New dimeric, trimeric and tetrameric quaternary ammonium salts were accomplished by reaction of tertiary alkyldimethyl amines with appropriate bromomethylbenzene derivatives. A series of new cationic surfactants contain different alkyl chain lengths (C4–C18), aromatic spacers and different numbers of quaternary nitrogen atoms. The structure of the products was confirmed by spectral analysis (FT-IR, ¹H-NMR, ¹³C-NMR and 2D-NMR), mass spectroscopy (ESI-MS), elemental analysis, as well as PM5 semiempirical methods. Compound (21) was also analyzed using X-ray crystallography. Critical micelle concentration (CMC) of 1,4-bis-[N-(1-alkyl)-N,N-dimethylammoniummethyl]benzene dibromides (3–9) was determined to characterize the aggregation behavior. The antimicrobial properties of novel QACs (Quaternary Ammonium Salts) were examined to set their minimal inhibitory concentration (MIC) values against fungi Aspergillus niger, Candida albicans, Penicillium chrysogenum and bacteria Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa.

Dimeric alkylammonium salts – gemini surfactants – due to their unusual very low critical micelle concentration and minimal inhibitory concentration are subject to intensive research as surface active and antimicrobial compounds. Thanks to the presence of two positively charged nitrogen atoms and a large molecular surface, gemini surfactants are also very efficient corrosion inhibitors. To strengthen the electrostatic adsorption of ammonium cations on a metal surface, which is a key parameter in the inhibition of corrosion, heteroatoms (O, S, N, or P) and π-electron systems can be introduced into the gemini surfactant structure to increase chemical adsorption. In this study, we investigated the relationship between the alkyl chain length and critical micelle concentration for gemini surfactants containing an oxygen atom in the spacer, that is, bis( N -alkyl- N,N -dimethylethylammonium)ether dibromides, for potential use as corrosion inhibitors.

A novel method for the synthesis of bile acid derivatives has been developed using “click chemistry”. Intermolecular 1,3-dipolar cycloaddition of the propargyl ester of bile acids and azide groups of 1,3,5-tris(azidomethyl)benzene gave a new quasi-podands with 1,2,3-triazole rings. The structures of the products were confirmed by spectral (¹H-NMR, ¹³C-NMR, and FT-IR) analysis, mass spectrometry and PM5 semiempirical methods. Estimation of the pharmacotherapeutic potential has been accomplished for synthesized compounds on the basis of Prediction of Activity Spectra for Substances (PASS).

Steroids have been pivotal in medicine and biology, with research into their therapeutic potential accelerating over the past few decades. This review examines recent steroid discoveries from marine and terrestrial sources, highlighting both novel compounds and those with newly identified biological activities. The structural diversity of these steroids contributes to their wide range of biological activity, including anticancer, antimicrobial, antidiabetic, anti-inflammatory, and immunomodulatory properties. Particular emphasis is placed on steroids derived from marine invertebrates, fungi, and medicinal plants, which have shown promising therapeutic potential. Advances in analytical techniques such as NMR spectroscopy and mass spectrometry have facilitated the identification of these compounds. These findings emphasize the growing importance of steroids in addressing pressing global health issues, particularly antibiotic resistance and cancer, where new therapeutic strategies are urgently needed. Although many newly identified steroids exhibit potent bioactivity, challenges remain in translating these findings into clinical therapies. Ongoing exploration of natural sources, along with the application of modern synthetic and computational methods, will be crucial in unlocking the full therapeutic potential of steroid-based compounds.