(+)-Biotin 4-amidobenzoic acid is a substrate of biotinidase, which cleaves biotin amide to give biotin in vivo. Biotin is an essential coenzyme for certain carboxylases and is used to modify histones and regulate gene transcription. Biotinidase has key roles in intestinal absorption of biotin, the transport of biotin in plasma, and in the regulation of histone biotinylation. (+)-Biotin 4-amidobenzoic acid is hydrolyzed by biotinidase to release 4-aminobenzoic acid (PABA), which can be quantified by either fluorescent or colorimetric methods. This approach is used in biotinidase activity assays in newborn screening protocols to evaluate biotinidase deficiency.
Urotensin II is a peptide vasoconstrictor and agonist of the urotensin (UT) receptor (Ki= 2.06 nM for the human recombinant receptor expressed in HEK293 cells).1It stimulates intracellular calcium mobilization in HEK293 cells expressing human and rat UT (EC50s = 0.47 and 0.78 nM, respectively) but decreases intracellular calcium concentration in goby (G. mirabilis) enterocytes when used at a concentration of 500 nM.2Urotensin II (20 mU/ml) stimulates active sodium and chloride absorption across isolated goby posterior intestine in 5% seawater-adapted solution.3In vivo, urotensin II (1.5-150 nmol/kg) decreases diastolic blood pressure and increases heart rate in anesthetized rats.4It also reduces the pressor responses to sympathetic nerve stimulation, norepinephrine , and vasopressin in pithed rats when administered at a dose of 150 nmol/kg. 1.Ames, R.S., Sarau, H.M., Chambers, J.K., et al.Human urotensin-II is a potent vasoconstrictor and agonist for the orphan receptor GPR14Nature401(6750)282-286(1999) 2.Loretz, C.A., and Assad, J.A.Urotensin II lowers cytoplasmic free calcium concentration in goby enterocytes: Measurements using quin2Gen. Comp. Endocrinol.64(3)355-361(1986) 3.Loretz, C.A., Freel, R.W., and Bern, H.A.Specificity of response of intestinal ion transport systems to a pair of natural peptide hormone analogs: Somatostatin and urotensin IIGen. Comp. Endocrinol.52(2)198-206(1983) 4.Gibson, A., Wallace, P., and Bern, H.A.Cardiovascular effects of urotensin II in anesthetized and pithed ratsGen. Comp. Endocrinol.64(3)435-439(1986)
Isotachysterol 3, an analog of 1,25-dihydroxy Vitamin D3, was found to enhance intestinal calcium transport and stimulate bone calcium mobilization in anephric rats[1].
Butyryl-L-carnitine is a butyrate ester of carnitine. It is an inhibitor of intestinaltransporters, blocking carnitine uptake by the carnitine transporter and glycine transport by the amino acid transporter in human retinal pigment epithelial (HRPE) cells (IC50s = 1.5 μM and 4.6 mM, respectively).
Guanylin (human) TFA is a 15-amino acid peptide that serves as an endogenous activator of intestinal guanylate cyclase. This compound is primarily located in the gastrointestinal tract, where it regulates electrolyte and water transport in the intestinal and renal epithelia through a mechanism dependent on cyclic GMP. [1][2]
C2 Adamantanyl globotriaosylceramide (AdaGb3) is a bioactive sphingolipid and water-soluble form of globotriaosylceramide that contains an adamantanyl group in place of the fatty acyl chain. It inhibits Vero toxin binding to globotriaosylceramide in an ELISA assay when used at a concentration of 10 μM. AdaGb3 decreases cell surface expression of P-glycoprotein (P-gp) and reduces efflux of rhodamine 123 in MDCK cells. It also increases apical-to-basal transport of vinblastine in human intestinal C2BBe1 cells.
Endogenous peptide activator of intestinal guanylyl cyclase; secreted mainly by the gastrointestinal mucosa. Regulates water and electrolyte transport in intestinal and renal epithelia.