Obestatin is a 23 amino acid peptide hormone with a conserved C-terminal glycine residue and amidation site that is formed by cleavage of the ghrelin and obestatin prepropeptide.1It binds to the orphan receptor GPR39 (Kd= 1 nM) and stimulates cAMP production in CHO and HEK293 cells overexpressing human GPR39. Obestatin inhibits contraction of isolated mouse jejunum muscle strips induced by ghrelin .In vivo, obestatin (12.5-1,000 nmol/kg) suppresses food intake in a time- and dose-dependent manner and reduces body weight gain and gastric emptying in mice. Obestatin (0.22 g per animal) also reduces food intake and glucose response without affecting plasma insulin responses in fasted high-fat diet fed mice.2 1.Zhang, J.V., Ren, P.C., Avsian-Kretchmer, O., et al.Obestatin, a peptide encoded by the ghrelin gene, opposes ghrelin's effects on food intakeScience310(5750)996-999(2005) 2.Subasinghage, A.P., Green, B.D., Flatt, P.R., et al.Metabolic and structural properties of human obestatin {1-23} and two fragment peptidesPeptides31(9)1697-1705(2010)
AAA is an antagonist of G protein-coupled receptor 75 (GPR75).1It increases basal GPR75 protein levels and inhibits 20-HETE-induced reductions in GPR75 protein levels in PC3 cells. AAA (5 and 10 μM) also reduces 20-HETE-induced phosphorylation of EGFR, NF-κB, and Akt in, and cell migration of, PC3 cells.In vivo, AAA (10 mg/kg per day) reduces systolic blood pressure, albuminuria, renal angiotensin II levels, and cardiac hypertrophy in a Cyp1a1-Ren-2 transgenic rat model of malignant hypertension when administered prior to induction or after establishment of hypertension.2 1.Cárdenas, S., Colombero, C., Panelo, L., et al.GPR75 receptor mediates 20-HETE-signaling and metastatic features of androgen-insensitive prostate cancer cellsBiochim. Biophys. Acta Mol. Cell Biol. Lipids1865(2)158573(2020) 2.Sedláková, L., Kikerlová, S., Husková, Z., et al.20-Hydroxyeicosatetraenoic acid antagonist attenuates the development of malignant hypertension and reverses it once established: a study in Cyp1a1-Ren-2 transgenic ratsBiosci. Rep.38(5)BSR20171496(2018)
3-Oxobetulin acetate is a derivative of the cholesterol biosynthesis inhibitor betulin. It inhibits the growth of P388 murine lymphocytic leukemia cells (EC50 = 0.12 µg ml), as well as human MCF-7 breast, SF-268 CNS, H460 lung, and KM20L2 colon cancer cells (GI50s = 8, 10.6, 5.2, and 12.7 µg ml, respectively), but not BxPC-3 pancreas or DU145 prostate cancer cells (GI50s = >10 µg ml for both). 3-Oxobetulin acetate inhibits replication of X4 tropic recombinant HIV (NL4.3-Ren) in MT-2 lymphoblastoid cells (IC50 = 13.4 µM). It is also active against L. donovani amastigotes when used at a concentration of 50 µM.