| Description | Isatin (also called tribulin or 2,3-dioxoindole) is an oxidized indole derivative. Indoles are compounds containing an indole moiety, which consists of pyrrole ring fused to benzene to form 2,3-benzopyrrole. More specifically, Isatin is an indoledione, meaning that is is the 2,3-diketo derivative of indole. Isatin exists as a bright orange/red powder and has been used in the production of dyes. In particular, the isatin core is responsible for the color of “Maya blue” and “Maya yellow” dyes. In humans and other mammals, isatin is a naturally occurring by-product of tryptophan catabolism. It is a microbial co-metabolite arising from the gut microbial metabolism of tryptophan to indole, followed by the oxidation of the indole (via indoxyl) by liver cytochrome P450 enzymes to produce various oxidation products including indoxyl, indoxyl sulfate and isatin (PMID: 19707325 ; PMID: 11076521 ). Isatin can be found in human urine and blood as well as brain, liver and kidney tissues. The isatin concentration in blood can exceed 1 μM. The highest concentrations of isatin in the brain are in hippocampus, cerebellum and striatum (1–1.3 μM), whereas in peripheral organs the highest concentrations are in seminal vesicles and vas deferens: 47.4–79 μM. In the heart the maximal basal concentration approaches to 3 μM (PMID: 19707325 ). Stress can cause a 2–3 fold increase of isatin content in the brain and heart. Isatin is an endogenous monoamine oxidase (A and B) inhibitor and benzodiazepine receptor binding inhibitory factor (PMID: 3392550 ). It has been shown to have significant anxiogenic activity (PMID: 22282556 ). Isatin is also known to inhibit the receptor-binding of atrial natriuretic peptides and ANP-stimulated guanylate cyclase (GC) (PMID: 10578664 ). Isatin is also a plant metabolite. Isatin’s name comes from the plant genus, Isatis, from which it was first isolated. Isatis is a genus of flowering plants in the family Brassicaceae, native to the Mediterranean region east to central Asia. Isatin has been employed as a precursor for the synthesis of a wide variety of biologically active compounds including antitumorals, antivirals, anti-HIVs, and antituberculars (PMID: 33296925 ). |
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