Synthesis and Biological Evaluation of New Isatin‐Based QACs with High Antimicrobial Potency

Abstract

A simple and easy condensation reaction of aryl‐ or N‐substituted isatins with Girard's reagents P and T was found to be useful in obtaining of water‐soluble isatin‐based quaternary ammonium compounds (QACs) bearing pyridinium or trimethylammonium moiety with high yields. Their antimicrobial activity was evaluated. Selective activity against Gram‐positive bacteria (S. aureus 209p and B. cereus 8035) and yeast‐like fungus Candida albicans 855–653 was shown. The influence of the substituent's nature as in the aromatic fragment as at position 1 on the activity was established. The most active are the pyridinium salts containing sterically hindered phenolic fragment at the position 1 of the heterocycle. The structures of all novel compounds were fully characterized using IR and NMR spectroscopies as well as XRD analysis.

Quaternary Ammonium Compounds (QACs) and Ionic Liquids (ILs) as Biocides: From Simple Antiseptics to Tunable Antimicrobials

“…Bogdanov and colleagues explored the microbiological effect of isatin-based QACs (Figure 13) [62]. As seen from the figure, the structures of these ammonium 25 and pyridine 26-27 salts contain no long alkyl chains.…”

“…Rusew and colleagues presented a work, in which long lipophilic tails in QACs were replaced by more compact aryl-containing substituents (Figure 14) [63]. Bogdanov and colleagues explored the microbiological effect of isatin-based QACs (Figure 13) [62]. As seen from the figure, the structures of these ammonium 25 and pyridine 26-27 salts contain no long alkyl chains.…”

Synthesis of Isatin and its derivatives containing heterocyclic compounds

“…, antioxidant (23), anti-tubercular (24), antifungal (25), anticonvulsant (26), antidepressant (27), anticancer (28,29), antiplasmodial activity (30), anti-corrosive (31), antiepileptic (32), antidiabetic (7) and antiviral (33) antianxiety (34), and antiasthma (35). In 1965, an isatin-2,3-dionebased compound Metisazone was developed, it is an antiviral agent used against viral infections as a prophylactic agent (36). Food and Drug Administration, USA (FDA) approved an isatin derivative Sunitinib maleate to treat different malignancies such as advanced renal-cell carcinoma, pancreatic neuroendocrine tumors and gastrointestinal stromal tumors (37,38).…”

Ammonium‐Charged Sterically Hindered Phenols with Antioxidant and Selective Anti‐Gram‐Positive Bacterial Activity

“…In our opinion, the combination of a phenolic substituent, a hydrazone moiety and an ammonium center in one molecule will solve the problem of the solubility of the target compounds in water along with high antioxidant and antimicrobial activities. The development of this study is based on our ongoing work on the design, synthesis and evaluation of the biological activity of positively charged isatin‐3‐acylhydrazones, and spatially hindered phenols . Our previous results showed that compounds containing a bulky phenolic fragment showed the best activity against Staphylococcus aureus ( Figure ) …”