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Synthesis of the C19-truncated maltepolide E has been accomplished via a diene–ene RCM strategy without damage to the C11–C14 alkenyl epoxy unit. Upon release of the C17-OH group, it attacked at the C14 position with double bond migration and epoxide ring-opening to furnish the C19-truncated maltepolide A and B as proposed for the biosynthesis of maltepolides. Preliminary cytotoxicity data of the synthesized C19-truncated maltepolides against L929 mouse fibroblast cell line suggest irrelevance of the vinyl epoxide and importance of the conjugated dienyl keto unit for the observed anticancer activity.

During a heart failure, higher amount of nucleoside diphosphate kinase (NDPK) enzyme in the sarcolemma membrane inhibits the synthesis of second messenger cyclic adenosine monophosphate (cAMP), which is required for the regulation of the calcium ion balance for normal functioning of the heart. In a dependent pathway, NDPK normally phosphorylates the stimulatory guanosine diphosphate, GDP(s), to a guanosine triphosphate, GTP(s), on the heterotrimeric (α, β and γ subunits) guanine nucleotide binding protein (G protein), resulting in the stimulation of the cAMP formation. In case of a heart failure, an increased quantity of NDPK also reacts with the inhibitory GDP(i), which is converted to a GTP(i), resulting in the inhibition of the cAMP formation. Typically, the βγ dimer of the G protein binds with hexameric NDPK-B/C complex and receives the phosphate at the residue His266 from residue His118 of NDPK-B. It is known that NDPK-C is required for NDPK-B to phosphorylate the G protein. In this work, the interactions between NDPK-B and NDPK-C are quantified in the presence and absence of graphene oxide (GO) as well as those between NDPK-B and GO through stability analysis involving hydrogen bonds, center of mass (COM), root mean square deviation (RMSD), and salt bridges, and energetics analysis involving van der Waals (VDW) and electrostatic energies. Furthermore, the role of water molecules at the interface of NDPK-B and NDPK-C as well as between NDPK-B and GO is investigated to understand the nature of interactions. It is found that the adsorption of NDPK-B on GO triggers a potential conformational change in the structure of NDPK-B, resulting in a diminished interaction with NDPK-C. This is confirmed through a reduced center of mass (COM) distance between NDPK-B and GO (from 40 A□ to 30 A□) and an increased COM distance between NDPK-B and NDPK-C (from 50 A□ to 60 A□). Furthermore, this is also supported by fewer salt bridges between NDPK-B and NDPK-C, and an increased number of hydrogen bonds formed by the interfacial water molecules. As NDPK-C is crucial to be complexed with NDPK-B for successful interaction of NDPK-B with the G protein, this finding shows that GO can suppress the interactions between NDPK-B/C and G proteins, thereby providing an additional insight into the role of GO in the heart failure mechanism.AUTHOR SUMMARYWe report a novel computational understanding of the interactions between the enzymes NDPK-B and NDPK-C with GO as a potential inhibitor to such interactions and its implications. These types of interactions can play influential roles in many biochemical processes including those that take place during heart failure. A second messenger called cAMP is needed for proper cardiac contraction through the actions of NDPK-B/NDPK-C. It is needed to study the interactions between NDPK-B and NDPK-C to control the synthesis of cAMP. Towards this end, GO is tested through molecular simulations to understand the interactions between NDPK-B and NDPK-C. Influencing or modifying such enzyme active sites has been very less explored and, in this work, the molecular simulations suggest that GO is able to interact with the active site of NDPK-B to provide a sustained cAMP synthesis for longer duration. We found that conformational changes within NDPK-B and NDPK-C influence the interactions between them and such conformational changes are found to be governed by their adsorption on GO. Finally, we found the role of interfacial water molecules between NDPK-B and GO to be crucial in maintaining the interface between them.

Background: The establishment of strategy to inhibit the virus replication is an attractive means in combating SARS-CoV-2 infection. Objective: We studied phyto-compounds from Strychnos nux-vomica (a poisonous plant) against SARS-CoV-2 RNA-dependent RNA polymerase by computational methods. Method: Molecular docking, molecular dynamics (MD) simulation and energetics calculations were employed to elucidate the role of the phyto-compounds. Results: Ergotamine with a binding free energy of -14.39 kcal/mol showed a promising capability in terms of binding affinity and the interaction to conserved motifs, especially the SDD signature sequence. The calculated dissociation constants for ATP, ergotamine, isosungucine and sungucine were 12 μM, 0.072 nM, 0.011 nM and 0.152 nM, respectively. The exhibited kd by these phyto-compounds reflected tens of thousands fold potency as compared to ATP. The binding free energies of sungucine and isosungucine were much lower (-13.93 and -15.55 kcal/mol, respectively) compared to that of ATP (-6.98 kcal/mol). Conclusion: Sharing the same binding location as that of ATP and having high binding affinities, Ergotamine, Isosungucine, Sungucine and Strychnine N-oxide could be effective in controlling the SARS-CoV-2 virus replication by blocking the ATP and inhibiting the enzyme function.

The positive charge on liposome surface is known to promote the crossing of the Blood brain barrier (BBB). However, when diastereomeric cationic gemini amphiphiles are among lipid membrane components, also the stereochemistry may affect the permeability of the vesicle across the BBB.Liposomes featuring cationic diasteromeric gemini amphiphiles were formulated, characterized, and their interaction with cell culture models of BBB investigated.Liposomes featuring the gemini amphiphiles were internalized in a monolayer of brain microvascular endothelial cells derived from human induced pluripotent stem cells (hiPSC) through an energy dependent transport, internalization involving both clathrin- and caveolae-mediated endocytosis. On the same formulations, the permeability was also evaluated across a human derived in vitro BBB transport model. The permeability of liposomes featuring the gemini amphiphiles was significantly higher compared to that of neutral liposomes (DPPC/Cholesterol), that were not able to cross BBB. Most importantly, the permeability was influenced by the stereochemistry of the gemini and pegylation of these formulations did not result in a drastic reduction of the crossing ability. The in vitro iPSC-derived BBB models used in this work represent an important advancement in the drug discovery research of novel brain delivery strategies and therapeutics for central nervous system diseases.

