Palladium-Catalyzed Dearomatization of Benzothiophenes: Isolation and Functionalization of a Discrete Dearomatized Intermediate

A Pd-catalyzed decarboxylative dearomatization reaction of a heterocyclic substrate enables access to an uncommon reaction intermediate that rearomatizes in the presence of amine bases in a net C-H functionalization sequence. The dearomatized benzo[b]thiophene intermediate bears an exocyclic alkene that can be functionalized through cycloaddition and halogenation reactions to deliver complex heterocyclic products.

Chemical-guided SHAPE sequencing (cgSHAPE-seq) informs the binding site of RNA-degrading chimeras targeting SARS-CoV-2 5' untranslated region

One of the hallmarks of RNA viruses is highly structured untranslated regions (UTRs) in their genomes. These conserved RNA structures are often essential for viral replication, transcription, or translation. In this report, we discovered and optimized a new type of coumarin derivatives, such as C30 and C34, which bind to a four-way RNA helix called SL5 in the 5' UTR of the SARS-CoV-2 RNA genome. To locate the binding site, we developed a novel sequencing-based method namely cgSHAPE-seq, in which the acylating chemical probe was directed to crosslink with the 2'-OH groups of ribose at the ligand binding site. This crosslinked RNA could then create read-through mutations during reverse transcription (i.e., primer extension) at single-nucleotide resolution to uncover the acylation locations. cgSHAPE-seq unambiguously determined that a bulged G in SL5 was the primary binding site of C30 in the SARS-CoV-2 5' UTR, which was validated through mutagenesis and in vitro binding experiments. C30 was further used as a warhead in RNA-degrading chimeras to reduce viral RNA expression levels. We demonstrated that replacing the acylating moiety in the cgSHAPE probe with ribonuclease L recruiter (RLR) moieties yielded RNA degraders active in the in vitro RNase L degradation assay and SARS-CoV-2 5' UTR expressing cells. We further explored another RLR conjugation site on the E ring of C30/C34 and discovered improved RNA degradation activities in vitro and in cells. The optimized RNA-degrading chimera C64 inhibited live virus replication in lung epithelial carcinoma cells.

Structural and Biological Evaluations of a Non-Nucleoside STING Agonist Specific for Human STINGA230 Variants

Previously we identified a non-nucleotide tricyclic agonist BDW568 that activates human STING (stimulator of interferon genes) gene variant containing A230 in a human monocyte cell line (THP-1). STINGA230 alleles, including HAQ and AQ, are less common STING variants in human population. To further characterize the mechanism of BDW568, we obtained the crystal structure of the C-terminal domain of STINGA230 complexed with BDW-OH (active metabolite of BDW568) at 1.95 Å resolution and found the planar tricyclic structure in BDW-OH dimerizes in the STING binding pocket and mimics the two nucleobases of the endogenous STING ligand 2',3'-cGAMP. This binding mode also resembles a known synthetic ligand of human STING, MSA-2, but not another tricyclic mouse STING agonist DMXAA. Structure-activity-relationship (SAR) studies revealed that all three heterocycles in BDW568 and the S-acetate side chain are critical for retaining the compound's activity. BDW568 could robustly activate the STING pathway in human primary peripheral blood mononuclear cells (PBMCs) with STINGA230 genotype from healthy individuals. We also observed BDW568 could robustly activate type I interferon signaling in purified human primary macrophages that were transduced with lentivirus expressing STINGA230, suggesting its potential use to selectively activate genetically engineered macrophages in macrophage-based approaches, such as chimeric antigen receptor (CAR)-macrophage immunotherapies.

Cellular Target Deconvolution of Small Molecules Using a Selection-Based Genetic Screening Platform

Small-molecule drug target identification is an essential and often rate-limiting step in phenotypic drug discovery and remains a major challenge. Here, we report a novel platform for target identification of activators of signaling pathways by leveraging the power of a clustered regularly interspaced short palindromic repeats (CRISPR) knockout library. This platform links the expression of a suicide gene to the small-molecule-activated signaling pathway to create a selection system. With this system, loss-of-function screening using a CRISPR single-guide (sg) RNA library positively enriches cells in which the target has been knocked out. The identities of the drug targets and other essential genes required for the activity of small molecules of interest are then uncovered by sequencing. We tested this platform on BDW568, a newly discovered type-I interferon signaling activator, and identified stimulator of interferon genes (STING) as its target and carboxylesterase 1 (CES1) to be a key metabolizing enzyme required to activate BDW568 for target engagement. The platform we present here can be a general method applicable for target identification for a wide range of small molecules that activate different signaling pathways.

