Free energy perturbation (FEP)-guided scaffold hopping

Scaffold hopping refers to computer-aided screening for active compounds with different structures against the same receptor to enrich privileged scaffolds, which is a topic of high interest in organic and medicinal chemistry. However, most approaches cannot efficiently predict the potency level of candidates after scaffold hopping. Herein, we identified potent PDE5 inhibitors with a novel scaffold via a free energy perturbation (FEP)-guided scaffold-hopping strategy, and FEP shows great advantages to precisely predict the theoretical binding potencies ΔG FEP between ligands and their target, which were more consistent with the experimental binding potencies ΔG EXP (the mean absolute deviations| Δ G FEP - Δ G EXP |  < 2 kcal/mol) than those ΔG MM-PBSA or ΔG MM-GBSA predicted by the MM-PBSA or MM-GBSA method. Lead L12 had an IC50 of 8.7 nmol/L and exhibited a different binding pattern in its crystal structure with PDE5 from the famous starting drug tadalafil. Our work provides the first report via the FEP-guided scaffold hopping strategy for potent inhibitor discovery with a novel scaffold, implying that it will have a variety of future applications in rational molecular design and drug discovery.

In vitro fecal fermentation characteristics of bamboo shoot (Phyllostachys edulis) polysaccharide

The effects of Moso bamboo (Phyllostachys edulis) shoot polysaccharide (BSP) on the human gut microbiota composition and volatile metabolite components were investigated by in vitro fermentation. After fermentation for 48 h, BSP utilization reached 40.29% and the pH of the fermentation solution decreased from 6.89 to 4.57. Moreover, the total short-chain fatty acid concentration significantly (P < 0.05) increased from 13.46 mM (0 h) to 43.20 mM (48 h). 16S rRNA analysis revealed several differences in the gut microbiota community structure of the BSP-treated and water-treated (control) cultures. In the BSP group, the abundance of Firmicutes, Actinobacteria, and Proteobacteria was significantly increased, while that of Bacteroidetes and Fusobacteria significantly decreased. Moreover, the concentrations of benzene, its substituted derivatives, and carbonyl compounds in the volatile metabolites of the BSP-treated group decreased, while that of organic acids significantly increased after 48 h of fermentation. These results demonstrate that BSP improves gastrointestinal health.

Comparative urinary globotriaosylceramide analysis by thin-layer chromatography-immunostaining and liquid chromatography-tandem mass spectrometry in patients with Fabry disease

In Fabry disease, accumulation of glycolipids, predominantly globotriaosylceramide (Gb3), affects the kidneys, and nephropathy is one of the important disorders that influence the disease severity and prognosis of patients. Urinary Gb3 has been analyzed for diagnosis and monitoring of Fabry disease. In this study, we analyzed urinary Gb3 by thin-layer chromatography (TLC)-immunostaining and liquid chromatography (LC)-tandem mass spectrometry (MS/MS). An improved qualitative method, TLC-immunostaining, revealed excessive urinary Gb3 excretion in 100 (8/8), 88 (14/16), and 74% (45/61) of the classic Fabry males, later-onset Fabry males, and Fabry females examined, respectively. This authentic method is robust, easy, economic, and hardly affected by abundant urinary sediment, and this is useful for diagnosing individual Fabry patients. LC-MS/MS can determine the level of Gb3 in urine with high sensitivity, and it revealed that the Gb3 excretion level was higher in the order of classic Fabry males, later-onset Fabry males, Fabry females, and controls, respectively, and this is expected to be a useful quantitative method not only for diagnosis but also for predicting the progression of Fabry nephropathy. As to the relation of the urinary Gb3 level and renal events, our study revealed that the urinary Gb3 level in Fabry patients experiencing renal events tended to be higher than that in ones who did not have any renal events in each phenotypic group of the disease.