Xanthones are valuable compounds in drug design and development, attributed to their multi-dimensional pharmacological properties, including anti-cancer, anti-bacterial, anti-malarial, anti-inflammatory and anti-cholinesterase. This study focused on the synthesis of 1,3-dihydroxyxanthone (1) and its new 1-hydroxy-3-O-substituted derivatives with alkyl (2a-2f), alkenyl (2g-2k), alkynyl (2l-2n) and alkylated phenyl (2o-2r) groups and were synthesised in a high percentage yield of >70%, except for 2l and 2p. Their structures were confirmed by MS, NMR and FTIR spectroscopic techniques. The evaluation of acetylcholinesterase (AChE) inhibitory activities showed that all the substituted xanthones (2a-2r) are more potent than 1. Compounds 2g and 2j are the strongest AChE inhibitors with the IC50 values of 20.8 and 21.5 μM and their enzyme kinetic analyses indicated that these derivatives possess a mixed-mode inhibition, where they targeted both the active sites and allosteric sites of AChE. Molecular docking study revealed that 2g binds favourably to the active site of AChE via π–π stacking and hydrogen bonding, in addition to π-alkyl interaction and alkyl interaction from the substituent group. The xanthone derivatives are identified as potential lead compounds for further development of Alzheimer’s disease treatments.

We explored the most expedient pathway for phenolic compound preparation using a combination of arylboronic acids, a green oxidant (H2O2) and a catalytic amount of readily available medicinal materials (TYLENOL® and ASPIRIN®). The arylboronic acids were successfully transformed into the corresponding phenols in high yields under metal- and base-free aqueous aerobic conditions. We demonstrated that enhanced availability and sustainability are some advantages associated with the use of medicinal supports.

The diastereoselectivity of conventional polyene cyclization reactions is highly dependent on the configuration of the internal alkenes, where E-polyenes provide trans-decalins, while Z-polyenes of...

(Z)-7-Aryl-5-acyldibenzo[e,g][1,4]diazocin-6(5H)-one, a unique saddle-shaped bridged biaryl containing synchronized aryl-aryl and N-aryl stereogenic axes, was constructed for the first time in good...

An atroposelectively diversity-oriented synthetic strategy was developed for the divergent synthesis of axially chiral heterocycles through organocatalytic asymmetric intramolecular annulation of a...

Abstract: The C-H and N-H functionalization of indoles is an interesting area of research that has a useful impact on organic synthesis due to the availability of chiral indole scaffolds in the discovery of drugs, synthetic bioactive compounds, and natural products. The chiral phosphoric acid catalysts (CPAs) have proven to be a powerful and versatile class of enantioselective organocatalysts. Many asymmetric syntheses of organic compounds have been carried out with these catalysts in C-C and CN bond formation reactions, and great progress has been reported. By 2011, several reviews were published covering some important topics and recent achievements in this field. Therefore, in this review, the most recent advances, research breakthroughs with key examples involving mechanisms of CPA-catalyzed C-H and N-H functionalization of indoles to form central chirality via Friedel Crafts, Michael type, and rearrangement reactions were reviewed and reported.

Two novel seco-polycyclic polyprenylated acylphloroglucinols (PPAPs), hyperbenzones A (1) and B (2), were isolated from the roots of Hypericum beanii, together with one known biosynthetic congener 3. Compound 1 incorporates a 6/5/5 ring system with an unprecedented spiro[bicyclo[3.3.0]octane-3,1ʹ-cyclohexane]-2,2ʹ-dione motif. The structures of 1 and 2 were determined by a combination of high resolution electrospray ionization mass spectroscopy (HRESIMS), nuclear magnetic resonance (NMR) spectroscopic analyses, gauge-independent atomic orbital (GIAO) NMR chemical shift calculation with DP4+ analyses, electronic circular dichroism (ECD) calculation, and X-ray diffraction analysis. A 1,2-seco retro-Claisen rearrangement from a bicyclo[3.3.1]nonane PPAP precursor and following chemodivergent radical cascade cyclizations are proposed as the key steps in the biosynthetic pathway to yield compounds 1 and 2. Biological investigations indicated that compounds 1 and 3 could decrease intracellular lipid accumulation in a palmitic acid-induced nonalcoholic steatohepatitis (NASH) cell model.

抽象 河北邢臺話的動後時體詞「了1」有兩個語音形式：強變體「咾 [lau]」和弱變體「囒 [læ͊]」，二者在很大程度上是條件變體。經考察，漢語「了1」的使用受制於謂語的整體屬性（現實性狀況、話語地位）和謂語的構件屬性（賓語類型、動詞類型）兩大類語法因素，而邢臺話「了1」兩變體的分佈同樣受制於這些因素：謂語的整體屬性決定「了1」兩變體分佈的基本格局，謂語的構件屬性決定既定的「咾」或「囒」可換為另一變體的特殊情況。各項語法因素制約「了1」變體的作用強度存在一個優先等級「現實性狀況＞話語地位＞賓語類型＞動詞類型」。最重要的是，「了1」兩變體的分佈呈現出一個顯著的態勢：某語法環境中「了1」的句法自由度越高，則越排斥強變體「咾」、越接受弱變體「囒」。由此可對其他方言「了1」變體的分佈態勢提出多項理論預測，該現象也反映出北方漢語的「了1」是一個複雜的語法異質語素。本文「了1」的語法分析範式應有助於深入發掘漢語方言「了1」語素的事實，並推進對多項理論問題的認識。

