Nitration Of Phenols Under Mild And Heterogeneous Conditions

Synthesis and Structure-Activity Relationship Studies of Novel Aryl Sulfonamides and Their Activity against Human Breast Cancer Cell Lines

A series of structural analogs of aryl sulfonamide hybrid compounds were synthesised and their cytotoxic activity was evaluated against three human breast cancer cell lines (MCF-7, MDA-MB-231 and Hs 578T). The compounds were designed through electronic, hydrophobic and steric modifications using the chemical structure of N-{4-[(2-hydroxy-3-methoxy-5-propylphenyl)sulfamoyl]phenyl}acetamide (referred to as compound 7) as a starting point to then assess a structure-activity relationship (SAR) study. From the data generated, we observed that compounds 9, 10 and 11 (which have modifications in the substituents of the aryl sulfonamide), efficiently reduced the cell viability of MCF-7 and MDA-MB-231 cell cultures. Based on initial data, we selected compounds 10 and 11 for further investigations into their antiproliferative and/or cytotoxic profile against MDA-MB-231 cells, and we noted that compound 10 was the most promising compound in the series. Compound 10 promoted morphological changes and altered the dynamics of cell cycle progression in MDA-MB-231 cells, inducing arrest in G1/S transition. Taken together, these results show that the dihydroeugenol-aryl-sulfonamide hybrid compound 10 (which has an electron withdrawing nitro group) displays promising antiproliferative activity against MDA-MB-231 cell lines.

2-Methoxyethyl Nitrite as a Reagent for Chemoselective On-Water Nitration

An on-water approach has been developed that allows a nitration of tyrosines and phenols under mild conditions. We envisioned that the assembly of tyrosine/tyrosyl radical couples with interfacial water molecules would realize a biomimetic stacking hydrogen atom transfer (HAT) transition state to facilitate the electron-transfer process. The optimal organic nitrite, 2-methoxyethyl nitrite, resulted in rapid coupling of the tyrosyl radicals with •NO 2 at the oil-water interface to afford the nitrated phenols. Many characteristics found in our on-water strategy are distinct from other complementary systems that include radical nitration. These enticing roles of water in the reaction process introduce new avenues to explore in the design of synthetic organic chemistry systems.

Phenylpropanoid-based sulfonamide promotes cyclin D1 and cyclin E down-regulation and induces cell cycle arrest at G1/S transition in estrogen positive MCF-7 cell line

Cancer is one of the most critical problems of public health in the world and one of the main challenges for medicine. Different biological effects have been reported for sulfonamide-based compounds including antibacterial, antifungal, and antitumor activities. Herein, a series of phenylpropanoid-based sulfonamides (4a, 4a', 4b, 4b', 5a, 5a', 5b and 5b') were synthesized and their cytotoxic activity was evaluated against four cell lines derived from human tumours (A549 - lung, MCF-7 - breast, Hep G2 - hepatocellular carcinoma, and HT-144-melanoma). Cell viability was significantly reduced in the MCF-7 cell line when compounds 4b, 4b' and 5a were used; IC₅₀ values were lower than those found for their precursors (eugenol and dihydroeugenol) and sulfanilamide. We observed that 4b induced cell cycle arrest at G1/S transition. This is probably due to its ability to reduce cyclin D1 and cyclin E expression. Moreover, 4b also induced apoptosis in MCF-7 cells as demonstrated by an increase in the cell population positive for annexin V in treated cultures in comparison to the control group. Taken together, the data showed that 4b is a promising antitumor agent and it should be considered for further in vivo studies.

Antifungal Activity of New Eugenol-Benzoxazole Hybrids against Candida spp

Eugenol is a natural allylphenol responsible for a wide range of biological activities, especially antimicrobial. Benzoxazoles are heterocycles with recognized antimicrobial activities. This paper describes the design, synthesis, and the biological results for benzoxazole type derivatives of eugenol as antifungal agents. The products were obtained in good yields by a four-step synthetic sequence involving aromatic nitration, nitroreduction, amide formation, and cycle condensation. They were evaluated against species of Candida spp. in microdilution assays, and four products (5a, 5b′, 5c, and 5d′) were about five times more active than eugenol against C. albicans and C. glabrata. Two of them (5b′ and 5d′) showed good activity against C. krusei, a species which is naturally resistant to fluconazole. Furthermore, the active products were more selective than eugenol against human blood cells, showing that they are interesting substances for further optimization.

Analysis of Nitrite and Nitrate in Foods: Overview of Chemical, Regulatory and Analytical Aspects

In this chapter, several factors that should be considered for selecting and developing suitable analytical methods for determining nitrite/nitrate are presented. Nitrite and nitrate occurrence and suitability are a controversial issue. Nitrite is an approved additive considered a foremost curing ingredient for the preservation of meat products. Nitrate is a natural constituent of the human diet that, however, raises fears for its suggested potential harmfulness related to carcinogenesis and environmental contamination. Chemical, regulatory, and analytical aspects are discussed in the light of the need to obtain reliable data of nitrite and nitrate for law enforcement purposes, exposure estimates, and investigation of their physiological role in the human body. In addition, current metrological aspects to ensure the "fitness for purpose" of the selected method are suggested and discussed.

Operative conversions of 3-carboxy-4-quinolones into 3-nitro-4-quinolones via ipso-nitration: potential antifilarial agents as inhibitors of Brugia malayi thymidylate kinase

An efficient, cost effective and green methodology for ipso nitration in the synthesis of the 3-nitro derivative of 3-carboxy 4-quinolones has been developed by the quantitative use of copper acetate and silver nitrate in water.

Energetic salts prepared from phenolate derivatives

Energetic salts with 1 : 1, 2 : 1, and 3 : 1 charge ratios (cation : anion) based on various nitrogen-rich cations and phenolate anions have been synthesized by a straightforward and simple method.

Highly Efficient Nitration of Phenolic Compounds using Some Nitrates and Oxalic Acid under Solvent-Free Conditions

Nitrophenols can be obtained by direct nitration of phenols with some nitrates and oxalic acid at room temperature in moderate to high yields under solvent-free conditions. A small amount of water proved to be important in the initial period of the reaction.

Ultrasound promoted regioselective nitration of phenols using dilute nitric acid in the presence of phase transfer catalyst

Phenols are selectively nitrated to o-nitrophenol along with rate enhancement using dilute nitric acid (6 wt%)/tetra butyl ammonium bromide (TBAB) under sonication. The selectivity can also be reversed to p-nitrophenol using NaBr as a catalyst. Kinetic analysis of nitration of phenol both with and without sonication has been investigated by variation of reaction parameters such as catalyst, nitric acid and substrate concentration.