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Benzocaine
Published in Anton C. de Groot, Monographs in Contact Allergy, 2021
Benzocaine is the ethyl ester of p-aminobenzoic acid, a so-called ‘para-compound’. A such, it can cross-react with related para-compounds, especially if they have an amino group in the para-position of the benzene ring. Cross-reactivity may be observed with other PABA ester-type local anesthetics (tetracaine, procaine, butamben, proparacaine [proxymetacaine], oxybuprocaine [78, 80, 81, 94]), p-phenylenediamine and related chemicals, other (hair) dyes (p-toluenediamine, p-aminophenol, p-aminoazobenzene), azo dyes (disperse blue 106, disperse orange 1, disperse orange 3, disperse red 1, disperse yellow 3), certain sulfonamides, and probably to many other chemicals which may also cross-react to p-phenylenediamine (105).
Laccase-Mediated Synthesis of Novel Antibiotics and Amino Acid Derivatives
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
The aromatic amino group of 4-aminobenzoic acid has decreased basicity because the lone pair of electrons from the nitrogen is delocalized into the ring and could not be used for protonation. In contrast, aliphatic amino groups like the amino group of the amino-ß-lactams have elevated basicity; they are protonated and have to be deprotonated for the amination by Michael addition. The highly reactive quinoid intermediates of 3,4-dihydroxybenzoic acid (64), 3,4-dihydroxyphenylacetic acid (65) and 3-(3,4-dihydroxyphenyl)-propionic acid (66) react to a variety of inseparable homomolecular dimers or oligomers or products formed by abiotic follow-up reactions in addition to the slower formation of heteromolecular dimers (Fig. 8.4).
Uro-Angiographic Contrast Agents—The Holy Grail
Published in Christoph de Haën, X-Ray Contrast Agent Technology, 2019
Sometime earlier it had been found that in rabbits p-aminobenzoic acid was detoxified by acetylation. Suspecting that the acetylated compounds of iodinated aminobenzoic acids might be analogously detoxified, Wallingford directed his efforts at such derivatives. Acetylation of the amino group of 2,4,6-triiodo-3-aminobenzoic acid yielded a highly water-soluble contrast agent with a promisingly low-toxicity, acetrizoate sodium (Figure 4.25, 14) (Wallingford 1950; Wallingford, Decker, and Kruty 1952). It achieved low toxicity without metabolization to a hippurate derivative. Typically for drug discovery research the sequence of insights and actions reflects a logic that appears tortuous. The reason for this is its modification along the way in response to unexpected experimental results.
L. reuteri JMR-01 adjuvant 12C6+ irradiation exerts anti-colon carcinoma effects by modulating the gut microbiota in mice
Published in International Journal of Radiation Biology, 2023
Jin Bai, Shuyang Wang, Fuqiang Xu, Miaoyin Dong, Junkai Wang, Xisi Sun, Guoqing Xiao
To determine fecal nitroreductase activities, fecal was collected at the beginning of treatment, at 16th day of treatment (tumor volumes of IR + IP group were significantly higher than PBS (p<.05)), at 30th day of treatment (the tumor volumes of LP, IP and LP + IP were significantly higher than PBS (p<.05)), at 40th day of treatment (the survival rate was 50% in tumor control group) and at 50th day of treatment (the end of experiment). The fecal samples were frozen immediately after collection and stored at −80 °C. Preweighted fecal were homogenized in PBS buffer and then centrifuged at 8000 r/min for 5 min. Its supernatant placed into tubes containing 100 μL 15 mmol/L p-nitrobenzoic acid solution, 500 μL 0.2 mol/L PBS. The incubations were performed at 37 °C for 30 min in the water bath. The reaction was stopped via adding 1 mL 20% trichloroacetic acid and read at 240 nm with microplate reader. The amount of decomposition of p-nitrobenzoic acid was calculated from the standard curve of p-aminobenzoic acid concentration, and the enzyme activity was calculated.
Design, synthesis, molecular modeling and biological evaluation of novel Benzoxazole-Benzamide conjugates via a 2-Thioacetamido linker as potential anti-proliferative agents, VEGFR-2 inhibitors and apoptotic inducers
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Ibrahim H. Eissa, Radwan El-Haggar, Mohammed A. Dahab, Marwa F. Ahmed, Hazem A. Mahdy, Reem I. Alsantali, Alaa Elwan, Nicolas Masurier, Samar S. Fatahala
Benzoxazole derivatives 1–15 were synthesised following the general methodologies outlined in Schemes 1 and 2. The key starting materials, 2-mercaptobenzoxazoles IIa-c were synthesised by refluxing the corresponding 2-aminophenol derivatives Ia-c, carbon disulphide, and potassium hydroxide in methanol, according to the reported procedure52. Then, compounds IIa-c were treated with alcoholic KOH to give the corresponding potassium salts, IIIa-c (Scheme 1). On the other hand, 4-aminobenzoic acid IV was reacted with chloroacetyl chloride in DMF to afford the chloroacetamide intermediate V. Then, treatment of compound V by thionyl chloride afforded 4-(2-chloroacetamido)benzoyl chloride VI53,54, which was then successively reacted with a set of commercially available amines namely, cyclohexylamine, aniline, 4-chloroaniline, 4-methoxyaniline in acetonitrile and triethylamine (TEA), to get the key intermediates VIIa-d. Finally, compounds VIIa-d were heated with the formerly prepared potassium salts IIIa-c in dry DMF to afford the final target compounds 1–12 (Scheme 1).
New benzoxazole derivatives as potential VEGFR-2 inhibitors and apoptosis inducers: design, synthesis, anti-proliferative evaluation, flowcytometric analysis, and in silico studies
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Hazem Elkady, Alaa Elwan, Hesham A. El-Mahdy, Ahmed S. Doghish, Ahmed Ismail, Mohammed S. Taghour, Eslam B. Elkaeed, Ibrahim H. Eissa, Mohammed A. Dahab, Hazem A. Mahdy, Mohamed M. Khalifa
The target benzoxazole derivatives 14a–o were synthesised following the general methodologies outlined in Schemes 1–3. The starting compounds, 2-mercapto-benzoxazoles 8a–c were synthesised by refluxing the appropriate 2-aminophenol derivatives 7a–c, carbon disulphide, and potassium hydroxide in methanol following the reported procedure33. Then, compounds 8a–c were treated with alcoholic KOH to afford the corresponding potassium salts, 9a–c (Scheme 1). On the other hand, 4-aminobenzoic acid 10 was reacted with chloroacetyl chloride in DMF to afford the chloroacetamide intermediate 11. Acylation of compound 11 was performed using thionyl chloride to yield 4–(2-chloroacetamido)benzoyl chloride 12 as described in the reported procedures14,34. Treating of 12 with commercially available amines namely, 2-methoxyaniline, 2,6-dimethoxyaniline, 2,6-dimethylaniline, 2,4-dichloroaniline, and 4-hydroxyaniline, in acetonitrile containing triethylamine (TEA), afforded the target key intermediates 13a–e (Scheme 2).