Molecular Iodine-Promoted [3 + 2] Oxidative Cyclization for the Synthesis of Heteroarene-Fused [1,2,4] Thiadiazoles/Selenadiazoles

Two new classes of heteroarene-fused [1,2,4]thiadiazole and [1,2,4]selenadiazole are synthesized through the iodine-mediated [3 + 2] oxidative cyclization of 2-aminoheteroarenes and isothiocyanates/isoselenocyanates. This oxidative [3 + 2] annulation strategy is highly regiospecific to proceed a selective C-N bond formation at the endo-nitrogen of 2-aminoheteroarenes followed by an intramolecular oxidative N-S/N-Se bond formation. It is the first example of an I₂-mediated oxidative nitrogen-selenium (N-Se) bond formation.

Connecting remote C-H bond functionalization and decarboxylative coupling using simple amines

Transition metal-catalyzed C–H functionalization and decarboxylative coupling are two of the most notable synthetic strategies developed in the last 30 years. Herein, we connect these two reaction pathways using bases and a simple Pd-based catalyst system to promote a para-selective C–H functionalization reaction from benzylic electrophiles. Experimental and computational mechanistic studies suggest a pathway involving an uncommon Pd-catalyzed dearomatization of the benzyl moiety followed by a base-enabled rearomatization through a formal 1,5-hydrogen migration. This reaction complements “C–H activation” strategies that convert inert C–H bonds into C–metal bonds prior to C–C bond formation. Instead, this reaction exploits an inverted sequence and promotes C–C bond formation prior to deprotonation. These studies provide an opportunity to develop general para-selective C–H functionalization reactions from benzylic electrophiles and show how new reactive modalities may be accessed with careful control of reaction conditions.

One-Pot Synthesis of Unsymmetrical Bis-Heterocycles: Benzimidazole-, Benzoxazole-, and Benzothiazole-Linked Thiazolidines

A one-pot, three-component synthesis of benzimidazole-linked thiazolidines from 2-cyanomethyl benzimidazole, iso-, isothio-, or isoselenocyanates and 1,2-dichloroethane is reported. Isolation of the key intermediate formed during the course of the reaction validates its mechanistic pathway. Under the same reaction conditions, benzimidazole-linked/fused thiazinanes were obtained when 1,3-dichloropropane or diiodomethane was used.

Phycoremediation resultant lipid production and antioxidant changes in green microalgae Chlorella Sp

In this investigation, we report on the treatment of tannery wastewater using microalgae Chlorella species to produce lipid and fatty acid as well as changes in antioxidant metabolism during the treatment. The variation in growth, production of pigments, antioxidant metabolism, lipid and fatty acids, and nutrient removal from wastewater during the remediation were observed. Surprisingly, a profuse growth was found in 50% diluted tannery wastewater (TW), which supported to accumulate high yield of lipid (18.5%) and unsaturated fatty acids (50.05%). The antioxidant activity of microalgae in both the concentrations (50% and 100% TW) were viz., lipid peroxidation 1.6 ± 0.1 and 2.3 ± 0.02nmol MDA mg^-1 protein, SOD 10.3 ± 0.4 and 15.7 ± 0.9 U mg^-1 protein, CAT 0.17 ± 0.036 and 0.52 ± 0.06 U mg^-1 protein, and APX 7.2 ± 0.8 and 11.2 ± 09 U mg^-1 protein respectively, which point out that the free radical scavenging mechanism against heavy metal stress. Maximum phycoremediation of heavy metals observed from both concentrations during the healthy growth period were Cr - 73.1, 45.7%, Cu - 90.4, 78.1%, Pb - 92.1, 52.2%, and Zn - 81.2, 44.6%, respectively. This study proved the potential use of Chlorella for heavy metal and nutrient removal from tannery wastewater. Moreover, an unaffected growth with high antioxidant activity of this species promises a sustainable lipid and fatty acid contents for biofuel production.

Regioselective Synthesis of Pyranone-Fused Indazoles via Reductive Cyclization and Alkyne Insertion

A novel and efficient method for the one-pot synthesis of 2 H-indazole from readily available building blocks is reported. The reaction of 2-nitrobenzylamines with zinc and ammonium formate underwent partial reduction to nitroso-benzylamine followed by an intramolecular cyclization to afford 2 H-indazole via N-N bond formation. The carboxylic acid moiety of indazole was proceeded to regioselective alkyne insertion under ruthenium catalysis to form pyranone-fused indazoles. The regioselectivity is influenced by the weak coordination of indazole ring nitrogen to the metal center.