Discovery of a potent and dual-selective bisubstrate inhibitor for protein arginine methyltransferase 4/5

Protein arginine methyltransferases (PRMTs) have been implicated in the progression of many diseases. Understanding substrate recognition and specificity of individual PRMT would facilitate the discovery of selective inhibitors towards future drug discovery. Herein, we reported the design and synthesis of bisubstrate analogues for PRMTs that incorporate a S-adenosylmethionine (SAM) analogue moiety and a tripeptide through an alkyl substituted guanidino group. Compound AH237 is a potent and selective inhibitor for PRMT4 and PRMT5 with a half-maximal inhibition concentration (IC50) of 2.8 and 0.42 nmol/L, respectively. Computational studies provided a plausible explanation for the high potency and selectivity of AH237 for PRMT4/5 over other 40 methyltransferases. This proof-of-principle study outlines an applicable strategy to develop potent and selective bisubstrate inhibitors for PRMTs, providing valuable probes for future structural studies.

MC5R Contributes to Sensitivity to UVB Waves and Barrier Function in Mouse Epidermis

MC5R is known for its role in the exocrine function of sebaceous glands, but other functions in the epidermis remain unclear. This study focused on the relationship between MC5R and homeostasis in the epidermis and examined the role of MC5R in mice whose skin was irradiated with UVB waves. UVB irradiation-induced skin ulcers and severe inflammation at lower doses in homozygotes of MC5R-deficient (i.e., MC5R -/- ) mice (150 mJ/cm2) than the doses in wild-type mice (500 mJ/cm2). Transepidermal water loss was increased (approximately 10-fold) in adult MC5R -/- mice compared with that in wild-type mice. In neonates, a dye exclusion assay showed no remarkable difference between MC5R -/- and wild-type mice. After UVB irradiation, compared with wild-type mice, MC5R -/- mice showed increased inflammatory cell infiltration in the dermis of the ulcerative region, significantly increased thickness of the epidermis in the nonulcerative region, significantly more prickle cells in the nonulcerative region, and increased serum IL-6 levels but decreased IL-10 levels. Transmission electron microscopy revealed fewer lamellar granules, less lipid secretion, and an expansion of the trans-Golgi network in the epidermis in MC5R -/- mice. This study elucidated the increased sensitivity to UVB irradiation and decreased barrier function in MC5R -/- mice.

Crystal structure of a homotrimeric verrucomicrobial exo-β-1,4-mannosidase active in the hindgut of the wood-feeding termite Reticulitermes flavipes

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First structure of a glycoside hydrolase from a bacterial symbiont isolated from the digestive tract of the notorious termite pest Reticulitermes flavipes.

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First example of a GH5 glycoside hydrolase that features a GH42-type homotrimeric structure.

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High exo-type specificity for the terminal ®-1,4-mannosidic linkages in mannooligosaccharides and unsubstituted®-mannans.

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Verrucomicrobial gut symbiont with high potential for hemicellulose degradation.

The termite Reticulitermes flavipes causes extensive damage due to the high efficiency and broad specificity of the ligno- and hemicellulolytic enzyme systems produced by its symbionts. Thus, the R. flavipes gut microbiome is expected to constitute an excellent source of enzymes that can be used for the degradation and valorization of plant biomass. The symbiont Opitutaceae bacterium strain TAV5 belongs to the phylum Verrucomicrobia and thrives in the hindgut of R. flavipes. The sequence of the gene with the locus tag opit5_10225 in the Opitutaceae bacterium strain TAV5 genome has been classified as a member of glycoside hydrolase family 5 (GH5), and provisionally annotated as an endo-β-mannanase. We characterized biochemically and structurally the opit5_10225 gene product, and show that the enzyme, Op5Man5, is an exo-β-1,4-mannosidase [EC 3.2.1.25] that is highly specific for β-1,4-mannosidic bonds in mannooligosaccharides and ivory nut mannan. The structure of Op5Man5 was phased using electron cryo-microscopy and further determined and refined at 2.2 Å resolution using X-ray crystallography. Op5Man5 features a 200-kDa large homotrimer composed of three modular monomers. Despite insignificant sequence similarity, the structure of the monomer, and homotrimeric assembly are similar to that of the GH42-family β-galactosidases and the GH164-family exo-β-1,4-mannosidase Bs164 from Bacteroides salyersiae. To the best of our knowledge Op5Man5 is the first structure of a glycoside hydrolase from a bacterial symbiont isolated from the R. flavipes digestive tract, as well as the first example of a GH5 glycoside hydrolase with a GH42 β-galactosidase-type homotrimeric structure.