Enantiopure vicinal diols are important building blocks used in the synthesis of fine chemicals and pharmaceutical compounds. Diol dehydrogenase (DDH) mediated stereoselective oxidation of racemic vicinal is an efficient way to prepare enantiopure vicinal diols. In this study, four new bacterial DDHs (AnDDH from Anoxybacillus sp. P3H1B, HcDDH from Hazenella coriacea, GzDDH from Geobacillus zalihae and LwDDH from Leptotrichia wadei) were mined from the GenBank database and expressed in E. coli T7. The four DDHs were purified and biochemically characterized for oxidation activity toward (R)-1-phenyl-1,2-ethanediol, with the optimal reaction condition of pH9.0 (AnDDH), 10.0 (HcDDH) and 11.0 (GzDDH and LwDDH) and the temperatures at 40°C (AnDDH), 50°C (HcDDH) and 60°C (GzDDH and LwDDH), respectively. The four enzymes were stable at the pH from 7.0 to 9.0 and below 40°C. Kinetic parameters of four DDHs showed that the HcDDH from Hazenella coriacea had high activity toward a broad range of vicinal diols. A series of racemic vicinal diols were successfully resolved by recombinant E. coli (HcDDH-NOX) resting cells co-expression of an NADH oxidase (NOX), affording (S)-diols and (1S, 2S)-trans-diols in ≥99% ee. The synthetic potential of HcDDH was proved by E. coli (HcDDH-NOX) via kinetic resolution of racemic trans-1,2-indandiol on a 100 ml scale reaction, (S, S)- trans-1,2-indandiol was prepared in 46.7% yield and >99% ee. In addition, asymmetric reduction of four α-hydroxy ketones (10-300 mmol•L-1) by E. coli (HcDDH-GDH) resting cells resulted in >99% ee and 69-98% yields of (R)-vicinal diols. The current research expands the toolbox of DDHs to synthesize chiral vicinal diols and demonstrated that the mined HcDDH is a potential enzyme in the synthesis of a broad range of chiral vicinal diols.

Background: From time immemorial, natural products have been used for the treatment of various diseases. Various natural products, their semisynthetic derivatives, and synthetic analogs have been explored for their anti-infective properties. One such group of natural compounds that has been widely explored is manzamine alkaloids. Manzamine alkaloids are complex natural compounds consisting of a β-carboline nucleus attached to a pentacyclic ring system; they were first isolated from a marine sponge during the 1980s. Objective: This review aims to provide a critical overview on the anti-infective potential of manzamine alkaloids. Method: A comprehensive and exhaustive review of the literature on manzamine alkaloids, and their isolation, anti-infective properties, and mechanism of action, is presented. Results: Various manzamine alkaloids have been isolated and have been found to exhibit potent antiinfective activities like antibacterial, antimalarial, antiviral, antifungal, antileishmanial, among others. These manzamine alkaloids exhibit their anti-infective activity by inhibiting targets like GSK-3β, MtSK. Conclusion: This present review along with structure-activity relationship study of manzamine alkaloids for their anti-infective activity will be useful for further development of semisynthetic manzamine analogs as potent anti-infective agents with better therapeutic potential and reduced toxicity.

γ-Aminobutyric acid is a major inhibitory neurotransmitter in the mammalian central nervous system that plays a substantial role in brain disorders. γ-Amino phosphonic acid is a unique surrogate of...

We report the first highly diastereo- and enantioselective C–C bond-forming reaction of racemic α-branched ketones to construct tertiary alcohols with adjacent stereocenters. Accordingly, a highly ...

Density functional theory (DFT) computations were performed to unveil the electronic structures and the Kohn-Sham Molecular Orbitals (MOs) of the dimeric aza-BODIPY molecule and its chlorinated form. The optimized conformation of dimers is well in alignment with the one provided in the literature. The HOMO LUMO gap of dichloro-derivative is smaller than that of the dimeric aza-BODIPY molecule by 35.0 meV. The predicted HOMO energies of -6.40 and -6.60 eV point out the good stabilities of both compounds. They were reported to demonstrate bathochromic shifts of 40 and 57 nm compared to their monomers substituted by H and Cl, respectively. The intriguing photophysical behaviors of these molecules were investigated by conducting the Tamm-Dancoff density functional theory (TDA-DFT) calculations. The max values emerge from the HOMO-1 -> LUMO+1 (83-86%) transitions, whereas the low energy transitions arise from HOMO -> LUMO (89%). Therefrom predicted ELUMO->HOMO of the dimeric aza-BODIPY and dichloro-derivative are 1.89 and 1.87 eV, respectively, which are matching well with the reported literature values.

Available online xxx Valeriaquinone A (1), an unprecedented anthraquinone–coumarin hybrid, was isolated from the roots of Knoxia valerianoides. Its structure was determined by extensive spectroscopic analyses and X-ray diffraction. The plausible biosynthetic pathways for 1 were proposed. Compound 1 exhibited strong protein tyrosine phosphatase 1B (PTP1B) inhibition with high selectivity (> 30 fold) over homologous T cell protein tyrosine phosphatase (TCPTP) potentially by binding to an allosteric site predicted by kinetic analysis and molecular docking. Moreover, compound 1 showed significant cytotoxic activities against three human hepatoma cell lines (HepG2, QGY-7703, and SMMC-7721) with half maximal inhibitory concentration (IC50) values of 1.39 ± 0.2, 10.34 ± 2.09, and 5.56 ± 0.47 µmol/L, respectively.

The first highly diastereoselective synthesis of β-anomers of 4’-thionucleosides has been carried out by means of electrophilic glycosidation utilizing 3,5-O-(di-tertbutylsilylene) (DTBS)-4-thiofuranoid glycal as a glycosyl donor. The resulting glycosides were transformed into ribo-, 2’-deoxy-, and arabinofuranosyl nucleosides through a chemical transformation of the 2’-substituent. The additive Pummerer reaction of the glycal Soxide gave 1,2-di-O-acetyl-3,5-O-DTBS-4-thioribofuranose. The utility of the DTBSprotected 4-thioribofuranose has been demonstrated by the preparation of 4’-thio analogues of pyrimidine- and purine-4’-thioribonucleosides based on the Vorbrüggen glycosidation. Synthesis of 4’-thio-counterpart of C-nucleoside antibiotic tiazofurin has also been carried out. α-Face selective hydroboration of 1-C-aryl- or 1-C-heteroaryl-glycals obtained by cross-coupling of 1-tributylstannylglycal has furnished the respective β- anomer of 4’-thio-C-ribonucleosides, including 4’-thio analogue of nucleoside antibiotic pseudouridine and 9-deazaadenosine. On the basis of lithiation chemistry, 1-C- and 2-Ccarbon- carbon-substituted 3,5-O-(1,1,3,3-tetraisopropyldisiloxane-1,3- diyl) (TIPDS)- 4- thiofuranoid glycal were synthesized. These glycals enabled us to prepare 1’-C- and 2’-β- C-carbon-substituted 2’-deoxy-4’-thionucleosides, including thio-counterpart of antitumor nucleoside antibiotic angustmycin C. Furthermore, 1’-C-methyl-4’-thiothymidine emerged as a potent inhibitor of angiogenesis. In addition, 1’-C-methyl-4’-thiothymidine exhibited more potent inhibitory activity against thymidine kinase-deficient mutant of herpes virus than that of ganciclovir. Among the 4’-substituted 4’-thiothymidines, the 4’- C-cyano- and 4’-C-ethynyl derivatives inhibited replication of HIV variant resistant to 3TC (HIVM184V) as potently as HIV-1IIIB. In terms of the value of selectivity index (SI), 4’-C-cyano-4’-thiothymidine showed a 3-fold selective index (SI) than that of the corresponding thymidine derivative. Furthermore, 4’-C-ethynyl-2’-deoxy-4’-thioguanosine has a 20-fold better value (>18,200) than that of 2’-deoxyguanosine counterpart (933). Furthermore, 4’-azido-4’-thiothymidine emerged as a selective and potent anti-EBV agent. In terms of antineoplastic activity, 4’-azido- and 4’-C-fluoromethyl-2’-deoxy-4’-thiocytidine inhibited proliferation of human B-cell (CCRF-SB) and T-cell leukemia (Molt-4) cell lines, although the parent compound 2’-deoxy-4’-thiocytidine did not exhibit any cytotoxicity up to 100 μM. These facts concerning the biological activities suggested that replacement of the furanose oxygen with a sulfur atom is a promising approach for the development of less toxic antiviral and antineoplastic nucleoside antimetabolites. 4’- Thionucleoside also acts as a monomer for oligonucleotides (ONs) therapeutics, exhibiting superior biological properties. Therefore, this review provides a wide range of potential monomers for antisense ON and siRNA.