Ruthenium(ii)-catalyzed C–H alkenylation/annulation cascade for the rapid synthesis of benzoimidazoisoindoles

A one pot synthesis of benzimidazole-fused isoindoles from 2-arylbenzimidazole and conjugated alkenes has been explored. The strategy involved the ruthenium-catalyzed formation of C–C and C–N bonds and a new five-membered ring.

One-pot synthesis of benzazoles and quinazolinones via iron pentacarbonyl mediated carbonylation of aryl iodides under microwave irradiation

A direct and unconventional method for the synthesis of benzazoles and quinazolinones is discovered by using iron pentacarbonyl as a reducing agent and a solid carbon monoxide source under microwave irradiation.

Copper catalyzed aerobic oxidative cyclization and ketonization: one pot synthesis of benzoimidazo[1,2-a]imidazolones

A highly efficient synthesis of benzoimidazo[1,2-a]imidazolone through a novel oxidative 5-exo-dig cyclization-ketonization cascade of 2-aminobenzimidazole, aldehyde and terminal alkyne has been explored under aerobic conditions.

Occurrence of <i>Microcystis</i> <i>aeruginosa</i> Kütz. Water Blooms in a Eutrophic Pond of Chidambaram Taluk

The occurrence and abundance of Microcystisaeruginosa were monitored monthly in eutrophic pond water of Ilamiyakkinar temple pond from July 2014 to June 2015. Some environmental factors such as water temperature, pH, free carbon-dioxide (FCO2), total alkalinity, Dissolved oxygen (DO2), biological oxygen demand (BOD), nitrate (NO2-N) and phosphate are recorded and their relationship with the bloom formation by Microcystisaeruginosa were discussed. The initiation and persistence of Microcystisaeruginosa were founded to be triggered by relatively high water temperature (24 °C to 36.5 °C), pH (7.3 to 8.72) and NO2-N concentration.

Occurrence of <i>Microcystis</i> <i>aeruginosa</i> Kütz. Water Blooms in a Eutrophic Pond of Chidambaram Taluk

The occurrence and abundance of Microcystisaeruginosa were monitored monthly in eutrophic pond water of Ilamiyakkinar temple pond from July 2014 to June 2015. Some environmental factors such as water temperature, pH, free carbon-dioxide (FCO2), total alkalinity, Dissolved oxygen (DO2), biological oxygen demand (BOD), nitrate (NO2-N) and phosphate are recorded and their relationship with the bloom formation by Microcystisaeruginosa were discussed. The initiation and persistence of Microcystisaeruginosa were founded to be triggered by relatively high water temperature (24 °C to 36.5 °C), pH (7.3 to 8.72) and NO2-N concentration.

Dynamics of Micro Algae in Relation to Water Quality Parameters of Pasupatheswarar Temple Pond, Annamalai Nagar, Tamil Nadu

The current study deals with water quality variations and micro algal community structure in the highly eutrophic pond. Several water quality parameters were evaluated during the period from July 2014 to June 2015 from sampling station sited from Annamalai Nagar viz., Pasupatheswarar temple pond. The water quality parameters like Air and water temperature, turbidity, electrical conductivity, total dissolved solids, total alkalinity, pH, free carbon-dioxide, dissolved oxygen, biological oxygen demand (BOD), chemical oxygen demand (COD), calcium, magnesium, phosphate and nitrate were analysed. A total 29 species were observed during the study period of which 11 species from the class Cynophyceae, 9 species from the class Chlorophyceae, 6 species from the class Bacillariophyceae and 3 species from the class Euglenophyceae. Maximum species of the class Cyanophyceae were observed during study period. The Microcystisaeruginosa species observed in the pond indicates the signs of eutrophication of pond. The water quality parameters such as temperature, alkalinity, phosphate and nitrates are favourable for the growth of phytoplankton.

Toxic Effect of Zinc on Growth and Nutrient Accumulation of Cow Pea (<i>Vigna unguiculata</i> L.)

Zinc is a heavy metal; this element is considered as environmental hazard.Toxicity effects of Zinc on growth and development of plants including inhibition of germination process decrease of growth and biomass of plant. The aim of this research is to study accumulation of Zinc along with nutrients and its effect on the growth of Cow pea plant (Vignaunguiculata.L). Thus, cow pea seedlings grown in petriplates lined with filter paper undergoing, different treatments of Zinc (control, 10, 25, 50, 75, 100, 150 and 200 ppm). After one week seedlings were removed and morpho physiological parameters like root length, shoot length and dry weight of plants and accumulation of nutrients along with Zinc in roots and shoots were determined. The results indicated that the concentrations more than Zinc 50 mg/L zinc cause the reduction of morphophysiology parameters in the treatment plants rather than control plant and zinc addition in the cultures caused enhancement of zinc content in roots and shoots of cow pea seedlings. Similarly nutrient accumulation also affected by increasing concentrations of cow pea. It was also noted that accumulation of zinc in the roots was much higher than the shoots of the seedlings under treatment.

