Cyclo(his-pro)

Cyclo(his-pro) (Cyclo(histidyl-proline)) is an orally active cyclic dipeptide structurally related to tyreotropin-releasing hormone^[1]. Cyclo(his-pro) could inhibit NF-κB nuclear accumulation. Cyclo(his-pro) can cross the brain-blood-barrier and affect diverse inflammatory and stress responses^[2]. IC50 & Target: NF-κB^[1] In Vitro: cyclo(his-pro) (Cyclo(histidyl-proline); 50 μM; 1-48 hours) increases the nuclear level of Nrf2 and inhibits NF-κB nuclear translocation. Cyclo(His-Pro) alone has no effect on nuclear translocation of these transcription factors^[2].
cyclo(his-pro) (50 μM; prior to PQ exposure for 48 hours) abolishes protein nitration that followed paraquat (PQ) exposure and lessenes its functional consequences, as shown by decrease in cell apoptosis, detected by caspase 3 activity and by cytochrome c release^[2].
Cyclo(his-pro) inhibits NF-κB nuclear accumulation induced by paraquat in rat pheochromocytoma PC12 cells via the Nrf2/heme oxygenase-1 pathway^[2].
In Vivo: Cyclo(his-pro) (Cyclo(histidyl-proline); 1.8 mg/ear; topical application on the right ear; 30 min prior to TPA) reduces TPA-induced ear oedema confirming that it can exert anti-inflammatory effect^[2].
Cyclo(his-pro) exerts in vivo anti-inflammatory effects in the central nervous system by down-regulating hepatic and cerebral TNFα expression thereby counteracting LPS-induced gliosis. Moreover, by up-regulating Bip, Cyclo(his-pro) increases the ER stress sensitivity andtriggers the unfolded protein response to alleviate the ER stress^[3].