Background: There has been tremendous pressure on healthcare facilities globally due to the recent emergence of novel coronavirus infection known as COVID-19 and its rapid spread across the continents. The lack of effective therapeutics for the management of the pandemic calls for the discovery of new drugs and vaccines. Objective: In the present study, a chemical library was screened for molecules against three coronavirus 3CL-like protease enzymes (SARS-CoV-2 3CLpro, SARS-CoV 3CLpro and MERS-CoV 3CLpro), which are a key player in the viral replication cycle. Methods: Extensive computational methods such as virtual screening and molecular docking were employed in this study. Results: Two lead molecules, ZINC08825480 (4-bromo-N'-(E)-[1-phenyl-3-(pyridin-3-yl)-1H-pyrazol- 4-yl]methylidenebenzene-1-sulfonohydrazide) and ZINC72009942 (N-[[2-[[(3S)-3-methyl-1-piperidyl] methyl]phenyl]methyl]-6-oxo-1-(p-tolyl)-4,5-dihydro-1,2,4-triazine-3-carboxamide), were identified with better affinity with the three target enzymes as compared to the approved antiviral drugs. Both the lead molecules possessed favorable drug-like properties, fit well into the active site pocket close to His- Cys dyad and showed a good number of hydrogen bonds with the backbone as well as side chains of key amino acid residues. Conclusion: Thus, the present study offers two novel chemical entities against coronavirus infections which can be validated through various biological assays.

A novel class of chiral spiro-fused bisoxazoline ligands possessing a deep chiral pocket was prepared. The developed ligands have been employed in the nickel-catalyzed highly enantioselective Michael-type Friedel-Crafts reaction, affording the products bearing a trifluoromethylated all-carbon quaternary stereocenter with moderate to excellent yields (up to 99%) and good to excellent enantioselectivies (up to > 99.9% ee). Moreover, a proposed model of chiral pocket revealed that the attack of indole from the Re-face of β-CF3-β-disubstituted nitroalkene was favorable.

Arnequinol A (1), featuring an unprecedented 6/6/3 tricyclic carbon skeleton fused with a heptatomic oxo-bridge, together with arnequinone A (2) bearing a highly conjugated methyl-shifting benzogeijerene skeleton, were isolated from Arnebia euchroma. Their structures were elucidated by extensive spectroscopic methods and quantum chemical calculations of the 13C nuclear magnetic resonance (NMR) data and electronic circular dichroism (ECD) spectra. The plausible biosynthetic pathways for 1 and 2 were presented. In an in vitro test, compound 2 showed potent neuroprotective activity against serum-deprivation induced PC12 cell damage at a concentration of 10 μmol/L.

Background: Candida albicans is one of the most important causes of fatal fungal infections. Ergosterol, the main sterol in the fungal cell membrane, is the resultant product of Lanosterol in the presence of the enzyme Lanosterolα-demethylase (Cytochrome P450DM). This enzyme is the target enzyme of azole antifungal agents. Aim: To evaluate the antifungal potency of some of the natural compounds via molecular modeling and Absorption, Distribution, Metabolism and Excretion (ADME) study. Method: The study involved the selection and modeling of the target enzyme, followed by the refinement of the model using molecular dynamic simulation. The modelled structure of the enzyme was validated using the Ramachandran plot and Sequence determination technique. A series of natural compounds was evaluated for cytochrome P450 inhibitory activity using molecular docking studies. The structures of compounds were prepared using a Chem sketch, and molecular docking was performed using Molergo Virtual Docker (MVD) program. Results: The docking study indicated that all the natural compounds have interactivity with protein residue of 14α-demethylase, and the heme prosthetic group and water molecules are present at the active site. The data were also correlated with the synthetic compounds that were experimentally inactive against the fungus and had a low docking score. The compounds with a high dock score were further screened for Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) profile, and it was predicted that these compounds can be used as lead with a good ADME profile and low toxicity. Conclusion: The natural compound, i.e., curcumin, can easily be used further for lead optimization.

Background: Integrase enzyme is a validated drug target to discover novel structures as anti-HIV-1 agents. Objective: This study aimed at developing a novel series of thioimidazolyl diketoacid derivatives characterizing various substituents at N-1 and 2-thio positions of the central ring as HIV-1integrase inhibitors. Methods: In this study, eighteen novel thioimidazolyl DKA derivatives were synthesized in a fivestep parallel procedure and tested in vitro for the inhibition of both IN ST reaction and the singlecycle HIV-1 replication in HeLa cell culture. Results: The obtained molecules were evaluated using the enzyme assay, displaying promising integrase inhibitory activity with IC50 values ranging from 0.9 to 7.7 mM. The synthesized compounds were also tested for antiviral activity and cytotoxicity using HeLa cells infected by the single-cycle replicable HIV-1 NL4-3. Conclusion: The most potent compound was found to be 18i with EC50 = 19 μM, IC50 = 0.9 μM, and SI = 10.5. Docking studies indicated that the binding mode of the active molecule is well aligned with the known HIV-1integrase inhibitor.

