Benzimidazole (BI) and their derivatives are interesting molecules in medicinal chemistry because several of these compounds have a diversity of biological activities and some of them are even used in clinical applications. In view of the importance of these compounds, synthetic chemists are still interested in finding new procedures for the synthesis of these classes of compounds. Astemizole (antihistaminic), Omeprazole (antiulcerative), and Rabendazole (fungicide) are important examples of compounds used in medicinal chemistry containing BI nuclei. It is interesting to observe that several of these compounds contain 2-aminobenzimidazole (2ABI) as the base nucleus. The structures of 2ABI derivatives are interesting because they have a planar delocalized structure with a cyclic guanidine group, which have three nitrogen atoms with free lone pairs and labile hydrogen atoms. The 10-π electron system of the aromatic BI ring conjugated with the nitrogen lone pair of the hexocyclic amino group, making these heterocycles to have an amphoteric character. Synthetic chemists have used 2ABI as a building block to produce BI derivatives as medicinally important molecules. In view of the importance of the BIs, and because no review was found in the literature about this topic, we reviewed and summarized the procedures related to the recent methodologies used in the N-substitution reactions of 2ABIs by using aliphatic and aromatic halogenides, dihalogenides, acid chlorides, alkylsulfonic chlorides, carboxylic acids, esters, ethyl chloroformates, anhydrides, SMe-isothioureas, alcohols, alkyl cyanates, thiocyanates, carbon disulfide and aldehydes or ketones to form Schiff bases. The use of diazotized 2ABI as intermediate to obtain 2-diazoBIs was included to produce N-substituted 2ABIs of pharmacological interest. Some commentaries about their biological activity were included.
Several pathological conditions have been associated with an oxidative stress state, due to several enzymatic systems such as peroxidation and chlorination of myeloperoxidase (MPO). Oxidative stress is defined as the loss of homeostasis by the increased amount of free radicals production and the amount of endogenous antioxidants, which, as consequence, generate systemic complications such as micro and macrovascular angiopathies. It has been shown that several exogenous compounds are able to counteract the noxious effects of free radicals, that's why the main aim of this study is to evaluate in vitro the antioxidant capacity of a family of 6 derivatives, using as a pattern drug 5‐aminosalycilic acid (5‐ASA).The antioxidant capacity of the proposed compounds, such as the witness drug 5‐ASA, where tested by the assay of the radical cation 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid (ABTS), the ferric reducing ability of plasma (FRAP) assay, and the discoloration of 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) assay.Inhibition of peroxidation of MPO was tested by the O‐dianisidine assay, using 4‐aminobenzoic hydrazide (4‐ABAH) as witness compound, and 5‐ASA as the pattern.Results so far show that the proposed compounds have antioxidant activity, so as they were able to inhibit peroxidation of MPO in a higher percentage than the witness drug and the pattern.
It is know that compounds with phenol and thiol moieties have antioxidant activity. Therefore, the aim of this study was to synthetized three compounds containing phenol and thiol groups ((cysteine‐phenol (1), benzothiazole‐phenol (2) and benzothiazole‐phenol (3)) to test then as antioxidant agents. The antioxidant activity evaluation was carried out by DPPH determination and by inactivation of •OH radical generated during the Fenton reaction. The results show that DPPH radical reduction is concetration dependent, the compounds (1) and (2) have higher DPPH radical reducing power (>90%) to 0.102 μM, in comparision with N‐acetylcysteine (NAC) which show 55%. The three compounds inhibit the formation of •OH radical during the Fenton reaction by reducing the signal strength between the adduct formed by •OH and N‐tert‐butyl‐á‐phenylnitrone. In conclussion these compounds have higher antioxidant activity than NAC
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.