Design, synthesis, and biological evaluation of quinazolin-4(3H)-one derivatives co-targeting poly(ADP-ribose) polymerase-1 and bromodomain containing protein 4 for breast cancer therapy

This study was aimed to design the first dual-target small-molecule inhibitor co-targeting poly (ADP-ribose) polymerase-1 (PARP1) and bromodomain containing protein 4 (BRD4), which had important cross relation in the global network of breast cancer, reflecting the synthetic lethal effect. A series of new BRD4 and PARP1 dual-target inhibitors were discovered and synthesized by fragment-based combinatorial screening and activity assays that together led to the chemical optimization. Among these compounds, 19d was selected and exhibited micromole enzymatic potencies against BRD4 and PARP1, respectively. Compound 19d was further shown to efficiently modulate the expression of BRD4 and PARP1. Subsequently, compound 19d was found to induce breast cancer cell apoptosis and stimulate cell cycle arrest at G1 phase. Following pharmacokinetic studies, compound 19d showed its antitumor activity in breast cancer susceptibility gene 1/2 (BRCA1/2) wild-type MDA-MB-468 and MCF-7 xenograft models without apparent toxicity and loss of body weight. These results together demonstrated that a highly potent dual-targeted inhibitor was successfully synthesized and indicated that co-targeting of BRD4 and PARP1 based on the concept of synthetic lethality would be a promising therapeutic strategy for breast cancer.

Design, synthesis and pharmacological evaluation of 4-(3-chloro-4-(3-cyclopropylthioureido)-2-fluorophenoxy)-7-methoxyquinoline-6-carboxamide (WXFL-152): a novel triple angiokinase inhibitor for cancer therapy

Angiokinases, such as vascular endothelial-, fibroblast- and platelet-derived growth factor receptors (VEGFRs, FGFRs and PDGFRs) play crucial roles in tumor angiogenesis. Anti-angiogenesis therapy using multi-angiokinase inhibitor has achieved great success in recent years. In this study, we presented the design, synthesis, target identification, molecular mechanism, pharmacodynamics (PD) and pharmacokinetics (PK) research of a novel triple-angiokinase inhibitor WXFL-152. WXFL-152, identified from a series of 4-oxyquinoline derivatives based on a structure-activity relationship study, inhibited the proliferation of vascular endothelial cells (ECs) and pericytes by blocking the angiokinase signals VEGF/VEGFR2, FGF/FGFRs and PDGF/PDGFRβ simultaneously in vitro. Significant anticancer effects of WXFL-152 were confirmed in multiple preclinical tumor xenograft models, including a patient-derived tumor xenograft (PDX) model. Pharmacokinetic studies of WXFL-152 demonstrated high favourable bioavailability with single-dose and continuous multi-dose by oral administration in rats and beagles. In conclusion, WXFL-152, which is currently in phase Ib clinical trials, is a novel and effective triple-angiokinase inhibitor with clear PD and PK in tumor therapy.