Background: Developing the high-efficiency and low-risk small-molecule greennematocide is the key of effective control of the nematodes. Paeonol, is a naturally occurring phenolic compound, isolated from the root bark of Paeonia suffruticosa and the whole plant of Cynanchum paniculatum. Due to its crucial phenolic ketone skeleton, modern biological science research has indicated that paeonol has a wide range of biological activities. The structural modification of paeonol into paeonol carbonyl hydrazone derivatives is a potential approach for the development of novel nematodes, which showed more toxicity than paeonol. However, there are no reports on the nematicidal activity of paeonol carbonyl hydrazone derivatives to control Heterodera glycines. Results: We always endeavor to discover and develop biorational natural products-based pesticidal agents, 4 significant intermediates and 21 novel 3/5(3,5)-(di)nitro/chloropaeonol carbonyl hydrazone derivatives were prepared, and their structures well characterized by 1H NMR, HRMS, MS, and mp. Due to the steric hindrance, the substituents on the C=N double bond of all hydrazine compounds adopted E configuration. Results of nematicidal activity revealed that, among all compounds, especially 5-nitropaeonol (5) and 3,5-dinitropaeonol (7) displayed the most potent nematicidal activity H. glycines in vivo with LC50 values of 0.0323 and 0.0367 mg/mL, respectively. Conclusion: It suggested that for the 3/5(3,5)-(di)nitro/chloropaeonol carbonyl hydrazone derivatives, a nitro group introduced at C5 position of 1 was necessary for obtaining the potent compound as nematicidal agents. These preliminary results will pave the way for further modification of paeonol in the development of potential new nematicides.

Background: Rituximab represents a drug used for standard Non-Hodgkin’s B-cell lymphoma therapy; however, it displays limited clinical efficacy. Antibody-drug conjugate (ADC) is one of the potential strategies to increase the antitumor activity of an antibody, with improved cytotoxicity directly resulting from the delivery of a molecular warhead. Currently, the warhead monomethyl auristatin E (MMAE) has been widely applied in the study of ADCs, conjugated to a carbamate-based linker (MCVC- PABC). However, the hydrophobic drug-linker (MC-VC-PABC-MMAE) may lead to ADC aggregation, ultimately resulting in decreased activity. Objective: In this study, we developed a hydrophilic drug-linker MC-VC-PABQ-AE linked to rituximab. If the replacement of the tertiary amine in AE for a secondary amine in MMAE represents a characteristic modification, the change of antitumor activity of two corresponding anti-CD20 ADC is unknown, requiring further verification. Method: The structural elucidation of MC-VC-PAB-AE was displayed by high-resolution mass spectra. The average drug antibody ratio (DAR) of rituximab-VC-AE/MMAE ADCs was performed by HICHPLC. The cell cycle arrest analysis of two ADCs was detected by flow cytometry and the antitumor activity of two ADCs was evaluated in vitro against Ramos and Daudi cells. Results: The average drug antibody ratio (DAR) of two ADCs was approximately 4.0. The activities of rituximab-VC-AE could be increased in CD20 positive B-lymphoma cell lines, most notably due to the higher cell viability inhibitory rates and apoptosis rates compared to rituximab-VC-MMAE. Conclusions: A hydrophilicity linker of ADC was developed and studied. Rituximab-VC-AE may potentially be used against CD20-positive cells, and the therapeutic efficacy and safety bring about further investigations.

Glycoside hydrolase family 31 (GH31) is a diversified family of anomer-retaining α-glycoside hydrolases, such as α-glucosidase and α-xylosidase, among others. Recently, GH31 α-N-acetylgalactosaminidases (Nag31s) have been identified to hydrolyze the core of mucin-type O-glycans and the crystal structure of a gut bacterium Enterococcus faecalis Nag31 has been reported. However, the mechanisms of substrate specificity and hydrolysis of Nag31s are not well investigated. Herein, we show that E. faecalis Nag31 has the ability to release N-acetylgalactosamine (GalNAc) from O-glycoproteins, such as fetuin and mucin, but has low activity against Tn antigen. Mutational analysis and crystal structures of the Michaelis complexes reveal that residues of the active site work in concert with their conformational changes to act on only α-N-acetylgalactosaminides. Docking simulations using GalNAc-attached peptides suggest that the enzyme mainly recognizes GalNAc and side chains of Ser/Thr, but not strictly other peptide residues. Moreover, quantum mechanics calculations indicate that the enzyme preferred p-nitrophenyl α-N-acetylgalactosaminide to Tn antigen and that the hydrolysis progresses through a conformational itinerary, 4C1 → 1S3 → 4C1, in GalNAc of substrates. Our results provide novel insights into the diversification of the sugar recognition and hydrolytic mechanisms of GH31 enzymes.

A new Staudinger strategy entails a unique C–P bond cleavage, instead of N–P bond cleavage, during the construction of N-acyl phosphinamidites by using acyl-phosphine substrates. The reaction is pe...

Background: Natural products (NPs) are important sources for the design of new drugs and agrochemicals. Neopeltolide, a marine NP, has been identified as a potent Qo-site inhibitor of cytochrome bc1 complex. Methods: In this study, a series of neopeltolide derivatives was designed and synthesized by the simplification of its 14-membered macrolactone ring with a diphenyl ether fragment. The enzymatic inhibition bioassays and mycelium growth inhibition experiments against a range of fungi were performed to determine their fungicidal activities. Results: The derivatives have potent activity against the porcine bc1 complex. Compound 8q showed the best activity with an IC50 value of 24.41 nM, which was 8-fold more effective than that of positive control azoxystrobin. Compound 8a exhibited a 100% inhibitory rate against Zymoseptoria tritici and Alternaria solani at a 20 mg/L dose. Conclusion: Computational results indicated that compounds with suitable physicochemical properties, as well as those forming a hydrogen bond with His161, would have good fungicidal activity. These data could be useful for the design of bc1 complex inhibitors in the future.

