Design,Synthesis, In Vitro Antimicrobial,Antioxidant Evaluation,and Molecular Docking Study of Novel Benzimidazole and Benzoxazole Derivatives

A series of novel 2‐substituted benzimidazole and benzoxazole derivatives as a potential antimicrobial and antioxidant agent were synthesized via coupling of N‐methyl‐o‐phenylenediamine or 2‐amino‐phenol with aromatic aldehyde and acid in the presence of polyphosphoric acid as an efficient catalyst as well as solvent by conventional method in short reaction times with excellent yield. The newly synthesized benzimidazole and benzoxazole derivatives were evaluated for antimicrobial and antioxidant activity and exhibited excellent to good activities compared to the standard drugs. Furthermore, the theoretical predictions based on molecular docking against microbial DNA gyrase could provide an insight into the plausible mechanism of action and establish a link between the observed antimicrobial activity and the binding affinity shedding light on specific thermodynamic (bonded and nonbonded) interactions governing the activity. Furthermore, the synthesized compounds were analyzed for absorption, distribution, metabolism, and excretion properties and exhibited potential properties to build up as good oral drug candidates.     

Efficient one-pot synthesis of tryptamines and tryptamine homologues by amination of chloroalkynes

A new method was developed for the one-pot synthesis of substituted 3-(2-aminoethyl)- and 3-(3-aminopropyl)indoles from commercially available aryl hydrazines and chloroalkylalkynes. Various tryptamine derivatives were prepared directly in good yield with excellent regioselectivity. The method involves a new domino reaction sequence consisting of a titanium-catalyzed amination of the chloroalkylalkyne, [3+3]-rearrangement of the resulting aryl hydrazone, and nucleophilic substitution of the chloride by ammonia.     

Cascade Syntheses Routes to the Centrocountins

Cascade and domino reactions that proceed through multiple steps in one pot and include multiple bond formations are promising methods for the rapid and efficient generation of complex molecular architectures, including the scaffolds of classes of complex natural product. We describe the development of various one‐pot cascade reaction sequences to yield centrocountins, which are tetracyclic indole derivatives with the basic scaffold of numerous polycyclic alkaloids. The mechanistic investigation of a sequence employing readily available alkynes and 3‐formylchromones as starting materials provided evidence that this one‐pot synthesis proceeds through at least twelve consecutive transformations and includes at least nine different chemical reactions, making it the longest cascade reaction sequence known to date. We describe the scope and limitations of the cascade synthesis approaches and the development of an enantioselectively catalyzed centrocountin synthesis.     

Mass Spectrometry Based Mechanistic Insights into Formation of Tris Conjugates: Implications on Protein Biopharmaceutics

We present here extensive mass spectrometric studies on the formation of a Tris conjugate with a therapeutic monoclonal antibody. The results not only demonstrate the reactive nature of the Tris molecule but also the sequence and reaction conditions that trigger this reactivity. The results corroborate the fact that proteins are, in general, prone to conjugation and/or adduct formation reactions and any modification due to this essentially leads to formation of impurities in a protein sample. Further, the results demonstrate that the conjugation reaction happens via a succinimide intermediate and has sequence specificity. Additionally, the data presented in this study also shows that the Tris formation is produced in-solution and is not an in-source phenomenon. We believe that the facts given here will open further avenues on exploration of Tris as a conjugating agent as well as ensure that the use of Tris or any ionic buffer in the process of producing a biopharmaceutical drug is monitored closely for the presence of such conjugate formation.

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Graphical Abstract ?

     

Maturation of auditory temporal integration and inhibition assessed with event-related potentials (ERPs)

Background

We examined development of auditory temporal integration and inhibition by assessing electrophysiological responses to tone pairs separated by interstimulus intervals (ISIs) of 25, 50, 100, 200, 400, and 800 ms in 28 children aged 7 to 9 years, and 15 adults.

Results

In adults a distinct neural response was elicited to tones presented at ISIs of 25 ms or longer, whereas in children this was only seen in response to tones presented at ISIs above 100 ms. In adults, late N1 amplitude was larger for the second tone of the tone pair when separated by ISIs as short as 100 ms, consistent with the perceptual integration of successive stimuli within the temporal window of integration. In contrast, children showed enhanced negativity only when tone pairs were separated by ISIs of 200 ms. In children, the amplitude of the P1 component was attenuated at ISIs below 200 ms, consistent with a refractory process.

Conclusions

These results indicate that adults integrate sequential auditory information into smaller temporal segments than children. These results suggest that there are marked maturational changes from childhood to adulthood in the perceptual processes underpinning the grouping of incoming auditory sensory information, and that electrophysiological measures provide a sensitive, non-invasive method allowing further examination of these changes.     

Synthesis,Antimicrobial Evaluation,and Docking Studies of Substituted Acetylphenoxymethyl‐triazolyl‐N‐phenylacetamides

A series of molecules containing acetylphenoxymethyl, triazole, and N‐phenylacetamide moieties were synthesized via the click chemistry approach. All the synthesized compounds were screened for their antimicrobial activities in vitro. The synthesized compounds 8a , 8b , 8m , and 8n showed better activities. We further performed exploratory docking studies to gain some insight regarding the molecular mechanism of antibacterial action of these compounds that could guide further structure‐activity relationship (SAR) studies. We examined the interaction of the most active compound with DNA gyrase (pdb id:1KZN). Based on antimicrobial and docking studies, the compounds 8a , 8b , 8m , and 8n were identified as potential antimicrobial agents.     

New pimarane diterpenes and other antimycobacterial metabolites from Anisochilus verticillatus

Phytochemical investigation of the acetone extract of the aerial parts of Anisochilus verticillatus afforded a new 8,9-secopimarane diterpene (1), two new isopimarane diterpenes (2, 3) and the known ursolic acid (4), α-amyrin (5), β-amyrin (6), stigmast-5-en-3-one (7) and hydroxychavicol (8). Structures of the new compounds were elucidated with the help of 1D and 2D nuclear magnetic resonance spectroscopic data, and single crystal X-ray crystallography of compound 3. Compounds 2 and 8 inhibited Mycobacterium tuberculosis H37Ra with an IC₅₀ of 11.3 (IC₉₀ of 20.0 μg/mL) and 12.5 μg/mL, respectively. Correspondingly, molecular docking studies with Extra Precision Glide revealed a correlation between score and biological activity for these compounds to describe the molecular basis for the most significant SAR results.     

In vitro and ex vivo antitubercular activity of diarylheptanoids from the rhizomes of Alpinia officinarum Hance

Phytochemical investigation of methanol extract of the rhizomes of Alpinia officinarum Hance afforded four known diarylheptanoids 1,7-diphenylhept-4-en-3-one (1), 5-hydroxy-1,7-diphenyl-3-heptanone (2), 5-hydroxy-7-(4″-hydroxy-3″-methoxyphenyl)-1-phenyl-3-heptanone (3), and 7-(4″-hydroxy-3″-methoxyphenyl)-1-phenyl heptan-3-one (4).The acetate derivative of (4), 7-(4″-actetate-3″-methoxy phenyl)-1-phenyl heptan-3-one (5), was prepared. These diarylheptanoids exhibited promising in vitro and ex vivo antitubercular activity for the first time against dormant Mycobacterium tuberculosis H37Ra with the IC₅₀ values between 0.34–47.69 and 0.13–22.91 μM, respectively. All compounds showed comparable activity against Mycobacterium bovis BCG (dormant phage) and did not show any activity against two gram + ve and two gram –ve bacterial strains. These compounds were also weakly cytotoxic up to 300 μM against three human cancer cell lines THP-1, Panc-1 and A549.