Toxic Effect of Zinc on Growth and Nutrient Accumulation of Cow Pea (<i>Vigna unguiculata</i> L.)

Zinc is a heavy metal; this element is considered as environmental hazard.Toxicity effects of Zinc on growth and development of plants including inhibition of germination process decrease of growth and biomass of plant. The aim of this research is to study accumulation of Zinc along with nutrients and its effect on the growth of Cow pea plant (Vignaunguiculata.L). Thus, cow pea seedlings grown in petriplates lined with filter paper undergoing, different treatments of Zinc (control, 10, 25, 50, 75, 100, 150 and 200 ppm). After one week seedlings were removed and morpho physiological parameters like root length, shoot length and dry weight of plants and accumulation of nutrients along with Zinc in roots and shoots were determined. The results indicated that the concentrations more than Zinc 50 mg/L zinc cause the reduction of morphophysiology parameters in the treatment plants rather than control plant and zinc addition in the cultures caused enhancement of zinc content in roots and shoots of cow pea seedlings. Similarly nutrient accumulation also affected by increasing concentrations of cow pea. It was also noted that accumulation of zinc in the roots was much higher than the shoots of the seedlings under treatment.

Microwave Controlled Reductive Cyclization: A Selective Synthesis of Novel Benzimidazole-alkyloxypyrrolo[1,2-a]quinoxalinones

An efficient cascade synthesis of novel benzimidazole linked alkyloxypyrrolo[1,2-a]quinoxalinones was explored on soluble polymer support under microwave irradiation. Two exclusive protocols have been developed for the partial and full reductive cyclization by controlling the microwave energy. Commencing from the same substrate, ortho nitro pyrrol carboxylates, N-hydroxy pyrroloquinoxalinones were obtained by partial reductive cyclization (60 °C, 7 min), and the synthesis of pyrroloquinoxalinones was accomplished by full reductive cyclization (85 °C, 12 min). This method represents the first synthesis of N-hydroxy pyrroloquinoxalinones using Pd/C and ammonium formate as reducing agents. Further employing a variety of alkyl bromides, the obtained pyrroloquinoxalinones were transformed to their corresponding O- and N-alkylated analogues to deliver the diversified, novel molecular entities.

Unprecedented one-pot chemocontrolled entry to thioxoimidazolidinones and aminoimidazolones: synthesis of kinase inhibitor leucettamine B

A novel and highly chemoselective protocol for the construction of thioxoimidazolidinone and aminoimidazolone frameworks was explored, and the influence of the reaction conditions on product formation was studied to establish two distinct approaches for their selective formation. In this one-pot reaction, ambient temperature generally resulted in the formation of thioxoimidazolidinones, whereas microwave irradiation provided aminoimidazolones exclusively. An attempt to elucidate the observed chemoselectivity is described, and the products were confirmed by X-ray studies. One-pot synthesis toward Leucettamine B, a marine alkaloid, was achieved on the basis of this protocol.

Parallel synthesis and biological evolution of quinic acid derivatives as immuno-suppressing agents against T-cell receptors

A parallel synthesis of quinic acid derivatives is explored and their biological evolution against T-cells is studied.

Studies on some Physico-Chemical Parameters of Cyanophycean Members and Correlation Coefficient of Eutrophic Ponds in Chidambaram, Tamil Nadu, India

The present study deals with the statistical analysis of physico-chemical parameters and cyanophycean members of two pond water quality of Chidambaram, Cuddalore district (Tamil Nadu). The qualities of pond water were analyzed for six months. Eleven important parameters were included in statistical analysis. The qualities of pond water have been assessed by calculating mean, standard deviation and correlation coefficient. Correlation studies of hydrobiology with physico-chemical parameters revealed that the relationship between phytoplankton density in general and that of the specific groups are highly complex and often controlled by interactions of different factors. In the both pond water the correlation coefficient test revealed that cyanophycean members positively correlated with temperature, pH, CO2, alkalinity, hardness, nitrate, BOD and COD at 1 % and 5 % level significant, where as it is negatively correlated with acidity and dissolved oxygen. In the present study it can be concluded that the cyanophycean members are highly tolerant organisms. They prefer to grow at higher temperatures and in highly alkaline, BOD and COD waters. Hence they can with stand high levels of contaminated waters of Thillai Kali Kovil pond, when compared to Ilamiyakkinar Kovil pond.

