Nanomaterial assisted bulk scale synthesis of 2-methyl-6-nitroquinoline.

Quinolines are an interesting class of moieties with various medicinal chemistry uses. The most prominent is their ability to be used as the last line of therapy for bacterial and viral infections including recent COVID-19. The synthesis of quinoline is through a cyclization reaction and overall reaction yields are about 20%. The bulky ring and the associated crowding of functional groups limit the catalyst options. In this publication, the use of Fe3O4@SiO2 for enhancing yield improvements, especially for heterocyclics is reported. The use of the 40 nm sized silica functionalized magnetite nanoparticles seems to help in both condensation and cyclization steps of representative 2-methyl-6-nitroquinoline. Reaction time reduction due to surface enabled catalysis of nanoparticles is 110 min to 80 min. The reaction yield has doubled due to the presence of catalyst and the mechanism suggests this drastic result is due to stabilization of unstable intermediate on the acidic surface of the silica coating. This near homogeneous catalysis of 40 nm sized, silica functionalized, magnetite nanoparticles have far reaching applications in bulk drug industry for drugs like chloroquine & hydroxychloroquine, the two essential drugs for prophylactic use for COVID-1.

Biodegradation of phenmedipham by novel Ochrobactrum anthropi NC-1.

An Ochrobactrum anthropi bacterial strain named as NC-1, capable of utilizing phenmedipham (PMP) herbicide as the sole of carbon source and energy for growth was isolated from pesticide-contaminated soil sample by enrichment culture technique. The isolated bacterial strain was identified as Ochrobactrum anthropi NC-1 (MH 796134) based on its morphological, cultural, biochemical characteristics and analysis of 16S rRNA gene sequence. The strain NC-1 could degrade more than 98.5% of PMP (2 mM) within 168 h. The optimal degradation pH and temperature were 7.0 and 30-35 °C, respectively. The strain NC-1 degraded PMP by a pathway involving its initial hydrolysis of their central amide carbamate linkage to yield m-aminophenol via methyl-N-(3-hydroxyphenyl) carbamate and m-toluidine were the major intermediates. However, m-aminophenol was not further metabolized, because they neither supported the growth of organism nor stimulated oxygen uptake. But m-toluidine released by dealkylation was followed by hydrolysis. Further, results also revealed that degradation of 4-methyl catechol proceeded via 2-hydroxy-5-methyl-6-oxohexa-2, 4-dienoate through meta cleavage ring processes. The formation of these compounds was confirmed by UV, TLC, HPLC, IR, NMR, and GC-MS spectral analysis. The cell-free extracts of O. anthropi NC-1 grown on PMP contained the activities of PMP hydrolase, toluidine dioxygenase, and 4-methyl catechol 1, 2-dioxygenase. These results demonstrate the biodegradation of PMP and promote the potential use of strain NC-1 to bioremediate PMP-contaminated environment.

Biodegradation of chlorpropham and its major products by Bacillus licheniformis NKC-1.

Chlorpropham [isopropyl N-(3-chlorophenyl) carbamate] (CIPC), an important phenyl carbamate herbicide, has been used as a plant growth regulator and potato sprout suppressant (Solanum tuberosum L) during long-term storage. A bacterium capable of utilizing the residual herbicide CIPC as a sole source of carbon and energy was isolated from herbicide-contaminated soil samples employing selective enrichment method. The isolated bacterial strain was identified as Bacillus licheniformis NKC-1 on the basis of its morphological, cultural, biochemical characteristics and also by phylogenetic analysis based on 16S rRNA gene sequences. The organism degraded CIPC through its initial hydrolysis by CIPC hydrolase enzyme to yield 3-chloroaniline (3-CA) as a major metabolic product. An inducible 3-CA dioxygenase not only catalyzes the incorporation of molecular oxygen but also removes the amino group by the deamination yielding a monochlorinated catechol. Further, degradation of 4-chlorocatechol proceeded via ortho- ring cleavage through the maleylacetate process. 3-Chloroaniline and 4-chlorocatechol are the intermediates in the CIPC degradation which suggested that dechlorination had occurred after the aromatic ring cleavage. The presence of these metabolites has been confirmed by using ultra-violet (UV), high-performance liquid chromatography (HPLC), thin layer chromatography (TLC), Fourier transmission-infrared (FT-IR), proton nuclear magnetic resonance (1H NMR) and gas chromatography-mass (GC-MS) spectral analysis. Enzyme activities of CIPC hydrolase, 3-CA dioxygenase and chlorocatechol 1, 2-dioxygenase were detected in the cell-free-extract of the CIPC culture and are induced by cells of NKC-1 strain. These results demonstrate the biodegradation pathways of herbicide CIPC and promote the potential use of NKC-1 strain to bioremediate CIPC-contaminated environment with subsequent release of ammonia, chloride ions and carbon dioxide.

Evaluation of p-cresol degradation with polyphenol oxidase (PPO) immobilized in various matrices.

p-Cresol is an environmental pollutant due to its vast use, toxicity and persistence, nevertheless, its degradation in an enzyme is unclear. In this study, we used Pleurotus sp. isolate VLECK02 polyphenol oxidase (PPO) for the determination of p-cresol degradation. On the basis of UV, FT-IR and chromatographic (HPLC and GC-MS) analysis, 4-methylcatechol was identified as the main metabolite of p-cresol catabolism. In addition, batch and semi-continuous degradation of p-cresol (10 and 20 mM) were studied and compared by free and immobilized PPO in different matrices like sodium alginate (SA), sodium alginate-polyvinyl alcohol (SA-PVA) and sodium alginate-polyvinyl alcohol-silver nanoparticles (SA-PVA-AgNPs). The experimental data showed that an enzyme (PPO) immobilized in SA-PVA-AgNPs was completely degraded p-cresol at initial concentrations of 10 and 20 mM within 30 h. These results suggest that the enzyme immobilized in SA-PVA-AgNPs has achieved higher degradation rates at a given time than free PPO and PPO immobilized in SA-PVA and SA. The SA-PVA-AgNPs and SA-PVA immobilized enzyme could be reused for more than 12 and 8 cycles, respectively, without losing any degradation capacity. Moreover, the immobilized PPO showed higher tolerance to various temperatures and pH than free PPO. Hence, immobilized PPO could be useful for the bioremediation of environment contaminated with phenolic compounds like p-cresol.

Synthesis and biological activities of some new fluorinated coumarins and 1-aza coumarins.

A series of new fluorinated coumarins and 1-aza coumarins have been synthesized and the presence of fluorine in these molecules and its effect on their anti-microbial, anti-inflammatory and analgesic activities are discussed. The results of bioassay showed that these newly synthesized compounds containing fluorine exhibit moderate analgesic and excellent anti-inflammatory and potential anti-bacterial and anti-fungal activities, compared to the other halogenated compounds. All the newly synthesized compounds were characterized by elemental analysis, IR, 1H NMR, 13C NMR, 19F NMR, EI-MS, and FAB-MS. The ORTEP diagram of one of the compounds is reported herein.

Biodegradation of DDT by a Pseudomonas species.

A bacterial strain capable of degrading 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) was isolated from insecticide-contaminated soil by biphenyl enrichment culture and identified as a Pseudomonas species. The organism degraded DDT through the intermediate formation of 2,3-dihydroxy-DDT, which undergoes meta-ring cleavage, ultimately yielding 4-chlorobenzoic acid as a stable metabolite.