Background: Cystic fibrosis (CF) is a genetic disease, which has no effective treatment. Objective: The aim of this study is to predict the EC50 value of 2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole core as a novel chemotype of potentiators to establish a highly predicting quantitative structure-activity relationship model. Methods: 41 products were optimized, and a linear model was built by a heuristic method in CODESSA program. In this study, 3 descriptors were selected and utilized to build a nonlinear model in gene expression programming. Results: The square of the correlation coefficient of the heuristic method is 0.57, and the s2 is 0.30. In gene expression programming, the square of correlation coefficient and the mean square error for the training set are 0.74 and 0.13, respectively. The square of correlation coefficient and the mean square error for the test set are 0.70 and 0.27, respectively. Conclusion: The GEP model has stronger predictive ability to help develop the novel structure of 2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole of cystic-brosis-transmembrane conductance-regulator gene potentiators.

A new phenylethyl glycoside (1), (S)-1-phenylethyl-6-α-L-arabinopyranosyl-β-D-glucopyranoside), and a new dibenzocyclooctadiene lignan (7), Kasuracin A, together with seven known compounds, were isolated and identified from the leaves of Kadsura coccinea. Their structures were determined by analysis of multinuclear and multidimensional nuclear magnetic resonance (NMR), circular dichroism (CD), mass spectrometry, hydrolysis analysis, or comparison to those reported in the literature. Then, all the isolates 1‒9 were evaluated for their inhibitory eff ;ects against nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Among them, compounds 2 and 3 were isolated for the first time from this plant and compounds 3, 7, 8, and 9 significantly inhibited NO production with IC50 values of 36.4, 10.2, 12.3, and 21.7 μM, respectively.

Saccharomyces cerevisiae, commonly known as baker’s yeast, has gained significant importance as a mild, low-cost, environmentally benign biocatalyst. Initially it was mostly employed as an efficient catalyst for the enantioselective reduction of carbonyl compounds. Over the last decade, baker’s yeast has found versatile catalytic applications in various organic transformations. Many multicomponent reactions were also catalyzed by baker’s yeast. Various heterocyclic scaffolds with immense biological activities were synthesized by employing baker’s yeast as catalyst at room temperature. In this communication, we have summarized baker’s yeast catalyzed various organic transformations focusing primarily on heterocyclic synthesis.

Ribonuclease HI (RNHI) non-specifically cleaves the RNA strand in RNA:DNA hybrid duplexes in a myriad of biological processes, including retroviral reverse transcription. Several RNHI homologs contain an extended domain, termed the handle region, that is critical to substrate binding. Nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations have suggested a kinetic model in which the handle region can exist in open (substrate-binding competent) or closed (substrate-binding incompetent) states in homologs containing arginine or lysine at position 88 (using sequence numbering of E. coli RNHI), while the handle region populates a state intermediate between the open and closed conformers in homologs with asparagine at residue 88 [Stafford, K. A., et al., PLoS Comput. Biol.2013, 9, 1-10]. NMR parameters characterizing handle region dynamics are highly correlated with enzymatic activity for RNHI homologs with two-state (open/closed) handle regions [Martin, J. A., et al., Biochemistry2020, 59, 3201-3205]. The work presented herein shows that homologs with one-state (intermediate) handle regions display distinct structural features compared with their two-state counterparts. Comparisons of RNHI homologs and site-directed mutants with arginine at position 88 support a kinetic model for handle region dynamics that includes 12 unique transitions between eight conformations. Overall, these findings present an example of the structure-function relationships of enzymes and spotlight the use of NMR spectroscopy and MD simulations in uncovering fine details of conformational preferences.

Seco-tetracyclic and seco-pentacyclic triterpenoids are a special class of triterpenoids with ring/rings cleaved on the original skeleton structures. A class of important triterpene derivatives, secotetracyclic and seco-pentacyclic triterpenoids, have long stimulated the interest and attention of botanists and natural products chemists. There is no systematic and comprehensive review for them. This review is focused on the phytochemical investigations and biological activities of seco-tetracyclic and seco-pentacyclic triterpenoids from nature, covering the literature from 2000-2019. This review describes 310 seco-tetracyclic and 139 seco-pentacyclic triterpenoids discovered from 154 species belong to 97 genera, which cover the chemical structures, types, sources, and bioactivities of compounds. The literature from 2000-2019 is reviewed and 208 references are cited.

Introduction The mechanisms of fluoroquinolone-resistance of Mycoplasma genitalium were analysed by a new method. Methods M. genitalium strains from urinary sediments of patients with urethritis were isolated and examined antimicrobial susceptibilities and the mutations in ParC, GyrA and 23S rRNA. Docking models between gyrase and topoisomerase IV with sitafloxacin showed that two binding modes in which the amine moiety at the C-7 position rotated could be constructed. Results Among 18 strains, 13 strains had mutations with amino-acid changes at Serine 83 in ParC. The MICs of moxifloxacin or sitafloxacin for three strains with only S83I in ParC were 2, 1 and 8 mg/L (moxifloxacin) or 0.13, 0.13 and 1 mg/L (sitafloxacin), respectively. In contrast, the MICs of moxifloxacin or sitafloxacin for 3 strain with S83N in ParC were 0.25, 0.13 and 0.25 mg/L (moxifloxacin) or 0.06, 0.03, and 0,03 mg/L (sitafloxacin), respectively, not significantly different from wild-type isolates. The docking model of sitafloxacin and topoisomerase IV showed that the oxygen atom at the gamma position of Serine 83 of ParC interacted with the sitafloxacin carboxylate moiety. When the S83I substitution occurs, the isoleucine side chain is lipophilic and the residue hydropathy changes from hydrophilicity to hydrophobicity and important H-bond interactions between serine and the carboxylate moiety are lost. When the serine 83 to asparagine substitution (S83N) occurred, the asparagine side chain is hydrophilic and the residue hydropathy does not change. Conclusion The docking model suggests that Ser83 replacements causes attenuation or loss of activity of fluoroquinolones such as sitafloxacin.