Studies on some Physico-Chemical Parameters of Cyanophycean Members and Correlation Coefficient of Eutrophic Ponds in Chidambaram, Tamil Nadu, India

The present study deals with the statistical analysis of physico-chemical parameters and cyanophycean members of two pond water quality of Chidambaram, Cuddalore district (Tamil Nadu). The qualities of pond water were analyzed for six months. Eleven important parameters were included in statistical analysis. The qualities of pond water have been assessed by calculating mean, standard deviation and correlation coefficient. Correlation studies of hydrobiology with physico-chemical parameters revealed that the relationship between phytoplankton density in general and that of the specific groups are highly complex and often controlled by interactions of different factors. In the both pond water the correlation coefficient test revealed that cyanophycean members positively correlated with temperature, pH, CO2, alkalinity, hardness, nitrate, BOD and COD at 1 % and 5 % level significant, where as it is negatively correlated with acidity and dissolved oxygen. In the present study it can be concluded that the cyanophycean members are highly tolerant organisms. They prefer to grow at higher temperatures and in highly alkaline, BOD and COD waters. Hence they can with stand high levels of contaminated waters of Thillai Kali Kovil pond, when compared to Ilamiyakkinar Kovil pond.

Heavy metal induced antioxidant defense system of green microalgae and its effective role in phycoremediation of tannery effluent

Investigation of tannery effluent toxicology in green microalgae is of great importance from ecological point of view, because heavy metal has become a major contaminant in recent years. The present study determined the effect of various concentrations (0, 10, 25, 50, 75 and 100%) of heavy metals containing tannery effluent on cell growth and antioxidant defense system of two green microalgae. Treatment with effluent induced accumulation of reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). Lower tannery effluent concentrations increased algal growth, whereas higher concentration suppressed the growth and photosynthetic content. Both strains of the microalgae had proven effective in removing heavy metals from aqueous solutions with the highest removal efficiency being near 100% and it can be used for phycoremediation of wastewater in large scale.

Multicomponent solvent-free synthesis of benzimidazolyl imidazo[1,2-a]-pyridine under microwave irradiation

A novel one-pot, three-component reaction employing variously substituted benzimidazole-linked amino pyridines, aldehydes, and isonitriles catalyzed by scandium(III) triflate under solvent-free conditions were accomplished. This new synthetic methodology facilitates the rapid generation of intricate molecular frameworks in three-dimensional fashion leading to benzimidazole-imidazo[1,2-a] pyridines. This approach is envisioned as an environmentally benign process and a simple operation to the biological interesting compounds. The present synthetic sequence permits the introduction of three points of structural diversity to expand chemical space with high purity and excellent yields.

Growth and heavy metals accumulation potential of microalgae grown in sewage wastewater and petrochemical effluents

Microalgae exhibit a number of heavy metal uptake process by different metabolism. In this study, the ability of microalgae for removal of heavy metal from wastewater was studied. Growth and biochemical contents of microalgae were determined by spectrophotometer. Heavy metal analysis of wastewater effluents were performed by atomic absorption spectrophotometer before and after treatment at laboratory scale. The growth of Scenedesmus bijuga and Oscillatoria quadripunctulata in sewage wastewater was higher than those grown in synthetic medium. Whereas, the growth of S. bijuga and O. quadripunctulata in sterilized petrochemical effluents was slightly lower than that grown in the standard synthetic medium. The chlorophyll, carotenoid and protein content of S. bijuga and O. quadripunctulata grown in sterilized sewage wastewater were higher than those grown in the standard medium. Similarly S. bijuga and O. quadripunctulata grown in sterilized petrochemical effluents showed lower contents of pigments and protein than those grown in sewage and synthetic medium. Heavy metals copper, cobalt, lead and zinc were removed by 37-50, 20.3-33.3, 34.6-100 and 32.1-100%, respectively from sewage wastewater and petrochemical effluent using Ocillatoria culture. The metal absorption by S. bijuga were (Cu, Co, Pb, Zn) 60-50, 29.6-66, 15.4-25 and 42.9-50%, respectively from sewage and petrochemical effluents. Both species showed high level of heavy metal removal efficiency and metal sorption efficiency of both microalgae depended on the type of biosorbent, the physiological status of the cells, availability of heavy metal, concentration of heavy metal and chemical composition of wastewater.

Perianal condylomata acuminata in a male child

A one year old male child presented with a perianal growth of two months' duration. Clinical and histopathological findings confirmed the diagnosis of condylomata acuminata, which regressed completely following topical treatment with podophyllin.