosage tested. Interestingly, in response to UV‐C irradiation the production of callose (β‐1,3‐glucan) was identified at all dosages examined. Together, these results show plant responses to UV‐C irradiation at much lower doses than have previously been reported, and that there is potential for the use of UV‐C as an inducer of plant defence.     

Anti‐Lipid Peroxidation, α‐Glucosidase and α‐Amylase Inhibitory Effects of the Extract of Capitula of Coreopsis tinctoria Nutt. and Protection Effects on High‐Fat/High‐Sugar and Streptozotocin‐Induced Type 2 Diabetes in Mice

Coreopsis tinctoria capitula (CTC) of the Compositae family has been used traditionally to treat various diseases in China, particularly type 2 diabetes mellitus (T2DM). This study evaluated the anti‐lipid peroxidation, α‐glucosidase and α‐amylase inhibitory effects of CTC extracts, and analyzed its chemical composition by HPLC. Moreover, the antioxidant activity and protection effects of CTC extracts were investigated on high‐fat/high‐sugar and streptozotocin‐induced T2DM mice. In vitro study, the ethyl acetate extract (EAE) and butanol extract (BE) of CTC exhibited anti‐lipid peroxidation (IC₅₀: BHA>BE or EAE>ascorbic acid, p<0.05) and α‐glucosidase inhibitory activity (IC₅₀: BE>EAE, p<0.05). In vivo, the BE at the dose of 600 mg/kg was intragastrically given to T2DM mice, which exhibited a certain extent of repair and improvement of the levels of CAT, GSH, GSH‐P_X, SOD, as well as plasma biomarkers, compared with those in the model group (p<0.05). These results demonstrated that CTC extracts have a positive effect to treat T2DM and it can be used for the treatment of T2DM in the future.     

A New 1,5‐Dihydroxy‐4‐methoxyisoquinoline from Scolopendra subspinipes mutilans

A new isoquinoline, 1,5‐dihydroxy‐4‐methoxyisoquinoline ( 1 ), was obtained from Scolopendra subspinipes mutilans. Compound 1 showed moderate cytotoxicity on tumour cells with IC₅₀ values ranging from 13 to 26 μm against five esophageal squamous cancer cells whereas low cytotoxicity against normal human esophageal epithelial cells. Isoquinoline ring oxidized at C(1), C(4), and C(5) can enhance its cytotoxicity. In addition, compound 1 showed potent inhibitory effect (inhibition rate > 50% at 13 μm ) on cell migration in human umbilical vein endothelial cells. This article mainly studies the structure and activity of 1 , and more modification of 1 as a potential anticancer agent.