As an important attempt towards creating hierarchical structures more like nature, the peptide is employed as a building block to build supramolecular architectures. An emerging question is whether the molecular mechanism of self-assembly obtained from the small molecule system, e.g., the driving forces of assembly are conventionally regarded as pairwise-additive, can be manifested in the self-association of biologically relevant amphiphilic peptides. A peptide, KRT-R, was derived from the 120-144 segment of keratin 14. The single cation-to-cation substitution with KRT-R at the site of 125 from arginine (R) to either lysine (K) or histidine (H) results in the peptide helices, KRT-K and KRT-H, sharing 96% sequence identity. These KRT-derived peptides possess similarities in the folding structures but exhibit divergent self-assembled structures. KRT-R and KRT-K self-assemble into sheets and fibrils, respectively. Whereas KRT-H associates into heterogeneous structures, including sheets, particles, and branched networks. The intrinsic tyrosine fluorescence spectroscopy measurements with the KRT-derived peptides within a temperature range of 25 °C to 95 °C reveal that the heating-triggered structural transitions of KRT-derived peptides are divergent. The alternation of single cationic residue changes the thermodynamic signature of peptide assemblies upon heating. A chemical denaturation experiment with KRT-derived peptides indicates that the intermolecular interactions that govern the supramolecular architectures formed by peptides are distinct. Overall, our work demonstrates the contribution of the interplay among various noncovalent interactions to supramolecular assembly.

A unified protecting group-free approach to two stemarene and two betaerene diterpenoids through a bioinspired two-phase strategy has been developed, and three of them were obtained for the first t...

In the quest for novel allosteric inhibitors of the p38 MAP kinase, we recently described the A-loop regulatory site, identified through molecular modeling studies together with the disclosure of a small molecule hit with a moderate inhibitory profile. Starting from this structure, we subsequently identified two additional hits with simpler molecular structures from an in silico screening study, using a substructure search in the SciFinder database. After corroboration of their inhibitory profile, analysis of their structures permitted to conclude about the suitability of the [1,2,5]oxadiazolo[3,4-b]pyrazine (furazano[3,4-b]pyrazine) scaffold for the development of potent A-loop regulatory site p38 MAP kinase inhibitors. Accordingly, we report the synthesis and pharmacological evaluation of a series of di-substituted analogs with a potent inhibitory profile of p38 MAP kinase, as shown by in vitro assays of their capability to inhibit IL-1β secretion in human monocyte-derived macrophages.

Two pairs of Pt(II) enantiomers ((RR)/(SS)-PyPt, ((RR)/(SS)-Py: N,N'-(1,2-diphenylethane-1,2-diyl)dipicolinamide; (RR)-P/M-QPt, ((RR)/(SS)-Q: N,N'-((1R,2R)-1,2-diphenylethane-1,2-diyl)bis(quinoline-2-carboxamide)) were synthesized, respectively, with good circularly polarized luminescence (CPL) and tunable dissymmetry factors (g) by molecular self-induction with (RR)/(SS)-1,2-diphenylethane-1,2-diamine as carbon chiral sources. In the (RR)-P-QPt and (SS)-M-QPt, specific P- and M-configurations were effectively induced from intrinsic chiral carbon centres (R or S), ingeniously avoiding the racemic mixture formation and chiral separation. Furthermore, the chirality originating from both chiral carbon centres and helicene-like structure improves the g factor significantly, which provides a new molecular design strategy for chiral Pt(II) enantiomers with good CPL properties.

Background: Fragment-based drug discovery in recent times has been explored in the design of highly potent therapeutics. Methods: In this study, we explored the inhibitory dynamics of Compound 38 (Cpd38), a newly synthesized Bromodomain-containing protein 4 bromodomain 1 (BRD4-BD1) protein inhibitor derived from the synthetic coupling of Fragment 47 (Fgt47) into ABBV-075 scaffold. Using dynamic simulation methods, we unraveled the augmentative effects of chemical fragmentation on improved BRD4- BD1 inhibition. Results: Findings from this study revealed that although Fgt47 exhibited a considerable ΔGbind, its incorporation into the difluoro-phenoxy pyridine scaffold (Cpd38) notably enhanced the binding affinity. Time-based analyses of interaction dynamics further revealed that the bulkiness of Cpd38 favored its interaction at the BRD4-BD1 active site relative to the fragment. Strikingly, compared to Fgt47, Cpd38 demonstrated high mobility, which could have enabled it to bind optimally and complementarily with key residues of the active site such as Ile146, Asn140, Cys136, Tyr98, Leu94, Val87, Phe83, and Trp81. Discussion: On the contrary, the majority of these interactions were gradually lost in Fgt47, which could further indicate the essence of coupling it with the difluoro-phenoxy pyridine scaffold. Furthermore, Cpd38 had a more altering effect on BRD4-BDI relative to Fgt47, which could also be a result of its higher inhibitory activity. Conclusion: Conclusively, the design of highly potent therapeutics could be facilitated by the incorporation of pharmacologically active small molecule fragments into the scaffold of existing drugs.

The flexibility of aβhairpin structure known as theflapplays a key role in catalytic activity and substrate intake in pepsin-like aspartic proteases. Most of these enzymes share structural and sequential similarity. In the apo form of the proteases, a conserved tyrosine residue in the flap region is in dynamic equilibrium between the normal and flipped states through rotation of theχ1andχ2angles. In this study, we have used apo Plm-II and BACE-1 as model systems. Independent MD simulations of Plm-II and BACE-1 remained stuck either in the normal or flipped state. Metadynamics simulations using side-chain torsion angles (χ1andχ2of tyrosine) as collective variables sampled the transition between the normal and flipped states. Qualitatively, the two states were predicted to be equally populated. The normal and flipped states were stabilised by H-bond interactions to a tryptophan residue and to the catalytic aspartate, respectively. Further, mutation of tyrosine to an amino-acid with smaller side-chain, such as alanine, reduced the flexibility of the flap and resulted in a flap collapse (flap loses flexibility and remains stuck in a particular state). This is in accordance with previous experimental studies, which showed that mutation to alanine resulted in loss of activity in pepsin-like aspartic proteases. Our results suggest that the rotation of the tyrosine side-chain is the key movement that governs flap dynamics and opening of the binding pocket in most pepsin-like aspartic proteases.

Pregnane glycosides are exist in Asclepiadaceae, Apocynaceae, Malpighiaceae, Ranunculaceae and Zygophyllaceae. This is a class of substances with steroids as the mother nucleus and containing a glyosidic bond structure. Modern pharmacology has shown that these compounds are a class of compounds with different structures and multiple biological activities. It has a good development prospect in anti-cancer and anti-tumor directions. This article reviews the chemical structures and biological activities of 345 compounds from 1984 to 2019.