Current intakes of trans-palmitoleic (trans-C16:1 n-7) and trans-vaccenic (trans-C18:1 n-7) acids in France are exclusively ensured by ruminant milk and ruminant meat: A market basket investigation

High circulating levels of trans-palmitoleic acid (TPA) are associated with a lower risk of type 2 diabetes in humans. Thus, the origin of circulating TPA matters. Direct intakes of TPA are ensured by dairy products, and perhaps by partially hydrogenated oils (PHOs). Indirect intakes of TPA rely on dietary trans-vaccenic acid (TVA), which occurs in ruminant-derived foods and PHOs. As it is usually assumed that PHOs are not used any longer, we analyzed here a wide range of foods currently available at retail in France. We report that TPA and TVA (1) do occur in ruminant milk and meat, dairy products and in foreign PHOs, (2) do occur in dairy fat-containing foods and (3) do not occur in dairy fat-free foods. Together, our findings demonstrate that ruminant fats are the only contributors to circulating levels of TPA in humans.

Nobiletin and its derivatives overcome multidrug resistance (MDR) in cancer: total synthesis and discovery of potent MDR reversal agents

Our recent studies demonstrated that the natural product nobiletin (NOB) served as a promising multidrug resistance (MDR) reversal agent and improved the effectiveness of cancer chemotherapy in vitro. However, low aqueous solubility and difficulty in total synthesis limited its application as a therapeutic agent. To tackle these challenges, NOB was synthesized in a high yield by a concise route of six steps and fourteen derivatives were synthesized with remarkable solubility and efficacy. All the compounds showed improved sensitivity to paclitaxel (PTX) in P-glycoprotein (P-gp) overexpressing MDR cancer cells. Among them, compound 29d exhibited water solubility 280-fold higher than NOB. A drug-resistance A549/T xenograft model showed that 29d, at a dose of 50 mg/kg co-administered with PTX (15 mg/kg), inhibited tumor growth more effective than NOB and remarkably increased PTX concentration in the tumors via P-gp inhibition. Moreover, Western blot experiments revealed that 29d inhibited expression of NRF2, phosphorylated ERK and AKT in MDR cancer cells, thus implying 29d of multiple mechanisms to reverse MDR in lung cancer.

Sparkling Reflective Stacks of Purine Crystals in the Nudibranch Flabellina iodinea

Although pigments contribute to much of the brilliant purple and orange coloration of the aeolid nudibranch Flabellina iodinea, the optical appearance of the animal was found to be augmented by dynamically sparkling, brightly reflective material in cells located throughout its epidermis. Electron microscopy revealed that specialized cells most abundant near the epithelial basal lamina contain numerous multilayer stacks of crystals, each within a fragile membrane capsule. High-resolution light microscopy of tissue sections showed that these crystalline stacks intermittently reflect light, with a temporally dynamic, sparkling appearance, suggesting that they are free to move-a phenomenon also observed in the live, intact whole animal and in the purified crystal stacks as well. Thin-layer chromatography and ultraviolet spectrometry show that the crystals isolated from all epithelial tissues are identical in composition, with guanine being the major component and its derivative, hypoxanthine, a minor component, regardless of the tissue's pigmentary color. Electron diffraction of the crystals purified separately from the orange and purple tissues exhibits nearly identical lattice parameters that closely match those measured for guanine crystals, which are widely distributed in other biophotonic systems ranging from marine invertebrates to terrestrial vertebrates. Heterogeneity of the thickness and spacing of the crystals within their stacks accounts for their broadband silvery reflectance. The optical appearance of the epidermis of this nudibranch thus results from the interaction of incident light with mobile stacks of purine crystals, augmenting the effects of its pigmentary colors.

Flavonoid glycosides in Malabar spinach Basella alba inhibit the growth of Spodoptera litura larvae

Basella alba is a perennial plant of the Basellaceae and is known by various common names including Malabar spinach. There are few insects that cause damage to B. alba. In this study, we examined the effect of B. alba leaves on the growth of Spodoptera litura larvae. B. alba leaves and a methanolic extract of the leaves inhibited the growth of S. litura larvae. Half of the larvae reared on the leaves died within 1 week. We found that two flavonoids, vitexin, and vitexin-2″-O-arabinofuranoside, were abundant in the methanol extract of leaves. When larvae were reared on purified vitexin or vitexin-2″-O-arabinofuranoside, their growth was significantly impaired compared with larvae reared on control spinach leaves. These results suggested that the flavonoid glycosides in B. alba leaves act as deterrents to S. litura larvae.

