Embryos of the shrimp Palaemon macrodactylus are remarkably resistant to infection by the fungus Lagenidium callinectes, a recognized pathogen of many crustaceans An Alteromonas sp bacterial strain consistently isolated from the surface of the embryos, produces 2,3-indolinedione (isatin), a compound that inhibits the pathogenic fungus If exposed to the fungus, bacteria-free embryos quickly die, whereas similar embryos reinoculated with the bacteria or treated only with 2,3-indolinedione live well The commensal Alteromonas sp bacteria protect shrimp embryos from fungal infection by producing and liberating the antifungal metabolite 2,3-indolinedione

https://science.sciencemag.org/content/sci/246/4926/116.full.pdf

Symbiotic marine bacteria chemically defend crustacean embryos from a pathogenic fungus.

Isatin is an endogenous compound identified in humans that possesses a wide range of biological activities. Isatin has anxiogenic, sedative, anticonvulsant activities and acts as a potent antagonist on atrial natriuretic peptide receptors in vitro. A series of p-substituted isatin semicarbazones have shown anticonvulsant activity in MES, scPTZ and scSTY tests. Various isatin-N-Mannich bases of isatin-3-thiosemicarbazones have shown antiviral and tuberculostatic activity. Methisazone is an effective compound against variola and vaccinia viruses. The N-dimethyl and morpholino derivative of 5-methyl isatin and trimethoprim exhibited an EC50 of more than 4.3 and 17.7 mg mL(-1), respectively. Isatin (3-o-nitrophenyl) hydrazone has shown activity against Walker carcinoma-256. Various substituted indolinones showed antitubercular activity against M. tuberculosis H37Rv with MIC ranging from 10-20 microg mL(-1). Isatin derivatives of Mannich bases had fibrinolytic, muscle relaxant, antiallergic, immunosuppressant, and antithrombotic activity. Isatin showed cardioinhibitory effect on frog heart, and hypotensive, respiratory depression and antidiuretic effects.

/pdf/biological-activities-of-isatin-and-its-derivatives-2n13cxnlnf.pdf

Biological activities of isatin and its derivatives.

Synthesis and antibacterial screening of hydrazones, Schiff and Mannich bases of isatin derivatives.

The development of monoamine oxidase (MAO) inhibitors has followed a winding path. At the origin was the finding of E. A. Zeller that iproniazid, a hydrazine derivative designed to improve the tuberculostatic action of isoniazid, caused potent inhibition of MAO in vitro and in vivo. The inhibitor also exerted in vivo activity in the brain, subsequent pharmacological research indicating that this inhibition led to changes of cerebral functions [1]. Although the drug had no overt behavioral effects in animals when given alone, it modified the action of reserpine, one of the first modern psychotropic drugs. Thus, administration of iproniazid prior to reserpine unexpectedly antagonized the decreases in locomotor activity and in 5-hydroxy-tryptamine (5 HT) levels induced by reserpine in the brain, the animals sometimes even showing locomotor stimulation [1]. Since one serious side effect of reserpine in man was known to be mental depression, the antagonism of reserpine by iproniazid hinted at the possibility that this drug might be of use in the treatment of mood disorders. However, the actual breakthrough for the development of iproniazid as an antidepressant came from clinical observations. Various investigators had reported psychostimulant side effects of the MAO inhibitor in patients with tuberculosis and other chronic diseases.

The new generation of monoamine oxidase inhibitors.

Is There a Future for Neuropeptide Receptor Ligands in the Treatment of Anxiety Disorders

Purified tribulin, an endogenous monoamine oxidase (MAO) inhibitor, has been identified by direct probe insertion mass spectrometry as the indole-2,3-dione, isatin. A gas chromatographic-mass spectrometric assay for isatin has been developed and used to measure its relatively high concentrations in unpurified human urine, and in rat heart and brain. Isatin is a known compound with a broad range of biological activity; this is the first report of its presence in the animal body. Isatin is a potent inhibitor of MAO, particularly of MAO B (IC50, 3 microM), and also binds to central benzodiazepine receptors (IC50 against clonazepam, 123 microM).

Isatin: Identity with the Purified Endogenous Monoamine Oxidase Inhibitor Tribulin

Isatin, regional distribution in rat brain and tissues.

Isatin (indole-2,3-dione) in urine and tissues. Detection and determination by gas chromatography-mass spectrometry.

Germ-free rats excreted considerably smaller amounts of the monoamine oxidase-inhibiting compound isatin than the substantially larger output by conventional animals of the same strain, although concentrations in brain and other tissues were similar in the two groups. Thus, isatin is likely to be elaborated both endogenously in rat tissues and "exogenously" by flora inhabiting the lumen of the alimentary tract.

P.J. Watkins

Papers

Isatin: Identity with the Purified Endogenous Monoamine Oxidase Inhibitor Tribulin

Isatin, regional distribution in rat brain and tissues.

Isatin (indole-2,3-dione) in urine and tissues. Detection and determination by gas chromatography-mass spectrometry.

Urinary but Not Brain Isatin Levels Are Reduced in Germ-Free Rats

Isatin and tribulin concentrations are increased in rabbit brain but not liver following pentylenetetrazole administration.