Background: Iminostilbene and 1,2,3-triazole ring containing compounds are considered as beneficial substrates in drug design. Objectives: This study was aimed at the synthesis of novel series of iminostilbene linked 1,2,3- triazole pharmacophores (7c-n) by Cu(I) catalyzed 1,3 dipolar cycloaddition reaction between 5- (Prop-2-yn-1-yl)-5H-dibenzo[b,f]azepine (7b) and various substituted azidobenzene derivatives (3cn). Methods: The chemical structures of compounds were confirmed by 1H NMR, 13C NMR, LC-MS and molecular docking studies were carried out through HEX docking software. Results: The in vivo anti anxiety capacity of the compounds was evaluated by using “elevated plus maze” (EPM), anxiety model. The results exhibited that compounds (7d, 7e, 7j and 7k) have a higher anti anxiety effect close to diazepam. The anti-inflammatory activities of the synthesized compounds were evaluated by “Carrageenan-induced rat paw edema” model, compounds (7b, 7c, 7d, 7f, and 7j) demonstrated statistically significant inflammatory activity. Molecular docking analysis revealed that compounds (7d, 7e and 7j) bound to GABA(A) proteins show more efficiency when compared to the other analogues in the series. Conclusion: These results suggest that compounds (7b, 7c, 7d, 7e, 7f, and 7j) can be considered as novel candidates for anti-anxiety and anti-inflammatory agents. Moreover, docking method was used to elucidate anti-anxiety effect of compounds. This study furnished insight into the molecular interactions of synthesized compounds with their physiological targets, and the potential to develop bioactive heterocyclic compounds.

A new, highly modified fatty acid ester, funitatin A (1), was isolated from the Yellow River wetland-derived fungus Talaromyces funiculosus HPU-Y01 cultivated with the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA). The structure of 1 was established by analysis of NMR and HRESIMS data. Compound 1 featured a rare dimeric cyclopaldic acid structure and showed promising antimicrobial activity against both Proteus species and Escherichia coli with MIC values of 3.13 μM.

Background and Objectives: SM-1 is a new synthetic small molecule compound with antitumor activity. The metabolism of SM-1 is a key parameter that needs to be evaluated to provide further insight into drug safety and efficacy in the early phases of drug development. Methods and Results: In this study, the biotransformation process of SM-1, including the metabolic pathways and major metabolites, was investigated based on a liquid chromatography-mass spectrometry method. Upon incubation of SM-1 with human liver microsomes, five metabolites were identified, namely dihydrodiol formation (R1), hydroxylation (R2, R3, and R5), and debenzylation (R4) of SM-1, with R1 and R4 being the major metabolites. The enzyme kinetic parameters of SM-1 were determined by a liquid chromatography-tandem mass spectrometry method. The enzyme kinetics of SM-1 obeyed the Michaelis-Menten equation. The Vmax, Km, and CLint of SM-1 in HLMs were 14.5 nmol/mg protein/h, 6.32 μM, and 2.29 mL/mg protein/h, respectively. Results: The chemical inhibition studies showed that CYP450 isoenzymes were responsible for SM-1 metabolism in HLMs, and CYP3A4 was the major CYP450 isoenzyme involved in the metabolism of SM-1; these findings were confirmed by using the human recombinant CYP3A4. Conclusion: Through the identification of the biotransformation pathways and enzyme kinetics of SM-1, the metabolic enzymes for SM-1 in HLMs are characterized.

The phosphorothioate (PS) linkage in an essential component of therapeutic oligonucleotides. PS in the DNA region of gapmer antisense oligonucleotides (ASOs) supports RNaseH1 activity and enhances nuclease stability. PS also promotes binding to plasma, cell surface, and intracellular proteins, which facilitates tissue distribution, cellular uptake, and endosomal escape of PS ASOs. We recently showed that site-specific replacement of PS in the DNA gap with methoxylpropyl phosphonate (MOP) linkages can enhance the therapeutic index of gapmer ASOs. In this article, we explored 18 phosphorus- and non-phosphorus-based neutral backbone modifications to determine the structure-activity relationship of neutral linkages for enhancing therapeutic index. Replacing MOP with other alkyl phosphonate and phosphotriester linkages enhanced therapeutic index, but these linkages were susceptible to chemical degradation during oligonucleotide deprotection from solid supports following synthesis. Replacing MOP with non-phosphorus linkages resulted in improved chemical stability, but these linkages were introduced into ASOs as nucleotide dimers, which limits their versatility. Overall, linkages such as isopropyl and isobutyl phosphonates and O-isopropyl and O-tetrahydrofuranosyl phosphotriesters, formacetal, and C3-amide showed improved activity in mice relative to MOP. Our data suggest that site-specific incorporation of any neutral backbone linkage can improve therapeutic index, but the size, hydrophobicity, and RNA-binding affinity of the linkage influence ASO activity.

Three previously undescribed triquinane type sesquiterpenoids, antrodiellins A‒C (1‒3), together with three known analogues 4‒6, were isolated from wild fungus Antrodiella albocinnamomea. Their structures were elucidated by means of spectroscopic analysis and single crystal X-ray diffraction. Compounds 3 and 4 exhibited weak inhibitions against Staphylococcus aureus with MIC values of 128 and 64 μg/mL, respectively.

Two new azaphilones, penicilazaphilones F (1) and G (2) together with two known analogs (3 and 4), were isolated from fermentation cultures of the marine-derived fungus Penicillium sclerotiorum E23Y-1A. Their structures were elucidated based on spectroscopic methods, including IR, MS, 1D and 2D NMR, as well as by comparison with published data. The absolute configuration of compound 1 was unambiguously determined using electronic circular dichroism (ECD) calculation. All isolated compounds were evaluated for their anti-inflammatory effects. Compounds 1-4 inhibited the lipopolysaccharide-induced production of nitric oxide (NO) in BV-2 cells, with IC50 values of 31.7 ± 1.5, 34.5 ± 1.4, 25.3 ± 2.2, and 34.8 ± 1.9 μM, respectively. In contrast, these compounds showed no obvious cytotoxicity at a concentration of 50.0 μM.