Ectopic overexpression of castor bean LEAFY COTYLEDON2 (LEC2) in Arabidopsis triggers the expression of genes that encode regulators of seed maturation and oil body proteins in vegetative tissues

The LEAFY COTYLEDON2 (LEC2) gene plays critically important regulatory roles during both early and late embryonic development. Here, we report the identification of the LEC2 gene from the castor bean plant (Ricinus communis), and characterize the effects of its overexpression on gene regulation and lipid metabolism in transgenic Arabidopsis plants. LEC2 exists as a single-copy gene in castor bean, is expressed predominantly in embryos, and encodes a protein with a conserved B3 domain, but different N- and C-terminal domains to those found in LEC2 from Arabidopsis. Ectopic overexpression of LEC2 from castor bean under the control of the cauliflower mosaic virus (CaMV) 35S promoter in Arabidopsis plants induces the accumulation of transcripts that encodes five major transcription factors (the LEAFY COTYLEDON1 (LEC1), LEAFY COTYLEDON1-LIKE (L1L), FUSCA3 (FUS3), and ABSCISIC ACID INSENSITIVE 3 (ABI3) transcripts for seed maturation, and WRINKELED1 (WRI1) transcripts for fatty acid biosynthesis), as well as OLEOSIN transcripts for the formation of oil bodies in vegetative tissues. Transgenic Arabidopsis plants that express the LEC2 gene from castor bean show a range of dose-dependent morphological phenotypes and effects on the expression of LEC2-regulated genes during seedling establishment and vegetative growth. Expression of castor bean LEC2 in Arabidopsis increased the expression of fatty acid elongase 1 (FAE1) and induced the accumulation of triacylglycerols, especially those containing the seed-specific fatty acid, eicosenoic acid (20:1^Δ11), in vegetative tissues.

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Castor bean LEC2 is single copy and shows seed-specific expression.

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Over-expression of castor LEC2 induces genes involved in seed maturation in leaves.

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Castor LEC2 induces the accumulation of triacylglycerols and 20:1 fatty acids in leaves.

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Ectopic expression of castor LEC2 in Arabidopsis affects plant growth.

Protective effect of black tea infusion on aflatoxin-induced hepatotoxicity in mice

BACKGROUND

Aflatoxins are a group of mycotoxins produced by Aspergillus flavus and Aspergillus parasiticus and are potent inducers of hepatotoxicity.

OBJECTIVE

The present study was carried out to investigate the effect of black tea infusion on aflatoxin-induced hepatotoxicity in male mice.

METHODS

A 2% black tea infusion in drinking water was prepared and orally administered along with aflatoxin (750 and 1500 μg/kg body weight) for 30 days. Morphological investigation, body weight and organ weight calculations and histopathological analysis were carried out. Serum hepatic marker enzymes namely alanine aminotransferase and aspartate aminotransferase were estimated.

RESULTS

The results clearly indicated that aflatoxin treatment for 30 days caused significant dose-dependent reduction in body weight and increase in liver weight. The activities of ALT and AST were found to be elevated while protein content was found to be decreased in aflatoxin-treated mice as compared to vehicle control. Histopathological analysis showed hepatocellular necrosis and cytoplasmic vacuolization along with fatty infiltration in toxin-treated animals. Results revealed significant (p < 0.05) restoration of aflatoxin-induced damages in body weight, organ weight, serum chemistry and histopathological features in aflatoxin plus black tea infusion administered mice in a dose dependant manner.

CONCLUSION

It is concluded from the present study that supplementation of black tea infusion can be beneficial in positively modulating aflatoxin-induced alterations in liver.