Benzothiazole: Pharmacological Actions and Applications in Drug Synthesis

Benzothiazole is a common skeletal structure in many compounds with therapeutic value. Benzothiazoles belong to heterocyclic systems, consisting of a benzene ring and a thiazole ring conjugated (Figure 1). Studies have shown that the nitrogen and sulfur atoms in the thiazole moiety are key elements for the diverse pharmacological activities of benzothiazoles. The benzothiazole skeleton can be substituted at multiple positions on the ring, allowing for the synthesis of novel derivatives with enhanced biological activity. The most common substitution site in the benzothiazole skeleton is at the 2-position, where various functional groups can be introduced, such as amines (2-aminobenzothiazole), thiols (2-mercaptobenzothiazole), or aryl groups (2-arylbenzothiazole), to produce molecules with potent biological activity.

Pharmacological Actions

Benzothiazoles possess a variety of pharmacological activities, including anticancer, anticonvulsant, antidiabetic, antioxidant, antiviral, anti-inflammatory, antituberculosis, antimalarial, anti-worm, analgesic, and antibacterial activities. They have been shown to be modulators of specific molecular targets. For example, benzothiazole compounds can inhibit acetylcholinesterase, L-type calcium channels, viral helicases, hepatitis C virus nonstructural protein 5A (NS5A), hepatitis C virus NS2B/NS3 proteases, and phosphatidylinositol 3-kinase/mammalian target of rapamycin. Furthermore, the therapeutic activity of benzothiazole drugs is recognized for the management of various diseases, such as central muscle relaxants, antidiabetic drugs, antiviral drugs, antiepileptic drugs, antimalarial drugs, focal cerebral ischemia, neurodegenerative diseases, and cancer.

Applications of Benzothiazole in Drug Synthesis

Several benzothiazole molecules have been used in clinical practice, such as riluzole, etorizol, flutezosin, zoprostal, and thiamine. Riluzole consists of two benzothiazole-containing molecules that exhibit neuroactive effects by interfering with glutamate receptor neurotransmission and electrophysiology. Riluzole, as a neuroprotective agent, has been approved for the treatment of amyotrophic lateral sclerosis (ALS). Ethoxzolamide is a sulfanilamide and a member of the benzothiazole class. It is used as a carbonic anhydrase inhibitor in the treatment of glaucoma and as a diuretic. Frentizole is a non-toxic, immunosuppressive, and antiviral drug with a benzothiazole ring, clinically used for rheumatoid arthritis and systemic lupus erythematosus. Zopolrestat is an aldose reductase inhibitor used to treat diabetic symmetrical polyneuropathy (DSPN). Thioflavin is a fluorescent benzothiazole dye commonly used as a marker for protein aggregates, applicable to the research and diagnosis of neurodegenerative diseases.

References:

[1] MARINA GJORGJIEVA. Benzothiazole-based Compounds in Antibacterial Drug Discovery.[J]. Current medicinal chemistry, 2018, 25 38: 5218-5236. DOI:10.2174/0929867324666171009103327.

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